THE OVULE AND THE EMBRYO SAC
THE OVULE AND THE EMBRYO SAC
复制标题
DOI：
10.1105/tpc.5.10.1291
复制
发表时间：
1993-10-01
期刊：
影响因子：
11.6
通讯作者：
FISCHER, RL
中科院分区：
文献类型：
--
作者：
REISER, L;FISCHER, RL
植物的生活史以二倍体孢子体和单倍体配子体的世代交替为特征。孢子体的功能是产生孢子，然后孢子发育成配子体。分化的配子体依次产生雄配子（精子）或雌配子（卵细胞）。与配子体占优势的低等植物不同，被子植物的配子体比孢子体更小，更不复杂，并且在花的专门器官中形成。雄配子体（花粉或小配子体）在花药内发育，而雌配子体（胚囊或雌配子体）是胚珠的产物。有性生殖需要将精核通过花粉传递到胚囊，在胚囊中受精并形成新的二倍体孢子体（见大仲马和莫根森，1993，本期）。被子植物生殖过程的这些独特特征说明了植物生物学中最基本的问题之一。也就是说，从孢子体发育到配子体发育的转变是如何在花的环境中发生的？配子体是如何相互作用并与母体植物产生种子的？通过花粉发育的遗传和分子分析（Mascarenhas，1990，1993，本期）和花粉-柱头相互作用（康沃尔语et al.，1988; Nasrallah和Nasrallah，1989，1993，本期; Newbigin等人，1993年，这个问题。相比之下，对雌配子体发育的调控以及受精前后胚囊与胚珠的关系知之甚少。胚珠是雌配子体的来源和种子的祖先。大孢子母细胞的特化、功能性大孢子的产生（大孢子发生）、胚囊的形成（大配子发生）和胚胎发生都发生在胚珠内。与花粉不同，胚囊在整个发育过程中与亲本孢子体保持物理接触，因此雌配子体和孢子体的这种结合为研究细胞、组织和基因组之间的相互作用提供了机会。
The plant life cycle is characterized by the alternation of generations between a diploid sporophyte and a haploid gametophyte. The sporophyte functions to produce spores, which then develop into gametophytes. The differentiated gametophytes in turn produce either the male gametes (sperm) or female gametes (egg cells). In contrast to lower plant species, in which the gametophyte is the dominant, free-living generation (see Cove and Knight, 1993, this issue), gametophytes of angiosperms are smaller and less complex than the sporophyte and are formed within specialized organs of the flower. The male gametophyte (pollen or microgametophyte) develops within the anther, whereas the female gametophyte (embryo sac or megagametophyte) is a product of the ovule. Sexual reproduction requires the delivery of the sperm nuclei, via the pollen, to the embryo sac, where fertilization occurs and the new diploid sporophyte is formed (see Dumas and Mogensen, 1993, this issue).These unique features of the angiosperm reproductive process illustrate one of the most fundamental problems in plant biology. That is, how does the transition from sporophytic to gametophytic development occur within the context of the flower? How do the gametophytes interact with each other and the maternal plant to produce a seed? A wealth of information has been obtained regarding sexual reproduction in plants by genetic and molecular analyses of pollen development (Mascarenhas, 1990, 1993, this issue) and pollen-stigmaktyle interactions (Cornish et al., 1988; Nasrallah and Nasrallah, 1989, 1993, this issue; Newbigin et al., 1993, this issue). By comparison, less is known about the regulation of female gametophyte development and the relationship of the embryo sac to the ovule before and after fertilization. The ovule is the source of the megagametophyte and the progenitor of the seed. Specification of the megasporocyte, production of a functional megaspore (megasporogenesis), formation of the embryo sac (megagametogenesis), and embryogenesis all occur within the ovule. Because embryo sacs, unlike pollen, maintain physical contact with the parent sporophyte throughout their development, this association of the female gametophyte and the sporophyte provides an opportunity to examine interactions between cells, tissues, and genomes.