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Fan XQ, Trunschke J, Ren ZX, Wang H, Pyke GH, van der Kooi CJ, Lunau K. Why are the inner and outer sides of many flower petals differently coloured? PLANT BIOLOGY (STUTTGART, GERMANY) 2024; 26:665-674. [PMID: 38935692 DOI: 10.1111/plb.13680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 05/30/2024] [Indexed: 06/29/2024]
Abstract
The flower perianth has various, non-mutually exclusive functions, such as visual signalling to pollinators and protecting the reproductive organs from the elements and from florivores, but how different perianth structures and their different sides play a role in these functions is unclear. Intriguingly, in many species there is a clear colour difference between the different sides of the perianth, with colour patterns or pigmentation present on only one side. Any adaptive benefit from such colour asymmetry is unclear, as is how the asymmetry evolved. In this viewpoint paper, we address the phenomenon of flowers with differently coloured inner and outer perianth sides, focusing on petals of erect flowers. Guided by existing literature and our own observations, we delineate three non-mutually exclusive evolutionary hypotheses that may explain the factors underlying differently coloured perianth sides. The pollen-protection hypothesis predicts that the outer side of petals contributes to protect pollen against UV radiation, especially during the bud stage. The herbivore-avoidance hypothesis predicts that the outer side of petals reduces the flower's visibility to herbivores. The signalling-to-pollinators hypothesis predicts that flower colours evolve to increase conspicuousness to pollinators. The pollen-protection hypothesis, the herbivore-avoidance hypothesis, and the signalling-to-pollinators hypothesis generate largely but not entirely overlapping predictions about the colour of the inner and outer side of the petals. Field and laboratory research is necessary to disentangle the main drivers and adaptive significance of inner-outer petal side colour asymmetry.
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Affiliation(s)
- X-Q Fan
- CAS Key Laboratory of Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- College of Life Sciences, Shaanxi Normal University, Xi'an, China
| | - J Trunschke
- CAS Key Laboratory of Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Z-X Ren
- CAS Key Laboratory of Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - H Wang
- CAS Key Laboratory of Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - G H Pyke
- CAS Key Laboratory of Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- School of Natural Sciences, Macquarie University, Ryde, NSW, Australia
| | - C J van der Kooi
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | - K Lunau
- CAS Key Laboratory of Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- Faculty of Mathematics and Natural Sciences, Institute of Sensory Ecology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
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2
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Lunau K, Dyer AG. The modelling of flower colour: spectral purity or colour contrast as biologically relevant descriptors of flower colour signals for bees depending upon the perceptual task. PLANT BIOLOGY (STUTTGART, GERMANY) 2024. [PMID: 38958933 DOI: 10.1111/plb.13682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Accepted: 05/07/2024] [Indexed: 07/04/2024]
Abstract
Flower colour is an important mediator of plant-pollinator interactions. While the reflectance of light from the flower surface and background are governed by physical properties, the perceptual interpretation of such information is generated by complex multilayered visual processing. Should quantitative modelling of flower signals strive for repeatable consistency enabled by parameter simplification, or should modelling reflect the dynamic way in which bees are known to process signals? We discuss why colour is an interpretation of spectral information by the brain of an animal. Different species, or individuals within a species, may respond differently to colour signals depending on sensory apparatus and/or individual experience. Humans and bees have different spectral ranges, but colour theory is strongly rooted in human colour perception and many principles of colour vision appear to be common. We discuss bee colour perception based on physiological, neuroanatomical and behavioural evidence to provide a pathway for modelling flower colours. We examine whether flower petals and floral guides as viewed against spectrally different backgrounds should be considered as a simple colour contrast problem or require a more dynamic consideration of how bees make perceptual decisions. We discuss that plants such as deceptive orchids may present signals to exploit bee perception, whilst many plants do provide honest signalling where perceived saturation indicates the probability of collecting nutritional rewards towards the centre of a flower that then facilitates effective pollination.
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Affiliation(s)
- K Lunau
- Faculty of Mathematics and Natural Sciences, Institute of Sensory Ecology, Heinrich-Heine University, Düsseldorf, Germany
| | - A G Dyer
- Department of Physiology, Monash University, Clayton, Australia
- Institut für Entwicklungsbiologie, und Neurobiologie, Johannes Gutenberg Universität, Mainz, Germany
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3
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Macedo KM, Tunes P, de Almeida Gonçalves L, Canaveze Y, Guimarães E, Machado SR. Osmophores and petal surface traits in Bignonieae species. THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 2023; 110:44. [PMID: 37682350 DOI: 10.1007/s00114-023-01873-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 08/25/2023] [Accepted: 08/31/2023] [Indexed: 09/09/2023]
Abstract
This study characterizes the osmophores and corolla traits in 18 species of Bignonieae Dumort., a Bignoniaceae tribe occurring in the Cerrado, a neotropical savanna in Brazil. To detect osmophore distribution, whole, newly opened flowers were immersed in Neutral Red Solution. Samples from the corolla tube and lobes were also fixed and analyzed micromorphologically, anatomically, and histochemically. The osmophores showed six markedly different distribution patterns that were not clearly associated with histological features. In most species, osmophores comprised papillose secretory epidermises and a few layers of subepidermal parenchyma. Starch grains, lipid droplets, and terpenes were detected in osmophores. An ornamented cuticle, cuticular folds, glandular and non-glandular trichomes, raised stomata and epicuticular wax granules are common traits in the species studied and may be useful in determining the taxonomy of the group. We found that 94% of the species visited by bees had papillose epidermises while the single hummingbird-pollinated species presented a flattened epidermis. Variations in osmophore pattern among species visited by bees, including variations within the same plant genus, are novel finding. Additionally, the Bignonieae species visited by bees presented a textured corolla surface, which has been reported as facilitating bee attachment and movement towards the floral resource. Future studies with a greater number of Bignonieae species and more detailed pollinator behavioral assays may help in the interpretation of the variations in corolla traits and functional relationships between flowers and pollinators.
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Affiliation(s)
- Karise Mamede Macedo
- Programa de Pós-graduação em Biologia Vegetal - Interunidades, Universidade Estadual Paulista "Júlio de Mesquita Filho" (UNESP), Botucatu/Rio Claro, SP, Brazil
| | - Priscila Tunes
- Instituto de Biociências, Departamento de Biodiversidade E Bioestatística, Universidade Estadual Paulista "Júlio de Mesquita Filho" (UNESP), Botucatu, SP, Brazil
| | - Letícia de Almeida Gonçalves
- Instituto de Ciências Biológicas, Departamento de Botânica, Universidade Federal de Goiás (UFG), Goiânia, GO, Brazil
| | - Yve Canaveze
- Instituto de Biologia, Departamento de Botânica, Universidade Federal Do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ, Brazil
| | - Elza Guimarães
- Instituto de Biociências, Departamento de Biodiversidade E Bioestatística, Universidade Estadual Paulista "Júlio de Mesquita Filho" (UNESP), Botucatu, SP, Brazil
| | - Silvia Rodrigues Machado
- Instituto de Biociências, Departamento de Biodiversidade E Bioestatística, Universidade Estadual Paulista "Júlio de Mesquita Filho" (UNESP), Botucatu, SP, Brazil.
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4
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Deng X, Hu C, Xie C, Lu A, Luo Y, Peng T, Huang W. Metabolomic and Transcriptomic Analysis Reveal the Role of Metabolites and Genes in Modulating Flower Color of Paphiopedilum micranthum. PLANTS (BASEL, SWITZERLAND) 2023; 12:2058. [PMID: 37653975 PMCID: PMC10220555 DOI: 10.3390/plants12102058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 05/16/2023] [Accepted: 05/19/2023] [Indexed: 09/02/2023]
Abstract
Food-deceptive flowers primarily use visual signals (such as color) to mimic model plants and deceive insects into achieving pollination. Paphiopedilum micranthum is a food-deceptive orchid that has a pink labellum and two purple petals with a yellow base and has been proven to be pollinated by bumblebees. However, the chemical and molecular bases of the floral color are not well understood. We conducted targeted metabolite profiling and transcriptomic analysis to determine the color signal and its genetic basis in P. micranthum. We found that both anthocyanins and carotenoids contribute significantly to the formation of floral color that determines the color signal. Higher concentrations of anthocyanins (cyanidin and peonidin) and carotenoids (primarily lutein and zeaxanthin) were detected in the petal compared to the labellum. The upregulation of structural genes of CHS, F3'H, DFR and ANS on the anthocyanin biosynthesis pathway in petals was identified, as well as three genes of LCYE, BCH, and CCD4 on the carotenoid biosynthesis pathway. Furthermore, we discovered that three R2R3-MYBs and one bHLH transcription factors were co-expressed with the expression of different genes. These genes and transcription factors may be responsible for the spatial color difference of P. micranthum. Our study emphasizes that the color of this food-deceptive orchids is achieved through specific genes and transcription factors associated with the pigment biosynthesis pathway.
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Affiliation(s)
- Xinyan Deng
- School of Life Sciences, Guizhou Normal University, Guiyang 550025, China;
- Eastern China Conservation Centre for Wild Endangered Plant Resources, Shanghai Chenshan Botanical Garden, Shanghai 201602, China; (C.H.); (C.X.); (A.L.)
| | - Chao Hu
- Eastern China Conservation Centre for Wild Endangered Plant Resources, Shanghai Chenshan Botanical Garden, Shanghai 201602, China; (C.H.); (C.X.); (A.L.)
| | - Chengzhi Xie
- Eastern China Conservation Centre for Wild Endangered Plant Resources, Shanghai Chenshan Botanical Garden, Shanghai 201602, China; (C.H.); (C.X.); (A.L.)
- College of Forestry, Hainan University, Haikou 570228, China
| | - Aixian Lu
- Eastern China Conservation Centre for Wild Endangered Plant Resources, Shanghai Chenshan Botanical Garden, Shanghai 201602, China; (C.H.); (C.X.); (A.L.)
| | - Yibo Luo
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100000, China
- China National Botanical Garden, Beijing 100000, China
| | - Tao Peng
- School of Life Sciences, Guizhou Normal University, Guiyang 550025, China;
| | - Weichang Huang
- Eastern China Conservation Centre for Wild Endangered Plant Resources, Shanghai Chenshan Botanical Garden, Shanghai 201602, China; (C.H.); (C.X.); (A.L.)
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5
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Zhou Y, Ye Y, Zhu G, Xu Y, Tan J, Liu J. Diversity, classification, and EST-SSR-based association analysis of caladium ornamental traits. PHYSIOLOGIA PLANTARUM 2023; 175:e13841. [PMID: 36513960 DOI: 10.1111/ppl.13841] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/28/2022] [Accepted: 12/05/2022] [Indexed: 06/17/2023]
Abstract
Caladium (Caladium × Hortulanum Birdsey) is a popular ornamental plant with a wide range of vibrant leaf color among Araceae. Even after years of breeding, creating new caladium leaf color variations is extremely difficult. Molecular marker-assisted selection is an effective approach for accelerating breeding, but few studies on the molecular markers associated with caladium traits have been performed. In the current study, 144 caladium accessions were used to examine 12 phenotypic characteristics. The coefficient of variation for four numerical characters ranged from 23.94% to 43.22%, and the Shannon-Wiener indexes for eight descriptive characters ranged from 0.13 to 1.52. Based on L*, a*, b*, C, h° values determined by a colorimeter and hierarchical cluster analysis, the leaf color can be divided into four groups: pale green, green, light pink, and red. Furthermore, 7708 new SSR loci were identified by transcriptome sequencing, and 26 SSR markers with high polymorphism and reproducibility were screened. Genetic structure, NJ clustering, and PCoA analysis revealed that 144 accessions could be divided into three clusters, with genetic structure being closely related to germplasm origin. An association analysis revealed that the SSR markers 2, 1, 1, 1, 1, and 1 were mainly associated with petiole color, main vein color, blade upperside glossiness, and C, b*, and L* of leaf color (p < 0.01). These findings will serve as a valuable reference for evaluating germplasm resources and caladium molecular marker-assisted breeding.
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Affiliation(s)
- Yiwei Zhou
- Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangdong Key Lab of Ornamental Plant Germplasm Innovation and Utilization, Guangzhou, China
| | - Yuanjun Ye
- Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangdong Key Lab of Ornamental Plant Germplasm Innovation and Utilization, Guangzhou, China
| | - Genfa Zhu
- Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangdong Key Lab of Ornamental Plant Germplasm Innovation and Utilization, Guangzhou, China
| | - Yechun Xu
- Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangdong Key Lab of Ornamental Plant Germplasm Innovation and Utilization, Guangzhou, China
| | - Jianjun Tan
- Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangdong Key Lab of Ornamental Plant Germplasm Innovation and Utilization, Guangzhou, China
| | - Jinmei Liu
- Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangdong Key Lab of Ornamental Plant Germplasm Innovation and Utilization, Guangzhou, China
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Yilmaz A, Hempel de Ibarra N, Kelber A. High diversity of arthropod colour vision: from genes to ecology. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210273. [PMID: 36058249 PMCID: PMC9441235 DOI: 10.1098/rstb.2021.0273] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Colour vision allows animals to use the information contained in the spectrum of light to control important behavioural decisions such as selection of habitats, food or mates. Among arthropods, the largest animal phylum, we find completely colour-blind species as well as species with up to 40 different opsin genes or more than 10 spectral types of photoreceptors, we find a large diversity of optical methods shaping spectral sensitivity, we find eyes with different colour vision systems looking into the dorsal and ventral hemisphere, and species in which males and females see the world in different colours. The behavioural use of colour vision shows an equally astonishing diversity. Only the neural mechanisms underlying this sensory ability seems surprisingly conserved—not only within the phylum, but even between arthropods and the other well-studied phylum, chordates. The papers in this special issue allow a glimpse into the colourful world of arthropod colour vision, and besides giving an overview this introduction highlights how much more research is needed to fill in the many missing pieces of this large puzzle. This article is part of the theme issue ‘Understanding colour vision: molecular, physiological, neuronal and behavioural studies in arthropods’.
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Affiliation(s)
- Ayse Yilmaz
- Department of Biology - Functional Zoology, Lund University, Lund 22362, Sweden
| | | | - Almut Kelber
- Department of Biology - Functional Zoology, Lund University, Lund 22362, Sweden
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7
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Hempel de Ibarra N, Holtze S, Bäucker C, Sprau P, Vorobyev M. The role of colour patterns for the recognition of flowers by bees. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210284. [PMID: 36058248 PMCID: PMC9441241 DOI: 10.1098/rstb.2021.0284] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Bees discriminate between many different colours of flower petals, but it is not well understood how they perceive and learn patterns frequently found in flowers with colourful structures. We used multi-spectral imaging to explore chromatic cues in concentric flower patterns as they are seen through the low-resolution eyes of the honeybee. We find a diversity of colour combinations, which suggests that plants might exploit the sensory capabilities of pollinators, like bees, that learn colours easily. A consistent feature is that the surround of the pattern has a stronger chromatic contrast to the foliage background than the centre. This can potentially facilitate the fast identification of floral objects within colourful scenes when a foraging bee moves through a flower patch. In behavioural experiments we trained and tested bees with three types of concentric patterns. They recognized and discriminated patterns accurately in most tests, relying flexibly on both chromatic and spatial cues. Only rarely, depending on the training stimulus, chromatic cues determined their choices whilst pattern cues were ignored. The variability of floral designs and the bees' flexibility in recalling colour and spatial information suggest a role for colour vision in pattern processing. Implications for the signalling strategies of flowers are discussed. This article is part of the theme issue ‘Understanding colour vision: molecular, physiological, neuronal and behavioural studies in arthropods’.
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Affiliation(s)
- Natalie Hempel de Ibarra
- Centre for Research in Animal Behaviour, Department of Psychology, University of Exeter, Exeter, UK.,Neurobiology, Institute of Biology, Freie Universität Berlin, Berlin, Germany
| | - Susanne Holtze
- Neurobiology, Institute of Biology, Freie Universität Berlin, Berlin, Germany
| | - Cornelia Bäucker
- Neurobiology, Institute of Biology, Freie Universität Berlin, Berlin, Germany
| | - Philipp Sprau
- Neurobiology, Institute of Biology, Freie Universität Berlin, Berlin, Germany
| | - Misha Vorobyev
- Department of Optometry and Vision Science, University of Auckland, Auckland, New Zealand
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8
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van der Kooi CJ, Spaethe J. Caution with colour calculations: spectral purity is a poor descriptor of flower colour visibility. ANNALS OF BOTANY 2022; 130:1-9. [PMID: 35726715 PMCID: PMC9295922 DOI: 10.1093/aob/mcac069] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 05/26/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND The colours of flowers are of key interest to plant and pollination biologists. An increasing number of studies have investigated the importance of saturation of flower colours (often called 'spectral purity' or 'chroma') for visibility to pollinators, but the conceptual, physiological and behavioural foundations for these metrics as well as the calculations used rest on slender foundations. METHODS We discuss the caveats of colour attributes that are derived from human perception, and in particular spectral purity and chroma, as variables in flower colour analysis. We re-analysed seven published datasets encompassing 774 measured reflectance spectra to test for correlations between colour contrast, spectral purity and chroma. MAIN FINDINGS AND CONCLUSIONS We identify several concerns with common calculation procedures in animal colour spaces. Studies on animal colour vision provide no ground to assume that any pollinator perceives (or responds to) saturation, chroma or spectral purity in the way humans do. A re-analysis of published datasets revealed that values for colour contrast between flowers and their background are highly correlated with measures for spectral purity and chroma, which invalidates treating these factors as independent variables as is currently commonplace. Strikingly, spectral purity and chroma - both of which are metrics for saturation and are often used synonymously - are not correlated at all. We conclude that alternative, behaviourally validated metrics for the visibility of flowers to pollinators, such as colour contrast and achromatic contrast, are better in understanding the role of flower colour in plant-pollinator signalling.
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Affiliation(s)
| | - Johannes Spaethe
- Department of Behavioral Physiology and Sociobiology, University of Würzburg, Germany
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van der Kooi CJ, Kelber A. Achromatic Cues Are Important for Flower Visibility to Hawkmoths and Other Insects. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.819436] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Studies on animal colour vision typically focus on the chromatic aspect of colour, which is related to the spectral distribution, and disregard the achromatic aspect, which is related to the intensity (“brightness”) of a stimulus. Although the chromatic component of vision is often most reliable for object recognition because it is fairly context independent, the achromatic component may provide a reliable signal under specific conditions, for example at night when light intensity is low. Here we make a case for the importance of achromatic cues in plant-pollinator signalling, based on experimental data on naïve Deilephila elpenor and Macroglossum stellatarum hawkmoths, optical modelling and synthesising published experiments on bees, flies, butterflies and moths. Our experiments show that in ecologically relevant light levels hawkmoths express a strong preference for brighter stimuli. Published experiments suggest that for flower-visiting bees, butterflies, moths and flies, achromatic cues may be more important for object detection than often considered. Our optical modelling enabled disentangling the contribution of pigments and scattering structures to the flower’s achromatic contrast, and illustrates how flower anatomy and background are important mediating factors. We discuss our findings in the context of the often-assumed dichotomy between detection and discrimination, chromatic versus achromatic vision, and the evolution of floral visual signals.
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10
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Zhou Y, Yin M, Abbas F, Sun Y, Gao T, Yan F, Li X, Yu Y, Yue Y, Yu R, Fan Y. Classification and Association Analysis of Gerbera ( Gerbera hybrida) Flower Color Traits. FRONTIERS IN PLANT SCIENCE 2022; 12:779288. [PMID: 35145530 PMCID: PMC8824200 DOI: 10.3389/fpls.2021.779288] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 12/31/2021] [Indexed: 05/17/2023]
Abstract
Floral color plays a crucial role in plant life such as plant-pollinator interactions and modifying the abiotic environment of reproductive structures. In the current study, 123 gerbera accessions were divided into six color groups (white, yellow, orange, pink, red, and purple), based on Royal Horticultural Society Color Chart calibration and colorimeter measurement. Partial least squares discriminant analysis showed that the white group was mainly affected by L* value, a* value, C value, and total anthocyanin contents, while the yellow group was positively correlated with L* value, b* value, and total anthocyanin contents. Similarly, the orange group was mainly affected by b* value and total carotenoid contents, whereas the pink group was positively correlated with L* and h values. Furthermore, the red group was affected by L* value, a* value, C value, and total anthocyanin contents, whilst the purple group was mainly distributed by L* value, a* value, b* value, and total anthocyanin contents. Based on 'Jin Xiang' transcriptome data, 14,106 expressed sequence tag (EST)-SSR markers were identified and 48 pairs of primers (19 newly developed primers) were screened. Population genetic structure, neighbor-joining clustering, and principal coordinate analysis showed that 123 gerbera accessions could be divided into two groups. EST-SSR-based association analysis showed that 1, 1, 2, 1, 1, 2, and 1 significant loci were related to L*, a*, b*, C, and h, total carotenoid, and total anthocyanin contents, respectively. These results provide an important reference for flower color classification and genetic improvement of gerbera.
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Affiliation(s)
- Yiwei Zhou
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Mao Yin
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Farhat Abbas
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Yue Sun
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Ting Gao
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Fulong Yan
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Xinyue Li
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Yunyi Yu
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
| | - Yuechong Yue
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, South China Agricultural University, Guangzhou, China
| | - Rangcai Yu
- College of Life Sciences, South China Agricultural University, Guangzhou, China
| | - Yanping Fan
- The Research Center for Ornamental Plants, College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, South China Agricultural University, Guangzhou, China
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11
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Wang LY, Stuart-Fox D, Walker G, Roberts NW, Franklin AM. Insect visual sensitivity to long wavelengths enhances colour contrast of insects against vegetation. Sci Rep 2022; 12:982. [PMID: 35046431 PMCID: PMC8770459 DOI: 10.1038/s41598-021-04702-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Accepted: 12/24/2021] [Indexed: 11/23/2022] Open
Abstract
The sensitivity of animal photoreceptors to different wavelengths of light strongly influence the perceived visual contrast of objects in the environment. Outside of the human visual wavelength range, ultraviolet sensitivity in many species provides important and behaviourally relevant visual contrast between objects. However, at the opposite end of the spectrum, the potential advantage of red sensitivity remains unclear. We investigated the potential benefit of long wavelength sensitivity by modelling the visual contrast of a wide range of jewel beetle colours against flowers and leaves of their host plants to hypothetical insect visual systems. We find that the presence of a long wavelength sensitive photoreceptor increases estimated colour contrast, particularly of beetles against leaves. Moreover, under our model parameters, a trichromatic visual system with ultraviolet (λmax = 355 nm), short (λmax = 445 nm) and long (λmax = 600 nm) wavelength photoreceptors performed as well as a tetrachromatic visual system, which had an additional medium wavelength photoreceptor (λmax = 530 nm). When we varied λmax for the long wavelength sensitive receptor in a tetrachromatic system, contrast values between beetles, flowers and leaves were all enhanced with increasing λmax from 580 nm to at least 640 nm. These results suggest a potential advantage of red sensitivity in visual discrimination of insect colours against vegetation and highlight the potential adaptive value of long wavelength sensitivity in insects.
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Affiliation(s)
- Lu-Yi Wang
- School of Biosciences, The University of Melbourne, Parkville, VIC, 3010, Australia.
| | - Devi Stuart-Fox
- School of Biosciences, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Geoff Walker
- School of Biosciences, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Nicholas W Roberts
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK
| | - Amanda M Franklin
- School of Biosciences, The University of Melbourne, Parkville, VIC, 3010, Australia
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12
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van der Kooi CJ. How Much Pigment Should Flowers Have? Flowers With Moderate Pigmentation Have Highest Color Contrast. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.731626] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Floral pigments are a core component of flower colors, but how much pigment a flower should have to yield a strong visual signal to pollinators is unknown. Using an optical model and taking white, blue, yellow and red flowers as case studies, I investigate how the amount of pigment determines a flower’s color contrast. Modeled reflectance spectra are interpreted using established insect color vision models. Contrast as a function of the amount of pigment shows a pattern of diminishing return. Low pigment amounts yield pale colors, intermediate amounts yield high contrast, and extreme amounts of pigment do not further increase, and sometimes even decrease, a flower’s color contrast. An intermediate amount of floral pigment thus yields the highest visibility, a finding that is corroborated by previous behavioral experiments on bees. The implications for studies on plant-pollinator signaling, intraspecific flower color variation and the costs of flower color are discussed.
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13
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Trunschke J, Lunau K, Pyke GH, Ren ZX, Wang H. Flower Color Evolution and the Evidence of Pollinator-Mediated Selection. FRONTIERS IN PLANT SCIENCE 2021; 12:617851. [PMID: 34381464 PMCID: PMC8350172 DOI: 10.3389/fpls.2021.617851] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 05/14/2021] [Indexed: 06/01/2023]
Abstract
The evolution of floral traits in animal-pollinated plants involves the interaction between flowers as signal senders and pollinators as signal receivers. Flower colors are very diverse, effect pollinator attraction and flower foraging behavior, and are hypothesized to be shaped through pollinator-mediated selection. However, most of our current understanding of flower color evolution arises from variation between discrete color morphs and completed color shifts accompanying pollinator shifts, while evidence for pollinator-mediated selection on continuous variation in flower colors within populations is still scarce. In this review, we summarize experiments quantifying selection on continuous flower color variation in natural plant populations in the context of pollinator interactions. We found that evidence for significant pollinator-mediated selection is surprisingly limited among existing studies. We propose several possible explanations related to the complexity in the interaction between the colors of flowers and the sensory and cognitive abilities of pollinators as well as pollinator behavioral responses, on the one hand, and the distribution of variation in color phenotypes and fitness, on the other hand. We emphasize currently persisting weaknesses in experimental procedures, and provide some suggestions for how to improve methodology. In conclusion, we encourage future research to bring together plant and animal scientists to jointly forward our understanding of the mechanisms and circumstances of pollinator-mediated selection on flower color.
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Affiliation(s)
- Judith Trunschke
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Klaus Lunau
- Institute of Sensory Ecology, Heinrich-Heine-University, Düsseldorf, Germany
| | - Graham H. Pyke
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
- Department of Biological Sciences, Macquarie University, Ryde, NSW, Australia
| | - Zong-Xin Ren
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Hong Wang
- CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
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14
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Schrieber K, Paul SC, Höche LV, Salas AC, Didszun R, Mößnang J, Müller C, Erfmeier A, Eilers EJ. Inbreeding in a dioecious plant has sex- and population origin-specific effects on its interactions with pollinators. eLife 2021; 10:65610. [PMID: 33988502 PMCID: PMC8159375 DOI: 10.7554/elife.65610] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 05/09/2021] [Indexed: 12/19/2022] Open
Abstract
We study the effects of inbreeding in a dioecious plant on its interaction with pollinating insects and test whether the magnitude of such effects is shaped by plant individual sex and the evolutionary histories of plant populations. We recorded spatial, scent, colour, and rewarding flower traits as well as pollinator visitation rates in experimentally inbred and outbred, male and female Silene latifolia plants from European and North American populations differing in their evolutionary histories. We found that inbreeding specifically impairs spatial flower traits and floral scent. Our results support that sex-specific selection and gene expression may have partially magnified these inbreeding costs for females, and that divergent evolutionary histories altered the genetic architecture underlying inbreeding effects across population origins. Moreover, the results indicate that inbreeding effects on floral scent may have a huge potential to disrupt interactions among plants and nocturnal moth pollinators, which are mediated by elaborate chemical communication.
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Affiliation(s)
- Karin Schrieber
- Kiel University, Institute for Ecosystem Research, Geobotany, Kiel, Germany
| | - Sarah Catherine Paul
- Bielefeld University, Faculty of Biology, Department of Chemical Ecology, Bielefeld, Germany
| | - Levke Valena Höche
- Kiel University, Institute for Ecosystem Research, Geobotany, Kiel, Germany
| | | | - Rabi Didszun
- Kiel University, Institute for Ecosystem Research, Geobotany, Kiel, Germany
| | - Jakob Mößnang
- Kiel University, Institute for Ecosystem Research, Geobotany, Kiel, Germany
| | - Caroline Müller
- Bielefeld University, Faculty of Biology, Department of Chemical Ecology, Bielefeld, Germany
| | - Alexandra Erfmeier
- Kiel University, Institute for Ecosystem Research, Geobotany, Kiel, Germany.,German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
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15
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Dudek B, Warskulat AC, Vogel H, Wielsch N, Menezes RC, Hupfer Y, Paetz C, Gebauer-Jung S, Svatoš A, Schneider B. An Integrated-Omics/Chemistry Approach Unravels Enzymatic and Spontaneous Steps to Form Flavoalkaloidal Nudicaulin Pigments in Flowers of Papaver nudicaule L. Int J Mol Sci 2021; 22:ijms22084129. [PMID: 33923591 PMCID: PMC8073789 DOI: 10.3390/ijms22084129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 03/26/2021] [Accepted: 04/13/2021] [Indexed: 11/16/2022] Open
Abstract
Flower colour is an important trait for plants to attract pollinators and ensure their reproductive success. Among yellow flower pigments, the nudicaulins in Papaver nudicaule L. (Iceland poppy) are unique due to their rarity and unparalleled flavoalkaloid structure. Nudicaulins are derived from pelargonidin glycoside and indole, products of the flavonoid and indole/tryptophan biosynthetic pathway, respectively. To gain insight into the molecular and chemical basis of nudicaulin biosynthesis, we combined transcriptome, differential gel electrophoresis (DIGE)-based proteome, and ultra-performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS)-based metabolome data of P. nudicaule petals with chemical investigations. We identified candidate genes and proteins for all biosynthetic steps as well as some key metabolites across five stages of petal development. Candidate genes of amino acid biosynthesis showed a relatively stable expression throughout petal development, whereas most candidate genes of flavonoid biosynthesis showed increasing expression during development followed by downregulation in the final stage. Notably, gene candidates of indole-3-glycerol-phosphate lyase (IGL), sharing characteristic sequence motifs with known plant IGL genes, were co-expressed with flavonoid biosynthesis genes, and are probably providing free indole. The fusion of indole with pelargonidin glycosides was retraced synthetically and promoted by high precursor concentrations, an excess of indole, and a specific glycosylation pattern of pelargonidin. Thus, nudicaulin biosynthesis combines the enzymatic steps of two different pathways with a spontaneous fusion of indole and pelargonidin glycoside under precisely tuned reaction conditions.
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16
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Yoshida K, Ito D, Miki N, Kondo T. Single-cell analysis clarifies mosaic color development in purple hydrangea sepal. THE NEW PHYTOLOGIST 2021; 229:3549-3557. [PMID: 33220077 DOI: 10.1111/nph.17099] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 11/16/2020] [Indexed: 06/11/2023]
Abstract
Hydrangea sepals exhibit a wide range of colors, from red, through purple, to blue; the purple color is a color mosaic. However, all of these colors are derived from the same components: simple anthocyanins, 3-O-glycosyldelphinidins, three co-pigment components, acylquinic acids and aluminum ions (Al3+ ). We show the color mosaic is a result of graded differences in intravacuolar factors. In order to clarify the mechanisms of mosaic color, we performed single-cell analyses of vacuolar pH, and anthocyanin, co-pigment and Al3+ content. From the sepals, a protoplast mixture of various colors was obtained. The cell color was evaluated by microspectrophotometry and vacuolar pH then was recorded by using a pH microelectrode. The organic and Al3+ contents were quantified by micro-HPLC. We found that the bluer the cell, the greater the ratio of 5-O-acylquinic acids and Al3+ to anthocyanins. Furthermore, reproducing experiments were conducted by mixing the components under various pH condition; all the colors could be reproduced in the various mixing conditions. Based on the above, we provide experimental evidence for cell color variation in hydrangea. Our study demonstrates the expression of phenotypic differences without any direct genomic control.
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Affiliation(s)
- Kumi Yoshida
- Graduate School of Informatics, Nagoya University, Chikusa, Nagoya, 464-8601, Japan
| | - Daisuke Ito
- Graduate School of Information Science, Nagoya University, Chikusa, Nagoya, 464-8601, Japan
| | - Naoko Miki
- Graduate School of Information Science, Nagoya University, Chikusa, Nagoya, 464-8601, Japan
| | - Tadao Kondo
- Graduate School of Informatics, Nagoya University, Chikusa, Nagoya, 464-8601, Japan
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17
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Dyer AG, Jentsch A, Burd M, Garcia JE, Giejsztowt J, Camargo MGG, Tjørve E, Tjørve KMC, White P, Shrestha M. Fragmentary Blue: Resolving the Rarity Paradox in Flower Colors. FRONTIERS IN PLANT SCIENCE 2021; 11:618203. [PMID: 33552110 PMCID: PMC7859648 DOI: 10.3389/fpls.2020.618203] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 12/17/2020] [Indexed: 05/05/2023]
Abstract
Blue is a favored color of many humans. While blue skies and oceans are a common visual experience, this color is less frequently observed in flowers. We first review how blue has been important in human culture, and thus how our perception of blue has likely influenced the way of scientifically evaluating signals produced in nature, including approaches as disparate as Goethe's Farbenlehre, Linneaus' plant taxonomy, and current studies of plant-pollinator networks. We discuss the fact that most animals, however, have different vision to humans; for example, bee pollinators have trichromatic vision based on UV-, Blue-, and Green-sensitive photoreceptors with innate preferences for predominantly short-wavelength reflecting colors, including what we perceive as blue. The subsequent evolution of blue flowers may be driven by increased competition for pollinators, both because of a harsher environment (as at high altitude) or from high diversity and density of flowering plants (as in nutrient-rich meadows). The adaptive value of blue flowers should also be reinforced by nutrient richness or other factors, abiotic and biotic, that may reduce extra costs of blue-pigments synthesis. We thus provide new perspectives emphasizing that, while humans view blue as a less frequently evolved color in nature, to understand signaling, it is essential to employ models of biologically relevant observers. By doing so, we conclude that short wavelength reflecting blue flowers are indeed frequent in nature when considering the color vision and preferences of bees.
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Affiliation(s)
- Adrian G. Dyer
- School of Media and Communication, RMIT University, Melbourne, VIC, Australia
| | - Anke Jentsch
- Department of Disturbance Ecology, Bayreuth Center for Ecology and Environmental Research, University of Bayreuth, Bayreuth, Germany
| | - Martin Burd
- School of Biological Sciences, Monash University, Melbourne, VIC, Australia
| | - Jair E. Garcia
- School of Media and Communication, RMIT University, Melbourne, VIC, Australia
| | - Justyna Giejsztowt
- Department of Disturbance Ecology, Bayreuth Center for Ecology and Environmental Research, University of Bayreuth, Bayreuth, Germany
| | - Maria G. G. Camargo
- Phenology Lab, Biosciences Institute, Department of Biodiversity, UNESP – São Paulo State University, São Paulo, Brazil
| | - Even Tjørve
- Inland Norway University of Applied Sciences, Lillehammer, Norway
| | | | - Peter White
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Mani Shrestha
- School of Media and Communication, RMIT University, Melbourne, VIC, Australia
- Faculty of Information Technology, Monash University, Melbourne, VIC, Australia
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18
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Stavenga DG, Leertouwer HL, Dudek B, van der Kooi CJ. Coloration of Flowers by Flavonoids and Consequences of pH Dependent Absorption. FRONTIERS IN PLANT SCIENCE 2021; 11:600124. [PMID: 33488645 PMCID: PMC7820715 DOI: 10.3389/fpls.2020.600124] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 12/08/2020] [Indexed: 05/13/2023]
Abstract
Flavonoid pigments are key determinants of flower colors. As absorption spectra of flavonoids are known to be severely pH-dependent, cellular pH will play a crucial role in flower coloration. The flavonoids are concentrated in the vacuoles of the flowers' epidermal cells, and thus the pigments' absorption spectra are modulated by the vacuolar pH. Here we study the pH dependence of flavonoid absorption spectra in extracts from flowers of two poppy species Papaver dubium (red) and Meconopsis cambrica (orange), and a white and red Mandevilla sanderi variety. In the red poppy and Mandevilla flowers, absorption spectra of the cyanidin- and pelargonidin-based anthocyanins peak in the blue-green-wavelength range at low pH, but exhibit a distinct bathochromic shift at higher pH. This shift to longer wavelengths is not found for the blue-absorbing nudicaulin derivatives of M. cambrica, which have a similar absorption spectrum at low and high pH. The pH-dependent absorption changes of the white M. sanderi's flavonoid remained restricted to the UV. An analysis of the spectra with logistic functions suggests that the pH-dependent characteristics of the basic states of flavonols and anthocyanins are related. The implications of tuning of pH and pigment absorption spectra for studies on flower color evolution are discussed.
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Affiliation(s)
- Doekele G. Stavenga
- Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - Hein L. Leertouwer
- Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - Bettina Dudek
- Research Group Biosynthesis/NMR, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Casper J. van der Kooi
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, Netherlands
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19
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van der Kooi CJ, Stavenga DG, Arikawa K, Belušič G, Kelber A. Evolution of Insect Color Vision: From Spectral Sensitivity to Visual Ecology. ANNUAL REVIEW OF ENTOMOLOGY 2021; 66:435-461. [PMID: 32966103 DOI: 10.1146/annurev-ento-061720-071644] [Citation(s) in RCA: 112] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Color vision is widespread among insects but varies among species, depending on the spectral sensitivities and interplay of the participating photoreceptors. The spectral sensitivity of a photoreceptor is principally determined by the absorption spectrum of the expressed visual pigment, but it can be modified by various optical and electrophysiological factors. For example, screening and filtering pigments, rhabdom waveguide properties, retinal structure, and neural processing all influence the perceived color signal. We review the diversity in compound eye structure, visual pigments, photoreceptor physiology, and visual ecology of insects. Based on an overview of the current information about the spectral sensitivities of insect photoreceptors, covering 221 species in 13 insect orders, we discuss the evolution of color vision and highlight present knowledge gaps and promising future research directions in the field.
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Affiliation(s)
- Casper J van der Kooi
- Faculty of Science and Engineering, University of Groningen, 9700 AK Groningen, The Netherlands;
| | - Doekele G Stavenga
- Faculty of Science and Engineering, University of Groningen, 9700 AK Groningen, The Netherlands;
| | - Kentaro Arikawa
- Department of Evolutionary Studies of Biosystems, SOKENDAI Graduate University for Advanced Studies, Kanagawa 240-0193, Japan;
| | - Gregor Belušič
- Department of Biology, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia;
| | - Almut Kelber
- Lund Vision Group, Department of Biology, University of Lund, 22362 Lund, Sweden;
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20
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Dalrymple RL, Kemp DJ, Flores-Moreno H, Laffan SW, White TE, Hemmings FA, Moles AT. Macroecological patterns in flower colour are shaped by both biotic and abiotic factors. THE NEW PHYTOLOGIST 2020; 228:1972-1985. [PMID: 32533864 DOI: 10.1111/nph.16737] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 05/24/2020] [Indexed: 05/22/2023]
Abstract
There is a wealth of research on the way interactions with pollinators shape flower traits. However, we have much more to learn about influences of the abiotic environment on flower colour. We combine quantitative flower colour data for 339 species from a broad spatial range covering tropical, temperate, arid, montane and coastal environments from 9.25ºS to 43.75ºS with 11 environmental variables to test hypotheses about how macroecological patterns in flower colouration relate to biotic and abiotic conditions. Both biotic community and abiotic conditions are important in explaining variation of flower colour traits on a broad scale. The diversity of pollinating insects and the plant community have the highest predictive power for flower colouration, followed by mean annual precipitation and solar radiation. On average, flower colours are more chromatic where there are fewer pollinators, solar radiation is high, precipitation and net primary production are low, and growing seasons are short, providing support for the hypothesis that higher chromatic contrast of flower colours may be related to stressful conditions. To fully understand the ecology and evolution of flower colour, we should incorporate the broad selective context that plants experience into research, rather than focusing primarily on effects of plant-pollinator interactions.
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Affiliation(s)
- Rhiannon L Dalrymple
- Evolution & Ecology Research Centre, School of Biological, Earth and Environmental Sciences, UNSW Sydney, Sydney, NSW, 2052, Australia
| | - Darrell J Kemp
- Department of Biological Sciences, Faculty of Science and Engineering, Macquarie University, North Ryde, Sydney, NSW, 2109, Australia
| | - Habacuc Flores-Moreno
- Evolution & Ecology Research Centre, School of Biological, Earth and Environmental Sciences, UNSW Sydney, Sydney, NSW, 2052, Australia
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St Paul, MN, 55108, USA
| | - Shawn W Laffan
- School of Biological, Earth and Environmental Sciences, UNSW Sydney, Sydney, NSW, 2052, Australia
| | - Thomas E White
- School of Life and Environmental Sciences, The University of Sydney, Camperdown, Sydney, NSW, 2109, Australia
| | - Frank A Hemmings
- John T. Waterhouse Herbarium, School of Biological, Earth and Environmental Sciences, UNSW Sydney, Sydney, NSW, 2052, Australia
| | - Angela T Moles
- Evolution & Ecology Research Centre, School of Biological, Earth and Environmental Sciences, UNSW Sydney, Sydney, NSW, 2052, Australia
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21
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Wilts BD. Fruit Coloration: Attractive, Fatty Blue Colours? Curr Biol 2020; 30:R1078-R1080. [PMID: 33022238 DOI: 10.1016/j.cub.2020.07.052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The use of visible colours as honest signals to attract seed-dispersers is a well-known property of fruits. While most of these colours are due to pigments, it has now been discovered that the evergreen Viburnum tinus shrubs display their edible and nutritious fruit with a blue structural colour based on lipid inclusions in the epidermal cells.
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Affiliation(s)
- Bodo D Wilts
- Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, 1700 Fribourg, Switzerland.
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22
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Dudek B, Schneider B, Hilger HH, Stavenga DG, Martínez-Harms J. Highly different flavonol content explains geographic variations in the UV reflecting properties of flowers of the corn poppy, Papaver rhoeas (Papaveraceae). PHYTOCHEMISTRY 2020; 178:112457. [PMID: 32692661 DOI: 10.1016/j.phytochem.2020.112457] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 06/24/2020] [Accepted: 07/05/2020] [Indexed: 05/26/2023]
Abstract
Papaver rhoeas, the corn poppy, is a very common weed in cereal fields all over the world. Its flowers generally display a bright red coloration, but their reflectance in the ultraviolet (UV) wavelength range varies geographically. Whereas the UV reflectance of East Mediterranean flowers is minor, that of Central European ones is substantial. By comparing the pigmentation of the differently reflecting flowers, we found that only East Mediterranean flower petals contain high amounts of UV absorbing flavonol glycosides. The most abundant compounds were isolated by solid phase extraction and preparative HPLC, and their structures were elucidated by NMR and HRESI-MS, yielding seven kaempferol and quercetin glycosides, mostly unknown in P. rhoeas petals. Additionally, reflectance and transmittance measurements revealed that wavelength-selective scattering effects do not contribute to the flower color differences observed within this species. Possible abiotic and biotic factors influencing the UV reflecting properties of East Mediterranean and Central European poppies are discussed.
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Affiliation(s)
- Bettina Dudek
- Research Group Biosynthesis/NMR, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, D-07745, Jena, Germany.
| | - Bernd Schneider
- Research Group Biosynthesis/NMR, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, D-07745, Jena, Germany
| | - Hartmut H Hilger
- Department of Biology, Chemistry, Pharmacy, Institute of Biology - Botany, Freie Universität Berlin, Altensteinstr 6, D-14195, Berlin, Germany
| | - Doekele G Stavenga
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, NL-9747, AG Groningen, the Netherlands
| | - Jaime Martínez-Harms
- INIA La Cruz, Instituto de Investigaciones Agropecuarias, Chorrillos 86, 2280454, La Cruz, Chile.
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23
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Abstract
Shifts in wildflower phenology in response to climate change are well documented in the scientific literature. The majority of studies have revealed phenological shifts using in-situ observations, some aided by citizen science efforts (e.g., National Phenology Network). Such investigations have been instrumental in quantifying phenological shifts but are challenged by the fact that limited resources often make it difficult to gather observations over large spatial scales and long-time frames. However, recent advances in finer scale satellite imagery may provide new opportunities to detect changes in phenology. These approaches have documented plot level changes in vegetation characteristics and leafing phenology, but it remains unclear whether they can also detect flowering in natural environments. Here, we test whether fine-resolution imagery (<10 m) can detect flowering and whether combining multiple sources of imagery improves the detection process. Examining alpine wildflowers at Mt. Rainier National Park (MORA), we found that high-resolution Random Forest (RF) classification from 3-m resolution PlanetScope (from Planet Labs) imagery was able to delineate the flowering season captured by ground-based phenological surveys with an accuracy of 70% (Cohen’s kappa = 0.25). We then combined PlanetScope data with coarser resolution but higher quality imagery from Sentinel and Landsat satellites (10-m Sentinel and 30-m Landsat), resulting in higher accuracy predictions (accuracy = 77%, Cohen’s kappa = 0.39). The model was also able to identify the timing of peak flowering in a particularly warm year (2015), despite being calibrated on normal climate years. Our results suggest PlanetScope imagery holds utility in global change ecology where temporal frequency is important. Additionally, we suggest that combining imagery may provide a new approach to cross-calibrate sensors to account for radiometric irregularity inherent in fine resolution PlanetScope imagery. The development of this approach for wildflower phenology predictions provides new possibilities to monitor climate change effects on flowering communities at broader spatiotemporal scales. In protected and tourist areas where the flowering season draws large numbers of visitors, such as Mt. Rainier National Park, the modeling framework presented here could be a useful tool to manage and prioritize park resources.
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24
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Garcia JE, Shrestha M, Ospina-Rozo L, Dekiwadia C, Field MR, Ma JS, Tran N, Dyer AG, Fox K, Greentree AD. Iridescence and hydrophobicity have no clear delineation that explains flower petal micro-surface. Sci Rep 2020; 10:10685. [PMID: 32606366 PMCID: PMC7326983 DOI: 10.1038/s41598-020-67663-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 03/18/2020] [Indexed: 11/13/2022] Open
Abstract
Plant organs including flowers and leaves typically have a variety of different micro-structures present on the epidermal surface. These structures can produce measurable optical effects with viewing angle including shifts in peak reflectance and intensity; however, these different structures can also modulate hydrophobic properties of the surfaces. For some species optical effects have been proposed to act as signals to enhance pollination interactions, whilst the ability to efficiently shed water provides physiological advantages to plants in terms of gas exchange and reducing infections. Currently, little is known about epidermal surface structure of flowering plants in the Southern Hemisphere, and how micro-surface may be related with either hydrophobicity or visual signalling. We measured four Australian native species and two naturalised species using a combination of techniques including SEM imaging, spectral sampling with a goniometer and contact angle measurements. Spectral data were evaluated in relation to published psychophysics results for important pollinators and reveal that potential visual changes, where present, were unlikely to be perceived by relevant pollinators. Nevertheless, hydrophobicity also did not simply explain petal surfaces as similar structures could in some cases result in very different levels of water repellency.
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Affiliation(s)
- Jair E Garcia
- Bio-Inspired Digital Sensing Solutions (BIDS) Lab, School of Media and Communication, RMIT University, Melbourne, 3001, Australia.
| | - Mani Shrestha
- Bio-Inspired Digital Sensing Solutions (BIDS) Lab, School of Media and Communication, RMIT University, Melbourne, 3001, Australia.,Faculty of Information Technology, Monash University, Clayton, 3800, Australia
| | - Laura Ospina-Rozo
- School of Biosciences, The University of Melbourne, Parkville, 3053, Australia
| | - Chaitali Dekiwadia
- RMIT Microscopy and Microanalysis Facility (RMMF), RMIT University, Melbourne, 3001, Australia
| | - Matthew R Field
- RMIT Microscopy and Microanalysis Facility (RMMF), RMIT University, Melbourne, 3001, Australia
| | - Ji Sheng Ma
- Monash Centre for Electron Microscopy (MCEM), Monash University, Clayton, 3800, Australia
| | - Nhiem Tran
- Applied Chemistry and Environmental Science, RMIT University, Melbourne, 3001, Australia
| | - Adrian G Dyer
- Bio-Inspired Digital Sensing Solutions (BIDS) Lab, School of Media and Communication, RMIT University, Melbourne, 3001, Australia.,Department of Physiology, Monash University, Clayton, 3800, Australia
| | - Kate Fox
- School of Engineering, RMIT University, Melbourne, 3001, Australia
| | - Andrew D Greentree
- ARC Centre of Excellence for Nanoscale BioPhotonics, School of Science, RMIT University, Melbourne, 3001, Australia
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25
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Peach K, Liu JW, Mazer SJ. Climate Predicts UV Floral Pattern Size, Anthocyanin Concentration, and Pollen Performance in Clarkia unguiculata. FRONTIERS IN PLANT SCIENCE 2020; 11:847. [PMID: 32612627 PMCID: PMC7308548 DOI: 10.3389/fpls.2020.00847] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 05/26/2020] [Indexed: 05/25/2023]
Abstract
Given that flower size and pigmentation can mediate plant-pollinator interactions, many studies have focused on pollinator-driven selection on these floral traits. However, abiotic factors such as precipitation, temperature, and solar radiation also contribute to geographic variation in floral color, pattern, and size within multiple species. Several studies have described an ecogeographic pattern within species in which high temperature, high ultraviolet (UV) radiation, low precipitation and/or low latitudes are associated with increased floral anthocyanin production, smaller flowers, and/or larger UV-absorbing floral patterns (nectar guides or bullseyes). However, latitude or elevation is often used as a proxy variable to study variation in floral traits associated with a wide range of climatic variables, making the proximate abiotic drivers of variation difficult to identify. In this study, we tested and corroborated several predictions for how the abiotic environment may directly or indirectly shape geographic patterns of floral color, pattern, and size in Clarkia unguiculata (Onagraceae). This study provides the first report of geographic variation in multispectral floral color and pattern in C. unguiculata, while also providing an experimental test of the putative protective role of UV absorption for pollen performance. We quantified geographic variation among greenhouse-raised populations in UV floral pattern size, mean UV petal reflectance, anthocyanin concentration, and petal area in C. unguiculata across its natural range in California and, using 30 year climate normals for each population, we identified climatic and topographic attributes that are correlated with our focal floral traits. In addition, we examined pollen performance under high and low UV light conditions to detect the protective function (if any) of UV floral patterns in this species. Contrary to our expectations, the nectar guide and the proportion of the petal occupied by the UV nectar guide were largest in low solar UV populations. Estimated floral anthocyanin concentration was highest in populations with high solar UV, which does support our predictions. The size of the UV nectar guide did not affect pollen performance in either of the light treatments used in this study. We conclude that, under the conditions examined here, UV-absorbing floral patterns do not serve a direct "pollen protection" function in C. unguiculata. Our results only partially align with expected ecogeographic patterns in these floral traits, highlighting the need for research in a wider range of taxa in order to detect and interpret broad scale patterns of floral color variation.
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Affiliation(s)
- Kristen Peach
- Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Jasen W. Liu
- Population Biology Graduate Group, University of California, Davis, Davis, CA, United States
| | - Susan J. Mazer
- Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
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Pollinator divergence and pollination isolation between hybrids with different floral color and morphology in two sympatric Penstemon species. Sci Rep 2020; 10:8126. [PMID: 32415216 PMCID: PMC7229217 DOI: 10.1038/s41598-020-64964-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 04/27/2020] [Indexed: 11/08/2022] Open
Abstract
Differential visitation of pollinators due to divergent floral traits can lead to reproductive isolation via assortative pollen flow, which may ultimately be a driving force in plant speciation, particularly in areas of overlap. We evaluate the effects of pollinator behavioral responses to variation of intraspecific floral color and nectar rewards, on reproductive isolation between two hybrid flower color morphs (fuchsia and blue) and their parental species Penstemon roseus and P. gentianoides with a mixed-pollination system. We show that pollinators (bumblebees and hummingbirds) exhibit different behavioral responses to fuchsia and blue morphs, which could result from differential attraction or deterrence. In addition to differences in color (spectral reflectance), we found that plants with fuchsia flowers produced more and larger flowers, produced more nectar and were more visited by pollinators than those with blue flowers. These differences influenced the foraging behavior and effectiveness as pollinators of both bumblebees and hummingbirds, which contributed to reproductive isolation between the two hybrid flower color morphs and parental species. This study demonstrates how differentiation of pollination traits promotes the formation of hybrid zones leading to pollinator shifts and reproductive isolation. While phenotypic traits of fuchsia and red flowers might encourage more efficient hummingbird pollination in a mixed-pollination system, the costs of bumblebee pollination on plant reproduction could be the drivers for the repeated shifts from bumblebee- to hummingbird-mediated pollination.
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Kraaij M, van der Kooi CJ. Surprising absence of association between flower surface microstructure and pollination system. PLANT BIOLOGY (STUTTGART, GERMANY) 2020; 22:177-183. [PMID: 31710761 PMCID: PMC7064994 DOI: 10.1111/plb.13071] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 11/03/2019] [Indexed: 05/25/2023]
Abstract
The epidermal cells of flowers come in different shapes and have different functions, but how they evolved remains largely unknown. Floral micro-texture can provide tactile cues to insects, and increases in surface roughness by means of conical (papillose) epidermal cells may facilitate flower handling by landing insect pollinators. Whether flower microstructure correlates with pollination system remains unknown. Here, we investigate the floral epidermal microstructure in 29 (congeneric) species pairs with contrasting pollination system. We test whether flowers pollinated by bees and/or flies feature more structured, rougher surfaces than flowers pollinated by non-landing moths or birds and flowers that self-pollinate. In contrast with earlier studies, we find no correlation between epidermal microstructure and pollination system. The shape, cell height and roughness of floral epidermal cells varies among species, but is not correlated with pollinators at large. Intriguingly, however, we find that the upper (adaxial) flower surface that surrounds the reproductive organs and often constitutes the floral display is markedly more structured than the lower (abaxial) surface. We thus conclude that conical epidermal cells probably play a role in plant reproduction other than providing grip or tactile cues, such as increasing hydrophobicity or enhancing the visual signal.
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Affiliation(s)
- M. Kraaij
- Groningen Institute for Evolutionary Life SciencesUniversity of GroningenGroningenthe Netherlands
| | - C. J. van der Kooi
- Groningen Institute for Evolutionary Life SciencesUniversity of GroningenGroningenthe Netherlands
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van der Kooi CJ, Kevan PG, Koski MH. The thermal ecology of flowers. ANNALS OF BOTANY 2019; 124:343-353. [PMID: 31206146 PMCID: PMC6798827 DOI: 10.1093/aob/mcz073] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 04/27/2019] [Indexed: 05/16/2023]
Abstract
BACKGROUND Obtaining an optimal flower temperature can be crucial for plant reproduction because temperature mediates flower growth and development, pollen and ovule viability, and influences pollinator visitation. The thermal ecology of flowers is an exciting, yet understudied field of plant biology. SCOPE This review focuses on several attributes that modify exogenous heat absorption and retention in flowers. We discuss how flower shape, orientation, heliotropic movements, pubescence, coloration, opening-closing movements and endogenous heating contribute to the thermal balance of flowers. Whenever the data are available, we provide quantitative estimates of how these floral attributes contribute to heating of the flower, and ultimately plant fitness. OUTLOOK Future research should establish form-function relationships between floral phenotypes and temperature, determine the fitness effects of the floral microclimate, and identify broad ecological correlates with heat capture mechanisms.
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Affiliation(s)
- Casper J van der Kooi
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | - Peter G Kevan
- School of Environmental Sciences, University of Guelph, Guelph, Canada
| | - Matthew H Koski
- Department of Biology, University of Virginia, Charlottesville, VA, USA
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29
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Liu HF, Chen FB. Candidate genes in red pigment biosynthesis of a red-fleshed radish cultivar (Raphanus sativus L.) as revealed by transcriptome analysis. BIOCHEM SYST ECOL 2019. [DOI: 10.1016/j.bse.2019.103933] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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30
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Klomberg Y, Dywou Kouede R, Bartoš M, Mertens JEJ, Tropek R, Fokam EB, Janeček Š. The role of ultraviolet reflectance and pattern in the pollination system of Hypoxis camerooniana (Hypoxidaceae). AOB PLANTS 2019; 11:plz057. [PMID: 31649811 PMCID: PMC6803167 DOI: 10.1093/aobpla/plz057] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 09/02/2019] [Indexed: 06/10/2023]
Abstract
Apart from floral morphology and colours perceived by the human eye, ultraviolet (UV) reflectance acts as an important visual advertisement of numerous flowering plant species for pollinators. However, the effect of UV signalling on attracting pollinators of particular plant species is still insufficiently studied, especially in the Afrotropics. Therefore, we studied the pollination system of Hypoxis camerooniana in montane grasslands of Mount Cameroon, West/Central Africa. We focused mainly on the effects of the flowers' UV reflectance on its visitors. We experimentally removed UV reflection from petals either completely or partially. Thereafter, flower visitors were recorded and pistils were collected post-flowering to quantify germinated pollen tubes per treatments. The most important visitors were bees, followed by flies. Due to their contacts with reproductive organs bees are considered as the primary pollinators. Visitation rates were lower when UV reflectance was completely removed, whereas the decrease of frequency on half-treated flowers did not differ significantly from control treatments. The complete removal of UV also affected bees' landing behaviour, but not that of flies. We showed that the presence of UV reflectance is more important than UV pattern for bees visiting flowers of H. camerooniana. We hypothesize that exploiting all flowers irrespective of their pattern can be more efficient for pollinators in the open grasslands of high altitudes to spot these relatively scarce flowers by their UV reflectance. Furthermore, we highlight the necessity of both experimental and natural controls in similar studies to control for additional effects of the used UV manipulations. Many plants advertise their flowers with UV reflectance visible to their insect visitors. By manipulating the UV reflectance and pattern of Hypoxis camerooniana in the Afromontane grasslands of Mount Cameroon, we have shown how crucial it is for the predominant visitor, bees. Both bees' preferences for flowers and their behaviour during visits are influenced by changes in UV reflectance. However, the presence of some UV signal is more important than the specific pattern. Especially in montane grasslands with higher UV irradiation, the UV floral colours are important for recognition of flowers by potential pollinators.
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Affiliation(s)
- Yannick Klomberg
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, 12844 Prague, Czechia
| | - Raissa Dywou Kouede
- Department of Zoology and Animal Physiology, Faculty of Science, University of Buea, PO Box 63 Buea, Cameroon
| | - Michael Bartoš
- Institute of Botany, Czech Academy of Sciences, Dukelská 135, 37901 Třeboň, Czechia
| | - Jan E J Mertens
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, 12844 Prague, Czechia
| | - Robert Tropek
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, 12844 Prague, Czechia
- Institute of Entomology, Biology Centre, Czech Academy of Sciences, Branišovská 31, 37005 České Budějovice, Czechia
| | - Eric B Fokam
- Department of Zoology and Animal Physiology, Faculty of Science, University of Buea, PO Box 63 Buea, Cameroon
| | - Štěpán Janeček
- Department of Ecology, Faculty of Science, Charles University, Viničná 7, 12844 Prague, Czechia
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Ortiz-Ramírez CI, Giraldo MA, Ferrándiz C, Pabón-Mora N. Expression and function of the bHLH genes ALCATRAZ and SPATULA in selected Solanaceae species. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 99:686-702. [PMID: 31009131 DOI: 10.1111/tpj.14352] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 03/27/2019] [Accepted: 04/08/2019] [Indexed: 06/09/2023]
Abstract
The genetic mechanisms underlying fruit development have been identified in Arabidopsis and have been comparatively studied in tomato as a representative of fleshy fruits. However, comparative expression and functional analyses on the bHLH genes downstream the genetic network, ALCATRAZ (ALC) and SPATULA (SPT), which are involved in the formation of the dehiscence zone in Arabidopsis, have not been functionally studied in the Solanaceae. Here, we perform detailed expression and functional studies of ALC/SPT homologs in Nicotiana obtusifolia with capsules, and in Capsicum annuum and Solanum lycopersicum with berries. In Solanaceae, ALC and SPT genes are expressed in leaves, and all floral organs, especially in petal margins, stamens and carpels; however, their expression changes during fruit maturation according to the fruit type. Functional analyses show that downregulation of ALC/SPT genes does not have an effect on gynoecium patterning; however, they have acquired opposite roles in petal expansion and have been co-opted in leaf pigmentation in Solanaceae. In addition, ALC/SPT genes repress lignification in time and space during fruit development in Solanaceae. Altogether, some roles of ALC and SPT genes are different between Brassicaceae and Solanaceae; while the paralogs have undergone some subfunctionalization in the former they are mostly redundant in the latter.
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Affiliation(s)
- Clara Inés Ortiz-Ramírez
- Instituto de Biología, Universidad de Antioquia, Medellín, Colombia
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Valencia, Spain
| | - Marco A Giraldo
- Instituto de Física, Universidad de Antioquia, Medellín, Colombia
| | - Cristina Ferrándiz
- Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Valencia, Spain
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Garcia JE, Shrestha M, Howard SR, Petersen P, Dyer AG. Signal or cue: the role of structural colors in flower pollination. Curr Zool 2019; 65:467-481. [PMID: 31413719 PMCID: PMC6688579 DOI: 10.1093/cz/zoy096] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 09/27/2017] [Accepted: 12/11/2018] [Indexed: 11/13/2022] Open
Abstract
Angle dependent colors, such as iridescence, are produced by structures present on flower petals changing their visual appearance. These colors have been proposed to act as signals for plant-insect communication. However, there is a paucity of behavioral data to allow for interpretations of how to classify these colors either as a signal or a cue when considering the natural conditions under which pollination occurs. We sampled flowers from 6 plant species across various viewpoints looking for changes in the visual appearance of the petals. Spectral characteristics were measured with different instruments to simulate both the spectral and spatial characteristics of honeybee's vision. We show the presence of color patches produced by angle dependent effects on the petals and the calyx of various species; however, the appearance of the angle dependent color patches significantly varies with viewpoint and would only be resolved by the insect eye at close distances. Behavior experiments with honeybees revealed that pollinators did not use angle dependent colors to drive behavior when presented with novel flower presentations. Results show that angle dependent colors do not comply with the requirements of a signal for plant-pollinator communication since the information transmitted by these colors would be unreliable for potential, free-flying pollination vectors. We thus classify angle dependent colors produced by micro- and ultra-structures as being a cue (a feature which has not evolved for communication), and observe no evidence supporting claims of these angle dependent colors having evolved as visual signal.
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Affiliation(s)
- Jair E Garcia
- School of Media and Communication, RMIT University, Melbourne, Victoria 3001, Australia
| | - Mani Shrestha
- School of Media and Communication, RMIT University, Melbourne, Victoria 3001, Australia
- Faculty of Information Technology, Monash University, Clayton, Victoria 3800, Australia
| | - Scarlett R Howard
- School of Media and Communication, RMIT University, Melbourne, Victoria 3001, Australia
| | - Phred Petersen
- School of Media and Communication, RMIT University, Melbourne, Victoria 3001, Australia
| | - Adrian G Dyer
- School of Media and Communication, RMIT University, Melbourne, Victoria 3001, Australia
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33
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Colour preferences of Tetragonula carbonaria Sm. stingless bees for colour morphs of the Australian native orchid Caladenia carnea. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2019; 205:347-361. [DOI: 10.1007/s00359-019-01346-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 05/08/2019] [Accepted: 05/13/2019] [Indexed: 01/09/2023]
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Shrestha M, Garcia JE, Chua JHJ, Howard SR, Tscheulin T, Dorin A, Nielsen A, Dyer AG. Fluorescent Pan Traps Affect the Capture Rate of Insect Orders in Different Ways. INSECTS 2019; 10:insects10020040. [PMID: 30717089 PMCID: PMC6410105 DOI: 10.3390/insects10020040] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 01/15/2019] [Accepted: 01/21/2019] [Indexed: 11/16/2022]
Abstract
To monitor and quantify the changes in pollinator communities over time, it is important to have robust survey techniques of insect populations. Pan traps allow for the assessment of the relative insect abundance in an environment and have been promoted by the Food and Agricultural Organization (FAO) as an efficient data collection methodology. It has been proposed that fluorescent pan traps are particularly useful, as it has been suggested that they capture high numbers of insects in an unbiased fashion. We use a simultaneous presentation of fluorescent and non-fluorescent pan trap colours to assess how flower-visiting insects of different orders respond to visual stimuli and reveal a significant interaction between trap fluorescence and captured insect type. In particular, Coleoptera (beetles) and Lepidoptera (butterflies and moths) were captured significantly more frequently by fluorescent traps, whilst Dipterans (flies) were captured significantly less frequently by this type of pan trap. Hymenopterans (bees and wasps) showed no significant difference in their preference for fluorescent or non-fluorescent traps. Our results reveal that the use of fluorescent pan traps may differently bias insect capture rates when compared to the typical experience of colour flower-visiting insects in natural environments. Correction factors may, therefore, be required for interpreting insect pan trap data collected with different methodologies.
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Affiliation(s)
- Mani Shrestha
- School of Media and Communication, RMIT University, Melbourne, VIC 3001, Australia.
- Faculty of Information Technology, Monash University, Melbourne, VIC 3800, Australia.
| | - Jair E Garcia
- School of Media and Communication, RMIT University, Melbourne, VIC 3001, Australia
| | - Justin H J Chua
- School of Media and Communication, RMIT University, Melbourne, VIC 3001, Australia
| | - Scarlett R Howard
- School of Media and Communication, RMIT University, Melbourne, VIC 3001, Australia
| | - Thomas Tscheulin
- Laboratory of Biogeography and Ecology, Department of Geography, University of the Aegean University Hill, GR-81100 Mytilene, Greece
| | - Alan Dorin
- Faculty of Information Technology, Monash University, Melbourne, VIC 3800, Australia
| | - Anders Nielsen
- Centre for Ecological and Evolutionary Synthesis (CEES), Dept. of Biosciences, University of Oslo, P.O. Box 1066 Blindern, 0316 Oslo, Norway
| | - Adrian G Dyer
- School of Media and Communication, RMIT University, Melbourne, VIC 3001, Australia
- Department of Physiology, Monash University, Melbourne, VIC 3800, Australia
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35
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van der Kooi CJ, Stavenga DG. Vividly coloured poppy flowers due to dense pigmentation and strong scattering in thin petals. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2019; 205:363-372. [PMID: 30689019 PMCID: PMC6579775 DOI: 10.1007/s00359-018-01313-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 12/19/2018] [Accepted: 12/24/2018] [Indexed: 11/29/2022]
Abstract
The flowers of poppies (Papaveraceae) exhibit bright colours, despite their thin and floppy petals. We investigated the optical properties of flowers of Papaver rhoeas, P. dubium, Meconopsis cambrica and Argemone polyanthemos using a combined approach of anatomy, spectrophotometry and optical modelling. The petals of Papaver flowers are composed of only three cell layers, an upper and lower epidermal layer, which are densely filled with pigment, and an unpigmented mesophyll layer. Dense pigmentation together with strong scattering structures, composed of serpentine cell walls and air cavities, cause the striking poppy colours. We discuss how various aspects of the optical signal contribute to the flower's visibility to pollinators.
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Affiliation(s)
- Casper J van der Kooi
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, 9747 AG, Groningen, The Netherlands.
| | - Doekele G Stavenga
- Computational Physics, Zernike Institute for Advanced Materials, University of Groningen, 9747 AG, Groningen, The Netherlands
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36
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van der Kooi CJ, Dyer AG, Kevan PG, Lunau K. Functional significance of the optical properties of flowers for visual signalling. ANNALS OF BOTANY 2019; 123:263-276. [PMID: 29982325 PMCID: PMC6344213 DOI: 10.1093/aob/mcy119] [Citation(s) in RCA: 106] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 06/06/2018] [Indexed: 05/20/2023]
Abstract
BACKGROUND Flower coloration is a key enabler for pollinator attraction. Floral visual signals comprise several components that are generated by specific anatomical structures and pigmentation, and often have different functions in pollinator attraction. Anatomical studies have advanced our understanding of the optical properties of flowers, and evidence from behavioural experiments has elucidated the biological relevance of different components of floral visual signals, but these two lines of research are often considered independently. SCOPE Here, we review current knowledge about different aspects of the floral visual signals, their anatomical and optical properties, and their functional significance in plant-pollinator visual signalling. We discuss common aspects, such as chromatic and achromatic contrast, hue, saturation and brightness, as well as less common types of visual signals, including gloss, fluorescence, polarization and iridescence in the context of salience of floral colour signals and their evolution, and highlight promising avenues for future research.
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Affiliation(s)
- Casper J van der Kooi
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, the Netherlands
- For correspondence. E-mail
| | - Adrian G Dyer
- School of Media and Communication, RMIT University, Melbourne, Australia
| | - Peter G Kevan
- School of Environmental Sciences, University of Guelph, Guelph, Canada
| | - Klaus Lunau
- Institute of Sensory Ecology, Heinrich-Heine-University, Dusseldorf, Germany
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37
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38
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Howard SR, Shrestha M, Schramme J, Garcia JE, Avarguès-Weber A, Greentree AD, Dyer AG. Honeybees prefer novel insect-pollinated flower shapes over bird-pollinated flower shapes. Curr Zool 2018; 65:457-465. [PMID: 31413718 PMCID: PMC6688580 DOI: 10.1093/cz/zoy095] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 12/04/2018] [Indexed: 11/18/2022] Open
Abstract
Plant–pollinator interactions have a fundamental influence on flower evolution. Flower color signals are frequently tuned to the visual capabilities of important pollinators such as either bees or birds, but far less is known about whether flower shape influences the choices of pollinators. We tested European honeybee Apis mellifera preferences using novel achromatic (gray-scale) images of 12 insect-pollinated and 12 bird-pollinated native Australian flowers in Germany; thus, avoiding influences of color, odor, or prior experience. Independent bees were tested with a number of parameterized images specifically designed to assess preferences for size, shape, brightness, or the number of flower-like shapes present in an image. We show that honeybees have a preference for visiting images of insect-pollinated flowers and such a preference is most-likely mediated by holistic information rather than by individual image parameters. Our results indicate angiosperms have evolved flower shapes which influence the choice behavior of important pollinators, and thus suggest spatial achromatic flower properties are an important part of visual signaling for plant–pollinator interactions.
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Affiliation(s)
- Scarlett R Howard
- Bio-inspired Digital Sensing (BIDS) Lab, School of Media and Communication, RMIT University, Melbourne, Victoria 3000, Australia
| | - Mani Shrestha
- Bio-inspired Digital Sensing (BIDS) Lab, School of Media and Communication, RMIT University, Melbourne, Victoria 3000, Australia.,Faculty of Information Technology, Monash University, Melbourne, Victoria 3800, Australia
| | - Juergen Schramme
- Institute of Developmental Biology and Neurobiology (iDn), Johannes Gutenberg University, Mainz 55122, Germany
| | - Jair E Garcia
- Bio-inspired Digital Sensing (BIDS) Lab, School of Media and Communication, RMIT University, Melbourne, Victoria 3000, Australia
| | - Aurore Avarguès-Weber
- Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative (CBI), Université de Toulouse, CNRS, UPS, Toulouse 31400, France
| | - Andrew D Greentree
- ARC Centre of Excellence for Nanoscale BioPhotonics, School of Science, RMIT University, Melbourne, Victoria 3000, Australia
| | - Adrian G Dyer
- Bio-inspired Digital Sensing (BIDS) Lab, School of Media and Communication, RMIT University, Melbourne, Victoria 3000, Australia.,Department of Physiology, Monash University, Clayton, Victoria 3800, Australia
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Kevan PG, Nunes-Silva P, Sudarsan R. Short communication: thermal regimes in hollow stems of herbaceous plants-concepts and models. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2018; 62:2057-2062. [PMID: 30209613 DOI: 10.1007/s00484-018-1602-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 08/09/2018] [Accepted: 08/17/2018] [Indexed: 06/08/2023]
Abstract
Although there have been studies of the temperature regimes within flowers, micrometeorology within stems seems to have been overlooked. We present ideas, hypotheses, and a diagrammatic model on the biophysical and thermodynamic processes that interact in complex ways to result in elevated temperature regimes within hollow stems of herbaceous plants. We consider the effects of the ambient air around the stems, the possible importance of insolation, and greenhouse effects as influenced by stems' orientation and optical properties, i.e., reflection, absorption, emissivity, translucence, pigmentation, and thermal conductivity. We propose that greenhouse effects contribute significantly to and are influenced by the above phenomena as well as by the gross anatomy (volume:surface ratio; wall thickness), evapotranspiration, and the thermal properties of the gas mixture in the lumen. We provide examples of those elevated temperatures that can be several degrees Celsius above the temperature of the surrounding atmosphere.
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Affiliation(s)
- Peter G Kevan
- School of Environmental Sciences, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada.
| | - Patrícia Nunes-Silva
- School of Environmental Sciences, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
| | - Rangarajan Sudarsan
- Department of Mathematics and Statistics, University of Guelph, 50 Stone Road East, Guelph, ON, N1G 2W1, Canada
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Ng L, Garcia JE, Dyer AG. Why colour is complex: Evidence that bees perceive neither brightness nor green contrast in colour signal processing. Facets (Ott) 2018. [DOI: 10.1139/facets-2017-0116] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Honey bees ( Apis mellifera Linnaeus, 1758) potentially rely on a variety of visual cues when searching for flowers in the environment. Both chromatic and achromatic (brightness) components of flower signals have typically been considered simultaneously to understand how flower colours have evolved. However, it is unclear whether honey bees actually use brightness information in their colour perception. We investigated whether free-flying honey bees can process brightness cues in achromatic stimuli when presented at a large visual angle of 28° to ensure colour processing. We found that green contrast (modulation of the green receptor against the background) and brightness contrast (modulation of all three receptors against the background) did not have a significant effect on the proportion of correct choices made by bees, indicating that they did not appear to use brightness cues in a colour processing context. Our findings also reveal that, even at a small visual angle, honeybees do not reliably process single targets solely based on achromatic information, at least considering values up to 60% modulation of brightness. We discuss these findings in relation to proposed models of bee colour processing. Therefore, caution should be taken when interpreting elemental components of complex flower colours as perceived by different animals.
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Affiliation(s)
- Leslie Ng
- Bio-Inspired Digital Sensing (BIDS) Lab, School of Media and Communication, RMIT University, Melbourne, VIC 3001, Australia
- School of Biosciences, University of Melbourne, Melbourne, Parkville, VIC 3010, Australia
| | - Jair E. Garcia
- Bio-Inspired Digital Sensing (BIDS) Lab, School of Media and Communication, RMIT University, Melbourne, VIC 3001, Australia
| | - Adrian G. Dyer
- Bio-Inspired Digital Sensing (BIDS) Lab, School of Media and Communication, RMIT University, Melbourne, VIC 3001, Australia
- Department of Physiology, Monash University, Melbourne, Clayton, VIC 3800, Australia
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41
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Garcia JE, Shrestha M, Dyer AG. Flower signal variability overwhelms receptor-noise and requires plastic color learning in bees. Behav Ecol 2018. [DOI: 10.1093/beheco/ary127] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Jair E Garcia
- Bio-Inspired Digital Sensing (BIDS) Lab, School of Media and Communication, RMIT University, Melbourne, Victoria, Australia
| | - Mani Shrestha
- Bio-Inspired Digital Sensing (BIDS) Lab, School of Media and Communication, RMIT University, Melbourne, Victoria, Australia
- APIS Lab, Faculty of Information Technology, Monash University, Clayton, Victoria, Australia
| | - Adrian G Dyer
- Bio-Inspired Digital Sensing (BIDS) Lab, School of Media and Communication, RMIT University, Melbourne, Victoria, Australia
- Department of Physiology, Monash University, Clayton, Victoria 3168, Australia
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42
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Wilts BD, Rudall PJ, Moyroud E, Gregory T, Ogawa Y, Vignolini S, Steiner U, Glover BJ. Ultrastructure and optics of the prism-like petal epidermal cells of Eschscholzia californica (California poppy). THE NEW PHYTOLOGIST 2018; 219:1124-1133. [PMID: 29856474 PMCID: PMC6055853 DOI: 10.1111/nph.15229] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 04/19/2018] [Indexed: 05/06/2023]
Abstract
The petals of Eschscholzia californica (California poppy) are robust, pliable and typically coloured intensely orange or yellow owing to the presence of carotenoid pigments; they are also highly reflective at certain angles, producing a silky effect. To understand the mechanisms behind colour enhancement and reflectivity in California poppy, which represents a model species among early-divergent eudicots, we explored the development, ultrastructure, pigment composition and optical properties of the petals using light microscopy and electron microscopy combined with both spectrophotometry and goniometry. The elongated petal epidermal cells each possess a densely thickened prism-like ridge that is composed primarily of cell wall. The surface ridges strongly focus incident light onto the pigments, which are located in plastids at the cell base. Our results indicate that this highly unusual, deeply ridged surface structure not only enhances the deep colour response in this desert species, but also results in strongly angle-dependent 'silky' reflectivity that is anisotropic and mostly directional.
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Affiliation(s)
- Bodo D. Wilts
- Adolphe Merkle InstituteUniversity of FribourgChemin des Verdiers 4CH‐1700FribourgSwitzerland
- Cavendish LaboratoryDepartment of PhysicsUniversity of CambridgeJJ Thomson AvenueCambridgeCB3 0HEUK
| | | | - Edwige Moyroud
- Department of Plant SciencesUniversity of CambridgeDowning StreetCambridgeCB2 3EAUK
- The Sainsbury LaboratoryUniversity of CambridgeBateman StreetCambridgeCB2 1LRUK
| | - Tom Gregory
- Royal Botanic GardensKewRichmondTW9 3ABUK
- UCL Institute of Archaeology31–34 Gordon SquareLondonWC1H 0PYUK
| | - Yu Ogawa
- Department of ChemistryUniversity of CambridgeLensfield RoadCambridgeCB2 1EWUK
| | - Silvia Vignolini
- Cavendish LaboratoryDepartment of PhysicsUniversity of CambridgeJJ Thomson AvenueCambridgeCB3 0HEUK
- Department of ChemistryUniversity of CambridgeLensfield RoadCambridgeCB2 1EWUK
| | - Ullrich Steiner
- Adolphe Merkle InstituteUniversity of FribourgChemin des Verdiers 4CH‐1700FribourgSwitzerland
- Cavendish LaboratoryDepartment of PhysicsUniversity of CambridgeJJ Thomson AvenueCambridgeCB3 0HEUK
| | - Beverley J. Glover
- Department of Plant SciencesUniversity of CambridgeDowning StreetCambridgeCB2 3EAUK
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43
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Shrestha M, Garcia JE, Bukovac Z, Dorin A, Dyer AG. Pollination in a new climate: Assessing the potential influence of flower temperature variation on insect pollinator behaviour. PLoS One 2018; 13:e0200549. [PMID: 30067757 PMCID: PMC6070230 DOI: 10.1371/journal.pone.0200549] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Accepted: 06/28/2018] [Indexed: 12/04/2022] Open
Abstract
Climate change has the potential to enhance or disrupt biological systems, but currently, little is known about how organism plasticity may facilitate adaptation to localised climate variation. The bee-flower relationship is an exemplar signal-receiver system that may provide important insights into the complexity of ecological interactions in situations like this. For example, several studies on bee temperature preferences show that bees prefer to collect warm nectar from flowers at low ambient temperatures, but switch their preferences to cooler flowers at ambient temperatures above about 30° C. We used temperature sensor thermal probes to measure the temperature of outdoor flowers of 30 plant species in the Southern regions of the Australian mainland, to understand how different species could modulate petal temperature in response to changes in ambient temperature and, potentially, influence the decision-making of bees in the flowering plant's favour. We found that flower petal temperatures respond in different ways to changing ambient temperature: linearly increasing or decreasing relative to the ambient temperature, dynamically changing in a non-linear manner, or varying their temperature along with the ambient conditions. For example, our investigation of the difference between ambient temperature and petal temperature (ΔT), and ambient temperature, revealed a non-linear relationship for Erysimum linifolium and Polygala grandiflora that seems suited to bee temperature preferences. The temperature profiles of species like Hibertia vestita and H. obtusifolia appear to indicate that they do not have a cooling mechanism. These species may therefore be less attractive to bee pollinators in changing climatic conditions with ambient temperatures increasingly above 30° C. This may be to the species' detriment when insect-pollinator mediated selection is considered. However, we found no evidence that flower visual characteristics used by bees to identify flowers at close range, such as colour or shape, were straightforward modulators of floral temperature. We could not identify any clear link to phylogenetic history and temperature modulation either. Mapping our test flower distribution on the Australian continent however, indicates a potential clustering that suggests different flower responses may constitute adaptations to local conditions. Our study proposes a framework for modelling the potential effects of climate change and floral temperature on flower pollination dynamics at local and global scales.
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Affiliation(s)
- Mani Shrestha
- School of Media and Communication, RMIT University, Melbourne, Australia
- Faculty of Information Technology, Monash University, Melbourne, Australia
| | - Jair E. Garcia
- School of Media and Communication, RMIT University, Melbourne, Australia
| | - Zoë Bukovac
- Faculty of Information Technology, Monash University, Melbourne, Australia
| | - Alan Dorin
- Faculty of Information Technology, Monash University, Melbourne, Australia
| | - Adrian G. Dyer
- School of Media and Communication, RMIT University, Melbourne, Australia
- Department of Physiology, Monash University, Melbourne, Australia
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44
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Del Valle JC, Gallardo-López A, Buide ML, Whittall JB, Narbona E. Digital photography provides a fast, reliable, and noninvasive method to estimate anthocyanin pigment concentration in reproductive and vegetative plant tissues. Ecol Evol 2018; 8:3064-3076. [PMID: 29607006 PMCID: PMC5869271 DOI: 10.1002/ece3.3804] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 10/31/2017] [Accepted: 12/06/2017] [Indexed: 02/03/2023] Open
Abstract
Anthocyanin pigments have become a model trait for evolutionary ecology as they often provide adaptive benefits for plants. Anthocyanins have been traditionally quantified biochemically or more recently using spectral reflectance. However, both methods require destructive sampling and can be labor intensive and challenging with small samples. Recent advances in digital photography and image processing make it the method of choice for measuring color in the wild. Here, we use digital images as a quick, noninvasive method to estimate relative anthocyanin concentrations in species exhibiting color variation. Using a consumer‐level digital camera and a free image processing toolbox, we extracted RGB values from digital images to generate color indices. We tested petals, stems, pedicels, and calyces of six species, which contain different types of anthocyanin pigments and exhibit different pigmentation patterns. Color indices were assessed by their correlation to biochemically determined anthocyanin concentrations. For comparison, we also calculated color indices from spectral reflectance and tested the correlation with anthocyanin concentration. Indices perform differently depending on the nature of the color variation. For both digital images and spectral reflectance, the most accurate estimates of anthocyanin concentration emerge from anthocyanin content‐chroma ratio, anthocyanin content‐chroma basic, and strength of green indices. Color indices derived from both digital images and spectral reflectance strongly correlate with biochemically determined anthocyanin concentration; however, the estimates from digital images performed better than spectral reflectance in terms of r2 and normalized root‐mean‐square error. This was particularly noticeable in a species with striped petals, but in the case of striped calyces, both methods showed a comparable relationship with anthocyanin concentration. Using digital images brings new opportunities to accurately quantify the anthocyanin concentrations in both floral and vegetative tissues. This method is efficient, completely noninvasive, applicable to both uniform and patterned color, and works with samples of any size.
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Affiliation(s)
- José C Del Valle
- Department of Molecular Biology and Biochemical Engineering Pablo de Olavide University Seville Spain
| | - Antonio Gallardo-López
- Department of Molecular Biology and Biochemical Engineering Pablo de Olavide University Seville Spain
| | - Mª Luisa Buide
- Department of Molecular Biology and Biochemical Engineering Pablo de Olavide University Seville Spain
| | | | - Eduardo Narbona
- Department of Molecular Biology and Biochemical Engineering Pablo de Olavide University Seville Spain
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45
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Narbona E, Wang H, Ortiz PL, Arista M, Imbert E. Flower colour polymorphism in the Mediterranean Basin: occurrence, maintenance and implications for speciation. PLANT BIOLOGY (STUTTGART, GERMANY) 2018; 20 Suppl 1:8-20. [PMID: 28430395 DOI: 10.1111/plb.12575] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 04/18/2017] [Indexed: 05/20/2023]
Abstract
Flower colour polymorphism (FCP) is the occurrence of at least two discrete flower colour variants in the same population. Despite a vast body of research concerning the maintenance and evolutionary consequences of FCP, only recently has the spatial variation in morph frequencies among populations been explored. Here we summarise the biochemical and genetic basis of FCP, the factors that have been proposed to explain their maintenance, and the importance of FCP and its geographic variation in the speciation process. We also review the incidence of FCP in the environmentally heterogeneous Mediterranean Basin. Nearly 88% of Mediterranean FCP species showed anthocyanin-based polymorphisms. Concerning the evolutionary mechanisms that contribute to maintain FCP, selection by pollinators is suggested in some species, but in others, selection by non-pollinator agents, genetic drift or gene flow are also found; in some cases different processes interact in the maintenance of FCP. We emphasise the role of both autonomous selfing and clonal reproduction in FCP maintenance. Mediterranean polymorphic species show mainly monomorphic populations with only a few polymorphic ones, which generate clinal or mosaic patterns of variation in FCP. No cases of species with only polymorphic populations were found. We posit that different evolutionary processes maintaining polymorphism the Mediterranean Basin will result in a continuum of geographic patterns in morph compositions and relative frequencies of FCP species.
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Affiliation(s)
- E Narbona
- Departamento de Biología Molecular e Ingeniería Bioquímica, Universidad Pablo de Olavide, Sevilla, Spain
| | - H Wang
- College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
- Institut des Sciences de l'Évolution de Montpellier (ISEM), Université de Montpellier, Montpellier, France
| | - P L Ortiz
- Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Sevilla, Spain
| | - M Arista
- Departamento de Biología Vegetal y Ecología, Universidad de Sevilla, Sevilla, Spain
| | - E Imbert
- Institut des Sciences de l'Évolution de Montpellier (ISEM), Université de Montpellier, Montpellier, France
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van der Kooi CJ, Elzenga JTM, Dijksterhuis J, Stavenga DG. Functional optics of glossy buttercup flowers. J R Soc Interface 2017; 14:rsif.2016.0933. [PMID: 28228540 DOI: 10.1098/rsif.2016.0933] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 01/27/2017] [Indexed: 11/12/2022] Open
Abstract
Buttercup (Ranunculus spp.) flowers are exceptional because they feature a distinct gloss (mirror-like reflection) in addition to their matte-yellow coloration. We investigated the optical properties of yellow petals of several Ranunculus and related species using (micro)spectrophotometry and anatomical methods. The contribution of different petal structures to the overall visual signal was quantified using a recently developed optical model. We show that the coloration of glossy buttercup flowers is due to a rare combination of structural and pigmentary coloration. A very flat, pigment-filled upper epidermis acts as a thin-film reflector yielding the gloss, and additionally serves as a filter for light backscattered by the strongly scattering starch and mesophyll layers, which yields the matte-yellow colour. We discuss the evolution of the gloss and its two likely functions: it provides a strong visual signal to insect pollinators and increases the reflection of sunlight to the centre of the flower in order to heat the reproductive organs.
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Affiliation(s)
- Casper J van der Kooi
- Computational Physics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands .,Department of Ecology and Evolution, University of Lausanne, Le Biophore, 1015 Lausanne, Switzerland
| | - J Theo M Elzenga
- Plant Ecophysiology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Jan Dijksterhuis
- CBS-KNAW Fungal Biodiversity Centre, Uppsalalaan 8, 3508 AD Utrecht, The Netherlands
| | - Doekele G Stavenga
- Computational Physics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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47
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Disorder in convergent floral nanostructures enhances signalling to bees. Nature 2017; 550:469-474. [DOI: 10.1038/nature24285] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 09/19/2017] [Indexed: 11/09/2022]
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48
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Garcia JE, Spaethe J, Dyer AG. The path to colour discrimination is S-shaped: behaviour determines the interpretation of colour models. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2017; 203:983-997. [DOI: 10.1007/s00359-017-1208-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 08/09/2017] [Accepted: 08/10/2017] [Indexed: 10/18/2022]
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49
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van der Kooi CJ. Plant Biology: Flower Orientation, Temperature Regulation and Pollinator Attraction. Curr Biol 2016; 26:R1143-R1145. [PMID: 27825450 DOI: 10.1016/j.cub.2016.08.071] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The reproductive performance of plants depends on the temperature of the flower. A recent study reports the mechanistic basis of flower head orientation in sunflowers and provides intriguing hints as to its functional significance.
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Affiliation(s)
- Casper J van der Kooi
- University of Lausanne, Department of Ecology and Evolution, CH 1015 Lausanne, Switzerland.
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50
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Assessing the ecological significance of bee visual detection and colour discrimination on the evolution of flower colours. Evol Ecol 2016. [DOI: 10.1007/s10682-016-9843-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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