Yu Hee-Ju, Hogan Pat, Sundaresan Venkatesan
Section of Plant Biology , University of California, Davis, California 95616, USA.
Plant Physiol. 2005 Dec;139(4):1853-69. doi: 10.1104/pp.105.067314. Epub 2005 Nov 18.
The extensive data on the transcription of the plant genome are derived primarily from the sporophytic generation. There currently is little information on genes that are expressed during female gametophyte development in angiosperms, and it is not known whether the female gametophyte transcriptome contains a major set of genes that are not expressed in the sporophyte or whether it is primarily a subset of the sporophytic transcriptome. Because the embryo sac is embedded within the maternal ovule tissue, we have utilized the Arabidopsis (Arabidopsis thaliana) mutant sporocyteless that produces ovules without embryo sacs, together with the ATH1 Arabidopsis whole-genome oligonucleotide array, to identify genes that are preferentially or specifically expressed in female gametophyte development. From analysis of the datasets, 225 genes are identified as female gametophyte genes, likely a lower limit as stringent criteria were used for the analysis, eliminating many low expressed genes. Nearly 45% of the identified genes were not previously detected by sporophytic expression profiling, suggesting that the embryo sac transcriptome may contain a significant fraction of transcripts restricted to the gametophyte. Validation of six candidate genes was performed using promoterbeta-glucuronidase fusions, and all of these showed embryo sac-specific expression in the ovule. The unfiltered expression data from this study can be used to evaluate the possibility of female gametophytic expression for any gene in the ATH1 array, and contribute to identification of the functions of the component of the Arabidopsis genome not represented in studies of sporophytic expression and function.
关于植物基因组转录的大量数据主要来自孢子体世代。目前，关于被子植物雌配子体发育过程中表达的基因的信息很少，并且尚不清楚雌配子体转录组是否包含一组在孢子体中不表达的主要基因，或者它是否主要是孢子体转录组的一个子集。由于胚囊包埋在母体胚珠组织中，我们利用了拟南芥（Arabidopsis thaliana）突变体无孢子细胞，该突变体产生没有胚囊的胚珠，结合ATH1拟南芥全基因组寡核苷酸阵列，来鉴定在雌配子体发育中优先或特异性表达的基因。通过对数据集的分析，鉴定出225个基因为雌配子体基因，由于分析使用了严格的标准，这可能是一个下限，排除了许多低表达基因。近45%的已鉴定基因以前未通过孢子体表达谱检测到，这表明胚囊转录组可能包含很大一部分仅限于配子体的转录本。使用启动子- β -葡萄糖醛酸酶融合对六个候选基因进行了验证，所有这些基因在胚珠中均显示出胚囊特异性表达。本研究未经过滤的表达数据可用于评估ATH1阵列中任何基因雌配子体表达的可能性，并有助于鉴定拟南芥基因组中在孢子体表达和功能研究中未涉及的组成部分的功能。
