Enhanced chemical and physical defense traits in a rice cultivar showing resistance to leaffolder infestation

Abstract The leaffolder (LF), Cnaphalocrocis medinalis , poses a significant threat to rice crops. The larvae feed on rice leaves, damaging both the epidermal and mesophyll tissues, and engage in leaf-folding behaviors to build shelters that can lead to significant yield losses. In this study, we discovered a rice cultivar, P213, that exhibits resistance to LF infestation. When compared to the susceptible cultivar XiuShui11 (XS11), the larvae on P213 exhibited reduced weight and took longer to build their silk-leaf shelters. Through a side-by-side analysis of phytohormones, metabolites and transcriptomes in the two cultivars, we found that jasmonate (JA)-induced defenses are not the main contributors to P213 resistance against LF. Rather, salicylic acid and flavonoids emerge as potential chemical defenses against this insect pest. Furthermore, the resistant cultivar P213 exhibited a greater density of micro hairs and long macro hairs, the latter of which were absent in the susceptible cultivar. The silicon contents in leaf tissues were also more prominent in the resistant cultivar, suggesting that the physical defenses against LF are enhanced in P213. These findings shed new light on the mechanisms of rice resistance to LF and provide a foundation for future research into the genetic basis of this resistance.