1
|
Trevizan R, Oliveira PE, Cardoso JCF. Investigating the longstanding mystery of stigma length differences between morphs of distylous plants. PLANT BIOLOGY (STUTTGART, GERMANY) 2024; 26:421-426. [PMID: 38315474 DOI: 10.1111/plb.13623] [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: 06/09/2023] [Accepted: 12/18/2023] [Indexed: 02/07/2024]
Abstract
Longer stigmas in short-styled morphs of distylous plants have been considered an adaptive characteristic that increases intermorph pollen deposition. The greater pollen deposition in short-styled stigmas may be a by-product of their longer length, making deposition effectiveness comparison between morphs unfeasible. Thus, investigating which morph has the relatively most efficient stigma (i.e., pollen deposition per unit length) can boost our understanding of the adaptive significance of longer stigmas. Here, we compared pollen deposition between morphs relative to stigma length and assessed whether short-styled stigmas are more, less, or equally effective in receiving pollen grains per unit length. We reviewed the literature to characterize the extent of sigma length differences between morphs using the two most speciose distylous genera as model systems: Palicourea and Psychotria (Rubiaceae). Then, we conducted a between-morph comparison of raw and relative pollen depositions in a Palicourea rigida population. We confirmed that short-styled stigmas were longer than long-styled stigmas in both Palicourea (194.31% longer) and Psychotria (52.59% longer) flowers. Furthermore, in the focal Pal. rigida, although short-styled stigmas were 268.04% longer and received 97.04% more pollen grains than long-styled stigmas, the relative pollen deposition had a reverse pattern, with short-styled stigmas being two-times less efficient in receiving pollen. Our results indicate that the longer length of the short-styled stigmas may have a compensatory effect, increasing the chances of pollen grains reaching the stigma and probably maintaining disassortative intermorph pollination in distylous plants.
Collapse
Affiliation(s)
- R Trevizan
- Instituto de Biologia, Universidade Estadual de Campinas, São Paulo, Brazil
| | - P E Oliveira
- Instituto de Biologia, Universidade Federal de Uberlândia, Campus Umuarama, Uberlândia, Minas Gerais, Brazil
| | - J C F Cardoso
- Instituto de Biologia, Universidade Federal de Uberlândia, Campus Umuarama, Uberlândia, Minas Gerais, Brazil
- Departamento de Biodiversidade Evolução e Meio Ambiente, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais, Brazil
| |
Collapse
|
2
|
Jiménez-López FJ, Arista M, Talavera M, Cerdeira Morellato LP, Pannell JR, Viruel J, Ortiz Ballesteros PL. Multiple pre- and postzygotic components of reproductive isolation between two co-occurring Lysimachia species. THE NEW PHYTOLOGIST 2023; 238:874-887. [PMID: 36683441 DOI: 10.1111/nph.18767] [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: 10/28/2022] [Accepted: 01/12/2023] [Indexed: 06/17/2023]
Abstract
Genetic divergence between species depends on reproductive isolation (RI) due to traits that reduce interspecific mating (prezygotic isolation) or are due to reduced hybrid fitness (postzygotic isolation). Previous research found that prezygotic barriers tend to be stronger than postzygotic barriers, but most studies are based on the evaluation of F1 hybrid fitness in early life cycle stages. We combined field and experimental data to determine the strength of 17 prezygotic and postzygotic reproductive barriers between two Lysimachia species that often co-occur and share pollinators. We assessed postzygotic barriers up to F2 hybrids and backcrosses. The two species showed near complete RI due to the cumulative effect of multiple barriers, with an uneven and asymmetric contribution to isolation. In allopatry, prezygotic barriers contributed more to reduce gene flow than postzygotic barriers, but their contributions were more similar in sympatry. The strength of postzygotic RI was up to three times lower for F1 progeny than for F2 or backcrossed progenies, and RI was only complete when late F1 stages and either F2 or backcrosses were accounted for. Our results thus suggest that the relative strength of postzygotic RI may be underestimated when its effects on late stages of the life cycle are disregarded.
Collapse
Affiliation(s)
- Francisco Javier Jiménez-López
- Department of Plant Biology and Ecology, Faculty of Biology, University of Seville, Apdo. 1095, 41080, Seville, Spain
- Phenology Lab, Department of Biodiversity, Biosciences Institute, UNESP - São Paulo State University, São Paulo, Brazil
| | - Montserrat Arista
- Department of Plant Biology and Ecology, Faculty of Biology, University of Seville, Apdo. 1095, 41080, Seville, Spain
| | - María Talavera
- Department of Plant Biology and Ecology, Faculty of Biology, University of Seville, Apdo. 1095, 41080, Seville, Spain
| | | | - John R Pannell
- Department of Ecology and Evolution, University of Lausanne, Lausanne, CH-1015, Switzerland
| | - Juan Viruel
- Royal Botanic Gardens, Kew, TW9 3DS, Richmond, UK
| | - Pedro L Ortiz Ballesteros
- Department of Plant Biology and Ecology, Faculty of Biology, University of Seville, Apdo. 1095, 41080, Seville, Spain
| |
Collapse
|
3
|
Opedal ØH, Hildesheim LS, Armbruster WS. Evolvability and constraint in the evolution of three-dimensional flower morphology. AMERICAN JOURNAL OF BOTANY 2022; 109:1906-1917. [PMID: 36371715 PMCID: PMC9827957 DOI: 10.1002/ajb2.16092] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 08/25/2022] [Accepted: 08/26/2022] [Indexed: 05/31/2023]
Abstract
PREMISE Flower phenotypes evolve to attract pollinators and to ensure efficient pollen transfer to and from the bodies of pollinators or, in self-compatible bisexual flowers, between anthers and stigmas. If functionally interacting traits are genetically correlated, response to selection may be subject to genetic constraints. Genetic constraints can be assessed by quantifying standing genetic variation in (multivariate) phenotypic traits and by asking how much the available variation is reduced under specific assumptions about phenotypic selection on functionally interacting and genetically correlated traits. METHODS We evaluated multivariate evolvability and potential genetic constraints underlying the evolution of the three-dimensional structure of Dalechampia blossoms. First, we used data from a greenhouse crossing design to estimate the G matrix for traits representing the relative positions of male and female sexual organs (anthers and stigmas) and used the G matrix to ask how genetic variation is distributed in multivariate space. To assess the evolutionary importance of genetic constraints, we related standing genetic variation across phenotypic space to evolutionary divergence of population and species in the same phenotypic directions. RESULTS Evolvabilities varied substantially across phenotype space, suggesting that certain traits or trait combinations may be subject to strong genetic constraint. Traits involved functionally in flower-pollinator fit and autonomous selfing exhibited considerable independent evolutionary potential, but population and species divergence tended to occur in phenotypic directions associated with greater-than-average evolvability. CONCLUSIONS These results are consistent with the hypothesis that genetic constraints can hamper joint trait evolution towards optimum flower-pollinator fit and optimum self-pollination rates.
Collapse
Affiliation(s)
| | | | - W. Scott Armbruster
- School of Biological SciencesUniversity of PortsmouthPortsmouthPO1 2DYUK
- Institute of Arctic BiologyUniversity of Alaska FairbanksFairbanksAK99775USA
| |
Collapse
|
4
|
Orsucci M, Sicard A. Flower evolution in the presence of heterospecific gene flow and its contribution to lineage divergence. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:971-989. [PMID: 33537708 DOI: 10.1093/jxb/eraa549] [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: 08/10/2020] [Accepted: 11/16/2020] [Indexed: 06/12/2023]
Abstract
The success of species depends on their ability to exploit ecological resources in order to optimize their reproduction. However, species are not usually found within single-species ecosystems but in complex communities. Because of their genetic relatedness, closely related lineages tend to cluster within the same ecosystem, rely on the same resources, and be phenotypically similar. In sympatry, they will therefore compete for the same resources and, in the case of flowering plants, exchange their genes through heterospecific pollen transfer. These interactions, nevertheless, pose significant challenges to species co-existence because they can lead to resource limitation and reproductive interference. In such cases, divergent selective pressures on floral traits will favour genotypes that isolate or desynchronize the reproduction of sympatric lineages. The resulting displacement of reproductive characters will, in turn, lead to pre-mating isolation and promote intraspecific divergence, thus initiating or reinforcing the speciation process. In this review, we discuss the current theoretical and empirical knowledge on the influence of heterospecific pollen transfer on flower evolution, highlighting its potential to uncover the ecological and genomic constraints shaping the speciation process.
Collapse
Affiliation(s)
- Marion Orsucci
- Department of Plant Biology, Swedish University of Agricultural, Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
| | - Adrien Sicard
- Department of Plant Biology, Swedish University of Agricultural, Sciences and Linnean Center for Plant Biology, Uppsala, Sweden
| |
Collapse
|
5
|
Sánchez-Cabrera M, Jiménez-López FJ, Narbona E, Arista M, Ortiz PL, Romero-Campero FJ, Ramanauskas K, Igić B, Fuller AA, Whittall JB. Changes at a Critical Branchpoint in the Anthocyanin Biosynthetic Pathway Underlie the Blue to Orange Flower Color Transition in Lysimachia arvensis. FRONTIERS IN PLANT SCIENCE 2021; 12:633979. [PMID: 33692818 PMCID: PMC7937975 DOI: 10.3389/fpls.2021.633979] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 02/01/2021] [Indexed: 05/27/2023]
Abstract
Anthocyanins are the primary pigments contributing to the variety of flower colors among angiosperms and are considered essential for survival and reproduction. Anthocyanins are members of the flavonoids, a broader class of secondary metabolites, of which there are numerous structural genes and regulators thereof. In western European populations of Lysimachia arvensis, there are blue- and orange-petaled individuals. The proportion of blue-flowered plants increases with temperature and daylength yet decreases with precipitation. Here, we performed a transcriptome analysis to characterize the coding sequences of a large group of flavonoid biosynthetic genes, examine their expression and compare our results to flavonoid biochemical analysis for blue and orange petals. Among a set of 140 structural and regulatory genes broadly representing the flavonoid biosynthetic pathway, we found 39 genes with significant differential expression including some that have previously been reported to be involved in similar flower color transitions. In particular, F3'5'H and DFR, two genes at a critical branchpoint in the ABP for determining flower color, showed differential expression. The expression results were complemented by careful examination of the SNPs that differentiate the two color types for these two critical genes. The decreased expression of F3'5'H in orange petals and differential expression of two distinct copies of DFR, which also exhibit amino acid changes in the color-determining substrate specificity region, strongly correlate with the blue to orange transition. Our biochemical analysis was consistent with the transcriptome data indicating that the shift from blue to orange petals is caused by a change from primarily malvidin to largely pelargonidin forms of anthocyanins. Overall, we have identified several flavonoid biosynthetic pathway loci likely involved in the shift in flower color in L. arvensis and even more loci that may represent the complex network of genetic and physiological consequences of this flower color polymorphism.
Collapse
Affiliation(s)
- Mercedes Sánchez-Cabrera
- Department of Plant Biology and Ecology, Faculty of Biology, University of Seville, Seville, Spain
| | | | - Eduardo Narbona
- Department of Molecular Biology and Biochemical Engineering, Pablo de Olavide University, Seville, Spain
| | - Montserrat Arista
- Department of Plant Biology and Ecology, Faculty of Biology, University of Seville, Seville, Spain
| | - Pedro L. Ortiz
- Department of Plant Biology and Ecology, Faculty of Biology, University of Seville, Seville, Spain
| | - Francisco J. Romero-Campero
- Institute for Plant Biochemistry and Photosynthesis, University of Seville – Centro Superior de Investigación Científica, Seville, Spain
- Department of Computer Science and Artificial Intelligence, University of Seville, Seville, Spain
| | - Karolis Ramanauskas
- Department of Biological Science, University of Illinois at Chicago, Chicago, IL, United States
| | - Boris Igić
- Department of Biological Science, University of Illinois at Chicago, Chicago, IL, United States
| | - Amelia A. Fuller
- Department of Chemistry and Biochemistry, Santa Clara University, Santa Clara, CA, United States
| | - Justen B. Whittall
- Department of Biology, College of Arts and Sciences, Santa Clara University, Santa Clara, CA, United States
| |
Collapse
|
6
|
Rodríguez-Castañeda NL, Ortiz PL, Arista M, Narbona E, Buide ML. Indirect Selection on Flower Color in Silene littorea. FRONTIERS IN PLANT SCIENCE 2020; 11:588383. [PMID: 33424884 PMCID: PMC7785944 DOI: 10.3389/fpls.2020.588383] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 11/25/2020] [Indexed: 05/07/2023]
Abstract
Flower color, as other floral traits, may suffer conflicting selective pressures mediated by both mutualists and antagonists. The maintenance of intraspecific flower color variability has been usually explained as a result of direct selection by biotic agents. However, flower color might also be under indirect selection through correlated traits, since correlations among flower traits are frequent. In this study, we aimed to find out how flower color variability is maintained in two nearby populations of Silene littorea that consistently differ in the proportions of white-flowered plants. To do that, we assessed natural selection on floral color and correlated traits by means of phenotypic selection analysis and path analysis. Strong directional selection on floral display and flower production was found in both populations through either male or female fitness. Flower color had a negative indirect effect on the total male and female fitness in Melide population, as plants with lighter corollas produced more flowers. In contrast, in Barra population, plants with darker corollas produced more flowers and have darker calices, which in turn were selected. Our results suggest that the prevalence of white-flowered plants in Melide and pink-flowered plants in Barra is a result of indirect selection through correlated flower traits and not a result of direct selection of either pollinators or herbivores on color.
Collapse
Affiliation(s)
| | - Pedro L. Ortiz
- Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Seville, Spain
| | - Montserrat Arista
- Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Seville, Spain
| | - Eduardo Narbona
- Departamento de Biología Molecular e Ingeniería Bioquímica, Universidad Pablo de Olavide, Seville, Spain
| | - Mª Luisa Buide
- Departamento de Biología Molecular e Ingeniería Bioquímica, Universidad Pablo de Olavide, Seville, Spain
| |
Collapse
|
7
|
Jiménez-López FJ, Ortiz PL, Talavera M, Arista M. Reproductive Assurance Maintains Red-Flowered Plants of Lysimachia arvensis in Mediterranean Populations Despite Inbreeding Depression. FRONTIERS IN PLANT SCIENCE 2020; 11:563110. [PMID: 33324430 PMCID: PMC7725749 DOI: 10.3389/fpls.2020.563110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Accepted: 10/28/2020] [Indexed: 06/12/2023]
Abstract
Flower color polymorphism, an infrequent but phylogenetically widespread condition in plants, is captivating because it can only be maintained under a few selective regimes but also because it can drive intra-morph assortative mating and promote speciation. Lysimachia arvensis is a polymorphic species with red or blue flowered morphs. In polymorphic populations, which are mostly Mediterranean, pollinators prefer blue-flowered plants to the red ones, and abiotic factors also favors blue-flowered plants. We hypothesize that the red morph is maintained in Mediterranean areas due to its selfing capacity. We assessed inbreeding depression in both color morphs in two Mediterranean populations and genetic diversity was studied via SSR microsatellites in 20 natural populations. Results showed that only 44-47% of selfed progeny of the red plants reached reproduction while about 72-91% of blue morph progeny did it. Between-morph genetic differentiation was high and the red morph had a lower genetic diversity and a higher inbreeding coefficient, mainly in the Mediterranean. Results suggest that selfing maintaining the red morph in Mediterranean areas despite its inbreeding depression. In addition, genetic differentiation between morphs suggests a low gene flow between them, suggesting reproductive isolation.
Collapse
Affiliation(s)
- Francisco J. Jiménez-López
- Departamento de Biología Vegetal y Ecología, Facultad de Biología, Universidad de Sevilla, Seville, Spain
| | | | | | | |
Collapse
|