Grossniklaus U, Schneitz K
Cold Spring Harbor Laboratory, NY 11724, USA.
Semin Cell Dev Biol. 1998 Apr;9(2):227-38. doi: 10.1006/scdb.1997.0214.
The formation of ovules is a key step in the plant life cycle which alternates between a diploid and haploid generation, the sporophyte and the gametophyte. The transitions between the two generations in the female occur in the ovule, the site of meiosis, female gametogenesis and double fertilization. The intimate association of sporophytic and gametophytic tissues in the ovule allows an investigation of their cellular interactions during ovule and seed development. In Arabidopsis, several sporophytically acting loci which primarily affect the morphogenesis of the integuments have been identified. Early acting genes may respond to positional information leading to a region-specific initiation of morphogenesis, whereas later acting genes affect cellular aspects of integument growth. Much less is known about the mechanisms controlling the development of the megagametophyte. Comparative morphology and genetic analyses suggests that regulatory mechanisms ensure a tight coordination of independently controlled cellular processes with cell specification and differentiation.
胚珠的形成是植物生命周期中的关键步骤，植物生命周期在二倍体和单倍体世代（孢子体和配子体）之间交替。雌性植株中这两个世代之间的转变发生在胚珠中，胚珠是减数分裂、雌配子体发生和双受精的场所。胚珠中孢子体组织和配子体组织的紧密联系使得对它们在胚珠和种子发育过程中的细胞相互作用进行研究成为可能。在拟南芥中，已经鉴定出几个主要影响珠被形态发生的孢子体作用位点。早期作用基因可能对位置信息作出反应，导致形态发生的区域特异性起始，而后期作用基因则影响珠被生长的细胞层面。关于控制雌配子体发育的机制，人们了解得要少得多。比较形态学和遗传学分析表明，调控机制确保了独立控制的细胞过程与细胞特化和分化之间的紧密协调。
