本研究以巴西蕉(Musa acuminata AAA group cv.Brazil)果实为材料,克隆到一个CDS序列长度为2 517 kb的MaPho2基因,其编码838个氨基酸,分子量为95.096 kD,等电点为6.09,具有糖原磷酸化酶保守结构域(29～832氨基酸),属于GT35基因家族蛋白.氨基酸序列比对及聚类分析发现,MaPho2与水稻等11种植物Pho2蛋白序列的同源性为77.60％～81.41％,与拟南芥、番茄、马铃薯和辣椒亲缘关系较近,属于胞质型淀粉磷酸化酶.实时荧光定量PCR结果(RT-qPCR)表明,MaPho2基因具有时空表达特异性,在果肉和球茎中高表达,根、叶等组织中表达量较低;在果实发育的后期该基因高表达;但随着果实采后成熟,MaPho2呈现明显上调趋势,在成熟度5时表达量达到高峰.本实验通过MaPho2基因生物信息学和表达模式分析,为后续研究Pho2在果实淀粉降解代谢中的功能提供了理论基础.
Cloning and Expression Analysis of the Starch Phosphorylase Encoding Gene MaPho2 from Banana
The fruits of banana(Musa acuminata AAA group cv.Brazil)were used to clone the gene sequence of MaPho2,with CDS sequence length of 2 517 kb,encoding 838 amino acids,molecular weight of 95.096 kD,and isoelectric point of 6.09.It had the conserved domain of glycogen phosphorylase(29～832 amino acids)and belonged to the GT35 gene family.Amino acid sequence alignment and phylogenetic analysis showed that the homology of MaPho2 was 77.60％～81.41％compared with other 11 plants such as rice,and it was closely related to Arabidop-sis,tomato,potato,and pepper,belonging to cytoplasmic starch phosphorylase.Quantitative real-time fluorescence PCR(RT-qPCR)showed that MaPho2 gene had significant spatiotemporal expression patterns,and it was highly expressed in pulp and corm,but was less expressed in root and leaf tissues.The gene is highly expressed in the late stage of fruit development.However,with the fruit ripening,the expression of MaPho2 showed a significant up-regulation trend,and reached the peak at the fifth maturity stage.Together,through bioinformatics and expres-sion pattern analysis,this study provides a theoretical basis for the follow-up study of the MaPho2 function in the metabolism of fruit starch degradation.
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