Genome-Wide Survey, Identification and Evolution Analysis of Aldo-Keto Reductase (AKR) Genes in Pear and Other Members in Rosaceae

Aldo-keto reductase (AKR) is a large gene superfamily encoding a number of monomeric NADPH-dependent oxidoreductases. The gene S6PDH in the AKR2 family encoded sorbitol-6-phosphate dehydrogenase, which played an important role in sorbitol metabolism in plants. Genes in AKR13 functioned as perakine reductase were involved in the biosynthesis of plant monoterpenoid indole alkaloids. Pear is a temperate fruit widespread in the world with nutrient and economic values, the available whole genome sequence of pear make it easy for gene discovery and evolution analysis. Thus, genome-wide investigation of AKR genes in pear will provide insights on the characteristics of AKR gene superfamily. In this study, a total of 197 genes were identified as members of AKR superfamily in five sequenced species in Rosaceae and they were clustered into 8 groups with four of which were characterized as new families in AKR superfamily. Most of pear AKR genes in the new families were found expressed. S6PDH were found highly expressed in the later stage of pear fruit development. Synteny analyses revealed that the expansion of AKR genes from subfamily of Maloideae to Rosoideae and from tribe of Amygdaleae to Pyreae was mainly driven by tandem duplication, whole genome duplication or segmental duplication.