Abstract: The effect of ε-poly-L-lysine (ε-PL) treatment on the occurrence of postharvest fruit rot caused by Neopestalotiopsis clavispora and disease resistance-related substance metabolism in guava were explored. Freshly harvested guavas (cv. Xiguahong) were soaked in sterile distilled water as a control or 2.0 g/L ε-PL solution for 10 min, inoculated with N. clavispora, and then stored at (28 ± 1) ℃ and a relative humidity of 90% for up to seven days. During the whole storage period, lesion diameter, cell membrane permeability, lignin content and disease resistance-related enzyme activities in guava fruit were measured every day. The results showed that compared with the control group, ε-PL could reduce the lesion diameter and cell membrane permeability, and maintain higher lignin content and higher activities of disease resistance-related enzymes including β-1,3-glucanase, cinnamate-4-hydroxylase, 4-coumarate CoA ligase, peroxidase, phenylalanine ammonia-lyase, chitinase and cinnamyl alcohol dehydrogenase. Therefore, we conclude that ε-PL enhanced the lignin level and the activities of disease resistance-related enzymes and consequently maintained cell membrane stability, which in turn enhanced the postharvest disease resistance of guavas and delayed the occurrence of guava fruit rot caused by N. clavispora.

Key words: guava fruit; ε-poly-L-lysine; Neopestalotiopsis clavispora; ring spot; disease resistance