Robinson-Beers K., Pruitt R. E., Gasser C. S.
Department of Biochemistry and Biophysics, University of California, Davis, California 95616.
Plant Cell. 1992 Oct;4(10):1237-1249. doi: 10.1105/tpc.4.10.1237.
Ovules are complex structures that are present in all seed bearing plants and are contained within the carpels in flowering plants. Ovules are the site of megasporogenesis and megagametogenesis and, following fertilization, develop into seeds. We combined genetic methods with anatomical and morphological analyses to dissect ovule development. Here, we present a detailed description of the morphological development of Arabidopsis ovules and report on the isolation of two chemically induced mutants, bell (bel1) and short integuments (sin1), with altered ovule development. Phenotypic analyses indicated that bel1 mutants initiate a single integument-like structure that develops aberrantly, sin1 mutants initiate two integuments, but growth of the integuments is disrupted such that cell division continues without normal cell elongation. Both mutants can differentiate archesporial cells, but neither forms a normal embryo sac. Genetic analyses indicated that bel1 segregates as a single recessive mutation, and complementation tests showed that the two mutants are not allelic. The phenotypes of the mutants indicate that normal morphological development of the integuments and proper embryo sac formation are interdependent or are governed in part by common pathways. The ovule mutants that we describe in Arabidopsis represent novel genetic tools for the study of this stage of reproductive development.
胚珠是所有种子植物中都存在的复杂结构，在开花植物中位于心皮内。胚珠是大孢子发生和雌配子体发生的场所，受精后发育成种子。我们将遗传学方法与解剖学和形态学分析相结合，以剖析胚珠发育过程。在此，我们详细描述了拟南芥胚珠的形态发育，并报告了两个化学诱导突变体的分离情况，即钟形胚珠（bell，bel1）和短珠被（short integuments，sin1），它们的胚珠发育发生了改变。表型分析表明，bel1突变体起始一个异常发育的单一珠被样结构，sin1突变体起始两个珠被，但珠被的生长受到破坏，导致细胞分裂继续进行而没有正常的细胞伸长。两个突变体都能分化出孢原细胞，但都不能形成正常的胚囊。遗传分析表明，bel1作为一个单一隐性突变进行分离，互补试验表明这两个突变体不是等位基因。突变体的表型表明，珠被的正常形态发育和正常胚囊形成是相互依赖的，或者部分受共同途径调控。我们在拟南芥中描述的胚珠突变体代表了研究生殖发育这一阶段的新型遗传工具。
