| Peach(Prunus persica L.)is one of the important cash crops in the world,with rich nutrition and pleasant flavor.Therefore,fruit aroma breeding has become an important research field that breeders pay attention to.This experiment used peach parents and hybrid progenies as experimental materials,the volatile components and content of peach fruit of ‘21shiji’,‘Jiucui’ peach and their hybrid progenies were analyzed by SPME-GC-MS,and the expression levels of genes related to ester synthesis Pp AAT1,Pp LOX1,Pp LOX4,Pp ADH1,Pp HPL1 and ester hydrolysis Pp CXE1,and the correlation between gene expression and ester content was analyzed.To reveal the variation characteristics of peach fruit aroma components and clear the main components and changes of peach fruit aroma components between parents and hybrid progenies,the fruit aroma components and content as well as the expression of key genes between peach parents and hybrid progenies were studied.These results would provide data support for further exploring the genetic and regulatory mechanism of fruit aroma and breeding of peach parents and hybrid progeny.The results show that:1.There were significant differences in volatile components and contents between the parents and hybrid progenies,125 volatile compounds were detected,and the volatile species of the hybrid progenies were all lower than that of the parent‘Jiucui’ except ‘Shijizhixing’,but 55.56% of the hybrid progenies had higher volatile components than that of the two parents.Esters were the most abundant volatile components,accounting for 50.98% of the total volatile content.Except hy-7(38.71%),the proportion of esters in other hybrids was higher than that in the parent’Jiucui’.The correlation analysis results showed that the content of ester aromatic substances was significantly positively correlated with the expression levels of Pp LOX1 genes,but not with Pp AAT1,Pp LOX4,Pp ADH1,Pp HPL1,Pp CXE1.2.Trans-3-hexene acetate,hexyl acetate,ethyl caprylate,linalool,and dihydrogen-β-ionone were the main components of peach fruit aroma(OAVs > 1).According to the OAVs summing distribution,‘21shiji’ and most of the hybrid progenies were mainly fruity type,only ‘Jiucui’and hy-7 were floral type.The hybrid progeny ‘Shijizhixing’ owned very strong aroma with both fruity and floral types characteristics,and its OAVs values were significantly higher than both parents and other hybrids.Nine substances with low threshold and high content were selected for diversity analysis.The results showed that hexyl acetate,ethyl caprylate and γ-decalactone had abundant genetic diversity.3.Principal component analysis was carried out on aromatic compounds of parents and hybrid progeny.The analysis results showed that there were only 3components with eigenvalues greater than 1.The cumulative contribution rate of these three components reaches 77.264%,which can represent most information of the original index.Comprehensive evaluation of different peach fruit was carried out by using the principal components of each aromatic substance.The results showed that ‘Shijizhixing’ranked the first.The aroma quality of ‘21shiji’,‘Jiucui’ and55.56% of hybrid progeny were lower than average.4.The results of 1-MCP and ethylene treatment showed that,compared with the control group,1-MCP treatment inhibited the synthesis of esters and lactones,and weakened the fruit aroma.However,exogenous ethylene promoted the early release of esters and the highest content of esters was not significantly different from that in the control group,but significantly reduced the content of lactones in fruits. |
