The Premilinary Study Of Rice KNOX 2 Protein HOS58 In Rice Blast Resistance And Development

Rice blast is devastating for rice and therefore a great threat to the safety of rice.The most economic method to solve rice blast stress is to breed disease resistance rice.H4,confers broad-spectrum rice blast resistance,was developed by us through space mutation and subsequent selection previously.A broad-spectrum rice blast resistance gene Pik-H4 was then mapped and cloned.Further studies indicated that Pik-H4 interact with homeodomain(HD)protein OsBIHD1 and involved in brassinosteroids(BRs)and ethene regulation.The differential genes expression profile of transcriptome and ITRAQ differential protome of Pik-H4 Nils showed that the expression level of HD transcription factor HOS58 was down-regulated,thus we study on HOS58 in this paper,the results are as follows:1.HOS58 is classified as KNOX 2 subclass,TALE class,HD family protein.The rest of KNOX 2 proteins in rice are HOS59,HOS66 and OSH45.There are 144 absolute conserved amino acid residues in their protein sequence,the most conserved domain is HD domain which accounts 84.75% similarity.They are all localized in the nuclear,indicating that KNOX 2 proteins are nuclear transcription factors;they expresse broadly in all organs of rice;with no ego-transcriptional activation characteristics,transcriptional activators are required for their transcriptional function.2.The expression level of rice KNOX 2 genes were repressed after rice blast treatment.HOS58 doesn't interact with Pik-H4 directly.The scabs of HOS58-ko mutants were fewer than those of HOS58-OX mutants.Overexpressing HOS58 enhances blast resistance and up-regulates disease progress genes PR-1b.And it was contrary in the HOS58-knockout mutants.While how HOS58 function downstream of Pik-H4 in blast resistance needs to be cleared.3.Overexpressing HOS58 results in BRs relative phenotypes as increasing lamina joint inclintion,elongation of mesocotyls during skotomorphogenesis and being sensitive to low concentration brassinolide.Besides,the expression of some BRs biosynthesis or signaling genes,BZR1,ILI1,DLT,BRD1 and BRD2,changes after overexpressing HOS58.Accordingly,HOS58 involves in BRs biosynthesis or signaling.4.We discovered various proteins that interact with HOS58 through yeast two hybridization and GO ontology analysis.We assume that the proteins may play a role in forming complexes with HOS58 during transcription due to most of the proteins have binding ability.One of the proteins,MSRB3,functions in the oxidative stress.MSRB3 may involve in the rice blast resistance by interacting with HOS58.Another protein called XEH/XET catalyzes the synthesis and degration of cell wall.We speculate that HOS58 and XEH/XET interact through some pathways and result in thickening of the cell wall as to prevent the invasion of penetration peg of Magnaporthe grisea.