Study On OsDGD Gene Responsed To Heat Stress

Rice growth, yield and quality were affected by high temperature stress. Therefore, it is extremely significant to excavate rice heat resistance genes for improving the yield and quality of rice. Thylakoid membrane permeability is closely associated with heat stress in plants. Studies have shown that the membrane permeability is controlled by digalactosyl-diacylglycerol synthase gene. Based on DGD gene is associated with heat resistance in arabidopsis lhaliana, our studies are carried out on rice DGD (OsDGD) expression analysis with heat stress and screened transgenic rice plants. The main conclusions are as following:(1) The analysis of arabidopsis lhaliana DGD (AtDGDl) gene expression under heat resistant suggested that AtDGDl had certain correlation with heat and cold stress. Chip analysis of AtDGDl expression under the photoperiod-temparature showed that the AtDGD1 expression has obvious rhythmicity. It is found that there are three co-expressed gene with AtDGD1 using TAIR site, they are At2g21320, At3gl0420 and At5gl5450, respectively.(2) Compared AtDGDl gene sequence, the evidence provides that its sequence is highly consistent with 0sDGD2 (LOC_Os11g05990). OsDGD2 located in chromosome 11, length of 4773 bp, and its protein containing 737 amino acid residues. Analysed cis elements in OsDGD promoter regions, the result shows that they have some cis elements with adversity, such as G-box, HSE and ABRE. Compared the five homologous gene of OsDGD by comparative genomics suggested that they all have digalactosyl-diacylglycerol synthase function. The phylogenetic tree indicated that this gene have a sequence conservation in several species.(3) Through bioinformatc website STRING, we found that there are 10 proteins interacted with OsDGD2, and monogalatosyl diglyceride synthetase is interacted with OsDGD2 strongestly, which is one of the main structural components involved in the synthesis of photosynthetic membrane. The result indicatd that the DGD is related to chloroplast thylakoid membrane permeability.(4) The result of biochip expression shows that OsDGD are involved in heat and drought stress signalling. The expressional quantities of OsDGD2, OsDGD3, OsDGD4 and OsDGD5 are increased under drought sress, while OsDGD1 is decreased. The expression of five OsDGD gene are decreased in response to heat stress. Five OsDGD were differentially expressed in different rice material. In oryza sativa Nipponbare,9311 and N22, the expressional quantities of OsDGD3 and OsDGD4 are higher, the expressional quantities of OsDGD1 and OsDGD5 are lower. While the expressional quantity of OsDGD2 is low in Nipponbare and 9311, and the expressional quantity is high in N22. Analysed OsDGD expression under the photoperiod-temparature, it is found that the expression of OsDGD1,OsDGD2 and OsDGD3 is rhythmical, and the rhythmicity is not affected by the photoperiod-temparature cycle.(5) The transcriptional expression of OsDGDs in response to heat stress in flag leaves of the young panicle differentiation 6-7 stages of oryza sativa Nipponbare,9311 and N22, are analyzed by real-time quantitative PCR. The results showed that the expressional quantities of OsDGD1, OsDGD2, OsDGD3 and OsDGD4 increased with the increasing hours of heat stress treated in N22, while the expressional quantities decreased in Nipponbare and 9311. This study showed that OsDGDs were induced both in 9311 and N22, while expression levels of OsDGDs in N22 is higher than in 9311, demonstrated that OsDGD is a potential regulatory element of thermotolerance-related signaling in Rice.(6) Through designed OsDGD2 specific primers and cloned promoter sequences from Oryza sativa Nipponbare, the OsDGD2 promoter sequence was introduced into the pCAMBIA1305-OsDGD vector containing GUS. The RNAi vector pCUbi1390-DGDR containing peculiar fragment DGDR is been constructed. The two expression vectors were constructed into the rice plant, and obtained the T1 generation of transgenic rice lines.