Exogenous chitosan enhances the resistance of apple to Glomerella leaf spot
Yutong Liu, Ruixuan Xu, Yuchen Tian, Hongtao Wang, Fengwang Ma, Changhai Liu, Wei Liang and Cuiying Li
Scientia Horticulturae
https://doi.org/10.1016/j.scienta.2022.111611
Abstract
Glomerella leaf spot (GLS), caused by the fungal phytopathogen Glomerella cingulata, is one of the most devas-tating premature defoliation diseases affecting apple production. Chitosan (CHT) is a degraded product of chitin and is used for bacteriostasis and postharvest preservation. Herein, we investigated the effects of CHT on improving the apple resistance to GLS. We identified that spraying with 0.5 g center dot L-1 exogenous CHT was the optimal concentration to reduce the G. cingulata disease severity on detached leaves of apple seedlings. Further study demonstrated that the exogenous CHT application significantly enhanced the superoxide dismutase (SOD) activity, elevated alicylic acid (SA) and jasmonic acid (JA) contents, increased certain kinds of phenolic com-pound contents and up-regulated the expression of different disease resistance-related genes in inoculated leaves than plants without CHT pretreatment. Furthermore, the exogenous CHT application significantly reduced the contents of abscisic acid (ABA), 1-aminocyclopropanecarboxylic acid (ACC), and auxin (IAA) of G. cingulata infection. Additionally, the CHT spraying treatment reduced the amino acid contents compared with the control plants. The results indicated that exogenous spraying of CHT improved the resistance of apples to GLS through enhancing plant immunity.