ABSTRACT

Root rot disease of cassava is one of the major diseases in Thailand, widespread incidence of soil-borne pathogens has been found to affect more than 80%. The research aims to investigate the effect of elicitors as salicylic acid and Bacillus subtilis strain JN2-007 for inducing resistance against root rot disease by Fusarium solani in cassava. The experiment was carried out in a susceptible cassava cultivar to test the efficacy of elicitors in the biochemical response of plant defense mechanisms pertaining to hydrogen peroxide (H₂O₂) and enzyme activities. The results indicated that pathogenicity test of F. solani isolate SHRD1 caused the brown lesions around the inoculation point on cassava roots. Subsequently, salicylic acid and JN2-007 reduced mycelial growth of F. solani (11.83%–57.73% at day 7), as well as disease severity in the cassava plants at 14 days after the inoculation compared to that of the negative control (28.12%–39.58% compared to 68.75%). Furthermore, salicylic acid at a concentration of 500 µl. L⁻¹ could induce H₂O₂, level of peroxidase, polyphenol oxidase, and catalase activities that were highest at 24 h after pathogen inoculation. The results suggested that elicitors played an important role as a plant defense inducer, leading to reduced Fusarium root rot disease.

摘要

木薯根腐病是泰国的主要病害之一，已发现土传病原体的广泛发生率影响了80％以上。本研究旨在探讨诱导剂如水杨酸和枯草芽孢杆菌菌株JN2-007诱导木薯镰刀菌根腐病抗性的作用。该实验在易感木薯品种中进行，以测试诱导剂在与过氧化氢 (H ₂ O ₂ ) 和酶活性有关的植物防御机制的生化反应中的功效。结果表明，F. solani的致病性检测分离株 SHRD1 引起木薯根部接种点周围出现褐色病斑。随后，与阴性对照相比，水杨酸和 JN2-007 在接种后 14 天降低了茄属植物的菌丝生长（第 7 天为 11.83%–57.73%）以及木薯植物的疾病严重程度（28.12 %–39.58% 相比 68.75%）。此外，水杨酸浓度为 500 µl。L ^-1可诱导H ₂ O ₂、过氧化物酶、多酚氧化酶和过氧化氢酶的活性在病原体接种后24小时最高。结果表明，诱导子作为植物防御诱导剂发挥了重要作用，从而减少了镰刀菌根腐病。