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Plant Science Today (PST)

Research Articles

Vol. 13 No. sp2 (2026): Recent Advances in Agriculture

Copper-chitosan nanocomposites enhance biochemical defence responses and suppress anthracnose in chilli (Capsicum annuum L.)

DOI
https://doi.org/10.14719/pst.14656
Submitted
23 March 2026
Published
19-05-2026

Abstract

Anthracnose caused by Colletotrichum truncatum (Schwein.) Andrus & W.D. Moore is a common fungal disease in chilli (Capsicum annuum L.) causing severe reduction in fruit quality and yield. There is a dire need for sustainable solutions to not only suppress the disease-causing agent but also strengthen the host defence responses. In this study, a nano-elicitor in the form of copper-chitosan nanocomposite (Cu-ChNC) was tested as a method to control anthracnose and activate the biochemical resistance in chilli plants grown under greenhouse conditions. Copper-chitosan nanocomposite significantly suppressed anthracnose with lesion formation and disease index to 11.88 % in the prophylactic treatment against copper (22.38 %), chitosan (17.93 %) and without any treatment (47 %). Reduction in anthracnose was observed to be associated with an increase in the activity of defence enzymes. Peroxidase exhibited maximum activity of 14.55 ΔOD min-1 g-1 FW, whereas polyphenol oxidase displayed its maximum activity of 54.22 ΔOD min-1 g-1 FW on the 15th day after inoculation. Maximum level of phenylalanine ammonia-lyase (105.84 µg trans-cinnamic acid min-1 g-1 FW), β-1,3-glucanase (7.67 µg glucose g-1 FW) and chitinase (40.91 µg N-acetyl glucosamine g-1 FW) was observed to be above pathogen controls. Moreover, Cu-ChNC treatment increased the accumulation of phenols (15.09 mg g-1 FW), tannins (7.52 mg g-1 DW), proteins (23.56 mg g-1 FW) and sugars (91.83 mg g-1 FW) suggesting an induction in phenylpropanoids and other pathways. Correlation analyses revealed highly significant positive correlation among the defence characteristics (r = 0.85–0.99) and a high negative correlation between defence enzymes, biochemicals and disease index (r = -0.88 to -0.99). Principal component analysis further supported the association between enzyme activity and phenolic compounds with anthracnose control. Overall, Cu-ChNCs demonstrate strong potential as nano-elicitor by enhancing defence enzymes, boosting phenolic accumulation and activating coordinated plant immune responses, offering an eco-friendly strategy for sustainable anthracnose management in chilli.

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