Comparative analysis of volatile compounds in different muskmelon cultivars in Xinjiang based on HS-SPME-GC-MS and transcriptomics

Abstract

Volatile flavor has prompted a great amount of influence in acceptance and view points in fruit products. Melon (Pyrus communis) is an aroma-dense fruit, thus, the evaluation of volatile flavor is crucial to melon-breeding. The volatile compounds present in nine varieties of Xinjiang muskmelons were identified and analyzed using the headspace solid-phase microextraction and gas chromatography-mass spectrometry methods. In addition, transcriptomics were used to discover the differential genes in fatty acid degradation pathways. It was found that a total of 170 volatile substances, including 52 alcohols, 41 esters, 24 aldehydes, 32 ketones, 14 acids and seven phenols, were identified in the nine melons. Results of PCA showed that 3-nonanol, 2-nonanol, bis (2-ethylhexyl) adipate, and 2-methylpropanal contributed more to the flavor of melon. It was verified that high activities of acyl-coenzyme A cholesterol acyltransferase (AAT) promoted the conversion of alcohols to esters, so that the melons have a high content of esters. Four genes of long-chain acyl-CoA synthetase were mainly responsible for the large difference in volatile substances. This practice may further undermine the primary rationale for the breeding and promotion in different cultivars of muskmelon.

Keywords

• muskmelon
• volatile compounds
• gas chromatography-mass spectrometry
• enzyme activities
• transcriptomics