Ovule Development in Higher Plants

高等植物的胚珠发育

• 批准号: 9505813
• 负责人: Robert Fischer
• 金额: $ 33.1万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-08-15 至 1999-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9505813&HistoricalAwards=false
• 关键词: Ovule; Development; Higher; Plants

9505813 Fischer The ovule is a fundamental unit of plant reproduction that generates the female gametophyte, mediates fertilization processes, and support the development of the embryo. The long term goal of this proposal is to understand the genetic circuits that control the early development of the ovule by analyzing two Arabidopsis genes, BELL1 (BEL1) and OVULE MUTATION2 (OVM2), that were cloned in Dr. Fischer's laboratory. The BEL1 gene product plays a role in the specification of ovule identity. bel1 mutant ovules are often transformed into carpel like structures, isolation and sequencing of the BEL1 gene indicates that it encodes a homeodomain transcription factor. It is thought that the BEL1 gene prevents the carpel developmental program from over-riding ovule development by negatively regulating expression of the floral homeotic gene, AGAMOUS(AG). The OVM2 gene product is needed at distinct threshold levels to control ovule and female gametophyte development, respectively. With no active OVM2 protein, both ovule and female gametophyte development are dramatically suppressed, whereas a low level of OVM2 protein results in nonfunctional ovules that specifically lack a female gametophyte. Isolation and sequencing of the OVM2 gene indicates that it is related to the floral homeotic gene APETALA2 (AP2). Thus, BEL1 and OVM2 genes are important regulators of ovule and female gametophyte development, with mutations resultilg in homeotic conversions and deletions of organs. To understand their mechanism of action, the critical steps that control early ovule development, and the relationship between ovule and floral developmental programs, experiments will be carried out to: 1) Determine the temporal and spatial localization of BEL1 and OVM2 activity, 2) Determine the genetic relationships between ovule and floral regulatory genes, 3) Carry out a molecular analysis of BEL1 and OVM2 function, and 4) Carry out a genetic screen to identify new genes that control megagametogenesis. ***

9505813 Fischer 胚珠是植物繁殖的基本单位，可产生雌配子体、介导受精过程并支持胚胎发育。该提案的长期目标是通过分析Fischer 博士实验室克隆的两个拟南芥基因BELL1 (BEL1) 和OVULE MUTATION2 (OVM2) 来了解控制胚珠早期发育的遗传回路。 BEL1 基因产物在胚珠身份的规范中发挥作用。 bel1 突变体胚珠经常转化为心皮样结构，BEL1 基因的分离和测序表明它编码同源域转录因子。据认为，BEL1 基因通过负向调节花同源异型基因 AGAMOUS(AG) 的表达来阻止心皮发育程序凌驾于胚珠发育之上。 OVM2 基因产物需要在不同的阈值水平来分别控制胚珠和雌配子体的发育。如果没有活性的 OVM2 蛋白，胚珠和雌配子体的发育都会受到显着抑制，而低水平的 OVM2 蛋白会导致胚珠无功能，特别缺乏雌配子体。 OVM2 基因的分离和测序表明它与花同源异型基因 APETALA2 (AP2) 相关。因此，BEL1 和 OVM2 基因是胚珠和雌配子体发育的重要调节因子，突变会导致同源异型转化和器官缺失。为了了解它们的作用机制、控制早期胚珠发育的关键步骤以及胚珠和花发育程序之间的关系，将进行实验：1) 确定 BEL1 和 OVM2 活性的时间和空间定位，2) 确定胚珠和花调控基因之间的遗传关系，3) 对 BEL1 和 OVM2 功能进行分子分析，4) 进行遗传筛选，以确定控制大配子发生的新基因。 ***