Foliar application of chitosan enhances growth and modulates expression of defense genes in chilli pepper (Capsicum annuum L.)

Abstract

Phytophthora capsici is one of the primary pathogens causing a global problem of severe losses in chilli production. The use of conventional fertilisers and fungicides to improve chilli production had been shown to elevate environmental and health issues. Hence, the foliar application of chitosan, natural deacylated chitin, to enhance growth and resistance in chilli pepper plants was investigated. The chilli plants were grown for 14 days before receiving chitosan application and 33 days before Phytophthora infection, physiological parameters were recorded during the growth period, and expression of resistance related genes was quantified at 72 hours after infection. Our results showed that physiological parameters, such as increment of height and leaves number, and chlorophyll content indicated an improved growth process in chitosan treated plants compared to the control. Plant resistance to Phytophthora infection was also investigated following chitosan application to highly (CM334), moderately (LABA), weakly (LADO) resistant and susceptible (15080) cultivars. The disease incidence and severity indices were reduced in chitosantreated plants, except in highly and moderately resistant cultivars. Further, expression was also quantified for defence-related genes, including 9-lipoxygenase (CaLOX), Ca2+-bound calmodulin 1 (CaCaM1), receptor-like cytoplasmic protein kinase (CaPIK), Pto-interacting1 (CaPTI1) and resistance gene analogue 2 (CaRGA2). The results suggest that CaLOX, CaPTI1 and CaRGA2 genes were involved in defence mechanism to Phytophthora, with increased expression during infection. However, expression levels were reduced when Phytophthora infection was coupled with foliar chitosan application, indicating that chitosan may play a direct role in decreasing the pathogenicity of Phytophthora. In conclusion, this study suggests the promising role of chitosan as an alternative to conventional fertiliser and fungicide in chilli pepper plant.

Effects of Chitosan and Salicylic Acid on Physiological Characteristics of Eggplant (Solanum melongena)

“…The same pattern was also found in chilli planted in Indonesia, as reported by Aziz et al (2020). Besides, Esyanti et al (2019) found that chitosan significantly increased the vegetative growth of chilli pepper in Indonesia. Moreover, spraying chitosan on summer squash has significantly increased plant growth characteristics, yield and its components (Ibraheim and Mohsen, 2015).…”

Chitin- and Chitosan-Based Derivatives in Plant Protection against Biotic and Abiotic Stresses and in Recovery of Contaminated Soil and Water

“…Whatever the mode of action, chitin, chitosan and their derivatives (e.g., nanoparticles (≤0.5 µm in size), microparticles (≥1 µm in size) and oligosaccharides, degradation products formed by no more than 12 glucosamine residues) permit a relevant increase in plant productivity by controlling several plant pathogens (Table 1). Foliar application of chitosan enhances growth and modulates expression of defense genes in chilli pepper (Capsicum annuum L.) thus reducing the severe losses in chilli production induced by Phytophthora capsici infection [9]. Shoot cultures of Melissa officinalis treated with chitosan accumulate several defense-related enzymes and phenolic compounds with antimicrobial activity [10].…”

Chitosan suppresses the expression level of WRKY17 on red chili (Capsicum annuum) plant under drought stress

“…Chitosan solution was prepared as described in Esyanti et al (2019) by diluting chitosan powder into a glacial acetic acid solution (0,07%) to a concentration of 1 mg/mL and sprayed weekly by foliar feeding technique to Chi and ChiD treatments. It suggested that the 1 mg/mL chitosan solution was able to maintain the cultivar's growth rate (Esyanti et al 2019). Drought treatment was applied to reach 50% of field water capacity by using 500 mL of wa ter in 2 d subjected to D and ChiD treatments.…”