李果实中两个糖转运蛋白SWEET基因克隆及表达

Cloning and expression analysis of two sugar transporter SWEET genes in plum(Prunus salicina)

SWEET糖转运蛋白在植物生长发育、生物和非生物胁迫反应中发挥了重要作用.为了解李果实SWEET基因的序列特性及其在果实发育过程中的表达模式,以‘皇冠李’果实为材料,采用聚合酶链式反应技术分别克隆两个SWEET基因cDNA和DNA序列全长,进行系统生物信息学分析,同时利用实时荧光定量技术研究它们在果实不同发育时期的表达情况,并分析与果实糖含量变化间的相关性.结果显示:李SWEET基因PsSWEET2a-like和PsSWEET17-like的cDNA序列长度分别为627 bp和597 bp,它们的编码蛋白分别隶属于SWEET家族的Ⅰ亚簇和Ⅳ亚簇,均为包含典型的Mtn3/saliva结构域的疏水性碱性蛋白.随着果实的发育,PsSWEET2a-like呈下调表达,而PsSWEET17-like呈上调表达.相关性分析显示皇冠李果实发育过程中,PsSWEET17-like与果糖和葡萄糖含量变化显著正相关,与蔗糖显著负相关,而PsSWEET2a-like与这3种糖含量均不相关.本研究表明李果实发育后期PsSWEET17-like表达显著,在葡萄糖、果糖积累和果实生长发育中可能发挥了重要作用;PsSWEET2a-like在果实糖的转运调控中无显著作用,可能更多参与植物其他生物过程.

SWEET transporters play a crucial role in plant growth,development,and resistance to biotic and abiotic stresses.To understand the sequence characteristics of the SWEET genes and their expression patterns during fruit development stages in plum(Prunus salicina),we amplified the full-length cDNA and DNA sequences of two SWEET genes from the‘Huangguan’genome.Systematic bioinformatics analysis was conducted,and their expression patterns were investigated by qRT-PCR at different developmental stages.Furthermore,the correlation between the two SWEET genes and sugar content in the fruit was analyzed.The results show that two plum SWEET genes,PsSWEET2a-like and PsSWEET17-like,contained the full-length cDNA sequences of 627 bp and 597 bp,respectively.Both their encoding proteins belong to the SWEET family with subgroups I and IV,respectively,which are hydrophobic basic proteins containing typical Mtn3/saliva domains.The PsSWEET2a-like gene was downregulated,while PsSWEET17-like was upregulated during fruit development.Correlation analysis showed that PsSWEET17-like was significantly positively correlated with fructose and glucose content;however,it was significantly negatively correlated with sucrose during fruit development.PsSWEET2a-like was not correlated with the above three kinds of sugars and was significantly expressed at the late stages of fruit development.It may play an important role in accumulating glucose and fructose during fruit development.PsSWEET2a-like has no significant role in regulating sugar transport in fruit but may be involved in other biological processes in plants.