Abstract:

The effects of hot air treatment on fruit decay and the activities and gene expression of defense-related enzymes in
postharvest loquat fruit were investigated. Freshly harvested loquat fruits were treated with hot air at 43 ℃ for 3 h, challenged
by being inoculated with Colletotrichum acutatum, and then stored at 20 ℃ for 8 d. The results showed that the fruit treated
with hot air had significantly lower natural disease incidence and smaller lesion diameter than the control fruit did. The hot air
treatment remarkably enhanced the activities of phenylalanine ammonia-lyase (PAL), chitinase, β-1,3-glucanase and polyphenol
oxidase(PPO). This hot air treatment also induced the expression of defense-related genes encoding PAL, PPO, peroxidase (POD)
and heat shock protein (HSP) 70. Meanwhile, this treatment did not significantly affect fruit firmness, titratable acidity and total
soluble solids, but enhanced the accumulation of carotenoids. These results suggest that hot air treatment can enhance disease
resistance of loquat fruit by inducing the activity and gene expression of defense-related enzymes.

Key words: loquat fruit, hot air treatment, challenging inoculation, induced disease resistance