Expression Analysis Of Sucrose-phosphate Synthase ⅢGene (SpsⅢ) In Saccharum Officinarum L.

Sugarcane (Saccharum officinarum L.) is an important sugar and energy crop in China. Sucrose content is the main objective of sugarcane cultivation, which depends on the efficiency of sucrose synthesis. Sucrose Synthesis in the level of efficiency is one of the criteria in the evaluation of sugarcane varieties of good or bad. Synthetic efficiency of sucrose and related enzymes related to the regulation of sucrose synthesis enzymes is very necessary. It has been suggested that sucrose phosphate synthase (SPS) is a key rate-limiting enzyme in sucrose formation and it also influences sucrose accumulation and carbon partitioning processes.Four sugarcane varieties, GT28, chewing cane Badila, ROC20and ROC22, were used as experimental materials. And the leave No.1(The youngest fully expanded leaf was designated leaf no.1), leaf No.0(the first upper one of leaf No.1), the young sheath and young stalk were sampled to assay the expression of SPSIII by semi-quantitative RT-PCR and real-time PCR in the technical maturing stage. The main results as follows:1. By homologous based cloning, two specific fragments isolated from sugarcane mRNA with specific primers, with123bp and108bp in length respectively. Comparing the sequence of SPS gene with that of SPS gene sequences reported in GeneBank, the nucleotide acid showed high identity (100%) with Saccharum officinarum sucrose phosphate synthase III (SPSIII) gene, SPSIII-2allele(EU278617.1) and Sorghum SPS3-1. And the fragment of control gene25S rRNA showed high identity (100%) with Saccharum officinarum EST((BQ536525.1). These results showed that the specific primers were used to semi-quantitative RT-PCR and real-time PCR.2. The results of SPSIII gene expression by semi-quantitative RT-PCR showed as the followings:in the early technical maturing phase, SPS III expression were showed in all four sampled sites, i.e. Leaf No.1, No.0, young sheath and young stalk among four sugarcane genotypes. But the expression value was different in different genotypes. The expression value of SPS III were very low install four sites in GT28, high and evenly in four sites in Badila, highest in young sheath in ROC20and highest in young stalk in ROC22. In the middle technical maturing phase, the expression of SPSIII had no difference that in the early technical maturing phase. And then in the late technical maturing phase, SPSIII expression in leaves, young sheath and young stalk increased rapidly than in the early and middle stages.3. The results of Real-time PCR showed as following:the relative expression of sugarcane gene in the early technical maturing phase, they were highest in young stalk in ROC22, and then for Leaf No.1. It is contrary for in Leaf No.1and young stalk in ROC20, and Leaf No.O in Badila. In the middle technical maturing phase, the relative expression of sugarcane SPSIII gene had no difference than those in the early technical maturing phase, and it decreased. After the late technical maturing phase, the relative expression of sugarcane SPSIII gene had no chance.