Differential Expression of VvLOXA Diversifies C6 Volatile Profiles in Some Vitis vinifera Table Grape Cultivars.

Xu Qian,Xiao-Qing Xu,Lei Sun,Hai-Ying Xu,Bao-Qing Zhu

doi:10.3390/ijms18122705

Xu Qian, Xiao-Qing Xu + Show 3 more

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https://doi.org/10.3390/ijms18122705

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Abstract

C6 volatiles are synthesized through lipoxygenase-hydroperoxide lyase (LOX-HPL) pathway and these volatiles play important roles in the aromatic quality of grape berries. This study investigated the evolution of both C6 volatiles and the key genes in the LOX-HPL pathway in different table grape cultivars during the berry development period, and further assessed the correlation between the accumulation of C6 volatiles and the expression of these genes in these cultivars. Results showed that hexanal, (E)-2-hexenal, (E)-2-hexen-1-ol and (Z)-3-hexen-1-ol were found to be the dominant C6 volatiles in these ripened grape cultivars under two consecutive vintages, and their flavor notes were incorporated in the overall aroma of these cultivars. The cultivar “Xiangfei” showed the most abundant level of C6 aldehydes and C6 acid, whereas the cultivar “Tamina” and “Moldova” possessed the highest C6 alcohol content. The “Muscat of Alexandria” cultivar was found to contain the highest level of C6 esters. C6 volatiles were grouped into three evolutionary patterns in these cultivars during berry development, and their evolution was consistent with the evolution of the LOX-HPL pathway genes’ expression. Pearson’s correlation analysis indicated that the LOX-HPL-pathway-related genes were correlated to the accumulation of C6 volatiles in these cultivars, and VvLOXA appeared to be an important gene that regulated the synthesis of all C6 volatiles.

Highlights

China has become one of the world’s leading grape-producing countries, with an annual grape yield of 12.6 million tons in 2014 [1]
C6 volatile compounds are accumulated in grape berries along with the berry development stages, and their level in ripened grape berries determines the overall aroma [18,24,26]
The concentration of these two aldehydes in these ripenedgrapes ranged between 1–5 mg/L and 2–10 mg/L, respectively, which was significantly higher than their odor threshold (4.5 μg/L and 17 μg/L, [32])

Summary

Introduction

China has become one of the world’s leading grape-producing countries, with an annual grape yield of 12.6 million tons in 2014 [1]. 15% of the total grape yield is used to produce wine, while grape raisins are made from 5% of the total grape output [2] Regarding table grapes, their berry size, appearance, texture, and sensory attributes play an essential role in determining the market value and acceptance of customers. C6 volatile compounds exist as one of the major volatile compounds in grape berries and other fruits [17,18,19,20] These volatiles have been reported to exhibit vegetable, fresh, green, fruity, almond, apple, or minty scents [21,22]

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Conclusion