Function Characterization Of A Phytophthora Capsici Effector PcRxLR207 And Its Host Binding Proteins

Phytophthora blight of pepper caused by Phytophthora capsici(P.capsici)which is an important pathogenic oomycetes.P.capsici can survive for many years as hyphal form in the plant residue or as spore morphology in the soil,and infect the plant at all stages of growth,eventually leading to stem blight,stem rot,leaf wilt and fruit decay and other symptoms on many vegetables.Besides it is easy to produce resistance to drugs,which has caused serious losses for the world's vegetable industry every year.Studying mechanism of its pathogenicity and host resistance can provide theoretical support and technical guidance for practical production.During infection,different pathogens can secrete a series of effectors to destroy the host defense responses by controlling its growth and development and other functions.As the same time,some effectors can also be recognized by the host to trigger immunity.RxLR effectors are a group of well-know pathogenetic determinants.Previously PcRxLR207 effector was shown to cause cell death in tobacco.The effector could interact with a class of proteins with RRM motif in Arabidopsis thaliana,whose functions in plant disease resistance have not been reported.Here,we analyzed functions of PcRxLR207 in virulence and 7 Arabidopsis RRM genes in resistance.The following studies are carried out in this paper.Obtaining of transgenic Arabidopsis lines expressing PcRxLR207 and RRM genes homozygous mutants:To clarify the biological functions of PcRxLR207,we generated the transgenic Arabidopsis lines expressing PcRxLR207 using Agrobacterium floral-dip.And the homozygous strains were further identified based on Western blot analysis.Arabidopsis contains 7 RRM genes which are clustered in a single clade in the phylogenetic tree.The corresponding mutant of 7 each RRM genes ordered from the NASC,then,the homozygous mutants were obtained by self propagation and molecular screening.The above genetic materials will be further used to study.Phenotypes of PcRxLR207 transgenic Arabidopsis lines:Inoculation with zoospores of P.capsici is carried out,and it is found that PcRxLR207 transgenic Arabidopsis is more resistant to P.capsici than Col-0 wild type Arabidopsis,by trypan blue staining,but the Arabidopsis is inoculated with Pseudomonas syringae pathovar tomato(Pst)and it is found that PcRxLR207 transgenic Arabidopsis thaliana is more susceptible to Pst than Col-0 wild type Arabidopsis.Further find cell death of PcRxLR207 transgenic Arabidopsis induced by effectors is more fast than that of Col-0 wild-type Arabidopsis.Resistance analysis of RRM mutant Arabidopsis lines:Similar to the above experiments,the RRM mutant Arabidopsis and wild type Arabidopsis inoculation same P.capsici and Pst,it is found that 1 of mutants Arabidopsis is more sensitive to Pc35,2 of them have no obvious difference,another 4 plants are more resistance to Pc35.5 of mutants Arabidopsis is more sensitive to Pst,residual plants are no obvious difference.On this basis,found that all of Arabidopsis mutants plants are induced cell death quicker than wild type by effector.In conclusion,the effector PcRxLR207 of P.capsici and its target RRM gene have important effects on plant disease resistance,and its mechanism may be the regulation of cell death process of host.