苹果MpSNAT1的克隆与表达特性分析

Cloning and expression characterization of MpSNAT1 in Malus pumila

以‘富士’和‘嘎啦’苹果(Malus pumila)叶片总RNA为模板,克隆5-羟色胺-N-乙酰基转移酶(SNAT)基因,利用DNAMAN、MEGA 5.1等软件对该基因进行生物信息学分析,采用荧光定量PCR技术测定SNAT的表达水平。结果表明,获得的苹果SNAT全长c DNA序列为750 bp,编码249个氨基酸,命名为Mp SNAT1(登录号MF443136)。Mp SNAT1编码蛋白的理论分子量约27.8 k Da,为非分泌型、亲水的不稳定蛋白,具有乙酰基转移酶(GNAT)功能结构域。序列多重比对及系统进化树分析表明,Mp SNAT1编码氨基酸序列与桃和拟南芥的同源性高,一致性分别为91.2%和63.6%。炭疽叶枯病菌接种后,苹果叶中Mp SNAT1表达量升高,但‘富士’和‘嘎啦’中基因上调水平和持续时间存在显著差异。此外,外源褪黑素处理后,苹果叶中Mp SNAT1显著上调表达,但外源水杨酸(SA)处理后,Mp SNAT1表达量均不同程度降低,表明该基因表达不受SA诱导。

Serotonin N-acetyltransferase gene（MpSNAT1） was amplified from leaves of Malus pumila ‘Fuji＇ and ‘Gala＇ with c DNA as the templates. Bioinformatics of the gene was analyzed by DNAMAN, MEGA 5.1 and other softwares. Then, the expression characteristics of the gene was detected by the fluorescence quantitative PCR（q PCR）. The results showed that the full-length c DNA sequence of MpSNAT1 is 750 bp（Gen Bank accession number MF443136）. The gene encodes 249 amino acid residues with a theoretical molecular weight of about 27.8 k Da. MpSNAT1 is a non-secretory and unstable protein with the characteristic conservative domains of acetyltransferase. The encoded protein shares the highest homology with Prunus persica and Arabidopsis thaliana SNATs, and similarities of amino acid sequences are 91.2% and 63.6%, respectively. The expression level of MpSNAT1 increased significantly in apple leaves after inoculation with Glomerella cingulata, whereas, gene up-regulation level and maintaining times were significantly different in ‘Fuji＇ and ‘Gala＇ leaves. In addition, the expression of MpSNAT1 was up-regulated significantly in apple leaves treated with exogenous melatonin, however, gene expression decreased in varying degrees after salicylic acid（SA） treatment, indicating that the expression of MpSNAT1 is not induced by SA.