小麦矮秆突变体jm22d响应赤霉素处理的转录组学分析

The Transcriptome Analysis of Wheat Dwarf Mutant jm22d Responding to GA Treatment

为拓宽小麦矮秆遗传资源,利用γ射线辐照济麦22获得了一个赤霉素不敏感型矮秆突变体jm22d。株高相关性状调查结果及茎秆细胞学试验显示,jm22d株高为53±1.8 cm,比野生型(WT)低约20 cm。jm22d整株茎秆共有4节,比WT少一节且各节间长度显著小于WT。与WT相比,jm22d茎秆细胞长度缩短。赤霉素含量测定发现,jm22d叶片中赤霉素含量高于WT,而茎秆中赤霉素含量低于WT(P<0.01),因此,jm22d株高降低与赤霉素转运途径出现异常有关。为了深入研究jm22d对赤霉素的响应机理,对jm22d和WT幼苗进行赤霉素处理,分别收取处理0(D0)、1(D1)和3 d(D3)的样品进行转录组学分析。结果表明,与WT相比,在jm22d中共筛选到696个上调和1 067个下调的表达基因,其中62个和349个基因在3个时间点分别表现为上调和下调表达。叶绿素含量测定表明,jm22d中叶绿素含量随赤霉素处理时间的延长而降低,聚类分析结果表明,差异表达基因主要富集在光合作用-天线蛋白(photosynthesis-antenna proteins,ko00196)、卟啉和叶绿素代谢(porphyrin and chlorophyll metabolism,ko00860)、亚油酸新陈代谢(linoleic acid metabolism,ko00591)等通路,因此赤霉素处理对jm22d体内叶绿素含量的积累具有抑制作用。通过KEGG分析在植物激素信号转导途径中挖掘到5个差异表达基因(TraesCS2B01G582300、TraesCS2B01G600800、TraesCS2B01G556600、TraesCS2B01G630000和TraesCS6B01G439600)参与生长素、细胞分裂素等激素代谢途径,这些基因在jm22d中显著下调,这可能是jm22d矮化的重要原因。研究结果为矮秆突变体矮化机制的解析提供了重要参考。

In order to enrich the genetic diversity of dwarf gene resource in wheat, we irradiated Jimai 22 by γ-rays and obtained a GA insensitive dwarf mutant, named as jm22d. Investigation of plant height and stem cell showed that jm22d was about 53±1.8 cm, 20 cm shorter than that of wild type(WT). The internodes number of jm22d was 4, one less than WT plants, and the internode length of the mutant was significantly shorter than that of WT. The endogenous gibberellin content in jm22d leaves was higher than WT, while endogenous gibberellin content in stem was significantly lower than WT, suggesting that the dwarfing of jm22d might be caused by the abnormal gibberellin transportation pathway. Both mutant and WT seedlings were treated with gibberellin to study the mechanism that jm22d response to gibberellin, and samples were collected from 0(D0),1(D1) and 3 days(D3) respectively. Transcriptome analysis was conducted to analyze the dwarfing mechanism of jm22d. Comparing to WT, totally 696 up-regulated genes and 1 067 down-regulated genes were identified in jm22d. Among of them, 62 genes were up-regulated and 349 genes were down-regulated at all of the three time points. The determination of chlorophyll content showed that the chlorophyll content in jm22d decreased with the extension of gibberellin treatment and the differentially expressed genes(DEGs) was significant enriched in photosynthesis-antenna proteins, porphyrin and chlorophyll metabolism, linoleic acid metabolism and zeatin biosynthesis pathways. Gibberellin can inhibit the accumulation of chlorophyll content in jm22d. Five differentially expressed genes were identified in plant hormone signal transduction pathway involved in auxin and cytokinin metabolic pathways(TraesCS2 B01 G582300, TraesCS2 B01 G600800, TraesCS2 B01 G556600, TraesCS2 B01 G630000 and TraesCS6 B01 G4396009) through KEGG analysis, and they were significant up-regulated in jm22d. This may be the main reason for the dwarfing of jm22d. The results of this research provide an important reference for the mechanism of wheat dwarf mutants.