| Peach(Prunus persica L.)is a plant of the Rosaceae and the genus of peach,which is native to China with a long cultivation history and rich variety resources.Peach belongs to the fruit of climacteric.Its quality characters such as fruit softening,fruit acidity and soluble solids content are controlled by mature genes.In this study,a late-ripening mutant,which ripened nearly 19 days later than ‘jinghong’ was found.‘Jinghong’ and late-ripening mutant fruits were studied as test materials.The transcriptome sequencing analysis of fruits at different stages of development and the changes of physiological indexes were comprehensively analyzed,by comparing the transcriptome.And then,the genes related to hormone metabolism pathway were screened during peach ripening.The main research results are as follows:1.The growth rule of the vertical and horizontal diameter and weight per fruit between the mutant and the parents basically showed “double S” type increasing.The growth rate of ‘Jinghong’ fruit was significantly higher than that of mutant.It was found that the time of mutant in the slow growth stage of fruit was 15 days longer than that of parent,and the duration of mutant in the second growth peak was also longer than that of parents.The whole fruit development period of mutant was 19 days longer than that of ‘Jinghong’.The softening rateand the softening degree at maturity of mutant were lower than that of parents.The trend of soluble solid accumulation was similar.The decrease rate of chlorophyll and carotenoid contents in mutant was slower than that of parents,and the final contents was lower than that of parents.The content of anthocyanin and flavonoids in the two cultivars decreased first and then increased,and the content of anthocyanin and flavonoids in the fruit ripening stage was higher than that of the parents.2.There were also differences in the changes of four endogenous hormones between the two groups.The change trend of ABA content in ‘Jinghong’ and its mutant fruit was the same,but the rising speed of mutant was later,the peak time was13 days later than that of ‘Jinghong’,and the relative content was higher than that in its parents when the fruit was mature.It showed an upward trend in the developmentof ‘Jinghong’ and mutant in the ethylene content,but the time of mutant was 20 days later than that of ‘Jinghong’.The contents of IAA and GA3 in ‘Jinghong’ peach and its mutant showed a decreasing trend,and the decreasing rate in mutant was relatively slow.The contents of IAA and GA3 in ‘Jinghong’ were higher than that in mutant.3.Through transcriptome sequencing analysis of ‘Jinghong’ peach and late-ripening mutant in different maturity stages,152.85 GB clean data was obtained,each library reached 6.68 GB or more,and the percentage of Q30 base was more than93.03%,each library obtained 44.79~69.72 million clean reads.It was sequenced with the reference genome of peach,and the ratio was 96.26%~97.5%.The results showed that there were 45,296 transcripts,including 33,075 known transcripts and12,221 new transcripts.23,419 genes were detected,including 22,625 known genes and 794 new genes.4.Among the plant hormone signal metabolic pathways with significant enrichment of DEGs,genes involved in AUX,ABA,CK,JA and eth hormone pathways were found to play an important role in fruit development.According to the significantly enriched DEGs in the pathway,a total of 85 DEGs related to fruit ripening were excavated,including 68 plant hormone signal transduction genes,16 carotenoid synthesis genes,14 flavonoids synthesis genes,5 amphetamine metabolism genes and 28 transcription factors.The 24 selected DEGs were verified by qRT-PCR,and the expression levelof these genes was similar to those of transcriptome data.‘Jinghong’ and its late-ripening mutant fruit ripening related genes were screened and identified.It will provide theoretical support for further research on hormone signal transduction related gene function,gene co-expression network and molecular regulation mechanism of peach ripening stage. |
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