菘蓝转录因子IiMYB的基因克隆及表达特征

Gene Cloning and Expression Characteristics of Transcription Factor liMYB from Isatis indigotica

MYB转录因子在植物生长发育、次生代谢产物生物合成以及抗逆应激等多个方面发挥重要作用。为了研究菘蓝中特异MYB转录因子的表达特征,本研究采用cDNA末端快速扩增(RACE)技术克隆菘蓝中目标MYB转录因子编码基因IiMYB的全长c DNA并获得其基因组DNA序列,通过RT-qPCR检测IiMYB在四倍体菘蓝和二倍体菘蓝各器官以及不同胁迫条件下的表达情况。IiMYB的c DNA序列全长926 bp(GenBank登录号:DQ468346),含600 bp的开放阅读框(ORF),编码199个氨基酸,其对应的基因组DNA序列含有3个外显子和2个内含子。生物信息学分析表明IiMYB与拟南芥的AtMYBL2同源性最高,遗传距离最近,并仅含有一个myb域(R3)。IiMYB在两种倍性菘蓝的根茎叶中均有表达,其中叶中最高,且在四倍体中的表达水平均高于二倍体。胁迫因素高盐(NaCl)、茉莉酸甲酯(MeJA)、赤霉素(GA3)、脱落酸(ABA)和水杨酸(SA)处理均能上调IiMYB的表达水平,而低温(4℃)处理对IiMYB的表达水平无显著影响。本研究首次从菘蓝植物中克隆得到MYB转录因子并进行了表达分析,为进一步阐明与MYB转录因子相关的四倍体菘蓝优良性状形成的分子机制提供一定基础,也为通过分子育种培育优质菘蓝品系提供了条件。

MYB transcription factors play an important role in plant growth and development,biosynthesis of secondary metabolites,as well as resistance to stresses.To explore the expression characteristics of a specific MYB transcription factor from Isatis indigotica,the full-length cDNA of the target MYB transcription factor encoding gene liMYB is cloned by rapid amplification of cDNA ends(RACE),and its genomic DNA sequence is further obtained.RT-qPCR is used to detect the expression levels of liMYB in different organs of tetraploid and diploid I.indigotica and under various stress conditions.The full-length cDNA of liMYB gene is 926 bp(GenBank accession number:DQ468346)long with an open reading frame(ORF)of 600 bp,encoding a polypeptide of 199 amino acid residues.The corresponding genomic DNA sequence contains 3 exons and 2 introns.Bioinformatics analysis shows that liMYB has the highest homology and closest genetic distance with AtMYBL2 from Arabidopsis,and also contains only one myb domain(R3).liMYB is expressed in the roots,stems and leaves of both diploid and tetraploid I.indigotica,with the highest expression level in leaves,and its expression in tetraploid one is higher than that in diploid.Stress treatments including salt(NaCI),methyl jasmonate(MeJA),gibberellin(GAs),abscisic acid(ABA),and salicylic acid(SA)can all increase liMYB expression level,while low temperature(4 C)treatment has no significant effect on liMYB expression.In this study,a MYB transcription factor is cloned from I.indigotica for the first time and its expression characteristics are analyzed,which provides a possibility to further elucidate the MYB relevant molecular mechanism of polyploidy vigor of I.indigotica,and also prompts to cultivate high-quality I.indigotica through molecular breeding.