Efficacy of silicate elicitors and their docking studies on managing bacterial leaf blight in glutinous rice plants

Abstract

Importance of the work: Bacterial leaf blight (BLB) is a serious disease in glutinous rice plants. Silicate elicitors could help to manage and reduce problems caused by BLB.
Objectives: To evaluate the effect of Si in different forms (CaSiO₃, K₂SiO₃ and Na₂SiO₃) and to understand resistance mechanisms against BLB.
Materials & Methods: The expression of phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO) was assessed. In silico research on interactions between Si and PAL/PPO was conducted and the endogenous salicylic acid accumulation and Xanthomonas oryzae pv. oryzae (Xoo) density inside glutinous rice plants were assessed. The efficacy of silicate elicitors against BLB was evaluated in field conditions.
Results: The Si elicitors helped glutinous rice plants resist BLB in field conditions. They improved disease resistance mechanisms, including salicylic acid accumulation, and activated defense enzymes, such as PAL and PPO. The amino acids LYS45, LEU56, ARG66 could be active sites of PAL, while the amino acids ASP86, PRO89, ARG103 could be active sites of PPO in forming a strong hydrogen bond with Si. Such interactions lead to the formation of active components of PAL or PPO, contributing to disease resistance. Furthermore, applying Si increased the density of Xoo, maintained the amylose percentage and increased the yield.
Main finding: Among the Si elicitors, K₂SiO₃ and CaSiO₃ showed higher efficacy than Na₂SiO₃ in glutinous rice plants. Based on the known studied literature, this was the first report showing the beneficial efficacy of silicate elicitors in glutinous rice plants.