| SEPALLATA genes are members of a subfamily of MADS-box transcription factors,are identified 3 SEP class by MADS genes in peach: Prp MADS2(AAZ16241),Prp MADS5(ABO27621),Prp MADS7(ABO27622),including Prp MADS2 and Prp MADS5 main regulation of flower organ and fruit development,and Prp MADS7 in flowers,pulp,and seeds with high expression level,according to the principle of peach gene named Prp MADS7 gene PpSEP1 of further research.It is not clear in seed development and fruit ripening of the regulation mechanism,this study choose ‘Jingchun’,‘Shahong’ and‘Zhaohui’ as research materials,In order to study the expression characteristics of PpSEP1 transcription factor embryo development and ethylene metabolism related genes in peach seed development and fruit ripening and softening.In order to elucidate the function clarify PpSEP1 transcription factors in the peach seed development and the regulating mechanism in the mature fruit softening.The research results are as follows:1.During the process of peach seed development,the relative expression of PpSEP1 gene in SH fruits was significantly higher than that of the JC fruit at various periods;In the embryo,the relative expression of PpSEP1 gene was higher than that of JC.When the fruit is in the hard nucleus(62d after flowering,the distance of the fruit reaches the maturity of the product is about 30d),the fruit is invaded and the 28 d harvest is infected.Silencing target gene PpSEP1,the determination of the infected fruit RNAi in physiological phenotype(fruit,seed,embryo of the transverse and longitudinal side and weight,ethylene and respiration rate,etc.)and transcription expression level(fruit and embryo of ethylene metabolism related genes,embryo development related genes)and other indicators.The PpSEP1 gene in RNAi treatment was significantly lower than that of control fruit,but Pp ACS2 and Pp EIN2 in embryo were significantly higher than control(TRV2)in certain periods,and only the transcription expression of RNAi,SSAHD,LEA,PRU transcription expression in TRV2-SEP1 infect fruit(RNAi)higher than the Control,higher than the control fruit in later periods.Finally,the correlation between PpSEP1 gene and other related genes was analyzed,and the transcription level of PpSEP1 gene in Shahong embryo was significantly positively correlated with Pp ACO1 and Pp PRP transcription levels(p< 0.01),but negatively correlated with Pp EIN2 and Pp PRU(P < 0.05).At the same time,the transcriptional level of PpSEP1 gene in JC embryo was significantly positively correlated with the transcriptional level of Pp PRP(P< 0.01),which was significantly correlated with the transcription level of Pp ACS2(P< 0.05).Therefore,we speculated that PpSEP1 gene may regulate the related genes of embryo development or the related pathway of ethylene metabolism pathway to control the fruit ripening and softening.2.In the fruit close to the mature stage(94d after flowering,the fruit reaches the maturity of the product is about 7d)infected with the ’ Zhao Hui ’ fruit,infected by 7d harvest.After silencing the target gene,the transcription expression of the PpSEP1 gene in the infected fruit was inhibited compared with the control fruit.In terms of physiological phenotype the fruit firmness was significantly higher than control,and the ethylene release and respiration rate were also significantly inhibited compared with control fruit,and the ripening and softening of the fruit was delayed.From the aspect of transcription expression,the RNAi fruit was significantly higher than that of control in ethylene biosynthesis(Pp ACS2,Pp ACO1)and signal transduction key genes(Pp EIN2 Pp ETR2,Pp EIL1,Pp EIL2,Pp ERF1 a,Pp ERF1 b and Pp CTR1)are lower than control fruit.Both the physiological phenotype and the related gene expression in the ’ SH ’ and ’ ZH ’ fruit maturation and softening period are the same results,are significantly inhibited.At the same time,ACC-related enzymes(ACS and ACO)were determined,the activity of ACC synthase(ACS)in RNAi was significantly lower than that control fruit during most of periods,and the activity of ACC oxidase(ACO)of RNAi fruit in 4 days,14 days and 16 days postharvested significantly lower than the control fruit,during the rest of the other difference is not obvious.In summary,the silencing PpSEP1 gene delayed fruits maturation and softening,and PpSEP1 transcription factor plays an important role in regulating the ripening and softening process of peach fruit. |
