Metabolomic analyses provides insight into the fruit nutritional and sensory attributes among 'Guanxi' pummelo and its bud mutants

Abstract

The biochemical compositions in pummelo (Citrus maxima) fruits are key determining factors for the formation of nutrients and flavor. In this study, sensory (soluble solids, acidity and volatiles) and nutritional (vitamin C, carotenoids, phenols, flavonoids and antioxidant activity) profiles of fruit samples from 'Guanxi' pummelo and its four bud mutants were investigated. 'Guanxi' and 'Hongzuan', two pale-fleshed pummelo cultivars, contained relatively lower levels of carotenoids, vitamin C, phenols and total antioxidant activity compared to the other pummelos with red or yellow flesh. A total of 92 and 167 volatile compounds were detected in the pulp and flavedo of pummelo fruits, respectively. The majority of the different pulp volatiles were ketones, terpenes, alcohols and aldehydes, and were highly accumulated in 'Guanxihuang' pummelo (yellow-fleshed). The contents of volatiles in flavedo (285.85−955.88) were much larger than those in pulp (6.05−26.85) samples. Limonene was the most abundant volatile in flavedo, ranging from 133.28 in 'Hongzuan' to 480.36 in 'Guanxi'. The candidate genes TPS1 and LOX2.1 were associated with the amounts of terpenes and aldehydes in pummelo fruits. 'Sanhong' and 'Guanxihuang' fruits were preferred by tasters for their strong aroma, rich sweet and moderately sour taste, and high nutritional constituents. These results may provide insight into understanding the flavor metabolism pathways in pummelo fruits and facilitate further genetic improvement of pummelo fruit quality.

Keywords

• citrus maxima
• fruit quality
• nutritional quality
• flavor
• aroma
• citrus breeding