The Research Of Disease Resistance And Phosphate Transport Function Of Rice OsPT8

BWMK1, a MPAK in rice, regulates plant disease resistance through phosphorylating transcription factors. In our previous research, our lab screened7interactors of BWMK1named BWIP1to BWIP7through yeast two-hybrid. Among these interactors, we are interested in BWIP4(i.e., OsPT8) which is classified into phosphate transporters Phtl family. OsPT8is expressed in various tissues and organs independent of phosphate supply. Overexpression (OX) of OsPT8resulted in excessive phosphate in both roots and shoots of rice. In contrast, phosphate uptake in OsPT8-RNAi plants was decreased.The disease resistance and phosphate transport phenotypes in OsPT8-OX plants were analyzed in this study. The transcriptional level of OsPT8was reduced after inoculation of rice blast. Moreover, we found the OsPT8-OX plants were more susceptible to rice blast, and the transcription levels of some resistance related genes were reduced in OsPT8-OX plants after inoculation of blast. Therefore, OsPT8is a negative regulator of disease resistance in rice. Based on test of hydroponics with different phosphate concentration, we found that OsPT8affected rice development as follows. the root length of OsPT8-OX plants was shorter than the control, however, plant height was higher than control under low phosphate condition; Under normal phosphate condition, both the root length and plant height of OsPT8-OX plants were shorter than control plants. Under high phosphate condition, both the root length and plant height of OsPT8-OX and control plants were decreased and there were no significant differences in root length and plant heigh between OsPT8-OX and control. According to these results, we conclued that OsPT8enhances the capacity of phosphate uptake in rice and makes plants grow better under low phosphate condition. But it makes plants over-absorb phosphate under sufficient phosphate condition, which is harmful to rice development.