Spatial And Temporal Expression Analysis Of The Starch Synthase Gene Family In Maize

Maize is the raw materials of feed crops and food industrial, and it plays an important role in the agriculture of the world. Maize starch is an important component of grain. research at home and abroad is mainly on the biosynthesis mechanism of starch of rice and wheat, but less study involved in maize starch. With more and more the starch synthase gene have been cloned, people have been fucos on using genetic engineering to elucidate the process of starch biosynthesis, and to regulate the content and activity of enzyme in process of starch synthase. Although there have been some reports of study on individual starch synthase gene, but little research on starch synthase gene family.In order to clarify the expression site and time of isozyme of maize starch synthase gene family, extensive searches for starch synthase genes were done in the databases of genebank, and we get 272 corn starch synthase genes. Through the Multi-sequence alignment and their conservative site, we got eight different sequences. Each sequence was then compared with the starch synthase gene in rice and wheat, which can be divided into SSI, SSII, SSIII, SSIV, SSV and GBSSI.The 18-599 maize inbred line was used as experimental material, and then the total RNA from grain, leaf, leaf vein, and root of various period were extracted. In the mean time, specific PCR primers were designed through Primer 5.0. Real time PCR was performed to analyse the expression in spatially and temporally of the eight genes, and the main results showed in the following:The starch synthase genes was divided into three groups according to the expression time: (i) early expressers (SSIIIa), which are expressed in the early stage of grain filling; (ii) late expressers (SSIIa, SSIIc, SSIIIb, SSV, GBSSI), which are expressed in the mid to later stage of grain filling; and (iii) steady expressers (SSI, SSIV), which are expressed relatively constantly during grain filling. The starch synthase genes was also divided into two groups according to their expression of different tissue: (i) grain-specific expression: SSIIa, SSIIIa, GBSSI, which are main expressed in grain. (ii) expression in various parts: SSI, SSIIIb, SSIV, SSIIc, SSIIIb. To compare the relative expression of different gene derived from the same period and tissue: (i) the relative expression of starch synthase gene entirety represented increasing trend in grain after pollination; (ii) The relative expression in vary tissue showed the similar trend, which was leaf > leaf vein > root; (iii) the expression of starch synthase gene displayed difference in root, leaf vein, leaf, the major expressed genes were SSI, SSIIc, SSIIIb, SSV.