Comparison between 'Fuyan' and 'Dongbi' longans in aril breakdown and respiration metabolism.

• Dongbi longan had a lower aril breakdown index and respiration rate than Fuyan longan. • Dongbi longan had lower aril PGI, SDH, CCO, AAO, PPO activities and NAD(H) content. • Dongbi longan had higher aril NADK and G-6-PDH+6-PGDH activities and NADP(H) content. • Lower aril breakdown of Dongbi via reducing EMP, TCA, CCP and raising PPP respiratory. • Higher aril breakdown of Fuyan by raising EMP, TCA, CCP, and reducing PPP respiratory. This study aimed to investigate the difference between 'Fuyan' longan (Dimocarpus longan Lour. cv. Fuyan) fruit and 'Dongbi' longan (Dimocarpus longan Lour. cv. Dongbi) fruit in term of their aril breakdown and respiratory metabolism. As compared to 'Fuyan' longans, the 'Dongbi' longans exhibited lower fruit respiration rate, lower aril breakdown index, higher NADK activity, higher total activities of G-6-PDH and 6-PGDH, higher contents of NADP and NADPH, lower activities of AAO, CCO, PPO, PGI, and SDH, and lower contents of NAD and NADH in aril. These findings suggest that better storability and lower aril breakdown index in 'Dongbi' longans than 'Fuyan' longans might be due to lower activities of respiratory terminal oxidases, and lower respiratory metabolic pathways of EMP-TCA cycle related-enzymes in 'Dongbi' longan aril, which decreased respiratory rate and reduced the consumption of substrates, and subsequently maintained the integrity of the aril of 'Dongbi' longans during storage. [ABSTRACT FROM AUTHOR]