【摘要】 利用RT-PCR技术,从条锈菌诱导的小麦叶片中分离出一个编码CaM基因的cDNA序列,经氨基酸序列分析确定其为一个新的小麦CaM亚型,暂被命名为TaCaM5。TaCaM5包含一个完整450bp的开放阅读框,编码149个氨基酸;编码的蛋白不含跨膜区、无信号肽、定位在胞内,具有4个EF-hand保守结构域。在目前已知的CaM基因中,TaCaM5与玉米CaM基因的亲缘关系最近,相似性高达97%。该基因在根、茎、叶等组织中均有不同程度的表达;并且受条锈菌诱导表达,在非亲和组合与亲和组合中,分别在接种后6h和24h表达量最高。外源植物激素脱落酸、茉莉酸甲酯和乙烯诱导TaCaM5上调表达,水杨酸诱导其下调表达。TaCaM5在机械伤害、干旱和低温条件下表达量上升,在高盐环境下表达量降低。表明TaCaM5可能通过茉莉酸和乙烯等信号途径参与小麦对条锈菌的防御反应,同时参与机械伤害、低温和干旱环境下的Ca2+-CaM信号转导途径。更多还原

【Abstract】 Calmodulin is a ubiquitous transducer of calcium signals in eukaryotes.It mediates a lot of cellular processes,such as transcription,cytoskeletal organization and motility,and amino acid metabolism.In diploid plant species,several isoforms of calmodulin have been described.A novel CaM gene was isolated from cDNA library of wheat leaves infected by Puccinia striiformis f.sp.tritici through RT-PCR approach.The gene was tentatively designated as TaCaM5 and encoded a novel CaM isoform based on protein sequence analysis.This open reading frame of TaCaM5 was 450 bp in length and 149 amino acids were encoded with four conserved EF-hand domains.TaCaM5,in which transmembrane domain or signal peptide sequence was absent,was predicted existing in cytoplasm.The amino acid sequence of TaCaM5 shares 97% identify with ZmCaM from Zea mays.TaCaM5 expressed differently in wheat leaf,stem,and root.Challenged by stripe rust fungus(Puccinia striiformis f.sp.tritici),TaCaM5 was induced by this fungus in both incompatible and compatible interactions,with the maximal expression at 6 h and 24 h post inoculation respectively.TaCaM5 was up-regualted by exogenous abscisic acid,ethylene,and jasmonic acid but down-regulated by salicylic acid.TaCaM5 was obviously up-regulated by various abiotic stresses,such as low temperature,mechanical wound,and drought.However,high salinity stress could not induce the expression of TaCaM5.These results suggest that TaCaM5 is probably involved in regulating the host defence responses through ethylene and jasmonic acid pathways,and also participate in Ca2+-CaM signal transmission pathways under mechanical wound,low temperature,and drought conditions.更多还原