Differential gene expression analysis of early-ripening mutants of grape (Vitis vinifera L.)

• Total 2991 and 5049 genes were expressed in the mutants (YH-20-1 and YH-20-2) respectively.
• Early-ripening and aroma formation related genes were up-regulated in the mutant YH-20-1.
• Resistance related genes and neutral amino acid related genes were up-regulated in both mutants.
• The time-intensity method showed strong fragrance in YH-20-1 as compared to YH-20-2 and Yinhong.

In the present study, digital gene expression (DGE) profiles of grape (Vitis vinifera L., cv. Yinhong) and its mutants (YH-20-1 and YH-20-2) were constructed to identify the functional genes associated to early-ripening, aroma and peel color. The DGE libraries were established from the leaves of Yinhong and its mutants, and then sequenced by the Illumina/Hisseq technique. The functional analyses of both GO enrichment and KEGG pathway enrichment were performed with transcriptome data as reference. The DGE analysis showed that the 2991 and 5049 different genes were expressed in the mutants (YH-20-1 and YH-20-2) as compared to their parent Yinhong, respectively. Combined with GO annotations and KEGG pathway enrichment analysis, the expression of two early-ripening related genes and six aroma formation related genes was significantly up-regulated in YH-20-1; while, in YH-20-2, only one early-ripening related gene was significantly up-regulated. Moreover, results showed that resistance and neutral amino acid related genes were also up-regulated in both mutants. Further, this study demonstrated that mutant YH-20-1 showed 3-lobed deeper leaf blade, and purple black fruit skin; while, mutant YH-20-2 showed pink fruit skin and denser leaf pubescence. The time-intensity method showed strong fragrance in YH-20-1 as compared to YH-20-2 and Yinhong. The expression levels of randomly selected genes were confirmed by quantitative real-time PCR. Findings of the present study revealed that both mutants were promising with stronger resistance, early-ripening by showing purple black fruit skin and pink fruit skin than their parent Yinhong, respectively.