Functional Identification Of Pathogen Induction Element AATCA And Its Interaction Transcription Factors In Rice

Rice is an important grain crop in the world.Rice sheath blight is caused by Rhizoctonia solani Kühn,and it is one of the most destructive diseases in rice.At present,the research of rice diseases is mostly focused on rice bacterial leaf blight and rice blast.There are few studies on rice sheath blight,and the research is even less on the resistance mechanism and regulation mechanism.The prevent and control crop diseases are mainly through cultivation of disease-resistant varieties in current production.However,the resistance of rice sheath blight is a quantitative trait,it is difficult to produce high resistance varieties to sheath blight by conventional breeding methods.It is limited resistance breeding that the lack of high resistance materials to rice sheath blight.Therefore,it is an effective strategy that identified promoters and interacting transcription factors and study the expression of resistance-related genes to control rice sheath blight.The previous laboratory studies showed that Os2H16 gene of rice could be induced by R.solani.Overexpresion of Os2H16 gene enhances resistance to R.Solani in rice.On the contrary,Os2H16 knockdown lines were more susceptible to R.solani.Os2H16 gene promoter is a pathogen-induced expression promoter which can be induced by R.solani.The main response regions of the promoter have been identified as-513 bp to-411 bp and-411 bp to-309 bp.A new cis-acting element AATCA,which can independently respond to R.solani,and was found in-513 bp to-411 bp region by previous studies on transient expression system of tobacco.In this study,the expression of AATCA element is showed that it could independently respond to the induction of R.solani in rice,and the results of previous laboratory were verified.The proteins interacting with AATCA elements were screened by DNA pull-down.The interaction between AATCA element and OsbHLH057 was verified by yeast one-hybrid technique.By analyzing the OsbHLH057 gene,it was found that can encode a protein with unknown function,which has a conserved domain of HLH and was located in the nucleus.The results showed that OsbHLH057 gene could be induced by R.solani,suggesting that it might be involved in the response of rice to R.solani.Then we constructed the expression vector of OsbHLH057 gene over-exprssion and knockout,obtained rice over-exprssion plant and knockout mutant plant.We are detected the expression of Os2H16 gene which is related to resistance disease gene in OsbHLH057 gene downstream.It was found that the expression of Os2H16 gene was down-regulated in knockout mutant plant,suggesting that OsbHLH057 gene may regulate the resistance of rice sheath blight by affecting the expression of Os2H16 gene.In conclusion,the study of cis-acting element AATCA and its interaction transcription factor OsbHLH057,that provided a new theoretical basis for improving rice resistance by regulating the expression of resistance genes to rice sheath blight.It is of great significance to further study the resistance mechanism of rice sheath blight and the breeding of resistant rice varieties.