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Shi T, Bai Y, Wu X, Wang Y, Iqbal S, Tan W, Ni Z, Gao Z. PmAGAMOUS recruits polycomb protein PmLHP1 to regulate single-pistil morphogenesis in Japanese apricot. PLANT PHYSIOLOGY 2023; 193:466-482. [PMID: 37204822 DOI: 10.1093/plphys/kiad292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 03/31/2023] [Accepted: 04/12/2023] [Indexed: 05/20/2023]
Abstract
Japanese apricot (Prunus mume Sieb. et Zucc.) is a traditional fruit tree with a long history. Multiple pistils (MP) lead to the formation of multiple fruits, decreasing fruit quality and yield. In this study, the morphology of flowers was observed at 4 stages of pistil development: undifferentiated stage (S1), predifferentiation stage (S2), differentiation stage (S3), and late differentiation stage (S4). In S2 and S3, the expression of PmWUSCHEL (PmWUS) in the MP cultivar was significantly higher than that in the single-pistil (SP) cultivar, and the gene expression of its inhibitor, PmAGAMOUS (PmAG), also showed the same trend, indicating that other regulators participate in the regulation of PmWUS during this period. Chromatin immunoprecipitation-qPCR (ChIP-qPCR) showed that PmAG could bind to the promoter and the locus of PmWUS, and H3K27me3 repressive marks were also detected at these sites. The SP cultivar exhibited an elevated level of DNA methylation in the promoter region of PmWUS, which partially overlapped with the region of histone methylation. This suggests that the regulation of PmWUS involves both transcription factors and epigenetic modifications. Also, the gene expression of Japanese apricot LIKE HETEROCHROMATIN PROTEIN (PmLHP1), an epigenetic regulator, in MP was significantly lower than that in SP in S2 to 3, contrary to the trend in expression of PmWUS. Our results showed that PmAG recruited sufficient PmLHP1 to maintain the level of H3K27me3 on PmWUS during the S2 of pistil development. This recruitment of PmLHP1 by PmAG inhibits the expression of PmWUS at the precise time, leading to the formation of 1 normal pistil primordium.
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Affiliation(s)
- Ting Shi
- College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Yang Bai
- College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Xinxin Wu
- College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
- College of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian 223003, China
| | - Yike Wang
- College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Shahid Iqbal
- College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
- Horticultural Science Department, North Florida Research and Education Center, University of Florida/IFAS, Quincy, FL 32351, USA
| | - Wei Tan
- College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Zhaojun Ni
- College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
| | - Zhihong Gao
- College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
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Bullones A, Castro AJ, Lima-Cabello E, Fernandez-Pozo N, Bautista R, Alché JDD, Claros MG. Transcriptomic Insight into the Pollen Tube Growth of Olea europaea L. subsp. europaea Reveals Reprogramming and Pollen-Specific Genes Including New Transcription Factors. PLANTS (BASEL, SWITZERLAND) 2023; 12:2894. [PMID: 37631106 PMCID: PMC10459472 DOI: 10.3390/plants12162894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Revised: 08/01/2023] [Accepted: 08/02/2023] [Indexed: 08/27/2023]
Abstract
The pollen tube is a key innovation of land plants that is essential for successful fertilisation. Its development and growth have been profusely studied in model organisms, but in spite of the economic impact of olive trees, little is known regarding the genome-wide events underlying pollen hydration and growth in this species. To fill this gap, triplicate mRNA samples at 0, 1, 3, and 6 h of in vitro germination of olive cultivar Picual pollen were analysed by RNA-seq. A bioinformatics R workflow called RSeqFlow was developed contemplating the best practices described in the literature, covering from expression data filtering to differential expression and clustering, to finally propose hub genes. The resulting olive pollen transcriptome consisted of 22,418 reliable transcripts, where 5364 were differentially expressed, out of which 173 have no orthologue in plants and up to 3 of them might be pollen-specific transcription factors. Functional enrichment revealed a deep transcriptional reprogramming in mature olive pollen that is also dependent on protein stability and turnover to allow pollen tube emergence, with many hub genes related to heat shock proteins and F-box-containing proteins. Reprogramming extends to the first 3 h of growth, including processes consistent with studies performed in other plant species, such as global down-regulation of biosynthetic processes, vesicle/organelle trafficking and cytoskeleton remodelling. In the last stages, growth should be maintained from persistent transcripts. Mature pollen is equipped with transcripts to successfully cope with adverse environments, even though the in vitro growth seems to induce several stress responses. Finally, pollen-specific transcription factors were proposed as probable drivers of pollen germination in olive trees, which also shows an overall increased number of pollen-specific gene isoforms relative to other plants.
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Affiliation(s)
- Amanda Bullones
- Department of Molecular Biology and Biochemistry, Universidad de Málaga, 29010 Malaga, Spain;
- Institute for Mediterranean and Subtropical Horticulture “La Mayora” (IHSM-UMA-CSIC), 29010 Malaga, Spain;
| | - Antonio Jesús Castro
- Plant Reproductive Biology and Advanced Imaging Laboratory (BReMAP), Estación Experimental del Zaidín (EEZ-CSIC), 18008 Granada, Spain; (A.J.C.); (E.L.-C.); (J.d.D.A.)
| | - Elena Lima-Cabello
- Plant Reproductive Biology and Advanced Imaging Laboratory (BReMAP), Estación Experimental del Zaidín (EEZ-CSIC), 18008 Granada, Spain; (A.J.C.); (E.L.-C.); (J.d.D.A.)
| | - Noe Fernandez-Pozo
- Institute for Mediterranean and Subtropical Horticulture “La Mayora” (IHSM-UMA-CSIC), 29010 Malaga, Spain;
| | - Rocío Bautista
- Plataforma Andaluza de Bioinformática, Supercomputing and Bioinnovation Center (SCBI), Universidad de Málaga, 29590 Malaga, Spain;
| | - Juan de Dios Alché
- Plant Reproductive Biology and Advanced Imaging Laboratory (BReMAP), Estación Experimental del Zaidín (EEZ-CSIC), 18008 Granada, Spain; (A.J.C.); (E.L.-C.); (J.d.D.A.)
- University Institute of Research on Olive Grove and Olive Oils (INUO), Universidad de Jaén, 23071 Jaen, Spain
| | - Manuel Gonzalo Claros
- Department of Molecular Biology and Biochemistry, Universidad de Málaga, 29010 Malaga, Spain;
- Institute for Mediterranean and Subtropical Horticulture “La Mayora” (IHSM-UMA-CSIC), 29010 Malaga, Spain;
- CIBER de Enfermedades Raras (CIBERER) U741, 29071 Malaga, Spain
- Institute of Biomedical Research in Málaga (IBIMA), IBIMA-RARE, 29010 Malaga, Spain
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3
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Inflorescence Traits and Floral Quality Parameters in Promising Olive Clones (cv Leccino): Influence of the Canopy Position. HORTICULTURAE 2022. [DOI: 10.3390/horticulturae8050402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In olive (Olea europaea L.), the floral quality is a key feature affecting the final fruit crop. The aim of this study was to evaluate the inflorescence traits and the floral quality parameters of three clones of Leccino cultivar (L 1.3, L 1.4, L 1.9). To assess a possible effect of light limitations on these parameters two canopy zones, internal (IZ) and external (EZ), were considered. The inflorescences were collected over two consecutive years in order to establish: (i) the characteristics of inflorescences (length, flowers per inflorescence) and flowers (open and perfect flowers); (ii) the ovary structure by histological analysis; and (iii) the viability and germination of pollen grains by in vitro culture. The preliminary results highlighted some differences among clones. The L 1.9 was the less affected by the canopy position for inflorescence morphological traits, and the presence of ovaries with at least three fully developed ovules denoting a high female fertility. Regardless of the canopy position, L 1.4 showed the highest pollen viability, suggesting its possible use as pollinator. The lower sensitivity of female and male floral organs to partial shading of L 1.9 and L 1.4 needs further investigations aimed at evaluating their suitability in high-density olive orchards.
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Liao J, Chen Z, Wei X, Tao K, Zhang J, Qin X, Pan Z, Ma W, Pan L, Yang S, Wang M, Ou X, Chen S. Identification of pollen and pistil polygalacturonases in Nicotiana tabacum and their function in interspecific stigma compatibility. PLANT REPRODUCTION 2020; 33:173-190. [PMID: 32880726 DOI: 10.1007/s00497-020-00393-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 08/18/2020] [Indexed: 06/11/2023]
Abstract
KEY MESSAGE The pollen and pistil polygalacturonases in Nicotiana tabacum were identified and found to regulate pollen tube growth and interspecific compatibility. Polygalacturonase (PG) is one of the enzymes catalyzing the hydrolysis of pectin. This process plays important roles in the pollen and pistil. In this research, the pollen and pistil PGs in Nicotiana tabacum (NtPGs) were identified, and their expression, localization and the potential function in the pollen and interspecific stigma incompatibility were explored. The results showed that 118 NtPGs were retrieved from the genome of N. tabacum. The phylogenetic tree and RT-qPCR analysis led to the identification of 10 pollen PGs; among them, two, seven and one showed specifically higher expression levels in the early development of anthers, during pollen maturation and in mature anthers, respectively, indicating their function difference. Immunofluorescence analysis showed that PGs were located in the cytoplasm of (1) mature pollen and (2) in vitro grown pollen tubes, as well as in the wall of in vivo grown pollen tubes. Four NtPGs in clade A were identified as the pistil PGs, and the pistil PGs were not found in clade E. Significantly higher PGs expression was recorded after incompatible pollination in comparison with the compatible stigma, indicating a potential function of PGs in regulating stigma incompatibility. The influence of PGs on pollen tube growth was explored in vitro and partly in vivo, showing that high PGs activity inhibited pollen tube growth. The application of PGs on the otherwise compatible stigma resulted in pollen tube growth inhibition or failure of germination. These results further supported that increased PGs expression in incompatible stigma might be partially responsible for the interspecific stigma incompatibility in Nicotiana.
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Affiliation(s)
- Jugou Liao
- School of Ecology and Environmental Sciences, Biocontrol Engineering Research Center of Plant Diseases and Pests, Biocontrol Engineering Research Center of Crop Diseases & Pests, Yunnan University, Kunming, 650091, Yunnan Province, China
| | - Zhiyun Chen
- School of Ecology and Environmental Sciences, Biocontrol Engineering Research Center of Plant Diseases and Pests, Biocontrol Engineering Research Center of Crop Diseases & Pests, Yunnan University, Kunming, 650091, Yunnan Province, China
| | - Xuemei Wei
- School of Ecology and Environmental Sciences, Biocontrol Engineering Research Center of Plant Diseases and Pests, Biocontrol Engineering Research Center of Crop Diseases & Pests, Yunnan University, Kunming, 650091, Yunnan Province, China
| | - Keliang Tao
- School of Ecology and Environmental Sciences, Biocontrol Engineering Research Center of Plant Diseases and Pests, Biocontrol Engineering Research Center of Crop Diseases & Pests, Yunnan University, Kunming, 650091, Yunnan Province, China
| | - Jingwen Zhang
- School of Ecology and Environmental Sciences, Biocontrol Engineering Research Center of Plant Diseases and Pests, Biocontrol Engineering Research Center of Crop Diseases & Pests, Yunnan University, Kunming, 650091, Yunnan Province, China
| | - Xiaojun Qin
- School of Ecology and Environmental Sciences, Biocontrol Engineering Research Center of Plant Diseases and Pests, Biocontrol Engineering Research Center of Crop Diseases & Pests, Yunnan University, Kunming, 650091, Yunnan Province, China
| | - Zihui Pan
- School of Ecology and Environmental Sciences, Biocontrol Engineering Research Center of Plant Diseases and Pests, Biocontrol Engineering Research Center of Crop Diseases & Pests, Yunnan University, Kunming, 650091, Yunnan Province, China
| | - Wenguang Ma
- Yunnan Academy of Tobacco Agricultural Sciences, Yuxi, 653100, China
| | - Lei Pan
- Yuxi China Tobacco Seed Co., Ltd., Yuxi, 653100, China
| | - Shuai Yang
- Yuxi China Tobacco Seed Co., Ltd., Yuxi, 653100, China
| | | | - Xiaokun Ou
- School of Ecology and Environmental Sciences, Biocontrol Engineering Research Center of Plant Diseases and Pests, Biocontrol Engineering Research Center of Crop Diseases & Pests, Yunnan University, Kunming, 650091, Yunnan Province, China.
| | - Suiyun Chen
- School of Ecology and Environmental Sciences, Biocontrol Engineering Research Center of Plant Diseases and Pests, Biocontrol Engineering Research Center of Crop Diseases & Pests, Yunnan University, Kunming, 650091, Yunnan Province, China.
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Hernández ML, Lima-Cabello E, Alché JDD, Martínez-Rivas JM, Castro AJ. Lipid Composition and Associated Gene Expression Patterns during Pollen Germination and Pollen Tube Growth in Olive (Olea europaea L.). PLANT & CELL PHYSIOLOGY 2020; 61:1348-1364. [PMID: 32384163 PMCID: PMC7377348 DOI: 10.1093/pcp/pcaa063] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 04/30/2020] [Indexed: 05/23/2023]
Abstract
Pollen lipids are essential for sexual reproduction, but our current knowledge regarding lipid dynamics in growing pollen tubes is still very scarce. Here, we report unique lipid composition and associated gene expression patterns during olive pollen germination. Up to 376 genes involved in the biosynthesis of all lipid classes, except suberin, cutin and lipopolysaccharides, are expressed in olive pollen. The fatty acid profile of olive pollen is markedly different compared with other plant organs. Triacylglycerol (TAG), containing mostly C12-C16 saturated fatty acids, constitutes the bulk of olive pollen lipids. These compounds are partially mobilized, and the released fatty acids enter the β-oxidation pathway to yield acetyl-CoA, which is converted into sugars through the glyoxylate cycle during the course of pollen germination. Our data suggest that fatty acids are synthesized de novo and incorporated into glycerolipids by the 'eukaryotic pathway' in elongating pollen tubes. Phosphatidic acid is synthesized de novo in the endomembrane system during pollen germination and seems to have a central role in pollen tube lipid metabolism. The coordinated action of fatty acid desaturases FAD2-3 and FAD3B might explain the increase in linoleic and alpha-linolenic acids observed in germinating pollen. Continuous synthesis of TAG by the action of diacylglycerol acyltransferase 1 (DGAT1) enzyme, but not phosphoplipid:diacylglycerol acyltransferase (PDAT), also seems plausible. All these data allow for a better understanding of lipid metabolism during the olive reproductive process, which can impact, in the future, on the increase in olive fruit yield and, therefore, olive oil production.
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Affiliation(s)
- M Luisa Hernández
- Department of Biochemistry and Molecular Biology of Plant Products, Instituto de la Grasa (CSIC), Seville 41013, Spain
- Departamento de Bioquímica Vegetal y Biología Molecular, Universidad de Sevilla, Avda. Reina Mercedes s/n, Sevilla 41012, Spain
| | - Elena Lima-Cabello
- Plant Reproductive Biology and Advanced Imaging Laboratory, Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín (CSIC), Granada 18008, Spain
| | - Juan de D Alché
- Plant Reproductive Biology and Advanced Imaging Laboratory, Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín (CSIC), Granada 18008, Spain
| | - José M Martínez-Rivas
- Department of Biochemistry and Molecular Biology of Plant Products, Instituto de la Grasa (CSIC), Seville 41013, Spain
| | - Antonio J Castro
- Plant Reproductive Biology and Advanced Imaging Laboratory, Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín (CSIC), Granada 18008, Spain
- Corresponding author: E-mail, ; Fax, +34-958-181609
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6
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Alagna F, Caceres ME, Pandolfi S, Collani S, Mousavi S, Mariotti R, Cultrera NGM, Baldoni L, Barcaccia G. The Paradox of Self-Fertile Varieties in the Context of Self-Incompatible Genotypes in Olive. FRONTIERS IN PLANT SCIENCE 2019; 10:725. [PMID: 31293602 PMCID: PMC6606695 DOI: 10.3389/fpls.2019.00725] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 05/16/2019] [Indexed: 05/09/2023]
Abstract
Olive, representing one of the most important fruit crops of the Mediterranean area, is characterized by a general low fruit yield, due to numerous constraints, including alternate bearing, low flower viability, male-sterility, inter-incompatibility, and self-incompatibility (SI). Early efforts to clarify the genetic control of SI in olive gave conflicting results, and only recently, the genetic control of SI has been disclosed, revealing that olive possesses an unconventional homomorphic sporophytic diallelic system of SI, dissimilar from other described plants. This system, characterized by the presence of two SI groups, prevents self-fertilization and regulates inter-compatibility between cultivars, such that cultivars bearing the same incompatibility group are incompatible. Despite the presence of a functional SI, some varieties, in particular conditions, are able to set seeds following self-fertilization, a mechanism known as pseudo-self-compatibility (PSC), as widely reported in previous literature. Here, we summarize the results of previous works on SI in olive, particularly focusing on the occurrence of self-fertility, and offer a new perspective in view of the recent elucidation of the genetic architecture of the SI system in olive. Recent advances in research aimed at unraveling the molecular bases of SI and its breakdown in olive are also presented. The clarification of these mechanisms may have a huge impact on orchard management and will provide fundamental information for the future of olive breeding programs.
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Affiliation(s)
- F. Alagna
- Dipartimento Tecnologie Energetiche (DTE), Centro Ricerche Trisaia, ENEA Agenzia nazionale per le nuove tecnologie, l’energia e lo sviluppo economico sostenibile, Rotondella, Italy
| | - M. E. Caceres
- Dipartimento di Scienze Bio Agroalimentari (DiSBA), Istituto di Bioscienze e Biorisorse (IBBR), Consiglio Nazionale Delle Ricerche (CNR), Perugia, Italy
| | - S. Pandolfi
- Dipartimento di Scienze Bio Agroalimentari (DiSBA), Istituto di Bioscienze e Biorisorse (IBBR), Consiglio Nazionale Delle Ricerche (CNR), Perugia, Italy
| | - S. Collani
- Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, Umeå, Sweden
| | - S. Mousavi
- Dipartimento di Scienze Bio Agroalimentari (DiSBA), Istituto di Bioscienze e Biorisorse (IBBR), Consiglio Nazionale Delle Ricerche (CNR), Perugia, Italy
| | - R. Mariotti
- Dipartimento di Scienze Bio Agroalimentari (DiSBA), Istituto di Bioscienze e Biorisorse (IBBR), Consiglio Nazionale Delle Ricerche (CNR), Perugia, Italy
| | - N. G. M. Cultrera
- Dipartimento di Scienze Bio Agroalimentari (DiSBA), Istituto di Bioscienze e Biorisorse (IBBR), Consiglio Nazionale Delle Ricerche (CNR), Perugia, Italy
| | - L. Baldoni
- Dipartimento di Scienze Bio Agroalimentari (DiSBA), Istituto di Bioscienze e Biorisorse (IBBR), Consiglio Nazionale Delle Ricerche (CNR), Perugia, Italy
- *Correspondence: L. Baldoni,
| | - G. Barcaccia
- Laboratorio di Genomica, Dipartimento di Agronomia, Animali, Alimenti, Risorse naturali e Ambiente (DAFNAE), Università di Padova, Legnaro, Italy
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Zafra A, M’rani-Alaoui M, Lima E, Jimenez-Lopez JC, Alché JDD. Histological Features of the Olive Seed and Presence of 7S-Type Seed Storage Proteins as Hallmarks of the Olive Fruit Development. FRONTIERS IN PLANT SCIENCE 2018; 9:1481. [PMID: 30369937 PMCID: PMC6194196 DOI: 10.3389/fpls.2018.01481] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 09/21/2018] [Indexed: 06/08/2023]
Abstract
The production of olive oil is an important economic engine in the Mediterranean area. Nowadays, olive oil is obtained mainly by mechanical processes, by using the whole fruit as the primary raw material. Although the mesocarp is the main source of lipids contributing to olive oil formation, the seed also contributes to the olive oil composition and attributes. The olive seed is also becoming an interesting emerging material itself when obtained after alternative processing of the olive fruit. Such seed is used for the production of differential oil and a unique flour among other bioactive products, with increasing uses and applications in cosmetics, nutrition, and health. However, olive seed histology has been poorly studied to date. A complete description of its anatomy is described for the first time in the present study by using the 'Picual' cultivar as a model to study the development of the different tissues of the olive seed from 60 to 210 days after anthesis. A deep analysis of the seed coats, endosperm storage tissue and the embryo during their development has been performed. Moreover, a panel of other olive cultivars has been used to compare the weight contribution of the different tissues to the seed, seed weight variability and the number of seeds per fruit. In addition to the histological features, accumulation of seed storage proteins of the 7S-type (β-conglutins) in the seed tissues has been assessed by both biochemical and immunocytochemical methods. These hallmarks will help to settle the basis for future studies related to the location of different metabolites along the olive seed and mesocarp development, and therefore helping to assess the appropriate ripening stage for different commercial and industrial purposes.
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Affiliation(s)
- Adoración Zafra
- Plant Reproductive Biology Laboratory, Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, Granada, Spain
| | | | - Elena Lima
- Plant Reproductive Biology Laboratory, Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, Granada, Spain
| | - Jose Carlos Jimenez-Lopez
- Plant Reproductive Biology Laboratory, Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, Granada, Spain
| | - Juan de Dios Alché
- Plant Reproductive Biology Laboratory, Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, Granada, Spain
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8
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Lau JYY, Pang C, Ramsden L, Saunders RMK. Stigmatic exudate in the Annonaceae: Pollinator reward, pollen germination medium or extragynoecial compitum? JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2017; 59:881-894. [PMID: 28880427 PMCID: PMC5725718 DOI: 10.1111/jipb.12598] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 09/05/2017] [Indexed: 05/10/2023]
Abstract
Although "dry-type" stigmas are widely regarded as ancestral in angiosperms, the early-divergent family Annonaceae has copious stigmatic exudate. We evaluate three putative functions for this exudate: as a nutritive reward for pollinators; as a pollen germination medium; and as an extragynoecial compitum that enables pollen tube growth between carpels. Stigmatic exudate is fructose dominated (72.2%), but with high levels of glucose and sucrose; the dominance of hexose sugars and the diversity of amino acids observed, including many that are essential for insects, support a nutritive role for pollinators. Sugar concentration in pre-receptive flowers is high (28.2%), falling during the peak period of stigmatic receptivity (17.4%), and then rising again toward the end of the pistillate phase (32.9%). Pollen germination was highest in sugar concentrations <20%. Sugar concentrations during the peak pistillate phase therefore provide optimal osmolarity for pollen hydration and germination; subsequent changes in sugar concentration during anthesis reinforce protogyny (in which carpels mature before stamens), enabling the retention of concentrated exudate into the staminate phase as a pollinator food reward without the possibility of pollen germination. Intercarpellary growth of pollen tubes was confirmed: the exudate therefore also functions as a suprastylar extragynoecial compitum, overcoming the limitations of apocarpy.
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Affiliation(s)
- Jenny Y. Y. Lau
- School of Biological Sciencesthe University of Hong KongPokfulam RoadHong KongChina
| | - Chun‐Chiu Pang
- School of Biological Sciencesthe University of Hong KongPokfulam RoadHong KongChina
| | - Lawrence Ramsden
- School of Biological Sciencesthe University of Hong KongPokfulam RoadHong KongChina
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9
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Deng Y, Sun X, Gu C, Jia X, Liang L, Su J. Identification of pre-fertilization reproductive barriers and the underlying cytological mechanism in crosses among three petal-types of Jasminum sambac and their relevance to phylogenetic relationships. PLoS One 2017; 12:e0176026. [PMID: 28419158 PMCID: PMC5395215 DOI: 10.1371/journal.pone.0176026] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 04/04/2017] [Indexed: 11/18/2022] Open
Abstract
Crosses among single-, double- and multi-petal jasmine cultivars (Jasminum sambac Aiton) are unable to easily generate hybrids. To identify the reproductive barriers restricting hybrid set, dynamic changes in jasmine pollen viability and pistil receptivity were compared at different flowering stages. Pollen-pistil interactions in six reciprocal crosses were also investigated to characterize pollen-stigma compatibility. Additionally, paraffin sections of pollinated embryo sacs were prepared for subsequent analyses of developmental status. Furthermore, pistil cell ultrastructural characteristics were observed to reveal cytological mechanism regulating pistil receptivity and the pollen-pistil interactions. We observed that pollen viability and stigma receptivity varied depending on petal phenotype and flowering stage and were easily lost during flowering. Different reciprocal crosses exhibited varied pollen-stigma compatibilities according to the pollen germination rates. Although some pollen grains germinated normally on maternal stigmas, the pollen tubes were arrested in the pistils and were unable to reach the ovaries. Additionally, the embryo sacs remained unfertilized until degenerating. Therefore, jasmine crosses are affected by pre-fertilization reproductive barriers. Low pollen fertility and poor stigma receptivity are detrimental to pollen germination and pollen-pistil compatibility, indicating they are two factors affecting hybrid set. Ultrastructural observation of the pistil cells revealed that cell death occurred during flowering. Thus, the early and rapid senescence of pistils is likely responsible for the decreased pistil receptivity and inhibited pollen tube growth. These findings may be relevant for future jasmine hybridizations. They provide new insights for the development of methods to overcome reproductive barriers and may also be useful for clarifying the phylogenetic relationships among jasmine cultivars with differing petal phenotypes.
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Affiliation(s)
- Yanming Deng
- Provincial Key Laboratory for Horticultural Crop Genetic Improvement, Institute of Leisure Agriculture, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, China
| | - Xiaobo Sun
- Provincial Key Laboratory for Horticultural Crop Genetic Improvement, Institute of Leisure Agriculture, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, China
| | - Chunsun Gu
- Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, Jiangsu, China
| | - Xinping Jia
- Provincial Key Laboratory for Horticultural Crop Genetic Improvement, Institute of Leisure Agriculture, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, China
| | - Lijian Liang
- Institute of Botany, Jiangsu Province and Chinese Academy of Sciences, Nanjing, Jiangsu, China
| | - Jiale Su
- Provincial Key Laboratory for Horticultural Crop Genetic Improvement, Institute of Leisure Agriculture, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu, China
- * E-mail:
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10
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Rejón JD, Delalande F, Schaeffer-Reiss C, Alché JDD, Rodríguez-García MI, Van Dorsselaer A, Castro AJ. The Pollen Coat Proteome: At the Cutting Edge of Plant Reproduction. Proteomes 2016; 4:E5. [PMID: 28248215 PMCID: PMC5217362 DOI: 10.3390/proteomes4010005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 01/18/2016] [Accepted: 01/21/2016] [Indexed: 01/09/2023] Open
Abstract
The tapetum is a single layer of secretory cells which encloses the anther locule and sustains pollen development and maturation. Upon apoptosis, the remnants of the tapetal cells, consisting mostly of lipids and proteins, fill the pits of the sculpted exine to form the bulk of the pollen coat. This extracellular matrix forms an impermeable barrier that protects the male gametophyte from water loss and UV light. It also aids pollen adhesion and hydration and retains small signaling compounds involved in pollen-stigma communication. In this study, we have updated the list of the pollen coat's protein components and also discussed their functions in the context of sexual reproduction.
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Affiliation(s)
- Juan David Rejón
- Plant Reproductive Biology Laboratory, Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Profesor Albareda 1, 18008 Granada, Spain.
| | - François Delalande
- Bio-Organic Mass Spectrometry Laboratory (LSMBO), IPHC, Université de Strasbourg, 25 rue Becquerel, 67087 Strasbourg, France.
- IPHC, Centre National de la Recherche Scientifique (CNRS), UMR7178, 67087 Strasbourg, France.
| | - Christine Schaeffer-Reiss
- Bio-Organic Mass Spectrometry Laboratory (LSMBO), IPHC, Université de Strasbourg, 25 rue Becquerel, 67087 Strasbourg, France.
- IPHC, Centre National de la Recherche Scientifique (CNRS), UMR7178, 67087 Strasbourg, France.
| | - Juan de Dios Alché
- Plant Reproductive Biology Laboratory, Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Profesor Albareda 1, 18008 Granada, Spain.
| | - María Isabel Rodríguez-García
- Plant Reproductive Biology Laboratory, Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Profesor Albareda 1, 18008 Granada, Spain.
| | - Alain Van Dorsselaer
- Bio-Organic Mass Spectrometry Laboratory (LSMBO), IPHC, Université de Strasbourg, 25 rue Becquerel, 67087 Strasbourg, France.
- IPHC, Centre National de la Recherche Scientifique (CNRS), UMR7178, 67087 Strasbourg, France.
| | - Antonio Jesús Castro
- Plant Reproductive Biology Laboratory, Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Profesor Albareda 1, 18008 Granada, Spain.
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Zafra A, Rejón JD, Hiscock SJ, Alché JDD. Patterns of ROS Accumulation in the Stigmas of Angiosperms and Visions into Their Multi-Functionality in Plant Reproduction. FRONTIERS IN PLANT SCIENCE 2016; 7:1112. [PMID: 27547207 PMCID: PMC4974276 DOI: 10.3389/fpls.2016.01112] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 07/13/2016] [Indexed: 05/20/2023]
Abstract
Accumulation of reactive oxygen species (ROS) in the stigma of several plant species has been investigated. Four developmental stages (unopened flower buds, recently opened flowers, dehiscent anthers, and flowers after fertilization) were analyzed by confocal laser scanning microscopy using the ROS-specific probe DCFH2-DA. In all plants scrutinized, the presence of ROS in the stigmas was detected at higher levels during those developmental phases considered "receptive" to pollen interaction. In addition, these molecules were also present at early (unopened flower) or later (post-fertilization) stages, by following differential patterns depending on the different species. The biological significance of the presence ROS may differ between these stages, including defense functions, signaling and senescence. Pollen-stigma signaling is likely involved in the different mechanisms of self-incompatibility in these plants. The study also register a general decrease in the presence of ROS in the stigmas upon pollination, when NO is supposedly produced in an active manner by pollen grains. Finally, the distribution of ROS in primitive Angiosperms of the genus Magnolia was determined. The production of such chemical species in these plants was several orders of magnitude higher than in the remaining species evoking a massive displacement toward the defense function. This might indicate that signaling functions of ROS/NO in the stigma evolved later, as fine tune likely involved in specialized interactions like self-incompatibility.
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Affiliation(s)
- Adoración Zafra
- Plant Reproductive Biology Laboratory, Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, Consejo Superior de Investigaciones CientíficasGranada, Spain
| | - Juan D. Rejón
- Plant Reproductive Biology Laboratory, Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, Consejo Superior de Investigaciones CientíficasGranada, Spain
| | | | - Juan de Dios Alché
- Plant Reproductive Biology Laboratory, Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, Consejo Superior de Investigaciones CientíficasGranada, Spain
- *Correspondence: Juan de Dios Alché,
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Rejón JD, Delalande F, Schaeffer-Reiss C, Carapito C, Zienkiewicz K, Alché JDD, Rodríguez-García MI, Van Dorsselaer A, Castro AJ. The plant stigma exudate: a biochemically active extracellular environment for pollen germination? PLANT SIGNALING & BEHAVIOR 2014; 9:e28274. [PMID: 24589550 PMCID: PMC4091586 DOI: 10.4161/psb.28274] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
During sexual reproduction, pollen performance is greatly influenced by the female tissues. The stigma exudate, i.e., the extracellular secretion that covers the stigma outermost surface, has been usually regarded as a reservoir of water, secondary metabolites, cell wall precursors and compounds that serve as energy supply for rapid pollen tube growth. In an attempt to identify the proteins present in the stigma secretome, we performed a large-scale analysis in two species (Lilium longiflorum and Olea europaea) following a proteomic-based approach. The resulting data strongly suggest that the stigma exudate is not a mere storage site but also a biochemically active environment with a markedly catabolic nature. Thus, this secretion may modulate early pollen tube growth and contribute to the senescence of stigma after pollination. In addition, a putative cross-talk between genetic programs that regulate stress/defense and pollination responses in the stigma is also suggested. The stigma exudate might also functionally diverge between species on the basis on their ecology and the biochemical, morphological and anatomical features of their stigmas. Unexpectedly, we identified in both exudates some intracellular proteins, suggesting that a mechanism other than the canonical ER-Golgi exocytic pathway may exist in the stigma and contribute to exudate secretion.
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Affiliation(s)
- Juan David Rejón
- Departamento de Bioquímica, Biología Celular y Molecular de Plantas; Estación Experimental del Zaidín; Consejo Superior de Investigaciones Científicas; Granada, Spain
| | - François Delalande
- Laboratoire de Spectrométrie de Masse Bio-Organique; IPHC-DSA; Université de Strasbourg-CNRS UMR 7178; Strasbourg, France
| | - Christine Schaeffer-Reiss
- Laboratoire de Spectrométrie de Masse Bio-Organique; IPHC-DSA; Université de Strasbourg-CNRS UMR 7178; Strasbourg, France
| | - Christine Carapito
- Laboratoire de Spectrométrie de Masse Bio-Organique; IPHC-DSA; Université de Strasbourg-CNRS UMR 7178; Strasbourg, France
| | - Krzysztof Zienkiewicz
- Departamento de Bioquímica, Biología Celular y Molecular de Plantas; Estación Experimental del Zaidín; Consejo Superior de Investigaciones Científicas; Granada, Spain
- Department of Cell Biology; Institute of General and Molecular Biology; Nicolaus Copernicus University; Toruń, Poland
| | - Juan de Dios Alché
- Departamento de Bioquímica, Biología Celular y Molecular de Plantas; Estación Experimental del Zaidín; Consejo Superior de Investigaciones Científicas; Granada, Spain
| | - María Isabel Rodríguez-García
- Departamento de Bioquímica, Biología Celular y Molecular de Plantas; Estación Experimental del Zaidín; Consejo Superior de Investigaciones Científicas; Granada, Spain
| | - Alain Van Dorsselaer
- Laboratoire de Spectrométrie de Masse Bio-Organique; IPHC-DSA; Université de Strasbourg-CNRS UMR 7178; Strasbourg, France
| | - Antonio J Castro
- Departamento de Bioquímica, Biología Celular y Molecular de Plantas; Estación Experimental del Zaidín; Consejo Superior de Investigaciones Científicas; Granada, Spain
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Rejón JD, Delalande F, Schaeffer-Reiss C, Carapito C, Zienkiewicz K, de Dios Alché J, Rodríguez-García MI, Van Dorsselaer A, Castro AJ. Proteomics profiling reveals novel proteins and functions of the plant stigma exudate. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:5695-705. [PMID: 24151302 PMCID: PMC3871823 DOI: 10.1093/jxb/ert345] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Proteomic analysis of the stigmatic exudate of Lilium longiflorum and Olea europaea led to the identification of 51 and 57 proteins, respectively, most of which are described for the first time in this secreted fluid. These results indicate that the stigmatic exudate is an extracellular environment metabolically active, participating in at least 80 different biological processes and 97 molecular functions. The stigma exudate showed a markedly catabolic profile and appeared to possess the enzyme machinery necessary to degrade large polysaccharides and lipids secreted by papillae to smaller units, allowing their incorporation into the pollen tube during pollination. It may also regulate pollen-tube growth in the pistil through the selective degradation of tube-wall components. Furthermore, some secreted proteins were involved in pollen-tube adhesion and orientation, as well as in programmed cell death of the papillae cells in response to either compatible pollination or incompatible pollen rejection. Finally, the results also revealed a putative cross-talk between genetic programmes regulating stress/defence and pollination responses in the stigma.
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Affiliation(s)
- Juan David Rejón
- Departamento de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín (C.S.I.C.), C/ Profesor Albareda 1,18008 Granada, Spain
- These authors contributed equally to this work
| | - François Delalande
- Laboratoire de Spectrométrie de Masse Bio-Organique, IPHC-DSA, UdS, CNRS, UMR 7178, 25 rue Becquerel, 67087 Strasbourg, France
- These authors contributed equally to this work
| | - Christine Schaeffer-Reiss
- Laboratoire de Spectrométrie de Masse Bio-Organique, IPHC-DSA, UdS, CNRS, UMR 7178, 25 rue Becquerel, 67087 Strasbourg, France
| | - Christine Carapito
- Laboratoire de Spectrométrie de Masse Bio-Organique, IPHC-DSA, UdS, CNRS, UMR 7178, 25 rue Becquerel, 67087 Strasbourg, France
| | - Krzysztof Zienkiewicz
- Departamento de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín (C.S.I.C.), C/ Profesor Albareda 1,18008 Granada, Spain
- Department of Cell Biology, Institute of General and Molecular Biology, Nicolaus Copernicus University, Gargarina 9, 87–100 Toruń, Poland
| | - Juan de Dios Alché
- Departamento de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín (C.S.I.C.), C/ Profesor Albareda 1,18008 Granada, Spain
| | - María Isabel Rodríguez-García
- Departamento de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín (C.S.I.C.), C/ Profesor Albareda 1,18008 Granada, Spain
| | - Alain Van Dorsselaer
- Laboratoire de Spectrométrie de Masse Bio-Organique, IPHC-DSA, UdS, CNRS, UMR 7178, 25 rue Becquerel, 67087 Strasbourg, France
| | - Antonio Jesús Castro
- Departamento de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín (C.S.I.C.), C/ Profesor Albareda 1,18008 Granada, Spain
- * To whom correspondence should be addressed. E-mail:
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Suárez C, Zienkiewicz A, Castro AJ, Zienkiewicz K, Majewska-Sawka A, Rodríguez-García MI. Cellular localization and levels of pectins and arabinogalactan proteins in olive (Olea europaea L.) pistil tissues during development: implications for pollen-pistil interaction. PLANTA 2013; 237:305-19. [PMID: 23065053 DOI: 10.1007/s00425-012-1774-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Accepted: 09/20/2012] [Indexed: 05/07/2023]
Abstract
Cell wall components in the pistil are involved in cell-cell recognition, nutrition and regulation of pollen tube growth. The aim of this work was to study the level, whole-organ distribution, and subcellular localization of pectins and arabinogalactan proteins (AGPs) in the olive developing pistil. Western blot analyses and immunolocalization with fluorescence and electron microscopy were carried out using a battery of antibodies recognizing different types of pectin epitopes (JIM7, JIM5, LM5, and LM6) and one anti-AGPs antibody (JIM13). In the olive pistil, highest levels of acid esterified and de-esterified pectins were observed at pollination. Moreover, pollination was accompanied by a slight decrease of the galactose-rich pectins pool, whereas arabinose-rich pectins were more abundant at that time. An increased expression of AGPs was also observed during pollination, in comparison to the pistil at the pre-anthesis stage. After pollination, the levels of pectins and AGPs declined significantly. Inmunofluorescence localization of pectins showed their different localization in the olive pistil. Pectins with galactose residues were located mainly in the cortical zones of the pistil, similar to the neutral pectins, which were found in the parenchyma and epidermis. In turn, the neutral pectins, which contain arabinose residues and AGPs, were localized predominantly in the stigmatic exudate, in the cell wall of secretory cells of the stigma, as well as in the transmitting tissue of the pistil during the pollination period. The differences in localization of pectins and AGPs are discussed in relation to their roles during olive pistil developmental course.
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Affiliation(s)
- Cynthia Suárez
- Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, CSIC, 18008 Granada, Spain
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Zienkiewicz A, Zienkiewicz K, Rejón JD, Rodríguez-García MI, Castro AJ. New insights into the early steps of oil body mobilization during pollen germination. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:293-302. [PMID: 23132905 PMCID: PMC3528035 DOI: 10.1093/jxb/ers332] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
In some plants, pollen grains accumulate storage lipids that serve as energy supply during germination. Here, three enzymes involved in early steps of oil body mobilization in the male gametophyte were functionally characterized for the first time. The effect of extracellular sugars on pollen performance and oil body dynamics was also analysed. Olive pollen oil bodies showed phospholipase A, lipase, and lipoxygenase activities on their surface. Enzyme activity levels increased during germination with a maximum after 3h. Removal of extracellular sugars from the germination medium did not affect pollen performance but increased enzyme activity rates and sped up oil body mobilization. Inhibitors seriously hampered pollen germination and pollen tube growth, leading to a characteristic accumulation of oil bodies in the germinative aperture. It can be concluded that storage lipids are sufficient for proper olive pollen germination. A lipase and a lipoxygenase are likely involved in oil body mobilization. Extracellular sugars may modulate their function, while a phospholipase A may promote their access to the storage lipids.
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Affiliation(s)
- Agnieszka Zienkiewicz
- Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), 18008 Granada, Spain
- Department of Cell Biology, Nicolaus Copernicus University, 87–100 Toruń, Poland
| | - Krzysztof Zienkiewicz
- Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), 18008 Granada, Spain
- Department of Physiology and Molecular Biology of Plants, Nicolaus Copernicus University, 87–100 Toruń, Poland
| | - Juan David Rejón
- Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), 18008 Granada, Spain
| | - María Isabel Rodríguez-García
- Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), 18008 Granada, Spain
| | - Antonio Jesús Castro
- Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), 18008 Granada, Spain
- * To whom correspondence should be addressed. E-mail:
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Jin B, Wang D, Lu Y, Zhang M, Wang L. Structure and function of the tentpole in the reproductive process of Ginkgo biloba L. PLANT SIGNALING & BEHAVIOR 2012; 7:1330-1336. [PMID: 22902707 PMCID: PMC3493421 DOI: 10.4161/psb.21306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The tentpole is a unique structure of the female gametophyte in Ginkgo biloba; however, its exact functions in the reproductive process are unclear. In the present study, we used semi-thin sectioning and electron microscopy to study the structure and function of the tentpole during fertilization in G. biloba. The tentpole was always initiated between two or more deeply immersed archegonia. Before fertilization, the tentpole had developed into a column-like structure, protruding toward the archegonial chamber; cells at the periphery of tentpole were loosely ranged, and abundant lipid droplets and starch grains were accumulated in the tentpole cells. After fertilization, the tentpole degenerated, and some membranous debris was overlaid on its surface. In addition, there were significant decreases in the lipids and starch grains. These results suggested that the tentpole led to the degeneration of the megaspore membrane and then supported the pliable apex of the nucellar tissues. Importantly, the tentpole also contributed to supplying nutrition for fertilization and embryo development.
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Affiliation(s)
- Biao Jin
- College of Horticulture and Plant Protection; Yangzhou University; Yangzhou, Jiangsu, China
- The Arnold Arboretum; Harvard University; Boston, MA USA
| | - Di Wang
- College of Horticulture and Plant Protection; Yangzhou University; Yangzhou, Jiangsu, China
| | - Yan Lu
- College of Horticulture and Plant Protection; Yangzhou University; Yangzhou, Jiangsu, China
| | - Min Zhang
- College of Horticulture and Plant Protection; Yangzhou University; Yangzhou, Jiangsu, China
| | - Li Wang
- College of Horticulture and Plant Protection; Yangzhou University; Yangzhou, Jiangsu, China
- Key Laboratory of Photosynthesis and Environmental Molecular Physiology; Institute of Botany; Chinese Academy of Sciences; Beijing, China
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