Comparative transcriptome analysis of ovules reveals stress related genes associated with nucellar polyembryony in citrus
Comparative transcriptome analysis of ovules reveals stress related genes associated with nucellar polyembryony in citrus
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DOI：
10.1007/s11295-013-0690-0
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发表时间：
2014-06-01
影响因子：
2.4
通讯作者：
Bhat, Shripad Ramachandra
中科院分区：
文献类型：
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作者：
Kumar, Vajinder;Malik, Surendra Kumar;Bhat, Shripad Ramachandra
外生多胚是一种无融合的形式，其中胚珠的孢子细胞直接产生由自主或性来源的胚乳滋养的胚胎。不成熟胚胎的分子基础尚不清楚。这是首次报道柑橘珠心胚形成过程中胚珠发育的转录组分析。采用抑制减法杂交（SSH）和微阵列技术寻找种子发育早期的差异表达转录本。两种方法的结果在富集氧化石墨烯术语（对应激和信号的反应）和差异基因表达水平上是一致的。SSH在柑橘EST数据库中添加了85个新的unigenes，并发现了443个柑橘Affymetrix数组中没有的新unigenes。对最特异的氧化石墨烯术语的研究显示，在胚珠发育的开花前阶段，当用于胚胎发育的珠心细胞开始分化时，与非生物应激相关的转录本（热敏感蛋白、HSF、丙酮酸脱羧酶）上调（123）和过度表达（92），而与信号相关的转录本（激酶和WRKYs）下调（92）。微阵列和实时定量聚合酶链反应（qRT-PCR）对多胚位点基因的分析发现，在多胚和单胚品种胚珠中，热休克相关基因和三个新的orf （orf21、22和25）的表达存在显著差异。qRT-PCR和芯片数据证实，在多胚品种的花前期胚珠中，HSP和WRKY转录本分别上调和下调。基于基因表达模式的差异，提出了多胚形成的可能机制序列。
Adventive polyembryony is a form of apomixis where sporophytic cells of the ovule directly give rise to embryos nourished by the endosperm of autonomous or sexual origin. Molecular basis of adventive embryony is poorly understood. This is the first report of transcriptome analysis of developing ovules during citrus nucellar embryo initiation. Suppression subtractive hybridization (SSH) and microarray were employed to find differentially expressed transcripts during early stages of seed development. Results of the two approaches were congruent for enriched GO terms (response to stress and signalling) and differential gene expression levels. SSH added 85 novel unigenes to the citrus EST database and revealed 443 new unigenes not represented in the Citrus Affymetrix array. Examination of the most-specific-GO-terms showed upregulation (123) and over-representation of transcripts related to abiotic stress (HSPs, HSF, pyruvate decarboxylase) and downregulation (92) of signalling-related (kinases and WRKYs) transcripts at the pre-anthesis stage of ovule development, when nucellar cells destined for embryogenesis begin to differentiate. Microarray and quantitative real-time polymerase chain reaction (qRT-PCR) analyses of genes present in the polyembryony locus identified significant differential expression of heat-shock-related genes and three novel ORFs (orf21, 22, and 25) between ovules of poly- and mono-embryonic varieties. qRT-PCR and microarray data confirmed the up- and downregulation of HSP and WRKY transcripts, respectively, in the pre-anthesis stage ovules of the polyembryonic variety. Based on differential gene expression pattern, a possible mechanistic sequence of polyembryony is presented.