| Melting peach is a typical climacteric fruit.It has a distinct peak of ethylene release in the late growth stage,accompanied by softening and senescence of fruit flesh,which is not conducive to storage and transportation and has a short shelf life.Studying the ripening and softening mechanism of peach fruit is important for peach breeding.This study consists of three parts: the solute type nectarine ‘CN13’ is used as the material,1-MCP separately treated the peach fruit before and after the climacteric,and performed transcriptome sequencing to screen the differentially expressed genes;PpGLV gene family bioinformatics analysis,with solute type nectarine ‘Zhong Ningtao 13’ and hard type nectarine ‘CN16’ as materials,preliminary identification of the effect of gene PpGLV4 on auxin and ethylene by real-time PCR;The functions of PpGLV4 were verified by transgenic tomato and transiently transformed peach fruit experiments.The main results were as follow:1.Transcriptomic analysis of CN13 treated by 1-MCPBases on the nectarine ‘CN13’(melting type)cultivars,the fruit before and after transition period were treated by 1-MCP,the changes of ethylene and firmness between the treatment and the control were observed.The result shown that 1-MCP inhibited the release of ethylene and the fruit firmness in preclimacteric and delayed the ripening of the fruit.After 1-MCP treatment,the peach fruit hardness decreased slowly but stimulated the release of ethylene in climacteric.Total RNA was extracted from peach fruit after 1-MCP treatment,and library construction and transcriptome sequencing were performed.It was found that there were differential expression of genes in pre-climacteric and climacteric after 1-MCP treatment.Clustering heat map analysis and enrichment analysis showed that differentially expressed genes were involved in the hormone signaling pathway,and annotated analysis of unknown functional genes revealed that the differentially expressed genes contained 11 polypeptide genes.2.Bioinformatics analysis of PpGLV family Genes in peachReferring to the peach genome sequence,eight PpGLV peptide genes were screened in peach.The bioinformatics analysis of the gene family showed that PpGLV family genes were similar to the Arabidopsis AtGLV peptide family genes with some homology.This indicated that the gene family may be involved in hormone synthesis and signaling processes.Expression analysis of PpGLV family genes in different plant tissues and at different developmental stages in fruit.It was found that the expression of PpGLV family genes were different in different tissues.The expression pattern of PpGLV4 and PpGLV8 in peach fruit at different developmental stages showed that it was expressed at both stages S1 and S4,increased dramatically at stage S4 I,and peaked at stage S4 III.we treated peach callus with different concentrations of a synthetic sulfated PpGLV4 peptide and investigated the expression levels of genes involved in auxin and ethylene biosynthesis and signal transduction pathways by qRT-PCR.The results showed that PpYUC11,PpIAA1,PpGH3-3,PpGH3-4,PpACS1,PpETR1,PpERF1,PpERF4 and PpERF5 were treated in response to PpGLV4 peptide,indicating that PpGLV4 is involved in crosstalk between auxin and ethylene signaling.3.Function verification of PpGLV4Functional verification of transgenic tomato showed that PpGLV4 gene made tomato fruits mature about 4d earlier,the ethylene release peak was advanced,the release amount was higher,and the fruit firmness decreased.the expression levels of genes involved in mature and ethylene synthesis-related were detected by qPCR,the results showed that PpGLV4 can regulate the expression of ethylene and maturation-related genes in tomato fruit,which indicated that the gene participates in the fruit ripening process in tomato fruit.It was further demonstrated by the peach transient transformation experiment that the PpGLV4 gene also has a regulatory effect on ethylene in peach fruit. |
