Plant Biotechnology Institute, National Research Council of Canada, 110 Gymnasium Place, Saskatoon, SK, S7N 0W9, Canada.
Plant Mol Biol. 2010 Feb;72(3):279-99. doi: 10.1007/s11103-009-9567-x. Epub 2009 Dec 1.
Transcriptome data for plant reproductive organs/cells currently is very limited as compared to sporophytic tissues. Here, we constructed cDNA libraries and obtained ESTs for Brassica napus pollen (4,864 ESTs), microspores (i.e., early stage pollen development; 6,539 ESTs) and ovules (10,468 ESTs). Clustering and assembly of the 21,871 ESTs yielded a total of 10,782 unigenes, with 3,362 contigs and 7,420 singletons. The pollen transcriptome contained high levels of polygalacturonases and pectinesterases, which are involved in cell wall synthesis and expansion, and very few transcription factors or transcripts related to protein synthesis. The set of genes expressed in mature pollen showed little overlap with genes expressed in ovules or in microspores, suggesting in the latter case that a marked differentiation had occurred from the early microspore stages through to pollen development. Remarkably, the microspores and ovules exhibited a high number of co-expressed genes (N = 1,283) and very similar EST functional profiles, including high transcript numbers for transcriptional and translational processing genes, protein modification genes and unannotated genes. In addition, examination of expression values for genes co-expressed among microspores and ovules revealed a highly statistically significant correlation among these two tissues (R = 0.360, P = 1.2 x 10(-40)) as well as a lack of differentially expressed genes. Overall, the results provide new insights into the transcriptional profile of rarely studied ovules, the transcript changes during pollen development, transcriptional regulation of pollen tube growth and germination, and describe the parallels in the transcript populations of microspore and ovules which could have implications for understanding the molecular foundation of microspore totipotency in B. napus.
与孢子体组织相比，目前植物生殖器官/细胞的转录组数据非常有限。在这里，我们构建了 cDNA 文库并获得了油菜花粉（4864 个 EST）、小孢子（即早期花粉发育；6539 个 EST）和胚珠（10468 个 EST）的 EST。对 21871 个 EST 的聚类和组装共得到 10782 个基因，其中 3362 个 contigs 和 7420 个 singletons。花粉转录组含有高水平的多聚半乳糖醛酸酶和果胶酯酶，它们参与细胞壁的合成和扩张，而转录因子或与蛋白质合成相关的转录本很少。在成熟花粉中表达的基因集与在胚珠或小孢子中表达的基因集重叠很少，这表明在后一种情况下，从小孢子早期阶段到花粉发育已经发生了明显的分化。值得注意的是，小孢子和胚珠表现出大量的共表达基因（N = 1283）和非常相似的 EST 功能谱，包括转录和翻译加工基因、蛋白质修饰基因和未注释基因的高转录本数量。此外，对小孢子和胚珠中共同表达的基因的表达值进行检查，发现这两种组织之间存在高度显著的相关性（R = 0.360，P = 1.2 x 10(-40))，并且没有差异表达的基因。总的来说，这些结果为研究较少的胚珠的转录谱、花粉发育过程中的转录变化、花粉管生长和萌发的转录调控以及描述小孢子和胚珠转录群体的相似性提供了新的见解，这可能对理解油菜小孢子全能性的分子基础具有重要意义。
