Molecular Mechanism Of Ethylene Regulates Fig(Ficus Carica L.)Fruit Ripening In An Abscisic Acid-dependent Manner

Fleshy fruit ripening is typically regulated by ethylene in climacteric fruits and abscisic acid(ABA)in non-climacteric fruits.Common fig(Ficus carica L.)exhibits a dual-ripening mechanism,shows a respiration peak and an ethylene release peak,but no post-ripening phenomenon;and ripening is regulated by ABA,but the molecular mechanism of fig ripening is not clear.Through the analysis of transcriptome data,based on the analysis of ABA and key genes of ethylene synthesis and signal transduction,the common fig variety ’Masui Dauphine’ was used as the test material,and 4 key genes Fc ACS1,Fc ACO2,Fc ETR1,Fc ETR2 in the the related genes in the ethylene synthesis and signal transduction and the related gene Fc AAO3 in ABA synthesis were used as the starting point to indicate the molecular basis of fig fruit ripening by means of pharmacology,physiology and molecular biology.It reveals a foundation for molecular breeding and ripening regulation of figs.The main results and conclusions are as follows:1.The appearance and microstructure changes of fig fruit development were recorded by using plant microscopic technology and physiological index measurement,shows that the development process of fig fruit can be divided into 6 periods;the development of seeds is stop at 30 days,and the embryo atrophy;The anthocyanin content in the receptacle continues to rise and reaches the peak when maturity,content in the internal flowers reached the peak in 50 days,and then decreased after a lower peak after the coloration of the peel;The length changes of flowers were more remarkable,the thickness of receptacle was substantially unchanged;The fruit is basically not accumulated starch in the whole development process,and there is no significant difference in sucrose content,the content of fructose and glucose is rapidly elevated and the peak is reached when maturity;The ABA contents changed little before 50 days and increased rapidly after this time,and reaching its highest level when maturity,ethylene production achieved the peak at 80 days,and then decreased till the maturity;Pharmacological Experiments show that the ripening of ethephon-treated figs is significantly accelerated,and the fruit ripening of AVG treatment is decelerated.This result show that ethylene plays a positive regulatory role in the ripening of fig fruits;2.Filter by transcription data,found that ethylene synthesis related genes FCACS1,FCACO2,ethylene receptor coding gene Fc ETR1,FCETR2 and ABA synthesis related genes FCAAO3 have significant increase in expression of fig fruit ripening,which may participate in the ripening regulation of fig fruits.FCACS1,FCACO2,FCETR1,FCACS1,FCAAO3-RNAi vector were constructed by molecular biology,and transient conversion to figs was achieved through Agrobacterium infected.In transgenic experiments,down-regulation Fc ACO2 inhibited fruit ripening,while down-regulation Fc ACS1,Fc ETR1,and Fc ETR2 had no obvious effects,silencing Fc AAO3 can inhibiting the ripening of fig fruits(30 DAA),but promoting the ripening of fig fruits(50 DAA).3.According to the different results of the Fc AAO3-RNAi decreasing different,pharmacological recovery experiments were designed and measured ethylene production and ABA content of the transgenic fruits,the results show that ABA can rescue the fig fruits ripening of ethylene is inhibited,but ethylene cannot rescue the fig fruits ripening of ABA is inhibited;Ethylene production and ABA content in Fc ACO2-RNAi fruit have a significant decrease,the ABA content of Fc AAO3-RNAi fruit is lowered,but the ethylene production is increased.