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Guo L, Huang Z, Chen X, Yang M, Yang M, Liu Z, Han X, Ma X, Wang X, Gao Q. SD-RLK28 positively regulates pollen hydration on stigmas as a PCP-Bβ receptor in Arabidopsis thaliana. J Integr Plant Biol 2023; 65:2395-2406. [PMID: 37485903 DOI: 10.1111/jipb.13547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 07/24/2023] [Indexed: 07/25/2023]
Abstract
Pollen hydration on dry stigmas is strictly regulated by pollen-stigma interactions in Brassicaceae. Although several related molecular events have been described, the molecular mechanism underlying pollen hydration remains elusive. Multiple B-class pollen coat proteins (PCP-Bs) are involved in pollen hydration. Here, by analyzing the interactions of two PCP-Bs with three Arabidopsis thaliana stigmas strongly expressing S-domain receptor kinase (SD-RLK), we determined that SD-RLK28 directly interacts with PCP-Bβ. We investigated pollen hydration, pollen germination, pollen tube growth, and stigma receptivity in the sd-rlk28 and pcp-bβ mutants. PCP-Bβ acts in the pollen to regulate pollen hydration on stigmas. Loss of SD-RLK28 had no effect on pollen viability, and sd-rlk28 plants had normal life cycles without obvious defects. However, pollen hydration on sd-rlk28 stigmas was impaired and pollen tube growth in sd-rlk28 pistils was delayed. The defect in pollen hydration on sd-rlk28 stigmas was independent of changes in reactive oxygen species levels in stigmas. These results indicate that SD-RLK28 functions in the stigma as a PCP-Bβ receptor to positively regulate pollen hydration on dry stigmas.
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Affiliation(s)
- Li Guo
- College of Horticulture and Landscape Architecture, Chongqing, 400716, China
- Ministry of Education, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Chongqing, 400716, China
| | - Ziya Huang
- College of Horticulture and Landscape Architecture, Chongqing, 400716, China
- Ministry of Education, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Chongqing, 400716, China
| | - Xingyu Chen
- College of Horticulture and Landscape Architecture, Chongqing, 400716, China
- Ministry of Education, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Chongqing, 400716, China
| | - Min Yang
- College of Horticulture and Landscape Architecture, Chongqing, 400716, China
- Ministry of Education, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Chongqing, 400716, China
| | - Miaomiao Yang
- College of Horticulture and Landscape Architecture, Chongqing, 400716, China
- Ministry of Education, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Chongqing, 400716, China
| | - Ziwei Liu
- College of Horticulture and Landscape Architecture, Chongqing, 400716, China
- Ministry of Education, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Chongqing, 400716, China
| | - Xuejie Han
- College of Horticulture and Landscape Architecture, Chongqing, 400716, China
- Ministry of Education, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Chongqing, 400716, China
| | - Xiangjie Ma
- College of Horticulture and Landscape Architecture, Chongqing, 400716, China
- Ministry of Education, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Chongqing, 400716, China
| | - Xiaoli Wang
- College of Horticulture and Landscape Architecture, Chongqing, 400716, China
- Ministry of Education, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Chongqing, 400716, China
| | - Qiguo Gao
- College of Horticulture and Landscape Architecture, Chongqing, 400716, China
- Ministry of Education, Key Laboratory of Horticulture Science for Southern Mountainous Regions, Chongqing, 400716, China
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Miller K, Strychalski W, Nickaeen M, Carlsson A, Haswell ES. In vitro experiments and kinetic models of Arabidopsis pollen hydration mechanics show that MSL8 is not a simple tension-gated osmoregulator. Curr Biol 2022; 32:2921-2934.e3. [PMID: 35660140 DOI: 10.1016/j.cub.2022.05.033] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 04/12/2022] [Accepted: 05/12/2022] [Indexed: 10/18/2022]
Abstract
Pollen, a neighbor-less cell containing the male gametes, undergoes mechanical challenges during plant sexual reproduction, including desiccation and rehydration. It was previously shown that the pollen-specific mechanosensitive ion channel MscS-like (MSL)8 is essential for pollen survival during hydration and proposed that it functions as a tension-gated osmoregulator. Here, we test this hypothesis with a combination of mathematical modeling and laboratory experiments. Time-lapse imaging revealed that wild-type pollen grains swell, and then they stabilize in volume rapidly during hydration. msl8 mutant pollen grains, however, continue to expand and eventually burst. We found that a mathematical model, wherein MSL8 acts as a simple-tension-gated osmoregulator, does not replicate this behavior. A better fit was obtained from variations of the model, wherein MSL8 inactivates independent of its membrane tension gating threshold or MSL8 strengthens the cell wall without osmotic regulation. Experimental and computational testing of several perturbations, including hydration in an osmolyte-rich solution, hyper-desiccation of the grains, and MSL8-YFP overexpression, indicated that the cell wall strengthening model best simulated experimental responses. Finally, the expression of a nonconducting MSL8 variant did not complement the msl8 overexpansion phenotype. These data indicate that contrary to our hypothesis and to the current understanding of MS ion channel function in bacteria, MSL8 does not act as a simple membrane tension-gated osmoregulator. Instead, they support a model wherein ion flux through MSL8 is required to alter pollen cell wall properties. These results demonstrate the utility of pollen as a cellular scale model system and illustrate how mathematical models can correct intuitive hypotheses.
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Affiliation(s)
- Kari Miller
- Department of Biology, Washington University, St. Louis, MO 63130, USA; NSF Center for Engineering Mechanobiology, Cleveland, OH, USA
| | - Wanda Strychalski
- Department of Mathematics, Applied Mathematics, and Statistics, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Masoud Nickaeen
- University of Connecticut School of Medicine, Farmington, CT 06030, USA
| | - Anders Carlsson
- NSF Center for Engineering Mechanobiology, Cleveland, OH, USA; Department of Physics, Washington University, St. Louis, MO 63130, USA
| | - Elizabeth S Haswell
- Department of Biology, Washington University, St. Louis, MO 63130, USA; NSF Center for Engineering Mechanobiology, Cleveland, OH, USA.
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Zhang Z, Zhan H, Lu J, Xiong S, Yang N, Yuan H, Yang ZN. Tapetal 3-Ketoacyl-Coenzyme A Synthases Are Involved in Pollen Coat Lipid Accumulation for Pollen-Stigma Interaction in Arabidopsis. Front Plant Sci 2021; 12:770311. [PMID: 34887893 PMCID: PMC8650583 DOI: 10.3389/fpls.2021.770311] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 10/26/2021] [Indexed: 06/01/2023]
Abstract
Pollen coat lipids form an outer barrier to protect pollen itself and play essential roles in pollen-stigma interaction. However, the precise molecular mechanisms underlying the production, deposition, regulation, and function of pollen coat lipids during anther development remain largely elusive. In lipid metabolism, 3-ketoacyl-coenzyme A synthases (KCS) are involved in fatty acid elongation or very-long-chain fatty acid (VLCFA) synthesis. In this study, we identified six members of the Arabidopsis KCS family expressed in anther. Among them, KCS7, KCS15, and KCS21 were expressed in tapetal cells at anther stages 8-10. Further analysis demonstrated that they act downstream of male sterility 1 (MS1), a regulator of late tapetum development. The kcs7/15/21 triple mutant is fertile. Both cellular observation and lipid staining showed pollen coat lipid was decreased in kcs7/15/21 triple mutant. After landing on stigma, the wild-type pollen grains were hydrated for about 5 min while the kcs7/15/21 triple mutant pollen took about 10 min to hydrate. Pollen tube growth of the triple mutant was also delayed. These results demonstrate that the tapetum-localized KCS proteins are involved in the accumulation of pollen coat lipid and reveal the roles of tapetal-derived pollen coat lipid for pollen-stigma interaction.
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Affiliation(s)
- Zaibao Zhang
- College of Life Science, Xinyang Normal University, Xinyang, China
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Huadong Zhan
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Agriculture, Nanjing Agricultural University, Nanjing, China
| | - Jieyang Lu
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Shuangxi Xiong
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Naiying Yang
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Hongyu Yuan
- College of Life Science, Xinyang Normal University, Xinyang, China
| | - Zhong-Nan Yang
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
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Ascari L, Cristofori V, Macrì F, Botta R, Silvestri C, De Gregorio T, Huerta ES, Di Berardino M, Kaufmann S, Siniscalco C. Hazelnut Pollen Phenotyping Using Label-Free Impedance Flow Cytometry. Front Plant Sci 2020; 11:615922. [PMID: 33370424 PMCID: PMC7753158 DOI: 10.3389/fpls.2020.615922] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Accepted: 11/13/2020] [Indexed: 05/23/2023]
Abstract
Impedance flow cytometry (IFC) is a versatile lab-on-chip technology which enables fast and label-free analysis of pollen grains in various plant species, promising new research possibilities in agriculture and plant breeding. Hazelnut is a monoecious, anemophilous species, exhibiting sporophytic self-incompatibility. Its pollen is dispersed by wind in midwinter when temperatures are still low and relative humidity is usually high. Previous research found that hazelnut can be characterized by high degrees of pollen sterility following a reciprocal chromosome translocation occurring in some cultivated genotypes. In this study, IFC was used for the first time to characterize hazelnut pollen biology. IFC was validated via dye exclusion in microscopy and employed to (i) follow pollen hydration over time to define the best pre-hydration treatment for pollen viability evaluation; (ii) test hazelnut pollen viability and sterility on 33 cultivars grown in a collection field located in central Italy, and two wild hazelnuts. The accessions were also characterized by their amount and distribution of catkins in the tree canopy. Pollen sterility rate greatly varied among hazelnut accessions, with one main group of highly sterile cultivars and a second group, comprising wild genotypes and the remaining cultivars, producing good quality pollen. The results support the hypothesis of recurring reciprocal translocation events in Corylus avellana cultivars, leading to the observed gametic semi-sterility. The measured hazelnut pollen viability was also strongly influenced by pollen hydration (R adj 2 = 0.83, P ≤ 0.0001) and reached its maximum at around 6 h of pre-hydration in humid chambers. Viable and dead pollen were best discriminated at around the same time of pollen pre-hydration, suggesting that high humidity levels are required for hazelnut pollen to maintain its functionality. Altogether, our results detail the value of impedance flow cytometry for high throughput phenotyping of hazelnut pollen. Further research is required to clarify the causes of pollen sterility in hazelnut, to confirm the role of reciprocal chromosome translocations and to investigate its effects on plant productivity.
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Affiliation(s)
- Lorenzo Ascari
- Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy
| | - Valerio Cristofori
- Department of Agriculture and Forest Sciences, University of Tuscia, Viterbo, Italy
| | - Federico Macrì
- Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy
| | - Roberto Botta
- Department of Agricultural, Forest and Food Sciences, University of Turin, Turin, Italy
| | - Cristian Silvestri
- Department of Agriculture and Forest Sciences, University of Tuscia, Viterbo, Italy
| | | | | | | | | | - Consolata Siniscalco
- Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy
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Moon S, Jung KH. First Steps in the Successful Fertilization of Rice and Arabidopsis: Pollen Longevity, Adhesion and Hydration. Plants (Basel) 2020; 9:E956. [PMID: 32751098 PMCID: PMC7465243 DOI: 10.3390/plants9080956] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 07/21/2020] [Accepted: 07/21/2020] [Indexed: 02/04/2023]
Abstract
Understanding the behavior of pollen during pollination is important for food security in the future. The elucidation of pollen development and growth regulation largely relies on the study of the dicotyledonous model plant Arabidopsis thaliana. However, rice (Oryza sativa) pollen exhibits different characteristics to that of Arabidopsis. The latter undergoes programmed dehydration and withstands adverse environmental conditions, whereas rice pollen is sensitive to desiccation. Moreover, the short longevity of rice pollen significantly hampers hybrid seed production. Although the "omics" data for mature rice pollen have been accumulated, few genes that control pollination and pollen hydration have been identified. Therefore, to facilitate future studies, it is necessary to summarize the developmental processes involved in pollen production in rice and to consolidate the underlying mechanisms discovered in previous studies. In this review, we describe the pollen developmental processes and introduce gametophytic mutants, which form defective pollen in Arabidopsis and rice. In addition, we discuss the perspectives on the research on pollen longevity, adhesion and hydration.
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Affiliation(s)
| | - Ki-Hong Jung
- Graduate School of Biotechnology and Crop Biotech Institute, Kyung Hee University, Yongin 17104, Korea;
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Yu B, Liu L, Wang T. Deficiency of very long chain alkanes biosynthesis causes humidity-sensitive male sterility via affecting pollen adhesion and hydration in rice. Plant Cell Environ 2019; 42:3340-3354. [PMID: 31380565 DOI: 10.1111/pce.13637] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 07/25/2019] [Accepted: 07/25/2019] [Indexed: 06/10/2023]
Abstract
Pollen adhesion and hydration are the earliest events of the pollen-stigma interactions, which allow compatible pollen to fertilize egg cells, but the underlying mechanisms are still poorly understood. Rice pollen are wind dispersed, and its pollen coat contains less abundant lipids than that of insect-pollinated plants. Here, we characterized the role of OsGL1-4, a rice member of the Glossy family, in pollen adhesion and hydration. OsGL1-4 is preferentially expressed in pollen and tapetal cells and is required for the synthesis of very long chain alkanes. osgl1-4 mutant generated apparently normal pollen but displayed excessively fast dehydration at anthesis and defective adhesion and hydration under normal condition, but the defective adhesion and hydration were rescued by high humidity. Gas chromatography-mass spectrometry analysis suggested that the humidity-sensitive male sterility of osgl1-4 was probably due to a significant reduction in C25 and C27 alkanes. These results indicate that very long chain alkanes are components of rice pollen coat and control male fertility via affecting pollen adhesion and hydration in response to environmental humidity. Moreover, we proposed that a critical point of water content in mature pollen is required for the initiation of pollen adhesion.
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Affiliation(s)
- Bo Yu
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Lingtong Liu
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Tai Wang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- College of Life Science, University of Chinese Academy of Sciences, Beijing, China
- Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, China
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Wang L, Clarke LA, Eason RJ, Parker CC, Qi B, Scott RJ, Doughty J. PCP-B class pollen coat proteins are key regulators of the hydration checkpoint in Arabidopsis thaliana pollen-stigma interactions. New Phytol 2017; 213:764-777. [PMID: 27596924 PMCID: PMC5215366 DOI: 10.1111/nph.14162] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 07/23/2016] [Indexed: 05/09/2023]
Abstract
The establishment of pollen-pistil compatibility is strictly regulated by factors derived from both male and female reproductive structures. Highly diverse small cysteine-rich proteins (CRPs) have been found to play multiple roles in plant reproduction, including the earliest stages of the pollen-stigma interaction. Secreted CRPs found in the pollen coat of members of the Brassicaceae, the pollen coat proteins (PCPs), are emerging as important signalling molecules that regulate the pollen-stigma interaction. Using a combination of protein characterization, expression and phylogenetic analyses we identified a novel class of Arabidopsis thaliana pollen-borne CRPs, the PCP-Bs (for pollen coat protein B-class) that are related to embryo surrounding factor (ESF1) developmental regulators. Single and multiple PCP-B mutant lines were utilized in bioassays to assess effects on pollen hydration, adhesion and pollen tube growth. Our results revealed that pollen hydration is severely impaired when multiple PCP-Bs are lost from the pollen coat. The hydration defect also resulted in reduced pollen adhesion and delayed pollen tube growth in all mutants studied. These results demonstrate that AtPCP-Bs are key regulators of the hydration 'checkpoint' in establishment of pollen-stigma compatibility. In addition, we propose that interspecies diversity of PCP-Bs may contribute to reproductive barriers in the Brassicaceae.
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Affiliation(s)
- Ludi Wang
- Department of Biology and BiochemistryUniversity of BathClaverton DownBathBA2 7AYUK
| | - Lisa A. Clarke
- Department of Biology and BiochemistryUniversity of BathClaverton DownBathBA2 7AYUK
| | - Russell J. Eason
- Department of Biology and BiochemistryUniversity of BathClaverton DownBathBA2 7AYUK
| | | | - Baoxiu Qi
- Department of Biology and BiochemistryUniversity of BathClaverton DownBathBA2 7AYUK
| | - Rod J. Scott
- Department of Biology and BiochemistryUniversity of BathClaverton DownBathBA2 7AYUK
| | - James Doughty
- Department of Biology and BiochemistryUniversity of BathClaverton DownBathBA2 7AYUK
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Pérez Di Giorgio JA, Barberini ML, Amodeo G, Muschietti JP. Pollen aquaporins: What are they there for? Plant Signal Behav 2016; 11:e1217375. [PMID: 27598621 PMCID: PMC5155453 DOI: 10.1080/15592324.2016.1217375] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 07/19/2016] [Accepted: 07/20/2016] [Indexed: 05/23/2023]
Abstract
In order to provide more insight into the function of aquaporins during pollination, we characterized NIP4;1 and NIP4;2, 2 pollen-specific aquaporins of Arabidopsis thaliana. NIP4;1 and NIP4;2 displayed high amino acid identity. RT-PCR and GUS promoter analysis showed that they have different expression patterns. NIP4;1 is expressed at low levels in mature pollen, while NIP4;2 is highly expressed only during pollen tube growth. Single T-DNA nip4;1 and nip4;2 mutants and double amiRNA nip4;1 nip4;2 knockdowns showed reduced male fertility due to deficient pollen germination and pollen tube length. Functional assays in oocytes showed that NIP4;1 and NIP4;2 transport water and nonionic solutes. Here, the participation of the different pollen aquaporins in pollen hydration and pollen tube growth is discussed.
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Affiliation(s)
- Juliana Andrea Pérez Di Giorgio
- a Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Dr. Héctor Torres (INGEBI-CONICET) , Vuelta de Obligado, Buenos Aires , Argentina
| | - María Laura Barberini
- a Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Dr. Héctor Torres (INGEBI-CONICET) , Vuelta de Obligado, Buenos Aires , Argentina
| | - Gabriela Amodeo
- b Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA-UBA-CONICET), Intendente Güiraldes, Ciudad Universitaria, Pabellón II , Buenos Aires , Argentina
- c Departamento de Biodiversidad y Biología Experimental , Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes, Ciudad Universitaria, Pabellón II , Buenos Aires , Argentina
| | - Jorge Prometeo Muschietti
- a Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Dr. Héctor Torres (INGEBI-CONICET) , Vuelta de Obligado, Buenos Aires , Argentina
- c Departamento de Biodiversidad y Biología Experimental , Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Intendente Güiraldes, Ciudad Universitaria, Pabellón II , Buenos Aires , Argentina
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Hiroi K, Sone M, Sakazono S, Osaka M, Masuko-Suzuki H, Matsuda T, Suzuki G, Suwabe K, Watanabe M. Time-lapse imaging of self- and cross-pollinations in Brassica rapa. Ann Bot 2013; 112:115-22. [PMID: 23644359 PMCID: PMC3690991 DOI: 10.1093/aob/mct102] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2012] [Accepted: 03/15/2013] [Indexed: 05/21/2023]
Abstract
BACKGROUND AND AIMS Pollination is an important process in the life cycle of plants and is the first step in bringing together the male and female gametophytes for plant reproduction. While pollination has been studied for many years, accurate knowledge of the morphological aspects of this process is still far from complete. This study therefore focuses on a morphological characterization of pollination, using time-series image analysis of self- and cross-pollinations in Brassica rapa. METHODS Time-lapse imaging of pollen behaviour during self- and cross-pollinations was recorded for 90 min, at 1 min intervals, using a stereoscopic microscope. Using time-series digital images of pollination, characteristic features of pollen behaviours during self- and cross-pollinations were studied. KEY RESULTS Pollen exhibited various behaviours in both self- and cross-pollinations, and these were classified into six representative patterns: germination, expansion, contraction, sudden contraction, pulsation and no change. It is noteworthy that in 'contraction' pollen grains shrunk within a short period of 30-50 min, and in 'pulsation' repeated expansion and contraction occurred with an interval of 10 min, suggesting that a dehydration system is operating in pollination. All of the six patterns were observed on an individual stigma with both self- and cross-pollinations, and the difference between self- and cross-pollinations was in the ratios of the different behaviours. With regard to water transport to and from pollen grains, this occurred in multiple steps, before, during and after hydration. Thus, pollination is regulated by a combination of multiple components of hydration, rehydration and dehydration systems. CONCLUSIONS Regulated hydration of pollen is a key process for both pollination and self-incompatibility, and this is achieved by a balanced complex of hydration, dehydration and nutrient supply to pollen grains from stigmatic papilla cells.
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Affiliation(s)
- Kenichiro Hiroi
- Graduate School of Life Sciences, Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Mikako Sone
- Graduate School of Life Sciences, Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Satomi Sakazono
- Graduate School of Life Sciences, Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Masaaki Osaka
- Graduate School of Life Sciences, Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Hiromi Masuko-Suzuki
- Graduate School of Life Sciences, Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Tomoki Matsuda
- Graduate School of Bioresources, Mie University, 1577, Kurima-machiya, Tsu 514-8507, Japan
| | - Go Suzuki
- Division of Natural Science, Osaka Kyoiku University, 4-698-1, Asahigaoka, Kashiwara, 582-8582, Japan
| | - Keita Suwabe
- Graduate School of Bioresources, Mie University, 1577, Kurima-machiya, Tsu 514-8507, Japan
| | - Masao Watanabe
- Graduate School of Life Sciences, Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai 980-8577, Japan
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