Functional Analysis Of Transcription Factor IPA1 And Kinase OsBSK1-2 In Rice Immunity

? Functional analysis of IPA1 against Magnaporthe oryzae in riceRice is an important crop that feeds half the world's population.The rice yield would be severely reduced by rice blast.Several genes involved in rice resistance have been identified and applied in rice breeding.However,plant development is usually slowed down by an active immune response,resulting in yield penalties for crops against pathogens.No genes have been reported to promote both yield and disease resistance.Ideal Plant Architecture 1(IPA1),encodes Os SPL14,a member of the SPL gene family that consists of plant specific transcription factors.As a pleomorphic gene,IPA1 contributes to ideal plant architecture generation with high yields.However,the molecular function of IPA1 in rice immunity was remained to be elucidated.To assess whether IPA1 affects plant immune response,we challenged the plants with M.oryzae and found that IPA1 overexpression lines show enhanced resistance whereas IPA1 RNAi lines display increased susceptibility to M.oryzae.Moreover,previous study showed that several defense related genes containing GTAC motif were identified as the targets of IPA1,including Os WRKY45.To ensure this result,we performed EMSA,Ch IP-q PCR and dual-reporter assay to detect the directly interaction of IPA1 and the promoter of Os WRKY45.As the results in our study indicated that IPA1 could target Os WRKY45 to promote its expression and then activate the IPA1-meditated signaling pathway in rice resistance to M.oryzae.? Functional analysis of Os BSK1-2 in Rice ImmunityBrassinosteroids(BRs)is identified as one of the most important hormones involved in controlling plant development.Recent studies indicated that several candidates in BRs signaling also regulate plant immunity.However,limited information about BRs function in rice resistance to Magnaporthe oryzae were reported.The Brassinosteroid-Signaling Kinase 1(BSK1)belongs to the receptor-like cytoplasmic kinase XII subgroup.BSK1 regulates development and immunity in Arabidopsis.Two homologs of At BSK1,Os BSK1-1 and Os BSK1-2 were identified in rice genome.Os BSK1-1 and Os BSK1-2 were predominantly expressed in the four-leaf stage of development,and the transcripts of Os BSK1-2 were more abundant than those of Os BSK1-1.To investigate the function of Os BSKs,we firstly detected the transcripts level of Os BSK1-1 and Os BSK1-2 upon flg22 or chitin treatment,and found that Os BSK1-2 was induced,while Os BSK1-1 was not.Furthermore,we also showed that silencing of Os BSK1-2 could comprise rice responses to chitin-or flg22-triggered immunity and resistance to Magnaporthe oryzae.Therefore,our study reveals that Os BSK1-2 is involved in rice immunity.