Female gamete specification in flowering plants

开花植物的雌配子规格

• 批准号: 1656584
• 负责人: Venkatesan Sundaresan
• 金额: $ 42.56万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-09-01 至 2022-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1656584&HistoricalAwards=false
• 关键词: Female; gamete; specification; flowering; plants

Part 1: Non-technicalSeeds provide a significant fraction of the protein and calories in the diets of humans and livestock. Formation of seeds requires specialized cells called gametes that develop within a flower. A mechanistic understanding of how gametes are produced by plants can lead to an improvement of seed quality and quantity in seed crops. This project will elucidate the genes and genetic networks underlying the process of gamete formation occurring within the flower organs. The project will also provide training in plant genetics and development for undergraduate students, graduate students, and postdoctoral researchers. An outreach program with Langston University, a primarily undergraduate and historically black university, will stimulate involvement by minority undergraduate students in plant biology research. Part 2: TechnicalFlowering plants produce two types of female gametes, the egg cell and the central cell, that are both specified within a haploid embryo sac which develops following meiosis in an ovule. The egg cell is haploid, specified from a single nucleus at the distal pole of the embryo sac, whereas the central cell is homodiploid, specified by two nuclei, one from each pole of the embryo sac. Double fertilization of the female gametes by pollen results in a seed containing a diploid embryo arising from the egg cell, and a triploid nourishing tissue, the endosperm, arising from the central cell. The molecular mechanisms by which two female gametes with very distinct characteristics are specified have been largely uncharacterized. Previous research has revealed that the CKI1 gene, encoding a histidine kinase activator of the cytokinin signaling pathway, plays a key role in female gamete specification in the model plant Arabidopsis. Loss of CKI1 expression results in conversion of the central cell to an egg cell leading to arrested seed development. Ectopic expression of CKI1 results in conversion of the egg cell to a central cell, producing seeds with dual endosperms and no embryos. These findings, together with observations of CKI1 protein localization in the developing embryo sac, lead to a model by which female gamete specification is controlled by differential expression and localization of CKI1 to the proximal domain of the embryo sac. This project will identify and characterize factors acting upstream and downstream of CKI1 in the female gametophyte. Transcription factors that activate or restrict CKI1 expression will be identified by screens for upstream regulators of CKI1. Candidate regulatory genes will be functionally characterized by genetic analysis. Transcription factors that act downstream of CKI1 to promote central cell fate will be sought by testing expression of candidate genes using mutant response regulators. The project will provide insights into the spatial regulatory networks that specify cell identities in the developing female gametophyte, and the mechanisms underlying the formation of female gametes in flowering plants.

第1部分：非技术种子在人类和牲畜的饮食中提供了很大一部分蛋白质和热量。种子的形成需要在花中发育的称为配子的特殊细胞。对植物如何产生配子的机理的理解可以导致种子作物种子质量和数量的改善。 本计画将阐明花器官内配子形成过程的基因与遗传网路。该项目还将为本科生、研究生和博士后研究人员提供植物遗传学和发育方面的培训。 与兰斯顿大学（一所主要是本科生和历史上的黑人大学）的一个外联方案将刺激少数民族本科生参与植物生物学研究。第二部分：有花植物产生两种类型的雌性配子，卵细胞和中央细胞，它们都在胚珠减数分裂后发育的单倍体胚囊内。卵细胞是单倍体，由胚囊远端的一个核决定，而中央细胞是同源二倍体，由两个核决定，胚囊的每一极各一个。雌配子通过花粉进行双受精，产生的种子含有由卵细胞产生的二倍体胚和由中央细胞产生的三倍体营养组织胚乳。两个具有非常不同特征的雌配子被指定的分子机制在很大程度上还没有被描述。先前的研究表明，CKI1基因编码细胞分裂素信号通路的组氨酸激酶激活剂，在模式植物拟南芥的雌性配子特化中起着关键作用。CKI1表达的丧失导致中央细胞转化为卵细胞，导致种子发育停滞。CKI1的异位表达导致卵细胞转化为中央细胞，产生具有双胚乳且无胚的种子。这些研究结果，连同观察CKI1蛋白定位在发育中的胚囊，导致一个模型，其中女性配子规范控制的差异表达和定位CKI1的近端域的胚囊。该项目将确定和表征在雌配子体中CKI1上游和下游作用的因素。 激活或限制CKI1表达的转录因子将通过筛选CKI1的上游调节因子来鉴定。候选调控基因将通过遗传分析进行功能表征。将通过使用突变反应调节剂测试候选基因的表达来寻找作用于CKI1下游以促进中央细胞命运的转录因子。该项目将提供对空间调控网络的见解，这些网络指定发育中的雌配子体的细胞身份，以及开花植物中雌配子形成的机制。

项目成果

Recent advances in understanding female gametophyte development

• DOI: 10.12688/f1000research.14508.1
• 发表时间: 2018-06
• 期刊: F1000Research
• 作者: D. Skinner;V. Sundaresan