Pagnussat Gabriela C, Yu Hee-Ju, Ngo Quy A, Rajani Sarojam, Mayalagu Sevugan, Johnson Cameron S, Capron Arnaud, Xie Li-Fen, Ye De, Sundaresan Venkatesan
Section of Plant Biology, University of California, One Shields Avenue, Davis, CA 95616, USA.
Development. 2005 Feb;132(3):603-14. doi: 10.1242/dev.01595. Epub 2005 Jan 5.
The plant life cycle involves an alternation of generations between sporophyte and gametophyte. Currently, the genes and pathways involved in gametophytic development and function in flowering plants remain largely unknown. A large-scale mutant screen of Ds transposon insertion lines was employed to identify 130 mutants of Arabidopsis thaliana with defects in female gametophyte development and function. A wide variety of mutant phenotypes were observed, ranging from defects in different stages of early embryo sac development to mutants with apparently normal embryo sacs, but exhibiting defects in processes such as pollen tube guidance, fertilization or early embryo development. Unexpectedly, nearly half of the mutants isolated in this study were found to be primarily defective in post-fertilization processes dependent on the maternal allele, suggesting that genes expressed from the female gametophyte or the maternal genome play a major role in the early development of plant embryos. Sequence identification of the genes disrupted in the mutants revealed genes involved in protein degradation, cell death, signal transduction and transcriptional regulation required for embryo sac development, fertilization and early embryogenesis. These results provide a first comprehensive overview of the genes and gene products involved in female gametophyte development and function within a flowering plant.
植物生命周期涉及孢子体和配子体世代交替。目前，开花植物中参与配子体发育和功能的基因及途径仍大多未知。利用Ds转座子插入系进行大规模突变体筛选，以鉴定130个拟南芥雌配子体发育和功能存在缺陷的突变体。观察到多种突变表型，从早期胚囊发育不同阶段的缺陷到胚囊明显正常但在花粉管引导、受精或早期胚胎发育等过程中表现出缺陷的突变体。出乎意料的是，在本研究中分离出的近一半突变体被发现主要在依赖母本等位基因的受精后过程中存在缺陷，这表明从雌配子体或母本基因组表达的基因在植物胚胎早期发育中起主要作用。对突变体中被破坏基因的序列鉴定揭示了参与胚囊发育、受精和早期胚胎发生所需的蛋白质降解、细胞死亡、信号转导和转录调控的基因。这些结果首次全面概述了开花植物中参与雌配子体发育和功能的基因及基因产物。
