Molecular Mechanism Of PhERF2-Mediated Jasmonic Acid And Ethylene In Petunia Resistance To Botrytis Cinerea

Petunia(Petunia hybrida)is a perennial herbaceous flower belonging to the Solanaceae family.It has high ornamental and economic value due to its wide variety and easy cultivation and has become a model plant for the study of flower traits and disease resistance mechanism due to its advantages of easy genetic transformation,complete genome sequencing,and short life cycle.During the growth and development of petunia,various types of diseases will occur,especially Botrytis cinerea is the most serious.However,little research has been done on the response to Botrytis cinerea and associated molecular mechanisms,making Botrytis cinerea resistance one of the main goals of petunia breeding.Jasmonic acid(JA)and ethylene(ET)are important plant hormones involved in adversity stress.However,the molecular mechanism of JA/ET signaling involved in botrytis resistance of ornamental flowers is rarely reported.In previous experiments,we found a key transcription factor PhERF2 in petunia stress response,which was significantly induced by jasmonic acid and ethylene exogenous hormone treatment,as well as necrotrophic Botrytis cinerea infection,and up-regulated the expression of Ph PDF1.2 and Ph Chi B,the defense marker gene.Through physiological and biochemical experiments,molecular biology and other means,the function of JA/ET pathway in petunia Botrytis cinerea resistance was determined.The main research results are as follows:1.Taking wild-type,PhERF2-RNAi lines and overexpression lines of petunia as materials,after inoculation with Botrytis cinerea,it was found that the lesion development area of overexpressing PhERF2 was smaller than that of RNAi plants,the resistance to Botrytis cinerea was enhanced.Inoculation of wild-type petunia increased endogenous jasmonic acid and ethylene content and up-regulated expression of related genes.After silencing Ph EIN2,Ph COI1,and Ph JAZ1,it was found that the expression abundance of PhERF2 was decreased.It is speculated that PhERF2 may be located downstream of the three genes to play a role.2.In order to further clarify the downstream signal transduction of PhERF2 mediated by jasmonic acid and ethylene against Botrytis cinerea,the downstream target genes PhERF16 and Ph Chi B of PhERF2 were screened by DAP-Seq(DNA affinity purification sequencing)technology.PhERF2 can combine with the promoters of PhERF16 and Ph Chi B and activate gene expression through yeast one-hybrid experiments and dual luciferase experiments.3.By constructing RNAi,overexpressing PhERF16 vector and genetically transforming wild-type petunia ‘Mitchell Diploid’,RNAi and PhERF16-overexpressing transgenic petunia were successfully obtained.The resistance identification experiment of Botrytis cinerea showed that the resistance of the overexpression lines was enhanced compared with the wild type,and the resistance of the RNAi transgenic plants was weakened.In conclusion,this study determined the molecular mechanism of PhERF2-mediated jasmonic acid/ethylene signaling pathway genes to regulate the transcription of Ph Chi B or PhERF16,respectively,and then promote the resistance of petunia to Botrytis cinerea,which provides a reliable genetic basis for disease resistance breeding of petunia.It also provides a theoretical basis for accurate molecular breeding of disease resistance for other garden plants and ornamental flowers.