Resistance induction with silicon in Hass avocado plants inoculated with Phytophthora cinnamomi Rands

Abstract

Root rot caused by Phytophthora cinnamomi Rands, is one of the main factors that limits avocado production worldwide; silicon as a defense inducer seems to be a viable strategy to integrate into the management of this disease. Hereby, the present study evaluated the induction of resistance with silicon in Hass avocado plants inoculated with P. cinnamomi , as a possible alternative to conventional agrochemical management. A potassium silicate solution (10 mL, 0.2 M expressed as SiO 2 ) was applied by irrigation, for ten days before inoculation with P. cinnamomi in Hass avocado plants. Leaf samples were taken at 3, 24, 144, and 312 h after inoculation with the pathogen. Peroxidase (POD) and polyphenol oxidase (PPO) enzymes had their highest activity 3 h after pathogen inoculation (p < .05). There was a decrease in the activity of the enzyme phenylalanine ammonialyase (PAL), in the content of total phenols, and the inhibition capacity of the DPPH ● radical, between 3 h and 24 h in the plants with the inducer and inoculated with P. cinnamomi (p < .05). The results suggest a beneficial effect of silicon as a defense inducer in Hass avocado plants, manifested in the activation of enzymatic pathways related to the regulation of oxidative stress and the synthesis of structural components. Therefore, the application of silicon as a defense inducer emerges as a strategy to include in the integrated management of the disease caused by P. cinnamomi in Hass avocado.

Silicon induces ROS scavengers, hormone signalling, antifungal metabolites, and silicon deposition against brown stripe disease in sugarcane

“…In our investigation, we observed that under Si treatment, the activities of key enzymes involved in secondary metabolite synthesis, namely PPO, POD, and PAL activity, were elevated compared to CK. In particular, under B. setariae stress, this augmentation was more pronounced, indicating a positive role of PPO, POD, and PAL activities in the Si‐mediated defence mechanism against sugarcane brown stripe disease, which is consistent with Álvarez et al (2023), who reported that Si enhanced the resistance of Hass avocado to Phytophthora cinnamomi with an increase in PPO, POD, and PAL activities. The pivotal roles of PPO, POD, and PAL enzymes in the synthesis of secondary metabolites in plants are well established (Ruiz & Romero, 2001).…”