苹果中磷酸蔗糖合酶家族基因的表达特性及其与蔗糖含量的关系

磷酸蔗糖合酶(sucrose phosphate synthase,SPS)是植物中蔗糖合成的主要限速酶,影响植物的生长发育和果实中蔗糖的含量。为探明苹果中SPS基因家族特性及其在蔗糖合成中的作用,该研究从苹果基因组中分离了MdSPS家族基因,分析了它们的进化关系以及mRNA表达特性与酶活性和蔗糖含量的关系。结果显示:(1)在苹果基因组中有8个SPS家族基因表达,它们分别属于双子叶植物的3个SPS亚家族。(2)荧光定量PCR分析显示,苹果C类的MdSPS6基因和A类的MdSPS1a/b基因是苹果中表达丰度最高的SPS基因成员,其中MdSPS6在苹果成熟果中表达丰度最高,其次是成熟叶片,而MdSPS1a/b在不积累蔗糖的幼果中表达丰度最高。(3)在果实发育过程中,除MdSPS1a/b之外,其它5个苹果MdSPS家族基因均随果实的生长表达丰度增加,与SPS活性和蔗糖含量明显呈正相关关系。研究表明,C类家族MdSPS6是苹果果实发育后期和叶片中蔗糖合成的主要SPS基因。

Expression Analysis of Apple Sucrose Phosphate Synthase Gene Families and Their Relationship with Sucrose Accumulation in Apple

Sucrose phosphate synthase (SPS) is a major rate limiting enzyme to sucrose synthesis in plant, which affects the growth of plants and sucrose content of fruits. To know the features of SPS family gene and their role in sucrose synthesis, we isolated MdSPS family genes from apple genome, analyzed the relationship between their evolutionary relationships, profiled the mRNA expression characteristics, measured the enzyme activity and sucrose content. The results showed that: (1) there were 8 genes of the SPS gene family expressing in the apple, they belong to three dicot SPS subfamilies. (2) Quantitative real time PCR analysis showed that C type MdSPS6 and A type MdSPS1a/b had the highest expression in apple. Especially, MdSPS6 expression levels are the highest in mature fruit, followed by those in mature leaves, meanwhile MdSPS1a/b was primarily expressed in young fruit which had no sucrose accumulation. (3) Apart from MdSPS1a/b, expression levels of other 5 MdSPS family genes had a significant positive correlation with SPS activity and sucrose concentration, and increased with fruit development. These results suggest that the class C of the SPS gene family is main genes related with sucrose syntheses in the development of apple leaves and fruits.