Proteomic analysis of rice cultivar, QingLiu, resistant to Cnaphalocrocis medinalis

Cnaphalocrocis medinalis (Guenée) is an economically important pest of rice, Oryza sativa L., throughout Asia, where damage caused by larvae, particularly during grain-filling stages, significantly increases yield losses. There is, therefore, a pressing need to develop cultivars that are resistant to C. medinalis. In this study, we assessed growth and mortality of first and third instar C. medinalis larvae fed on six rice cultivars that had previously been identified as resistant to the pest, and we quantified production of defense enzymes in plants exposed to herbivory. We found that mortality rates were highest in larvae fed on the resistant cultivars Baiqiaowan, Sasanishiki, Qingliu, and Kasalasu, while relative growth rates were lower for larvae fed on Baiqiaowan and Qingliu. Higher levels of phenylalanine ammonia lyase were expressed in the resistant cultivars. Furthermore, a differential proteomic analysis was performed between Qingliu and TN1 rice varieties to identify differentially expressed proteins after leaffolder infestation. Notably, phenylalanine ammonia lyase and chalcone synthase which catalyze flavonoid biosynthesis together with lipoxygenase that catalyzes jasmonic acid biosynthesis exhibited higher expression in Qingliu compared with TN1 even prior to insect herbivory. They might be responsible for priming the flavonoid biosynthesis and jasmonic acid signaling in Qingliu during leaffolder infestation. Subsequently, at 72 h of insect herbivory, amino acid biosynthesis and glutathione-mediated antioxidation were uniquely activated in Qingliu.