Pathogenic IAA In Rice-pathogen Interaction And The Preliminary Explotation Of Two T?SS Effectors

Rice is one of the most important grain crops in the world,and its production is threatened by verious kinds of diseases.Bacterial blight caused by Xanthomonas oryzae pv.Oryzae?Xoo?is a worldwide spreaded disease of rice which can make much losses to the rice production every year.Research into the plant-pathogen interactions can help us to understand the mechanism of how pathogens infect rices which can lay the foundation of disease control for us.The plant growth hormone auxin is generally recognized to regulate plant growth and development.But recent studies have shown that auxin can also play as a virulence factor during infection process.Indole-3-acetic acid?IAA?is the generally occuring form of auxin in plant and the infection of bacteria induce rice to accumulate IAA.In addition,some kinds of pathogens can synthesize IAA.Researches have shown that Xoo also possess the capability to synthesize IAA.Analyze of bioinformatics helped us to find out two gene PXO₀0197 and PXO₀3984,which encode amidohydorlase;one gene PXO 01485,which encode a monooxygenase and one gene PXO₄627,which encode a aldehyde dehydrogenase.We have obtain the deletion mutants and the complements,the delection mutants screate less amount of IAA,and their pathogenity is enhenced.These results indicate that pathogenity IAA may have negative effect on it's pathogenity on rice.Rice line IRBB4 contains resistance gene Xa4,it is susceptible to PX099A and is resistant to PX061,our lab have found that Xa4 encode a protein located on cell wall.Type II secretion system is important to pathogenity for pathogens,it can secreat lots of virulence factors and some exzyme to attact host cells.In this study we have found two genes PXO₀4151?PXO₀4176,which sequences are different in PX099A and PX061.To comfirm whether can these two genes result in the different pathogenity of PXO99A and PXO61,we first knock out these two genes in PX099A and then complement the PX061 original genes into the mutants.But the PX061 original genes can not function in the mutants.But PXO₀4151? PXO 04176 knock out mutants possess much reduced virulence,this indicate that these two genes are important for Xoo's pathogenity.