Identification and expression profile analysis of the sucrose phosphate synthase gene family in Sonn.

Sucrose phosphate synthase (SPS, EC 2.4.1.14) is a key enzyme that regulates sucrose biosynthesis in plants. SPS is encoded by different gene families which display differential expression patterns and functional divergence. Genome-wide identification and expression analyses of gene families have been performed in Arabidopsis, rice, and sugarcane, but a comprehensive analysis of the gene family in Sonn. has not yet been reported. In the current study, four gene (, , , and ) were isolated from litchi. The genomic organization analysis indicated the four litchi genes have very similar exon-intron structures. Phylogenetic tree showed - were grouped into different SPS families ( and in A family, in B family, and in C family). and were strongly expressed in the flowers, while most expressed in mature leaves. RT-qPCR results showed that genes expressed differentially during aril development between cultivars with different hexose/sucrose ratios. A higher level of expression of genes was detected in Wuheli, which accumulates higher sucrose in the aril at mature. The tissue- and developmental stage-specific expression of - genes uncovered in this study increase our understanding of the important roles played by these genes in litchi fruits.