Cloning And Expression Of Polygalacturonase Inhibiting Protein Gene Ospgip1 In Rice Plants

Polygalacturonase inhibiting proteins (PGIPs) are anti-fungal proteins with leucine-rich repeat (LRR), which could inhibit the catalytic activity of fungal endo-PG.In this study, gene Ospgip1 encoding OsPGIP1 in rice plants was cloned by PCR. The sequence and structure of OsPGIP1 was infered by biological information analysis and its inhibition to the activity of Rhictonia solani PG was surveyed. Furthermore, Ospgip1 expression in E. coli, its time and spatial expression in rice plants and its expression induced by the yellowing treatment and the pathogen inoculation were conducted. The detailed results are as follows:1. Ospgip1 was a sequence of 1 184 bp, which contained a complete ORF of 930bp in length and encoded a protein of 309 amino acids with hydrophobic N-terminal signal peptide and 9 LRR, called OsPGIP1. The secondary structure of OsPGIP1's LRR had 9α-helixes and 9β-sheets that sat at the front or end of LRR, and more irregular coils (53%). At last, the protein formed one fibriform structure.2. According to RT-PCR, OsPGIP1 could be constritutively expressed in rice varieties resistant and susceptible to R. solani, but there was some difference in the expression in different growth stages or organs. Real Time PCR indicated that OsPGIP1 was expressed in rice resistant varieties (YSBR1 and Jasmine85) significantly higher than in the susceptible one (Lemont), which showed that there was a postive relationship of OsPGIP1 expression with the resistance of rice varieties.3. OsPGIP1 expression induced by the yellowing treatment and the pathogen inoculation was studied by Real Time PCR. The results showed that OsPGIP1 expressed in rice seedlings was recreased after the yellowing treatment. But, in the infection of R. solani, OsPGIP1 exprossion in the resistant varieties was significantly stronger than that in the control, and no change occurred in the exprossion in the susceptible one.