Chorisia speciosa Extract Induces Systemic Resistance against Tomato Root Rot Disease Caused by Rhizoctonia solani

Chemical pesticides and fungicides are used extensively, negatively affecting people’s health and the environment. Reducing synthetic pesticides and increasing the efficiency of sustainable food production using plant extracts as natural chemicals is a win–win. Here, we first describe and evaluate an ethanolic extract of Chorisia speciosa for its protective and curative activities against Rhizoctonia solani in greenhouse-grown tomato plants. The results showed that the mycelial growth of R. solani was completely suppressed in vitro by C. speciosa extract (10 µg/mL). Twenty days after fungal inoculation, the results demonstrated that using C. speciosa extract (10 µg/mL) in vivo significantly improved shoot and root growth parameters in protective and curative treatments. Further, the protective and curative treatments decreased the disease index by 26.67% and 53.33%, respectively. C. speciosa-treated tomato plants showed significantly increased antioxidant enzyme production (PPO, CAT, and SOD) and up-regulated PR-1, PR-2,PR-3, PAL, and CHS expression levels compared to untreated plants. According to HPLC examination, the most prevalent phenolic acids or flavonoid components quantities (µg/mL) noticed in C. speciosa extract were 7-OH-flavone (10.36), kaempferol (9.23), p-coumaric acid (8.65), ferulic acid (8.14), caffeic acid (7.59), gallic acid (6.33), and iso-ferulic (5.71). Our findings are the first to demonstrate that a C. speciosa extract can assist plants in combating fungal infestation. Therefore, the data imply that C. speciosa extract, as a natural and renewable product, could be adopted as a long-term approach for regulating plant fungus.