Role of the SPS Gene Families in the Regulation of Sucrose Accumulation in Sugarcane

摘要

High sugar content is an essential goal in breeding new sugarcane varieties. Sucrose-phosphate synthase (SPS) is a key enzyme that regulates sucrose biosynthesis in plants. Four families of the SPS gene exist in sugarcane. It is important to elucidate the biological functions of SPS genes from different gene families, so as to regulate the expression of sugarcane SPS for improving sugarcane varieties. In this study, we cloned the full-length cDNA sequences of three SPS genes (SofSPSA, SofSPSB, and SofSPSDIII) from four SPS gene families in sugarcane. The full-length cDNA sequence of the SofSPSA gene is 3906 base pairs (bp) in length, and it contains a 3183 bp open reading frame (ORF) that encodes 1060 amino acids (GenBank Accession No.: HM854011). The full-length cDNA sequence of the SofSPSB gene is 3481 bp in length and contains a 3225 bp ORF that encodes 1074 amino acids (GenBank Accession No.: JN584485). The full-length cDNA sequence of SofSPSDIII gene is 3252 bp in length, and it contains a 2895 bp ORF that encodes 964 amino acids (GenBank Accession No.: HQ117935). Analyses of spatial and temporal expression features of SPS genes from different families in high-, moderate-, and low-sugar content varieties showed that the SPS gene from family D maintains the basic function of sucrose synthesis in sugarcane, whereas the intensity of sucrose synthesis is controlled by regulating the expressions of SPS genes from family C and family A. SPS gene from family B is not involved in sucrose synthesis in source leaf but involved in sucrose accumulation and utilization in sugarcane. This study would provide a theoretical basis to accurately elucidate the biological functions of sugarcane SPS genes from different families, as well as to improve sugarcane varieties by regulating the expression of SPS genes.