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Tong L, Wang J. Morphological Study on the Differentiation of Flower Buds and the Embryological Stages of Male and Female Floral Organs in Lespedeza davurica (Laxm.) Schindl. cv. JinNong ( Fabaceae). PLANTS (BASEL, SWITZERLAND) 2024; 13:1661. [PMID: 38931095 PMCID: PMC11207519 DOI: 10.3390/plants13121661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Revised: 06/09/2024] [Accepted: 06/13/2024] [Indexed: 06/28/2024]
Abstract
Lespedeza davurica (Laxm.) is a leguminous plant with significant ecological benefits, but its embryonic development mechanism remains unclear. We investigated the flower bud differentiation, megaspore and microspore formation, gametophyte development, and embryo and endosperm development in L. davurica. Our aim was to elucidate the relationship between the external morphology and internal development processes of male and female floral organs during growth, as well as the reproductive factors influencing fruiting. The results indicated that although the pistil develops later than the stamen during flower bud differentiation, both organs mature synchronously before flowering. L. davurica pollen exhibits three germination grooves, a reticulate outer wall, and papillary structures on the anther surface. In vivo pollination experiments revealed abnormal spiral growth of L. davurica pollen tubes within the style and the occurrence of callus plugs, which may reduce the seed setting rate. The anther wall development follows the dicotyledonous type, with tetrads formed through microspore meiosis exhibiting both left-right symmetry and tetrahedral arrangements. L. davurica has a single ovule, and the embryo sac develops in the monosporic polygonum type. After dormancy, the zygote undergoes multiple divisions, progressing through spherical, heart-shaped, and torpedo-shaped embryo stages, culminating in a mature embryo. A mature seed comprises cotyledons, hypocotyl, embryo, radicle, and seed coat. Phylogenetic tree analysis reveals a close genetic relationship between L. davurica and other leguminous plants from the genera Lespedeza and Medicago. This study provides valuable insights into the regulation of flowering and hybrid breeding in leguminous plants and offers a new perspective on the development of floral organs and seed setting rates.
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Affiliation(s)
- Lirong Tong
- College of Grassland Science, Shanxi Agricultural University, Taigu 030800, China;
| | - Juan Wang
- College of Grassland Science, Shanxi Agricultural University, Taigu 030800, China;
- Forage Seed Laboratory, College of Grassland Science and Technology, China Agricultural University, Beijing 100193, China
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Wang X, Chen J, Hu L, Zhang J, Xiao F, Zhang S, Shao F, Huang L. Embryological observations on seed abortion in Hibiscus syriacus L. and physiological studies on nutrients, enzyme activity and endogenous hormones. BMC PLANT BIOLOGY 2023; 23:665. [PMID: 38129795 PMCID: PMC10740302 DOI: 10.1186/s12870-023-04669-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 12/07/2023] [Indexed: 12/23/2023]
Abstract
Under natural conditions, most Hibiscus syriacus L. individuals form very few mature seeds or the mature seeds that do form are of poor quality. As a result, seed yield is poor and seeds have low natural germinability. These phenomena strongly hinder utilization of the excellent germplasm resources of H. syriacus. The study has shown that pollen activity and stigma receptivity were high on the day of anthesis, and the pistils and stamens were fertile. Pollen release and stigma receptivity were synchronous. But in styles following self and cross-pollination, pollen tube abnormalities (distortion and twisting of the pollen tubes) and callose deposition were observed. Cross-pollinated pollen tubes elongated faster and fewer pollen tube abnormalities were observed compared with self-pollinated pollen tubes. And during embryo development, abnormalities during the heart-shaped embryo stage led to embryo abortion. Imbalance in antioxidant enzyme activities and low contents of auxin and cytokinin during early stages of embryo development may affect embryo development. Therefore, a low frequency of outcrossing and mid-development embryo abortion may be important developmental causes of H. syriacus seed abortion. Nutrient deficiencies, imbalance in antioxidant enzyme activities, and a high content of abscisic acid at advanced stages of seed development may be physiological causes of seed abortion.
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Affiliation(s)
- Xiaohong Wang
- College of Landscape Architecture, Central South University of Forestry & Technology, Changsha, 410004, China.
- Hunan Big Data Engineering Technology Research Center of Natural Protected Areas Landscape Resources, Changsha, 410004, China.
| | - Jiajia Chen
- College of Landscape Architecture, Central South University of Forestry & Technology, Changsha, 410004, China
- Hunan Big Data Engineering Technology Research Center of Natural Protected Areas Landscape Resources, Changsha, 410004, China
| | - Lingxuan Hu
- College of Landscape Architecture, Central South University of Forestry & Technology, Changsha, 410004, China
| | - Jingwen Zhang
- College of Landscape Architecture, Central South University of Forestry & Technology, Changsha, 410004, China
| | - Fen Xiao
- College of Landscape Architecture, Central South University of Forestry & Technology, Changsha, 410004, China
| | | | - Fengxia Shao
- College of Landscape Architecture, Central South University of Forestry & Technology, Changsha, 410004, China
| | - Liqun Huang
- College of Landscape Architecture, Central South University of Forestry & Technology, Changsha, 410004, China
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Wu L, Xu Y, Qi K, Jiang X, He M, Cui Y, Bao J, Gu C, Zhang S. Self S-RNase reduces the expression of two pollen-specific COBRA genes to inhibit pollen tube growth in pear. MOLECULAR HORTICULTURE 2023; 3:26. [PMID: 38037174 PMCID: PMC10691131 DOI: 10.1186/s43897-023-00074-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 10/30/2023] [Indexed: 12/02/2023]
Abstract
Due to self-incompatibility (SI) prevents self-fertilization, natural or artificial cross-pollination has been conducted in many orchards to stabilize fruit yield. However, it is still puzzled which routes of self S-RNase arresting pollen tube growth. Herein, 17 COBRA genes were isolated from pear genome. Of these genes, the pollen-specifically expressed PbCOB.A.1 and PbCOB.A.2 positively mediates pollen tube growth. The promoters of PbCOB.A.1 and/or PbCOB.A.2 were bound and activated by PbABF.E.2 (an ABRE-binding factor) and PbC2H2.K16.2 (a C2H2-type zinc finger protein). Notably, the expressions of PbCOB.A.1, PbCOB.A.2, and PbC2H2.K16.2 were repressed by self S-RNase, suggesting that self S-RNase reduces the expression of PbCOB.A.1 and PbCOB.A.2 by decreasing the expression of their upstream factors, such as PbC2H2.K16.2, to arrest pollen tube growth. PbCOB.A.1 or PbCOB.A.2 accelerates the growth of pollen tubes treated by self S-RNase, but can hardly affect level of reactive oxygen species and deploymerization of actin cytoskeleton in pollen tubes and cannot physically interact with any reported proteins involved in SI. These results indicate that PbCOB.A.1 and PbCOB.A.2 may not relieve S-RNase toxicity in incompatible pollen tube. The information provides a new route to elucidate the arresting pollen tube growth during SI reaction.
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Affiliation(s)
- Lei Wu
- Centre of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Ying Xu
- Centre of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Kaijie Qi
- Centre of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Xueting Jiang
- College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Min He
- Centre of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Yanbo Cui
- Nanjing Ningcui Biological Seed Company Limited, Nanjing, Jiangsu, China
| | - Jianping Bao
- College of Plant Science, Tarim University, Alaer, Xinjiang, 843300, China
| | - Chao Gu
- Centre of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, Jiangsu, China.
| | - Shaoling Zhang
- Centre of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, Jiangsu, 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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Wang Y, Liu P, Cai Y, Li Y, Tang C, Zhu N, Wang P, Zhang S, Wu J. PbrBZR1 interacts with PbrARI2.3 to mediate brassinosteroid-regulated pollen tube growth during self-incompatibility signaling in pear. PLANT PHYSIOLOGY 2023; 192:2356-2373. [PMID: 37010117 PMCID: PMC10315279 DOI: 10.1093/plphys/kiad208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 03/15/2023] [Accepted: 03/15/2023] [Indexed: 06/19/2023]
Abstract
S-RNase-mediated self-incompatibility (SI) prevents self-fertilization and promotes outbreeding to ensure genetic diversity in many flowering plants, including pear (Pyrus sp.). Brassinosteroids (BRs) have well-documented functions in cell elongation, but their molecular mechanisms in pollen tube growth, especially in the SI response, remain elusive. Here, exogenously applied brassinolide (BL), an active BR, countered incompatible pollen tube growth inhibition during the SI response in pear. Antisense repression of BRASSINAZOLE-RESISTANT1 (PbrBZR1), a critical component of BR signaling, blocked the positive effect of BL on pollen tube elongation. Further analyses revealed that PbrBZR1 binds to the promoter of EXPANSIN-LIKE A3 (PbrEXLA3) to activate its expression. PbrEXLA3 encodes an expansin that promotes pollen tube elongation in pear. The stability of dephosphorylated PbrBZR1 was substantially reduced in incompatible pollen tubes, where it is targeted by ARIADNE2.3 (PbrARI2.3), an E3 ubiquitin ligase that is strongly expressed in pollen. Our results show that during the SI response, PbrARI2.3 accumulates and negatively regulates pollen tube growth by accelerating the degradation of PbrBZR1 via the 26S proteasome pathway. Together, our results show that an ubiquitin-mediated modification participates in BR signaling in pollen and reveal the molecular mechanism by which BRs regulate S-RNase-based SI.
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Affiliation(s)
- Yicheng Wang
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Panpan Liu
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Yiling Cai
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Yu Li
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Chao Tang
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Nan Zhu
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Peng Wang
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Shaoling Zhang
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
| | - Juyou Wu
- Sanya Institute of Nanjing Agricultural University, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China
- Jiangsu Key Laboratory for Horticultural Crop Genetic Improvement, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
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