Regulation Of Abscisic Acid And Indole-3-Acetic Acid On Ripening Of Banana And Strawberry Fruit

Fruit ripening was affected by many kinds of phytohormones.Many researches have reported that one single phytohormone regulated fruit ripening,however,the interaction of phytohormones on fruit ripening have not been studied sufficiently,and the mechanism of phytohormone crosstalk network is limited known.To exclude the influence of abscisic acid(ABA)and indole-3-acetic acid(IAA)on fruit ripening,banana(climacteric fruit)and strawberry(non-climacteric fruit)fruits were treated with ABA,IAA,and ABA combining with IAA,respectively.Physiological and biochemical tests,DGE-seq and yeast one-hybride assays were carried out to interpret the function of ABA and IAA on fruit ripening.The results were as follows:1.Banana fruit(Musa acuminate L.AAA group,cv.Brazilian)were treated by exogenous phytohormones and analyzed using DGE-seq.The results showed that ABA promoted postharvest banana fruit ripening by inducing the transcription level of PaO,DXR,PSY,PME,and PL.IAA inhibited fruit ripening by reducing the transcription level of PaO,DXR,PSY,PME,and PL.PaO,DXR,PSY mRNA levels in ABA+IAA treated fruit were close to the control,which was consistent with the coloration process.In addition,PME and PL mRNA levels in ABA+IAA treated fruit were close to the control,which was also consistent with the softening phenotype.Therefore,ABA+IAA treatment might inhibit the action of the individual ABA or IAA through the antagonistic mechanism of neutralizing the specific gene expression either induced by ABA or reduced by IAA in the postharvest ripening of banana.2.Octaploid strawberry(Fragaria x ananassa Duch,cv.Akihime)were treated with different phytohormones.The results indicated that ABA promoted the strawberry fruit ripening by inducing the transcription level of PAL,DFR,PME,and PL.IAA inhibited fruit ripening by reducing the transcription level of PAL,DFR,PME,and PL.ABA+IAA might maintain fruit color the same as control by regulating PAL and DFR genes.The enzyme activities and gene expressions of cell wall degradation were detected,and the results showed that ABA+IAA might maintain fruit firmness the same as control by regulating PME and PL genes.Therefore,ABA+IAA treatment might inhibit the action of the individual ABA or IAA through the antagonistic mechanism of neutralizing the specific gene expression either induced by ABA or reduced by IAA in the ripening of strawberry fruit.3.Two MADS-box genes were cloned from strawberry,which were FaMADSl and FaMADS2.Phylogenetic analysis suggested that FaMADSl and FaMADS2 belonged to the SEP 1/2 proteins and SEP3 proteins,respectively.Temporospatial expression of FaMADS1 and FaMADS2 suggested that they expressed both only in strawberry petal and fruit.Expression level of the two genes gradually decreased with the fruit maturation.Transient overexpression and VIGS-induced silence of FaMADS1 showed that FaMADS1 regulated fruit ripening by modulating anthocyanin biosynthesis related genes(PAL,C4H,4CL,DFR,and UFGT),softening related genes(PL and XTH),and aroma related genes(QR and AAT).In addition,FaMADS2 affected fruit firmness through regulating softening related genes(?-Gal and Xyl1).4.The transcript levels of FaMADS1 and FaMADS2 were in response to ABA and IAA.Promoter analysis of FaMADS1 and FaMADS2 showed that they have ABA-related cis-elements.Five transcription factors(ABI5-5,TRAB1,ABI5,ABI5-2 and ABI5-3)involved in ABA signal pathway were screened by yeast one-hybrid system.The results indicated that ABA mediated FaMADS1 transcription level through ABI5-5,TRAB1 and ABI5,and mediated FaMADS1 transcription level via TRAB1 and ABI5 to regulate the strawberry fruit ripening.