The Research On The Functions Of Rice OsPT8 Protein In Phosphorus Transport And Disease Resistance Signaling Pathway

Absorption of nutrients from the environment and defense responses to pathogens are two physiological processes indispensable for plant survival.However,it is still largely unknown about the interaction between their molecular signaling pathways.Phosphorus(Pi)is one of the major nutrients to plants normal growth,development and metabolism.It plays a key role in various physiological processes of plants.Phosphorus is involved in vital substance synthesis,energy transfer,and signal transduction.However,the effective absorption of phosphorus by crops has always been a problem in actual production.Phosphorus nutrition can be unevenly distributed in the soil,and it is difficult to move.Usually,additional phosphate fertilizer is needed to ensure the fine growth of plants.However,the application of phosphate fertilizer often causes pollution of the environment,especially water pollution.People have been eager to cultivate economic crops with strong phosphorus absorption capacity to change this problem.Rice is an important staple food for more than half of the world’s population.Rice diseases are a serious threat to rice production.Safe and effective control of rice diseases is a serious global problem.BWMK1 is a mitogen-activated protein kinase(MAPK)in rice,which positively regulates the disease resistance of plants to pathogenic bacteria.In the previous experiment,we used BWMK1 as a bait to screen for the BWMK1 interaction protein OsPT8,which is a member of the Pht1(Phosphate Transporter 1)family.In this paper,the function of OsPT8 in phosphorus transport and disease resistance molecular signaling pathways was studied.The main results are as follows:1.Using yeast two-hybrid,GST pull-down and LCI experiments to verify the specific interaction between OsPT8 and BWMK1 in vivo and in vitro;OsPT8-OXand RNAi plants were constructed to study the function of OsPT8 in rice.It was found that the expression level of BWMK1 gene was inhibited in OsPT8-OX plants;2.The hydroponic experiments with different phosphorus concentrations showed that the plant height of OsPT8-OX plants was higher than that of the control group under low phosphorus conditions,but the plant height of OsPT8-OX plants decreased with the increase of phosphorus concentration.In normal phosphorus and high phosphorus conditions,the control group will have a higher plant height.The field experiment found that OsPT8-OX plants increased the plant height,panicle length and seed setting of rice under low phosphorus conditions,which increased by 4.4%,8.0% and 4.9%,respectively;3.The transcription level of OsPHR2 was detected in OsPT8-OX plants under the conditions of low and normal phosphorus concentrations.It was found that the OsPHR2 transcription level of OsPT8-OX plants was up-regulated with the increase of phosphorus concentration;4.Inoculation with Magnaporthe oryzae and Xanthomonas oryzae pv.oryzae with wild-type Nipponbare,and treatment cut leaves of NPB with chitin and flg22 revealed that the transcription level of OsPT8 gene was inhibited by pathogens,chitin and flg22.After inoculation with pathogens,it was found that the expression level of BWMK1 gene was inhibited in OsPT8-OX plants;5.The wild type Nipponbare was used as a control to inoculate OsPT8 transgenic plants with pathogens.It was found that overexpression of OsPT8 gene reduced the resistance of rice to fungi or bacteria;6.The alter genes expression of OsPT8 transgenic plants after inoculation were further studied.It was found that overexpression of OsPT8 gene inhibited the transcription levels of related positive-regulatory resistance related genes;7.Using chitin and flg22 to treat OsPT8 transgenic plants and detecting the transcriptional levels of pathogen-associated molecular pattern-triggered immunity(PTI)related genes,it was found that overexpression of OsPT8 gene inhibited the transcription levels of related positive-regulatory resistance related genes;These results indicate that OsPT8 plays an important role in the disease resistance and growth of rice,providing clues for further study of the cross-function of rice phosphorus signal and resistance signal.