Computational identification and systematic classification of novel GRAS genes in Isatis indigotica

Isatis indigotica Fort., belonging to Cruciferae, is one of the most commonly used plants in traditional Chinese medicine. The accumulation of the effective components of I. indigotica is related with its growth conditions. The GRAS genes are members of a multigene family of transcriptional regulators that play a crucial role in plant growth. Although the activities of many GRAS genes have long been recognized, only in recent years were some of them identified and functionally characterized in detail. In the present study, 41 GRAS genes were identified from 1. indigotica through bioinformatics methods for the first time. They were classified into ten groups according to the classification of Arabidopsis and rice. The characterization, gene structure, conserved motifs, disordered N-terminal domains, and phylogenetic reconstruction of these GRASs were analyzed. Forty-three orthologous gene pairs were shared by I. indigotica and Arabidopsis, and interaction networks of these orthologous genes were constructed. Furthermore, gene expression patterns were investigated by analysis in methyl jasmonate （MeJA）-treated I. indigotica hairy roots based on RNA-seq data. In conclusion, this comprehensive analysis would provide rich resources for further studies of GRAS protein functions in this plant.

菘蓝中咖啡酰辅酶A氧甲基转移酶基因克隆与表达特征

咖啡酰辅酶A氧甲基转移酶是植物中参与木脂素前体松柏醇生物合成的关键酶,为了研究菘蓝中CCoAOMT的表达特征,采用c DNA末端快速扩增(RACE)、PCR克隆IiCCoAOMT的全长cDNA及其基因组DNA序列;通过RT-qPCR检测比较IiCCoAOMT在四倍体菘蓝和二倍体菘蓝各器官中的表达以及不同胁迫刺激下的表达情况。IiCCoAOMT的c DNA序列全长1 098 bp (GenBank登录号:DQ115904),含774 bp的开放阅读框(ORF),编码257个氨基酸残基,对应的DNA序列含有5个外显子和4个内含子。多重序列比对结果显示Ii CCoAOMT与拟南芥At CCoAOMT同源性最高,且含有植物氧甲基转移酶-I的三个特征元件:motif A、motif B、motif C。在两种倍性菘蓝的根和叶中,四倍体表达量高于二倍体,而在两种倍性菘蓝的茎中表达量接近相同。冷处理(4℃)、盐处理(NaCl)、茉莉酸甲脂(MeJA)、赤霉素(GA_(3))、脱落酸(ABA)和水杨酸(SA)均能诱导IiCCoAOMT表达水平的上调。首次从菘蓝中克隆得到IiCCoAOMT并进行了表达特征研究,为进一步阐明菘蓝多倍性优势的分子机制提供理论基础,也为通过基因工程技术提高菘蓝中活性木脂素的含量提供了条件。