Gene Evolution And Function Of Sucrose Phosphate Synthase In Saccharum

Sugarcane(Saccharum spp.) is a large,perenial,tropical or subtropical crop grown worldwide.Sugarcane is an economically important crop.Some genes involved in stress resistance,sugar content and biomass are the hot spots in recent research. Sucrose phosphate synthase (SPS;EC 2.4.1.14) is one of importants enzymes involved in the sucrose pathway which control the sucrose synthesis.Researches have found that the activity of the SPS is in proportion to the sucrose content. But the sugarcane genome sequencing will not be able to start in the short term because of the complexity of its genomeics. In recent years,the sorghum allied with the sugarcane has been completed of the entire genome sequencing and the sugarcane EST database provided a possible of th eprecise comparision of the genome research.what’s more,based on the comparative genomics and second generation sequencing technology platforms, the comparative analysis was taken in the evolution profilling of some important gene involved in the surcose synthesis aimed at figuring out the mechanime of the dark/light phosphoryla tion of sucrose phospathe synthase. The main contents of this research are as follow:Firstly,based on the comparative genomics analysis of the Arabidopsis,sorghum and Oryza sativa,14 BACs that contains the SPS gene family were screened and annotated.We found that there are five SPS genes in s.officinarum and s.spontaneum wihch named SPSA、SPSB、SPSC、SPSD1、SPSD2. And the SPSD is specific in monocotyledon whose ancestor may be the SPSA.Secondly, the sugarcane SPS genes were homology cloned on the strength of RNA-seq and experimental verification.We got a conclusion that SPSB plays a important role in the sucrose synthesis,while in the sugar accumulation is SPSA.However, under the condition of stress treatment,SPSD2 plays a important role in the sucrose synthesis. This argument requires further experiment.Thirdly, gateway technology was used to obtain the full-length of SPS genes in saccharum based on the sorghum genome.we figured it out that the subcellular localization of SPS is cell membrance through transient transfection tobacco.Finally, through determination of carbohydrate content of transgeneic arabidopsis which has different stie-directed mutagenesis, we found that the Ser-153 was the key point of the dark/light phosphorylation in the SPSD2.