1
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MacAulay S, Cable J. Gyrodactylus in the spotlight: how exposure to light impacts disease and the feeding behavior of the freshwater tropical guppy (Poecilia reticulata). JOURNAL OF FISH BIOLOGY 2024. [PMID: 38828698 DOI: 10.1111/jfb.15816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 05/07/2024] [Accepted: 05/13/2024] [Indexed: 06/05/2024]
Abstract
Artificial light at night (ALAN) negatively impacts organisms in many ways, from their feeding behaviors to their response and ability to deal with disease. Our knowledge of ALAN is focused on hosts, but we must also consider their parasites, which constitute half of all described animal species. Here, we assessed the impact of light exposure on a model host-parasite system (Poecilia reticulata and the ectoparasitic monogenean Gyrodactylus turnbulli). First, parasite-free fish were exposed to 12:12 h light:dark (control) or 24:0 h light:dark (ALAN) for 21 days followed by experimental infection. Second, naturally acquired G. turnbulli infections were monitored for 28 days during exposure of their hosts to a specified light regime (6:18 h, 12:12 h, or 24:0 h light:dark). Experimentally infected fish exposed to constant light had, on average, a greater maximum parasite burden than controls, but no other measured parasite metrics were impacted. Host feeding behavior was also significantly affected: fish under ALAN fed faster and took more bites than controls, whilst fish exposed to reduced light fed slower. Thus, ALAN can impact parasite burdens, even in the short term, and altering light conditions will impact fish feeding behavior. Such responses could initiate disease outbreaks or perturb food-webs with wider ecological impacts.
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Affiliation(s)
| | - Jo Cable
- School of Biosciences, Cardiff University, Cardiff, UK
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2
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Londoño-Lemos V, Torres-Gonzáles AM, Madriñán S. Linking Seed Traits and Germination Responses in Caribbean Seasonally Dry Tropical Forest Species. PLANTS (BASEL, SWITZERLAND) 2024; 13:1318. [PMID: 38794387 PMCID: PMC11124875 DOI: 10.3390/plants13101318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 03/28/2024] [Accepted: 04/18/2024] [Indexed: 05/26/2024]
Abstract
Understanding the relationships between seed traits and germination responses is crucial for assessing natural regeneration, particularly in threatened ecosystems like the seasonally dry tropical forest (SDTF). This study explored links between seed traits (mass, volume, moisture content, and dispersal type), germination responses (germinability, germination speed (v¯), time to 50% of germination (T50), synchrony, and photoblastism), and physical dormancy (PY) in 65 SDTF species under experimental laboratory conditions. We found that species with smaller seeds (low mass and volume) had higher v¯ and reached T50 faster than species with larger seeds. For moisture content, species with lower moisture content had higher germinability and reached the T50 faster than seeds with high moisture content. Abiotic dispersed species germinated faster and reached the T50 in fewer days. Most of the SDTF species (60%) did not present PY, and the presence of PY was associated with seeds with lower moisture content. As for photoblastism (germination sensitivity to light), we classified the species into three ecological categories: generalists (42 species, non-photoblastic), heliophytes (18 species, positive photoblastic, germination inhibited by darkness), and sciadophytes (5 species, negative photoblastic, light inhibited germination). This study intends to be a baseline for the study of seed ecophysiology in the SDTF.
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Affiliation(s)
- Viviana Londoño-Lemos
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN 55108, USA;
- Jardín Botánico de Cartagena “Guillermo Piñeres”, Bolívar 131007, Colombia
| | | | - Santiago Madriñán
- Jardín Botánico de Cartagena “Guillermo Piñeres”, Bolívar 131007, Colombia
- Departamento de Ciencias Biológicas, Universidad de los Andes, Bogotá 111711, Colombia
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3
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Huang Y, Mei G, Zhu K, Ruan X, Wu H, Cao D. Shading treatment during late stage of seed development promotes subsequent seed germination and seedlings establishment in sunflower. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2024; 341:111996. [PMID: 38272070 DOI: 10.1016/j.plantsci.2024.111996] [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: 09/05/2023] [Revised: 01/15/2024] [Accepted: 01/21/2024] [Indexed: 01/27/2024]
Abstract
During the sunflower seed production process, the role of artificial shading treatment (ST) in seed development and subsequent seed germination remains largely unknown. In the present study, sunflower mother plants were artificially shaded during 1-34 (full period-ST, FST), 1-22 (early period-ST, EST), and 22-34 (late period-ST, LST) days after pollination (DAP), to examine the effects of parental shading on subsequent seed germination. Both FST and EST significantly reduced the photosynthetic efficiency of sunflower, manifested as decreased seed dry weight and unfavorable seed germination. On the contrary, LST remarkably increased seed dry weight and promoted subsequent seed germination and seedling establishment. LST enhanced the activities of several key enzymes involved in triglyceride anabolism and corresponding-genes expression, which in turn increased the total fatty acid contents and altered the fatty acid composition. During early germination, the key enzyme activities involved in triglyceride disintegration and corresponding-gene expressions in LST seeds were apparently higher than those in seeds without the shading treatment (WST). Consistently, LST seeds had significant higher contents of ATP and soluble sugar. Moreover, enzyme activities related to abscisic acid (ABA) biosynthesis and corresponding gene expressions decreased within LST seeds, whereas the enzyme activities and corresponding gene expressions associated with gibberellin (GA) biosynthesis were increased. These results were also evidenced by the reduced ABA content but elevated GA level within LST seeds, giving rise to higher GA/ABA ratio. Our findings suggested that LST could promote sunflower seed development and subsequent seed germination as well as seedling establishment through modulating the dynamic metabolism of triglycerides, fatty acid and GA/ABA balance.
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Affiliation(s)
- Yutao Huang
- Institute of Crop and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Sciences, 310021 Hangzhou, China
| | - Gaofu Mei
- Institute of Crop and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Sciences, 310021 Hangzhou, China
| | - Kehua Zhu
- Institute of Crop and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Sciences, 310021 Hangzhou, China
| | - Xiaoli Ruan
- Zhejiang Nongke Seed Co.Ltd, 310021 Hangzhou, China
| | - Huaping Wu
- Huzhou Keao Seed Co.Ltd, 313000 Huzhou 313000, China
| | - Dongdong Cao
- Institute of Crop and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Sciences, 310021 Hangzhou, China.
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4
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Pi K, Luo J, Lu A, Chen G, Long B, Zhang J, Mo Z, Duan L, Liu R. Negative regulation of tobacco cold stress tolerance by NtPhyA. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2023; 204:108153. [PMID: 37931558 DOI: 10.1016/j.plaphy.2023.108153] [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: 07/21/2023] [Revised: 10/12/2023] [Accepted: 10/30/2023] [Indexed: 11/08/2023]
Abstract
Cold stress is a non-biological stressor that adversely affects tobacco yield and leaf quality. Plant photoreceptor proteins, which function as dual light-temperature sensors, play a vital role in temperature changes, making them crucial for responses to non-biological stressors. However, the regulatory mechanisms of PhyA in tobacco remain poorly understood. Therefore, in this study, we aimed to clone the NtPhyA gene from tobacco and generate overexpression (OE-NtPhyA) and mutant (KO-NtPhyA) constructs of NtPhyA. By assessing the physiological and biochemical responses of the mutants under cold stress and performing transcriptome sequencing, we determined the signalling mechanism of NtPhyA under cold stress. Comparative analysis with wild-type (WT) NtPhyA revealed that KO-NtPhyA exhibited increased seed germination rates and reduced wilting under cold stress. In additional, the degree of damage to leaf cells, cell membranes, and stomatal structures was mitigated, and the levels of reactive oxygen species (ROS) were significantly decreased. Antioxidant enzyme activity, net photosynthetic rate, and Fv/Fm were significantly enhanced in KO-NtPhyA, whereas the opposite effects were observed in OE-NtPhyA. These findings indicate that KO-NtPhyA augments tobacco tolerance to cold stress, implying a negative regulatory role of NtPhyA in tobacco during cold stress. Transcriptome analysis revealed that NtPhyA governs the expression of a cascade of genes involved in the response to oxygen-containing compounds, hydrogen peroxide (H2O2), ROS, temperature stimuli, photosystem II oxygen-evolving complex assembly, water channel activity, calcium channel activity, and carbohydrate transport. Collectively, our findings indicate that NtPhyA activates downstream gene expression to enhance the resilience of tobacco to cold stress.
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Affiliation(s)
- Kai Pi
- College of Tobacco, Guizhou University, Guiyang, 550025, PR China; Key Laboratory for Tobacco Quality Research Guizhou Province, Guizhou University, Guiyang, 550025, PR China
| | - Jiajun Luo
- College of Tobacco, Guizhou University, Guiyang, 550025, PR China; Key Laboratory for Tobacco Quality Research Guizhou Province, Guizhou University, Guiyang, 550025, PR China
| | - Anbin Lu
- College of Tobacco, Guizhou University, Guiyang, 550025, PR China; Key Laboratory for Tobacco Quality Research Guizhou Province, Guizhou University, Guiyang, 550025, PR China
| | - Gang Chen
- College of Agriculture, Guizhou University, Guiyang, 550025, PR China
| | - Benshan Long
- College of Tobacco, Guizhou University, Guiyang, 550025, PR China; Key Laboratory for Tobacco Quality Research Guizhou Province, Guizhou University, Guiyang, 550025, PR China
| | - Jingyao Zhang
- College of Tobacco, Guizhou University, Guiyang, 550025, PR China; Key Laboratory for Tobacco Quality Research Guizhou Province, Guizhou University, Guiyang, 550025, PR China
| | - Zejun Mo
- College of Tobacco, Guizhou University, Guiyang, 550025, PR China; Key Laboratory for Tobacco Quality Research Guizhou Province, Guizhou University, Guiyang, 550025, PR China; College of Agriculture, Guizhou University, Guiyang, 550025, PR China
| | - Lili Duan
- College of Tobacco, Guizhou University, Guiyang, 550025, PR China; Key Laboratory for Tobacco Quality Research Guizhou Province, Guizhou University, Guiyang, 550025, PR China; College of Agriculture, Guizhou University, Guiyang, 550025, PR China
| | - Renxiang Liu
- College of Tobacco, Guizhou University, Guiyang, 550025, PR China; Key Laboratory for Tobacco Quality Research Guizhou Province, Guizhou University, Guiyang, 550025, PR China.
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5
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Ren M, Liu S, Tang C, Mao G, Gai P, Guo X, Zheng H, Tang Q. Photomorphogenesis and Photosynthetic Traits Changes in Rice Seedlings Responding to Red and Blue Light. Int J Mol Sci 2023; 24:11333. [PMID: 37511093 PMCID: PMC10378807 DOI: 10.3390/ijms241411333] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2023] [Revised: 07/05/2023] [Accepted: 07/10/2023] [Indexed: 07/30/2023] Open
Abstract
The purpose of this study is to determine the effects of red and blue lights on the photomorphogenesis and photosynthetic traits of rice seedlings. The rice seedlings were cultured with red light (R), blue light (B), combined red and blue lights (R3B1/R1B1/R1B3), and white light (CK) as the control. The combined application of red and blue lights could promote the growth of rice seedlings to varying degrees; enhance photosynthesis by increasing the seedling leaf area, chlorophyll content, and chlorophyll fluorescence; improve root characteristics by increasing root number, root volume, and root activity; and thus increase the dry matter accumulation of rice seedlings. In addition, the combination of red and blue lights could regulate the expression of genes related to photosynthesis in rice leaves, affect the activity of the Rubisco enzyme, and then affect the photosynthesis of rice seedlings. These results indicate that red and blue lights have direct synergistic effects, which can regulate the growth of rice seedlings and promote the morphogenesis of rice seedlings. The combined application of red and blue lights can be used to supplement the light in rice-factory seedling raising.
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Affiliation(s)
- Maofei Ren
- College of Agronomy, Hunan Agricultural University, Changsha 410128, China
| | - Shanzhen Liu
- College of Agronomy, Hunan Agricultural University, Changsha 410128, China
| | - Chengzhu Tang
- College of Agronomy, Hunan Agricultural University, Changsha 410128, China
| | - Guiling Mao
- College of Horticulture, Shanxi Agricultural University, Jinzhong 030801, China
| | - Panpan Gai
- College of Agronomy, Hunan Agricultural University, Changsha 410128, China
| | - Xiaoli Guo
- College of Agronomy, Henan Agricultural University, Zhengzhou 450046, China
| | - Huabin Zheng
- College of Agronomy, Hunan Agricultural University, Changsha 410128, China
| | - Qiyuan Tang
- College of Agronomy, Hunan Agricultural University, Changsha 410128, China
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6
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Naze M, Riviere JNE, Chiroleu F, Franck A, Fock-Bastide I. Seed germination of five species from the subalpine shrubland of a mountainous oceanic island with high conservation value (Reunion Island). Glob Ecol Conserv 2022. [DOI: 10.1016/j.gecco.2022.e02269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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7
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Geshnizjani N, Snoek BL, Willems LAJ, Rienstra JA, Nijveen H, Hilhorst HWM, Ligterink W. Detection of QTLs for genotype × environment interactions in tomato seeds and seedlings. PLANT, CELL & ENVIRONMENT 2020; 43:1973-1988. [PMID: 32419153 PMCID: PMC7496158 DOI: 10.1111/pce.13788] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 04/01/2020] [Accepted: 05/12/2020] [Indexed: 05/17/2023]
Abstract
Seed quality and seedling establishment are the most important factors affecting successful crop development. They depend on the genetic background and are acquired during seed maturation and therefor, affected by the maternal environment under which the seeds develop. There is little knowledge about the genetic and environmental factors that affect seed quality and seedling establishment. The aim of this study is to identify the loci and possible molecular mechanisms involved in acquisition of seed quality and how these are controlled by adverse maternal conditions. For this, we used a tomato recombinant inbred line (RIL) population consisting of 100 lines which were grown under two different nutritional environmental conditions, high phosphate and low nitrate. Most of the seed germination traits such as maximum germination percentage (Gmax ), germination rate (t50 ) and uniformity (U8416 ) showed ample variation between genotypes and under different germination conditions. This phenotypic variation leads to identification of quantitative trait loci (QTLs) which were dependent on genetic factors, but also on the interaction with the maternal environment (QTL × E). Further studies of these QTLs may ultimately help to predict the effect of different maternal environmental conditions on seed quality and seedling establishment which will be very useful to improve the production of high-performance seeds.
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Affiliation(s)
- Nafiseh Geshnizjani
- Wageningen Seed Lab, Laboratory of Plant PhysiologyWageningen UniversityWageningenThe Netherlands
| | - Basten L. Snoek
- Theoretical Biology and BioinformaticsUtrecht UniversityUtrechtThe Netherlands
- Laboratory of NematologyWageningen UniversityWageningenThe Netherlands
| | - Leo A. J. Willems
- Wageningen Seed Lab, Laboratory of Plant PhysiologyWageningen UniversityWageningenThe Netherlands
| | - Juriaan A. Rienstra
- Wageningen Seed Lab, Laboratory of Plant PhysiologyWageningen UniversityWageningenThe Netherlands
| | - Harm Nijveen
- Bioinformatics GroupWageningen UniversityWageningenThe Netherlands
| | - Henk W. M. Hilhorst
- Wageningen Seed Lab, Laboratory of Plant PhysiologyWageningen UniversityWageningenThe Netherlands
| | - Wilco Ligterink
- Wageningen Seed Lab, Laboratory of Plant PhysiologyWageningen UniversityWageningenThe Netherlands
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8
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El-Keblawy A, Soliman S, Al-Khoury R, Ghauri A, Al Rammah H, Hussain SE, Rashid S, Manzoor Z. Effect of maturation conditions on light and temperature requirements during seed germination of Citrullus colocynthis from the Arabian Desert. PLANT BIOLOGY (STUTTGART, GERMANY) 2019; 21:292-299. [PMID: 30311346 DOI: 10.1111/plb.12923] [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: 09/20/2017] [Accepted: 10/07/2018] [Indexed: 06/08/2023]
Abstract
Seed germination of Citrullus colocynthis, as in many other species of Cucurbitaceae, is inhibited by light, particularly at low temperatures. Germination response to light and temperature has been attributed to day length and temperature during seed maturation. This study assessed the effects of these factors on the germination response of C. colocynthis to temperature and light quality. Ripe fruits were collected from natural habitats during December and February and germinated at three temperatures (15/25, 20/30 and 25/35 °C) in five light treatments (dark, white light and Red:Far Red (R:FR) ratios of 0.30, 0.87 and 1.19). Additionally, unripe fruits were also collected from natural habitats and completed their maturation in growth chambers under different day lengths (6, 16 and 24 h of darkness) at 10/20 °C, and in darkness at both 10/20 °C and 25/35 °C. Mature seeds of the different treatments were germinated in the same five light treatments at 15/25 °C. Germination was significantly higher in the dark than that in any light treatment. Seeds matured at higher temperatures (i.e. seeds from the December collection and those matured at 25/35 °C) had significantly higher germination than those matured at lower temperatures (i.e. seeds from the February collection and those matured at 10/20 °C). Dark germination was significantly higher for the December collection than for the February collection. Seeds of the two collections germinated in the dark only at 15/25 °C. However, seeds matured in a growth chamber at 10/20 °C in darkness germinated at 15/25 °C in all light treatments, except for the R:FR ratio 0.30. Seeds of the different treatments failed to germinate in FR-rich light. This study demonstrates that both temperature and day length during seed maturation play significant roles in the germination response of C. colocynthis. Additionally, the dark requirement for germination is likely beneficial for species with the larger seeds, such as C. colocynthis, which produce bigger seedlings that are able to emerge from deep soils and are competitively superior under dense vegetation and resource-limited conditions.
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Affiliation(s)
- A El-Keblawy
- Department of Biology, Faculty of Science, Al-Arish University, Al-Arish, Egypt
| | - S Soliman
- Department of Medicinal Chemistry, College of Pharmacy, University of Sharjah, Sharjah, UAE
| | - R Al-Khoury
- Department of Applied Biology, Faculty of Science, University of Sharjah, Sharjah, UAE
| | - A Ghauri
- Department of Applied Biology, Faculty of Science, University of Sharjah, Sharjah, UAE
| | - H Al Rammah
- Department of Applied Biology, Faculty of Science, University of Sharjah, Sharjah, UAE
| | - S E Hussain
- Department of Applied Biology, Faculty of Science, University of Sharjah, Sharjah, UAE
| | - S Rashid
- Department of Applied Biology, Faculty of Science, University of Sharjah, Sharjah, UAE
| | - Z Manzoor
- Department of Applied Biology, Faculty of Science, University of Sharjah, Sharjah, UAE
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9
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Susila H, Nasim Z, Ahn JH. Ambient Temperature-Responsive Mechanisms Coordinate Regulation of Flowering Time. Int J Mol Sci 2018; 19:ijms19103196. [PMID: 30332820 PMCID: PMC6214042 DOI: 10.3390/ijms19103196] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 10/09/2018] [Accepted: 10/13/2018] [Indexed: 12/23/2022] Open
Abstract
In plants, environmental conditions such as temperature affect survival, growth, and fitness, particularly during key stages such as seedling growth and reproduction. To survive and thrive in changing conditions, plants have evolved adaptive responses that tightly regulate developmental processes such as hypocotyl elongation and flowering time in response to environmental temperature changes. Increases in temperature, coupled with increasing fluctuations in local climate and weather, severely affect our agricultural systems; therefore, understanding the mechanisms by which plants perceive and respond to temperature is critical for agricultural sustainability. In this review, we summarize recent findings on the molecular mechanisms of ambient temperature perception as well as possible temperature sensing components in plants. Based on recent publications, we highlight several temperature response mechanisms, including the deposition and eviction of histone variants, DNA methylation, alternative splicing, protein degradation, and protein localization. We discuss roles of each proposed temperature-sensing mechanism that affects plant development, with an emphasis on flowering time. Studies of plant ambient temperature responses are advancing rapidly, and this review provides insights for future research aimed at understanding the mechanisms of temperature perception and responses in plants.
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Affiliation(s)
- Hendry Susila
- Department of Life Sciences, Korea University, Seoul 02841, Korea.
| | - Zeeshan Nasim
- Department of Life Sciences, Korea University, Seoul 02841, Korea.
| | - Ji Hoon Ahn
- Department of Life Sciences, Korea University, Seoul 02841, Korea.
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10
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Fernández-Pascual E, Mattana E, Pritchard HW. Seeds of future past: climate change and the thermal memory of plant reproductive traits. Biol Rev Camb Philos Soc 2018; 94:439-456. [PMID: 30188004 DOI: 10.1111/brv.12461] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 07/30/2018] [Accepted: 08/02/2018] [Indexed: 01/21/2023]
Abstract
Plant persistence and migration in face of climate change depends on successful reproduction by seed, a central aspect of plant life that drives population dynamics, community assembly and species distributions. Plant reproduction by seed is a chain of physiological processes, the rates of which are a function of temperature, and can be modelled using thermal time models. Importantly, while seed reproduction responds to its instantaneous thermal environment, there is also evidence of phenotypic plasticity in response to the thermal history experienced by the plant's recent ancestors, by the reproducing plant since seedling establishment, and by its seeds both before and after their release. This phenotypic plasticity enables a thermal memory of plant reproduction, which allows individuals to acclimatise to their surroundings. This review synthesises current knowledge on the thermal memory of plant reproduction by seed, and highlights its importance for modelling approaches based on physiological thermal time. We performed a comprehensive search in the Web of Science and analysed 533 relevant articles, of which 81 provided material for a meta-analysis of thermal memory in reproductive functional traits based on the effect size Zr. The articles encompassed the topics of seed development, seed yield (mass and number), seed dormancy (physiological, morphological and physical), germination, and seedling establishment. The results of the meta-analysis provide evidence for a thermal memory of seed yield, physiological dormancy and germination. Seed mass and physiological dormancy appear to be the central hubs of this memory. We argue for integrating thermal memory into a predictive framework based on physiological time modelling. This will provide a quantitative assessment of plant reproduction, a complex system that integrates past and present thermal inputs to achieve successful reproduction in changing environments. The effects of a warming environment on plant reproduction cannot be reduced to a qualitative interpretation of absolute positives and negatives. Rather, these effects need to be understood in terms of changing rates and thresholds for the physiological process that underlie reproduction by seed.
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Affiliation(s)
- Eduardo Fernández-Pascual
- Comparative Plant and Fungal Biology, Royal Botanic Gardens, Kew; Wellcome Trust Millennium Building, Wakehurst Place, Ardingly, West Sussex, RH17 6TN, U.K.,Departamento de Biología de Organismos y Sistemas, Universidad de Oviedo; C/ Catedrático Rodrigo Uría, 33006, Oviedo/Uviéu, Spain
| | - Efisio Mattana
- Natural Capital and Plant Health, Royal Botanic Gardens, Kew; Wellcome Trust Millennium Building, Wakehurst Place, Ardingly, West Sussex, RH17 6TN, U.K
| | - Hugh W Pritchard
- Comparative Plant and Fungal Biology, Royal Botanic Gardens, Kew; Wellcome Trust Millennium Building, Wakehurst Place, Ardingly, West Sussex, RH17 6TN, U.K
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11
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Lymperopoulos P, Msanne J, Rabara R. Phytochrome and Phytohormones: Working in Tandem for Plant Growth and Development. FRONTIERS IN PLANT SCIENCE 2018; 9:1037. [PMID: 30100912 PMCID: PMC6072860 DOI: 10.3389/fpls.2018.01037] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 06/26/2018] [Indexed: 05/07/2023]
Abstract
Being sessile organisms, plants need to continually adapt and modulate their rate of growth and development in accordance with the changing environmental conditions, a phenomenon referred to as plasticity. Plasticity in plants is a highly complex process that involves a well-coordinated interaction between different signaling pathways, the spatiotemporal involvement of phytohormones and cues from the environment. Though research studies are being carried out over the years to understand how plants perceive the signals from changing environmental conditions and activate plasticity, such remain a mystery to be resolved. Among all environmental cues, the light seems to be the stand out factor influencing plant growth and development. During the course of evolution, plants have developed well-equipped signaling system that enables regulation of both quantitative and qualitative differences in the amount of perceived light. Light influences essential developmental switches in plants ranging from germination or transition to flowering, photomorphogenesis, as well as switches in response to shade avoidances and architectural changes occurring during phototropism. Abscisic acid (ABA) is controlling seed germination and is regulated by light. Furthermore, circadian clock adds another level of regulation to plant growth by integrating light signals with different hormonal pathways. MYB96 has been identified as a regulator of circadian gating of ABA-mediated responses in plants by binding to the TIMING OF CAB EXPRESSION 1(TOC1) promoter. This review will present a representative regulatory model, highlight the successes achieved in employing novel strategies to dissect the levels of interaction and provide perspective for future research on phytochrome-phytohormones relationships toward facilitating plant growth, development, and function under abiotic-biotic stresses.
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Affiliation(s)
| | - Joseph Msanne
- New Mexico Consortium, Los Alamos, NM, United States
| | - Roel Rabara
- New Mexico Consortium, Los Alamos, NM, United States
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12
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Vayda K, Donohue K, Auge GA. Within- and trans-generational plasticity: seed germination responses to light quantity and quality. AOB PLANTS 2018; 10:ply023. [PMID: 29770181 PMCID: PMC5951028 DOI: 10.1093/aobpla/ply023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 04/08/2018] [Indexed: 05/28/2023]
Abstract
Plants respond not only to the environment in which they find themselves, but also to that of their parents. The combination of within- and trans-generational phenotypic plasticity regulates plant development. Plants use light as source of energy and also as a cue of competitive conditions, since the quality of light (ratio of red to far-red light, R:FR) indicates the presence of neighbouring plants. Light regulates many aspects of plant development, including seed germination. To understand how seeds integrate environmental cues experienced at different times, we quantified germination responses to changes in light quantity (irradiance) and quality (R:FR) experienced during seed maturation and seed imbibition in Arabidopsis thaliana genotypes that differ in their innate dormancy levels and after treatments that break or reinduce dormancy. In two of the genotypes tested, reduced irradiance as well as reduced R:FR during seed maturation induced higher germination; thus, the responses to light quantity and R:FR reinforced each other. In contrast, in a third genotype, reduced irradiance during seed maturation induced progeny germination, but response to reduced R:FR was in the opposite direction, leading to a very weak or no overall effect of a simulated canopy experienced by the mother plant. During seed imbibition, reduced irradiance and reduced R:FR caused lower germination in all genotypes. Therefore, responses to light experienced at different times (maturation vs. imbibition) can have opposite effects. In summary, seeds responded both to light resources (irradiance) and to cues of competition (R:FR), and trans-generational plasticity to light frequently opposed and was stronger than within-generation plasticity.
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13
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Viczián A, Klose C, Ádám É, Nagy F. New insights of red light-induced development. PLANT, CELL & ENVIRONMENT 2017; 40:2457-2468. [PMID: 27943362 DOI: 10.1111/pce.12880] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 12/04/2016] [Accepted: 12/05/2016] [Indexed: 05/14/2023]
Abstract
The red/far-red light absorbing photoreceptors phytochromes regulate development and growth and thus play an essential role in optimizing adaptation of the sessile plants to the ever-changing environment. Our understanding of how absorption of a red/far-red photon by phytochromes initiates/modifies diverse physiological responses has been steadily improving. Research performed in the last 5 years has been especially productive and led to significant conceptual changes about the mode of action of these photoreceptors. In this review, we focus on the phytochrome B photoreceptor, the major phytochrome species active in light-grown plants. We discuss how its light-independent inactivation (termed dark/thermal reversion), post-translational modification, including ubiquitination, phosphorylation and sumoylation, as well as heterodimerization with other phytochrome species modify red light-controlled physiological responses. Finally, we discuss how photobiological properties of phytochrome B enable this photoreceptor to function also as a thermosensor.
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Affiliation(s)
- András Viczián
- Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, H-6726, Szeged, Hungary
| | - Cornelia Klose
- Institute of Biology2/Botany, University of Freiburg, Schänzlestrasse 1, D-79104, Freiburg, Germany
| | - Éva Ádám
- Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, H-6726, Szeged, Hungary
| | - Ferenc Nagy
- Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, Temesvári krt. 62, H-6726, Szeged, Hungary
- Institute of Molecular Plant Science, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3JH, UK
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Mawphlang OIL, Kharshiing EV. Photoreceptor Mediated Plant Growth Responses: Implications for Photoreceptor Engineering toward Improved Performance in Crops. FRONTIERS IN PLANT SCIENCE 2017; 8:1181. [PMID: 28744290 PMCID: PMC5504655 DOI: 10.3389/fpls.2017.01181] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 06/20/2017] [Indexed: 05/18/2023]
Abstract
Rising temperatures during growing seasons coupled with altered precipitation rates presents a challenging task of improving crop productivity for overcoming such altered weather patterns and cater to a growing population. Light is a critical environmental factor that exerts a powerful influence on plant growth and development ranging from seed germination to flowering and fruiting. Higher plants utilize a suite of complex photoreceptor proteins to perceive surrounding red/far-red (phytochromes), blue/UV-A (cryptochromes, phototropins, ZTL/FKF1/LKP2), and UV-B light (UVR8). While genomic studies have also shown that light induces extensive reprogramming of gene expression patterns in plants, molecular genetic studies have shown that manipulation of one or more photoreceptors can result in modification of agronomically beneficial traits. Such information can assist researchers to engineer photoreceptors via genome editing technologies to alter expression or even sensitivity thresholds of native photoreceptors for targeting aspects of plant growth that can confer superior agronomic value to the engineered crops. Here we summarize the agronomically important plant growth processes influenced by photoreceptors in crop species, alongwith the functional interactions between different photoreceptors and phytohormones in regulating these responses. We also discuss the potential utility of synthetic biology approaches in photobiology for improving agronomically beneficial traits of crop plants by engineering designer photoreceptors.
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Leverett LD, Auge GA, Bali A, Donohue K. Contrasting germination responses to vegetative canopies experienced in pre- vs. post-dispersal environments. ANNALS OF BOTANY 2016; 118:1175-1186. [PMID: 27551028 PMCID: PMC5091727 DOI: 10.1093/aob/mcw166] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 06/24/2016] [Indexed: 05/08/2023]
Abstract
BACKGROUND Seeds adjust their germination based on conditions experienced before and after dispersal. Post-dispersal cues are expected to be more accurate predictors of offspring environments, and thus offspring success, than pre-dispersal cues. Therefore, germination responses to conditions experienced during seed maturation may be expected to be superseded by responses to conditions experienced during seed imbibition. In taxa of disturbed habitats, neighbours frequently reduce the performance of germinants. This leads to the hypotheses that a vegetative canopy will reduce germination in such taxa, and that a vegetative canopy experienced during seed imbibition will over-ride germination responses to a canopy experienced during seed maturation, since it is a more proximal cue of immediate competition. These hypotheses were tested here in Arabidopsis thaliana METHODS: Seeds were matured under a simulated canopy (green filter) or white light. Fresh (dormant) seeds were imbibed in the dark, white light or canopy at two temperatures (10 or 22 °C), and germination proportions were recorded. Germination was also recorded in after-ripened (less dormant) seeds that were induced into secondary dormancy and imbibed in the dark at each temperature, either with or without brief exposure to red and far-red light. KEY RESULTS Unexpectedly, a maturation canopy expanded the conditions that elicited germination, even as seeds lost and regained dormancy. In contrast, an imbibition canopy impeded or had no effect on germination. Maturation under a canopy did not modify germination responses to red and far-red light. Seed maturation under a canopy masked genetic variation in germination. CONCLUSIONS The results challenge the hypothesis that offspring will respond more strongly to their own environment than to that of their parents. The observed relaxation of germination requirements caused by a maturation canopy could be maladaptive for offspring by disrupting germination responses to light cues after dispersal. Alternatively, reduced germination requirements could be adaptive by allowing seeds to germinate faster and reduce competition in later stages even though competition is not yet present in the seedling environment. The masking of genetic variation by maturation under a canopy, moreover, could impede evolutionary responses to selection on germination.
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Affiliation(s)
- Lindsay D Leverett
- University Program in Ecology, Duke University, Durham, NC 27708, USA Department of Biology, Duke University, Durham, NC 27708, USA
| | - Gabriela A Auge
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - Aman Bali
- Department of Biology, Duke University, Durham, NC 27708, USA
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Roig-Villanova I, Martínez-García JF. Plant Responses to Vegetation Proximity: A Whole Life Avoiding Shade. FRONTIERS IN PLANT SCIENCE 2016; 7:236. [PMID: 26973679 PMCID: PMC4770057 DOI: 10.3389/fpls.2016.00236] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 02/12/2016] [Indexed: 05/20/2023]
Abstract
In high density of vegetation, plants detect neighbors by perceiving changes in light quality through phytochrome photoreceptors. Close vegetation proximity might result in competition for resources, such as light. To face this challenge, plants have evolved two alternative strategies: to either tolerate or avoid shade. Shade-avoiding species generally adapt their development by inducing hypocotyl, stem, and petiole elongation, apical dominance and flowering, and decreasing leaf expansion and yield, a set of responses collectively known as the shade avoidance syndrome (SAS). The SAS responses have been mostly studied at the seedling stage, centered on the increase of hypocotyl elongation. After compiling the main findings about SAS responses in seedlings, this review is focused on the response to shade at adult stages of development, such as petioles of adult leaves, and the little information available on the SAS responses in reproductive tissues. We discuss these responses based on the knowledge about the molecular mechanisms and components with a role in regulating the SAS response of the hypocotyls of Arabidopsis thaliana. The transcriptional networks involved in this process, as well as the communication among the tissues that perceive the shade and the ones that respond to this stimulus will also be briefly commented.
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Affiliation(s)
- Irma Roig-Villanova
- Centre for Research in Agricultural Genomics (CRAG), Consejo Superior de Investigaciones Científicas – Institut Recerca i Tecnologia Agroalimentaries – Universitat Autònoma de Barcelona – Universitat de BarcelonaBarcelona, Spain
- *Correspondence: Irma Roig-Villanova, ; Jaime F. Martínez-García,
| | - Jaime F. Martínez-García
- Centre for Research in Agricultural Genomics (CRAG), Consejo Superior de Investigaciones Científicas – Institut Recerca i Tecnologia Agroalimentaries – Universitat Autònoma de Barcelona – Universitat de BarcelonaBarcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA)Barcelona, Spain
- *Correspondence: Irma Roig-Villanova, ; Jaime F. Martínez-García,
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Gururani MA, Venkatesh J, Ganesan M, Strasser RJ, Han Y, Kim JI, Lee HY, Song PS. In Vivo Assessment of Cold Tolerance through Chlorophyll-a Fluorescence in Transgenic Zoysiagrass Expressing Mutant Phytochrome A. PLoS One 2015; 10:e0127200. [PMID: 26010864 PMCID: PMC4444231 DOI: 10.1371/journal.pone.0127200] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 04/13/2015] [Indexed: 01/06/2023] Open
Abstract
Chlorophyll-a fluorescence analysis provides relevant information about the physiology of plants growing under abiotic stress. In this study, we evaluated the influence of cold stress on the photosynthetic machinery of transgenic turfgrass, Zoysia japonica, expressing oat phytochrome A (PhyA) or a hyperactive mutant phytochrome A (S599A) with post-translational phosphorylation blocked. Biochemical analysis of zoysiagrass subjected to cold stress revealed reduced levels of hydrogen peroxide, increased proline accumulation, and enhanced specific activities of antioxidant enzymes compared to those of control plants. Detailed analyses of the chlorophyll-a fluorescence data through the so-called OJIP test exhibited a marked difference in the physiological status among transgenic and control plants. Overall, these findings suggest an enhanced level of cold tolerance in S599A zoysiagrass cultivars as reflected in the biochemical and physiological analyses. Further, we propose that chlorophyll-a fluorescence analysis using OJIP test is an efficient tool in determining the physiological status of plants under cold stress conditions.
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Affiliation(s)
- Mayank Anand Gururani
- Subtropical Horticulture Research Institute, Faculty of Biotechnology, Jeju National University, Jeju 690–756, South Korea
- School of Biotechnology, Yeungnam University, Gyeongsan, Gyeongbook 712–749, South Korea
| | - Jelli Venkatesh
- Department of Molecular Biotechnology, Konkuk University, Seoul 143–701, South Korea
| | - Markkandan Ganesan
- Subtropical Horticulture Research Institute, Faculty of Biotechnology, Jeju National University, Jeju 690–756, South Korea
- Department of Biological Sciences, Presidency University, Kolkata 700073, West Bengal, India
| | - Reto Jörg Strasser
- Bioenergetics Laboratory, University of Geneva, Jussy, CH-1254, Geneva, Switzerland
| | - Yunjeong Han
- Department of Biotechnology and Kumho Life Science Laboratory, Chonnam National University, Gwangju 500–757, South Korea
| | - Jeong-Il Kim
- Department of Biotechnology and Kumho Life Science Laboratory, Chonnam National University, Gwangju 500–757, South Korea
| | - Hyo-Yeon Lee
- Subtropical Horticulture Research Institute, Faculty of Biotechnology, Jeju National University, Jeju 690–756, South Korea
| | - Pill-Soon Song
- Subtropical Horticulture Research Institute, Faculty of Biotechnology, Jeju National University, Jeju 690–756, South Korea
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Geilen K, Böhmer M. Dynamic subnuclear relocalization of WRKY40, a potential new mechanism of ABA-dependent transcription factor regulation. PLANT SIGNALING & BEHAVIOR 2015; 10:e1106659. [PMID: 26479147 PMCID: PMC4883866 DOI: 10.1080/15592324.2015.1106659] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The phytohormone ABA plays a major role during plant development, e.g. seed maturation and seed germination, and during adaptation to abiotic stresses like stomatal aperture regulation. The three closely related WRKY transcription factors WRKY18, WRKY40 and WRKY60 function in ABA signal transduction. We recently demonstrated that WRKY18 and WRKY40 but not WRKY60 localize to nuclear bodies in A. thaliana mesophyll protoplasts. WRKY40, a negative regulator of ABA-dependent inhibition of seed germination, relocalizes from PNBs to the nucleoplasm in the presence of ABA in a dynamic and phosphorylation-dependent manner. We propose that subnuclear relocalization of WRKY40 might constitute a new regulatory mechanism of ABA-dependent modulation of transcription factor activity.
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Affiliation(s)
- Katja Geilen
- Institut für Biologie und Biotechnologie der Pflanzen; Westfälische Wilhelms-Universität; Münster, Germany
| | - Maik Böhmer
- Institut für Biologie und Biotechnologie der Pflanzen; Westfälische Wilhelms-Universität; Münster, Germany
- Correspondence to: Maik Böhmer;
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Photo-biotechnology as a tool to improve agronomic traits in crops. Biotechnol Adv 2014; 33:53-63. [PMID: 25532679 DOI: 10.1016/j.biotechadv.2014.12.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Revised: 12/15/2014] [Accepted: 12/15/2014] [Indexed: 01/09/2023]
Abstract
Phytochromes are photosensory phosphoproteins with crucial roles in plant developmental responses to light. Functional studies of individual phytochromes have revealed their distinct roles in the plant's life cycle. Given the importance of phytochromes in key plant developmental processes, genetically manipulating phytochrome expression offers a promising approach to crop improvement. Photo-biotechnology refers to the transgenic expression of phytochrome transgenes or variants of such transgenes. Several studies have indicated that crop cultivars can be improved by modulating the expression of phytochrome genes. The improved traits include enhanced yield, improved grass quality, shade-tolerance, and stress resistance. In this review, we discuss the transgenic expression of phytochrome A and its hyperactive mutant (Ser599Ala-PhyA) in selected crops, such as Zoysia japonica (Japanese lawn grass), Agrostis stolonifera (creeping bentgrass), Oryza sativa (rice), Solanum tuberosum (potato), and Ipomea batatas (sweet potato). The transgenic expression of PhyA and its mutant in various plant species imparts biotechnologically useful traits. Here, we highlight recent advances in the field of photo-biotechnology and review the results of studies in which phytochromes or variants of phytochromes were transgenically expressed in various plant species. We conclude that photo-biotechnology offers an excellent platform for developing crops with improved properties.
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20
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Maternal environmental effects of competition influence evolutionary potential in rapeseed (Brassica rapa). Evol Ecol 2014. [DOI: 10.1007/s10682-014-9735-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Footitt S, Clay HA, Dent K, Finch-Savage WE. Environment sensing in spring-dispersed seeds of a winter annual Arabidopsis influences the regulation of dormancy to align germination potential with seasonal changes. THE NEW PHYTOLOGIST 2014; 202:929-939. [PMID: 24444091 PMCID: PMC4235297 DOI: 10.1111/nph.12694] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 12/14/2013] [Indexed: 05/18/2023]
Abstract
Seed dormancy cycling plays a crucial role in the lifecycle timing of many plants. Little is known of how the seeds respond to the soil seed bank environment following dispersal in spring into the short-term seed bank before seedling emergence in autumn. Seeds of the winter annual Arabidopsis ecotype Cvi were buried in field soils in spring and recovered monthly until autumn and their molecular eco-physiological responses were recorded. DOG1 expression is initially low and then increases as dormancy increases. MFT expression is negatively correlated with germination potential. Abscisic acid (ABA) and gibberellin (GA) signalling responds rapidly following burial and adjusts to the seasonal change in soil temperature. Collectively these changes align germination potential with the optimum climate space for seedling emergence. Seeds naturally dispersed to the soil in spring enter a shallow dormancy cycle dominated by spatial sensing that adjusts germination potential to the maximum when soil environment is most favourable for germination and seedling emergence upon soil disturbance. This behaviour differs subtly from that of seeds overwintered in the soil seed bank to spread the period of potential germination in the seed population (existing seed bank and newly dispersed). As soil temperature declines in autumn, deep dormancy is re-imposed as seeds become part of the persistent seed bank.
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Affiliation(s)
- Steven Footitt
- School of Life Sciences, University of Warwick, Wellesbourne Campus, Warwickshire, CV35 9EF, UK
| | - Heather A Clay
- School of Life Sciences, University of Warwick, Wellesbourne Campus, Warwickshire, CV35 9EF, UK
| | - Katherine Dent
- School of Life Sciences, University of Warwick, Wellesbourne Campus, Warwickshire, CV35 9EF, UK
| | - William E Finch-Savage
- School of Life Sciences, University of Warwick, Wellesbourne Campus, Warwickshire, CV35 9EF, UK
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Dechaine JM, Brock MT, Weinig C. QTL architecture of reproductive fitness characters in Brassica rapa. BMC PLANT BIOLOGY 2014; 14:66. [PMID: 24641198 PMCID: PMC4004417 DOI: 10.1186/1471-2229-14-66] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 03/03/2014] [Indexed: 05/19/2023]
Abstract
BACKGROUND Reproductive output is critical to both agronomists seeking to increase seed yield and to evolutionary biologists interested in understanding natural selection. We examine the genetic architecture of diverse reproductive fitness traits in recombinant inbred lines (RILs) developed from a crop (seed oil) × wild-like (rapid cycling) genotype of Brassica rapa in field and greenhouse environments. RESULTS Several fitness traits showed strong correlations and QTL-colocalization across environments (days to bolting, fruit length and seed color). Total fruit number was uncorrelated across environments and most QTL affecting this trait were correspondingly environment-specific. Most fitness components were positively correlated, consistent with life-history theory that genotypic variation in resource acquisition masks tradeoffs. Finally, we detected evidence of transgenerational pleiotropy, that is, maternal days to bolting was negatively correlated with days to offspring germination. A QTL for this transgenerational correlation was mapped to a genomic region harboring one copy of FLOWERING LOCUS C, a genetic locus known to affect both days to flowering as well as germination phenotypes. CONCLUSIONS This study characterizes the genetic structure of important fitness/yield traits within and between generations in B. rapa. Several identified QTL are suitable candidates for fine-mapping for the improvement of yield in crop Brassicas. Specifically, brFLC1, warrants further investigation as a potential regulator of phenology between generations.
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Affiliation(s)
- Jennifer M Dechaine
- Department of Biological Sciences, Central Washington University, Ellensburg, WA 98926, USA
| | - Marcus T Brock
- Department of Botany, University of Wyoming, Laramie, WY 82071, USA
| | - Cynthia Weinig
- Department of Botany, University of Wyoming, Laramie, WY 82071, USA
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Chen H, Cao M, Baskin JM, Baskin CC. Temperature regulates positively photoblastic seed germination in four ficus (moraceae) tree species from contrasting habitats in a seasonal tropical rainforest. AMERICAN JOURNAL OF BOTANY 2013; 100:1683-1687. [PMID: 23942086 DOI: 10.3732/ajb.1200479] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
PREMISE OF THE STUDY Differences in seed germination responses of trees in tropical forests to temperature and light quality may contribute to their coexistence. We investigated the effects of temperature and red:far-red light (R:FR ratio) on seed germination of two gap-demanding species (Ficus hispida and F. racemosa) and two shade-tolerant species (F. altissima and F. auriculata) in a tropical seasonal rainforest in southwest China. METHODS A R:FR ratio gradient was created by filtering fluorescent light through polyester filters. Four temperature treatments were used to test the effect of temperature on seed germination of the four Ficus tree species across the R:FR gradient. KEY RESULTS Seeds of the four Ficus species were positively photoblastic. Seed germination of F. hispida and F. racemosa was not affected across the R:FR ratio gradient (0.25-1.19) at 25/35°C, but it was inhibited under low R:FR at 22/23°C. By contrast, germination percentages of F. altissima and F. auriculata were not inhibited along the entire light gradient in all temperature treatments. CONCLUSIONS Differences in germination responses of Ficus species might contribute to differences in their habitat preferences. The inhibitory effect of understory temperatures in the forest might be a new mechanism that prevents positively photoblastic seeds of the gap-demanding species such as F. hispida and F. racemosa from germinating in the understory and in small canopy gaps.
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Affiliation(s)
- Hui Chen
- Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, Yunnan, P.R. China
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Footitt S, Huang Z, Clay HA, Mead A, Finch-Savage WE. Temperature, light and nitrate sensing coordinate Arabidopsis seed dormancy cycling, resulting in winter and summer annual phenotypes. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 74:1003-15. [PMID: 23590427 PMCID: PMC3764396 DOI: 10.1111/tpj.12186] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 03/25/2013] [Indexed: 05/18/2023]
Abstract
Seeds use environmental cues to sense the seasons and their surroundings to initiate the life cycle of the plant. The dormancy cycling underlying this process is extensively described, but the molecular mechanism is largely unknown. To address this we selected a range of representative genes from published array experiments in the laboratory, and investigated their expression patterns in seeds of Arabidopsis ecotypes with contrasting life cycles over an annual dormancy cycle in the field. We show how mechanisms identified in the laboratory are coordinated in response to the soil environment to determine the dormancy cycles that result in winter and summer annual phenotypes. Our results are consistent with a seed-specific response to seasonal temperature patterns (temporal sensing) involving the gene DELAY OF GERMINATION 1 (DOG1) that indicates the correct season, and concurrent temporally driven co-opted mechanisms that sense spatial signals, i.e. nitrate, via CBL-INTERACTING PROTEIN KINASE 23 (CIPK23) phosphorylation of the NITRATE TRANSPORTER 1 (NRT1.1), and light, via PHYTOCHROME A (PHYA). In both ecotypes studied, when all three genes have low expression there is enhanced GIBBERELLIN 3 BETA-HYDROXYLASE 1 (GA3ox1) expression, exhumed seeds have the potential to germinate in the laboratory, and the initiation of seedling emergence occurs following soil disturbance (exposure to light) in the field. Unlike DOG1, the expression of MOTHER of FLOWERING TIME (MFT) has an opposite thermal response in seeds of the two ecotypes, indicating a role in determining their different dormancy cycling phenotypes.
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Wang Y, Folta KM. Contributions of green light to plant growth and development. AMERICAN JOURNAL OF BOTANY 2013; 100:70-8. [PMID: 23281393 DOI: 10.3732/ajb.1200354] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Light passing through or reflected from adjacent foliage provides a developing plant with information that is used to guide specific genetic and physiological processes. Changes in gene expression underlie adaptation to, or avoidance of, the light-compromised environment. These changes have been well described and are mostly attributed to a decrease in the red light to far-red light ratio and/or a reduction in blue light fluence rate. In most cases, these changes rely on the integration of red/far-red/blue light signals, leading to changes in phytohormone levels. Studies over the last decade have described distinct responses to green light and/or a shift of the blue-green, or red-green ratio. Responses to green light are typically low-light responses, suggesting that they may contribute to the adaptation to growth under foliage or within close proximity to other plants. This review summarizes the growth responses in artificially manipulated light environments with an emphasis on the roles of green wavebands. The information may be extended to understanding the influence of green light in shade avoidance responses as well as other plant developmental and physiological processes.
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Affiliation(s)
- Yihai Wang
- Graduate Program in Plant Molecular and Cellular Biology, University of Florida, Gainesville, Florida 32611 USA
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Lee KP, Piskurewicz U, Turečková V, Carat S, Chappuis R, Strnad M, Fankhauser C, Lopez-Molina L. Spatially and genetically distinct control of seed germination by phytochromes A and B. Genes Dev 2012; 26:1984-96. [PMID: 22948663 DOI: 10.1101/gad.194266.112] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Phytochromes phyB and phyA mediate a remarkable developmental switch whereby, early upon seed imbibition, canopy light prevents phyB-dependent germination, whereas later on, it stimulates phyA-dependent germination. Using a seed coat bedding assay where the growth of dissected embryos is monitored under the influence of dissected endosperm, allowing combinatorial use of mutant embryos and endosperm, we show that canopy light specifically inactivates phyB activity in the endosperm to override phyA-dependent signaling in the embryo. This interference involves abscisic acid (ABA) release from the endosperm and distinct spatial activities of phytochrome signaling components. Under the canopy, endospermic ABA opposes phyA signaling through the transcription factor (TF) ABI5, which shares with the TF PIF1 several target genes that negatively regulate germination in the embryo. ABI5 enhances the expression of phytochrome signaling genes PIF1, SOMNUS, GAI, and RGA, but also of ABA and gibberellic acid (GA) metabolic genes. Over time, weaker ABA-dependent responses eventually enable phyA-dependent germination, a distinct type of germination driven solely by embryonic growth.
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Affiliation(s)
- Keun Pyo Lee
- Département de Biologie Végétale, 30, quai Ernest-Ansermet-Sciences III, Université de Genève, 1211 Genève 4, Switzerland
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Brock MT, Kover PX, Weinig C. Natural variation in GA1 associates with floral morphology in Arabidopsis thaliana. THE NEW PHYTOLOGIST 2012; 195:58-70. [PMID: 22510148 DOI: 10.1111/j.1469-8137.2012.04145.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
• The genetic architecture of floral traits is evolutionarily important due to the fitness consequences of quantitative variation in floral morphology. Yet, little is known about the genes underlying these traits in natural populations. Using Arabidopsis thaliana, we examine molecular variation at GIBBERELLIC ACID REQUIRING 1 (GA1) and test for associations with floral morphology. • We examined full-length sequence in 32 accessions and describe two haplotypes (comprising four nonsynonymous polymorphisms) in GA1 that segregate at intermediate frequencies. In 133 A. thaliana accessions, we test for genotype-phenotype associations and corroborate these findings in segregating progenies. • The two common GA1 haplotypes were associated with the length of petals, stamens, and to a lesser extent style-stigma length. Associations were confirmed in a segregating progeny developed from 19 accessions. We find analogous results in recombinant inbred lines of the Bayreuth × Shahdara cross, which differ only at one of 4 SNPs, suggesting that this SNP may contribute to the observed association. • Assuming GA1 causally affects floral organ size, it is interesting that adjacent petal and stamen whorls are most strongly affected. This pattern suggests that GA1 could contribute to the greater strength of petal-stamen correlations relative to other floral-length correlations observed in some Brassicaceous species.
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Affiliation(s)
- Marcus T Brock
- Department of Botany, University of Wyoming, Laramie, WY 82071, USA.
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Joosen RVL, Arends D, Willems LAJ, Ligterink W, Jansen RC, Hilhorst HW. Visualizing the genetic landscape of Arabidopsis seed performance. PLANT PHYSIOLOGY 2012; 158:570-89. [PMID: 22158761 PMCID: PMC3271751 DOI: 10.1104/pp.111.186676] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Accepted: 12/11/2011] [Indexed: 05/18/2023]
Abstract
Perfect timing of germination is required to encounter optimal conditions for plant survival and is the result of a complex interaction between molecular processes, seed characteristics, and environmental cues. To detangle these processes, we made use of natural genetic variation present in an Arabidopsis (Arabidopsis thaliana) Bayreuth × Shahdara recombinant inbred line population. For a detailed analysis of the germination response, we characterized rate, uniformity, and maximum germination and discuss the added value of such precise measurements. The effects of after-ripening, stratification, and controlled deterioration as well as the effects of salt, mannitol, heat, cold, and abscisic acid (ABA) with and without cold stratification were analyzed for these germination characteristics. Seed morphology (size and length) of both dry and imbibed seeds was quantified by using image analysis. For the overwhelming amount of data produced in this study, we developed new approaches to perform and visualize high-throughput quantitative trait locus (QTL) analysis. We show correlation of trait data, (shared) QTL positions, and epistatic interactions. The detection of similar loci for different stresses indicates that, often, the molecular processes regulating environmental responses converge into similar pathways. Seven major QTL hotspots were confirmed using a heterogeneous inbred family approach. QTLs colocating with previously reported QTLs and well-characterized mutants are discussed. A new connection between dormancy, ABA, and a cripple mucilage formation due to a naturally occurring mutation in the MUCILAGE-MODIFIED2 gene is proposed, and this is an interesting lead for further research on the regulatory role of ABA in mucilage production and its multiple effects on germination parameters.
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Barua D, Butler C, Tisdale TE, Donohue K. Natural variation in germination responses of Arabidopsis to seasonal cues and their associated physiological mechanisms. ANNALS OF BOTANY 2012; 109:209-26. [PMID: 22012958 PMCID: PMC3241586 DOI: 10.1093/aob/mcr264] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 09/20/2011] [Indexed: 05/25/2023]
Abstract
BACKGROUND AND AIMS Despite the intense interest in phenological adaptation to environmental change, the fundamental character of natural variation in germination is almost entirely unknown. Specifically, it is not known whether different genotypes within a species are germination specialists to particular conditions, nor is it known what physiological mechanisms of germination regulation vary in natural populations and how they are associated with responses to particular environmental factors. METHODS We used a set of recombinant inbred genotypes of Arabidopsis thaliana, in which linkage disequilibrium has been disrupted over seven generations, to test for genetic variation and covariation in germination responses to distinct environmental factors. We then examined physiological mechanisms associated with those responses, including seed-coat permeability and sensitivity to the phytohormones gibberellic acid (GA) and abscisic acid (ABA). KEY RESULTS Genetic variation for germination was environment-dependent, but no evidence for specialization of germination to different conditions was found. Hormonal sensitivities also exhibited significant genetic variation, but seed-coat properties did not. GA sensitivity was associated with germination responses to multiple environmental factors, but seed-coat permeability and ABA sensitivity were associated with specific germination responses, suggesting that an evolutionary change in GA sensitivity could affect germination in multiple environments, but that of ABA sensitivity may affect germination under more restricted conditions. CONCLUSIONS The physiological mechanisms of germination responses to specific environmental factors therefore can influence the ability to adapt to diverse seasonal environments encountered during colonization of new habitats or with future predicted climate change.
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Affiliation(s)
- Deepak Barua
- Indian Institute of Science Education and Research, Pune 411021, India
| | - Colleen Butler
- Department of Biology, Tufts University, Medford, MA 02155, USA
| | - Tracy E. Tisdale
- Rowland Institute at Harvard, Harvard University, Cambridge, MA 02142, USA
| | - Kathleen Donohue
- Department of Biological Sciences, Duke University, Durham, NC 27708, USA
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Carvalho RF, Campos ML, Azevedo RA. The role of phytochrome in stress tolerance. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2011; 53:920-929. [PMID: 22040287 DOI: 10.1111/j.1744-7909.2011.01081.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
It is well-documented that phytochromes can control plant growth and development from germination to flowering. Additionally, these photoreceptors have been shown to modulate both biotic and abiotic stress. This has led to a series of studies exploring the molecular and biochemical basis by which phytochromes modulate stresses, such as salinity, drought, high light or herbivory. Evidence for a role of phytrochromes in plant stress tolerance is explored and reviewed.
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Carvalho RF, Campos ML, Azevedo RA. The role of phytochrome in stress tolerance. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2011. [PMID: 22040287 DOI: 10.1007/978-1-4614-6108-1_12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
It is well-documented that phytochromes can control plant growth and development from germination to flowering. Additionally, these photoreceptors have been shown to modulate both biotic and abiotic stress. This has led to a series of studies exploring the molecular and biochemical basis by which phytochromes modulate stresses, such as salinity, drought, high light or herbivory. Evidence for a role of phytrochromes in plant stress tolerance is explored and reviewed.
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32
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Ruberti I, Sessa G, Ciolfi A, Possenti M, Carabelli M, Morelli G. Plant adaptation to dynamically changing environment: the shade avoidance response. Biotechnol Adv 2011; 30:1047-58. [PMID: 21888962 DOI: 10.1016/j.biotechadv.2011.08.014] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Revised: 07/23/2011] [Accepted: 08/16/2011] [Indexed: 11/30/2022]
Abstract
The success of competitive interactions between plants determines the chance of survival of individuals and eventually of whole plant species. Shade-tolerant plants have adapted their photosynthesis to function optimally under low-light conditions. These plants are therefore capable of long-term survival under a canopy shade. In contrast, shade-avoiding plants adapt their growth to perceive maximum sunlight and therefore rapidly dominate gaps in a canopy. Daylight contains roughly equal proportions of red and far-red light, but within vegetation that ratio is lowered as a result of red absorption by photosynthetic pigments. This light quality change is perceived through the phytochrome system as an unambiguous signal of the proximity of neighbors resulting in a suite of developmental responses (termed the shade avoidance response) that, when successful, result in the overgrowth of those neighbors. Shoot elongation induced by low red/far-red light may confer high relative fitness in natural dense communities. However, since elongation is often achieved at the expense of leaf and root growth, shade avoidance may lead to reduction in crop plant productivity. Over the past decade, major progresses have been achieved in the understanding of the molecular basis of shade avoidance. However, uncovering the mechanisms underpinning plant response and adaptation to changes in the ratio of red to far-red light is key to design new strategies to precise modulate shade avoidance in time and space without impairing the overall crop ability to compete for light.
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Affiliation(s)
- I Ruberti
- Institute of Molecular Biology and Pathology, National Research Council, Piazzalle Aldo Moro 5, Rome, Italy.
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Jiao Y, Wickett NJ, Ayyampalayam S, Chanderbali AS, Landherr L, Ralph PE, Tomsho LP, Hu Y, Liang H, Soltis PS, Soltis DE, Clifton SW, Schlarbaum SE, Schuster SC, Ma H, Leebens-Mack J, dePamphilis CW. Ancestral polyploidy in seed plants and angiosperms. Nature 2011; 473:97-100. [PMID: 21478875 DOI: 10.1038/nature09916] [Citation(s) in RCA: 1320] [Impact Index Per Article: 101.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2010] [Accepted: 02/10/2011] [Indexed: 11/09/2022]
Abstract
Whole-genome duplication (WGD), or polyploidy, followed by gene loss and diploidization has long been recognized as an important evolutionary force in animals, fungi and other organisms, especially plants. The success of angiosperms has been attributed, in part, to innovations associated with gene or whole-genome duplications, but evidence for proposed ancient genome duplications pre-dating the divergence of monocots and eudicots remains equivocal in analyses of conserved gene order. Here we use comprehensive phylogenomic analyses of sequenced plant genomes and more than 12.6 million new expressed-sequence-tag sequences from phylogenetically pivotal lineages to elucidate two groups of ancient gene duplications-one in the common ancestor of extant seed plants and the other in the common ancestor of extant angiosperms. Gene duplication events were intensely concentrated around 319 and 192 million years ago, implicating two WGDs in ancestral lineages shortly before the diversification of extant seed plants and extant angiosperms, respectively. Significantly, these ancestral WGDs resulted in the diversification of regulatory genes important to seed and flower development, suggesting that they were involved in major innovations that ultimately contributed to the rise and eventual dominance of seed plants and angiosperms.
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Affiliation(s)
- Yuannian Jiao
- Intercollege Graduate Degree Program in Plant Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Foreman J, Johansson H, Hornitschek P, Josse EM, Fankhauser C, Halliday KJ. Light receptor action is critical for maintaining plant biomass at warm ambient temperatures. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2011; 65:441-52. [PMID: 21265897 DOI: 10.1111/j.1365-313x.2010.04434.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The ability to withstand environmental temperature variation is essential for plant survival. Former studies in Arabidopsis revealed that light signalling pathways had a potentially unique role in shielding plant growth and development from seasonal and daily fluctuations in temperature. In this paper we describe the molecular circuitry through which the light receptors cry1 and phyB buffer the impact of warm ambient temperatures. We show that the light signalling component HFR1 acts to minimise the potentially devastating effects of elevated temperature on plant physiology. Light is known to stabilise levels of HFR1 protein by suppressing proteasome-mediated destruction of HFR1. We demonstrate that light-dependent accumulation and activity of HFR1 are highly temperature dependent. The increased potency of HFR1 at warmer temperatures provides an important restraint on PIF4 that drives elongation growth. We show that warm ambient temperatures promote the accumulation of phosphorylated PIF4. However, repression of PIF4 activity by phyB and cry1 (via HFR1) is critical for controlling growth and maintaining physiology as temperatures rise. Loss of this light-mediated restraint has severe consequences for adult plants which have greatly reduced biomass.
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Affiliation(s)
- Julia Foreman
- Department of Biological Sciences, CH Waddington Building, Kings Buildings, University of Edinburgh, Edinburgh, UK
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Kami C, Lorrain S, Hornitschek P, Fankhauser C. Light-regulated plant growth and development. Curr Top Dev Biol 2010; 91:29-66. [PMID: 20705178 DOI: 10.1016/s0070-2153(10)91002-8] [Citation(s) in RCA: 428] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Plants are sessile and photo-autotrophic; their entire life cycle is thus strongly influenced by the ever-changing light environment. In order to sense and respond to those fluctuating conditions higher plants possess several families of photoreceptors that can monitor light from UV-B to the near infrared (far-red). The molecular nature of UV-B sensors remains unknown, red (R) and far-red (FR) light is sensed by the phytochromes (phyA-phyE in Arabidopsis) while three classes of UV-A/blue photoreceptors have been identified: cryptochromes, phototropins, and members of the Zeitlupe family (cry1, cry2, phot1, phot2, ZTL, FKF1, and LKP2 in Arabidopsis). Functional specialization within photoreceptor families gave rise to members optimized for a wide range of light intensities. Genetic and photobiological studies performed in Arabidopsis have shown that these light sensors mediate numerous adaptive responses (e.g., phototropism and shade avoidance) and developmental transitions (e.g., germination and flowering). Some physiological responses are specifically triggered by a single photoreceptor but in many cases multiple light sensors ensure a coordinated response. Recent studies also provide examples of crosstalk between the responses of Arabidopsis to different external factors, in particular among light, temperature, and pathogens. Although the different photoreceptors are unrelated in structure, in many cases they trigger similar signaling mechanisms including light-regulated protein-protein interactions or light-regulated stability of several transcription factors. The breath and complexity of this topic forced us to concentrate on specific aspects of photomorphogenesis and we point the readers to recent reviews for some aspects of light-mediated signaling (e.g., transition to flowering).
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Affiliation(s)
- Chitose Kami
- Center for Integrative Genomics, University of Lausanne, Lausanne, Switzerland
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Mathews S. Evolutionary studies illuminate the structural-functional model of plant phytochromes. THE PLANT CELL 2010; 22:4-16. [PMID: 20118225 PMCID: PMC2828699 DOI: 10.1105/tpc.109.072280] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Revised: 01/12/2010] [Accepted: 01/13/2010] [Indexed: 05/18/2023]
Abstract
A synthesis of insights from functional and evolutionary studies reveals how the phytochrome photoreceptor system has evolved to impart both stability and flexibility. Phytochromes in seed plants diverged into three major forms, phyA, phyB, and phyC, very early in the history of seed plants. Two additional forms, phyE and phyD, are restricted to flowering plants and Brassicaceae, respectively. While phyC, D, and E are absent from at least some taxa, phyA and phyB are present in all sampled seed plants and are the principal mediators of red/far-red-induced responses. Conversely, phyC-E apparently function in concert with phyB and, where present, expand the repertoire of phyB activities. Despite major advances, aspects of the structural-functional models for these photoreceptors remain elusive. Comparative sequence analyses expand the array of locus-specific mutant alleles for analysis by revealing historic mutations that occurred during gene lineage splitting and divergence. With insights from crystallographic data, a subset of these mutants can be chosen for functional studies to test their importance and determine the molecular mechanism by which they might impact light perception and signaling. In the case of gene families, where redundancy hinders isolation of some proportion of the relevant mutants, the approach may be particularly useful.
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Affiliation(s)
- Sarah Mathews
- Arnold Arboretum of Harvard University, Cambridge, Massachusetts 02138, USA.
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