Scott R, Dagless E, Hodge R, Paul W, Soufleri I, Draper J
Department of Botany, University of Leicester, UK.
Plant Mol Biol. 1991 Aug;17(2):195-207. doi: 10.1007/BF00039494.
The relationship between bud length, anther length and stage of anther development has been investigated in Brassica napus using a series of cytological markers that define steps in the process of male gametogenesis. It was determined that bud length is directly related to anther length and that anther or bud length is tightly linked to the stage of male gametogenesis within the anther. This simple correlation has enabled the construction of cDNA libraries representing transcripts expressed in defined stages of anther development, and the detailed examination of the developmental pattern of expression of anther RNAs. Two anther cDNA libraries were constructed, one from anthers of 1.2-1.8 mm long buds (sporogenesis library) and one from anthers of 1.8-4.0 mm long buds (microspore development library). A total of 19 independent cDNAs have been isolated by differential screening whose temporal expression patterns overlap and which together cover the stages of anther development from pre-meiotic microsporocytes to tri-nucleate pollen grains. The pattern of expression of each of these clones is unique and indicates that stages of anther development which cannot be easily distinguished by light microscopy can be recognised by virtue of the absence or presence of certain RNAs. Three cDNAs isolated from the sporogenesis library have been shown by in situ hybridisation to be tapetum-specific. In contrast, five clones isolated from the microspore development library are microspore-specific. These clones exhibit a pattern of expression different to those previously described in that their transcripts are absent in mature pollen grains. Thus these RNAs are probably required in microspore development rather than for the growth of the germinating pollen grain.
利用一系列定义雄配子发生过程中各个步骤的细胞学标记，对甘蓝型油菜中花蕾长度、花药长度与花药发育阶段之间的关系进行了研究。结果表明，花蕾长度与花药长度直接相关，且花药或花蕾长度与花药内雄配子发生阶段紧密相连。这种简单的相关性使得构建代表花药发育特定阶段表达转录本的cDNA文库成为可能，并能详细研究花药RNA的表达发育模式。构建了两个花药cDNA文库，一个来自长度为1.2 - 1.8毫米花蕾的花药（孢子发生文库），另一个来自长度为1.8 - 4.0毫米花蕾的花药（小孢子发育文库）。通过差异筛选共分离出19个独立的cDNA，其时间表达模式重叠，共同涵盖了从减数分裂前的小孢子母细胞到三核花粉粒的花药发育阶段。这些克隆中每个的表达模式都是独特的，表明借助某些RNA的有无，可以识别出光学显微镜下难以区分的花药发育阶段。通过原位杂交显示，从孢子发生文库中分离出的三个cDNA是绒毡层特异性的。相比之下，从小孢子发育文库中分离出的五个克隆是小孢子特异性的。这些克隆表现出与先前描述不同的表达模式，因为它们的转录本在成熟花粉粒中不存在。因此，这些RNA可能是小孢子发育所必需的，而不是用于萌发花粉粒的生长。
