Biochemical Alterations in Indian Mustard (Brassica juncea L.) Genotypes in Response to Alternaria brassicae Infection: Implications for Disease Resistance

Abstract

The third most significant source of edible vegetable oil in the world is Indian mustard (Brassica juncea L. Czern. & Coss.). However, a number of abiotic as well as biotic constraints have a negative impact on its production. Among the biotic factors, Alternaria blight caused by the soil-borne necrotrophic fungal pathogen Alternaria brassicae (Berk.) Sacc.- was a severe disease that damaged all growing parts of the mustard plant worldwide, including the stems, leaves, and pods. The primary objective of this study was to assess the impact of Alternaria blight infection on the biochemical attributes of Indian mustard. The biochemical contents of healthy and Alternaria brassicae- infected mustard leaves from various cultivars were examined and compared in the experiment. The biochemical analysis revealed distinct alterations due to the fungal infection. Phenol and proline concentrations were significantly higher in the infected leaves compared to the healthy leaves across all analyzed cultivars. In contrast, the levels of total chlorophyll, total sugar, and reducing sugars were notably higher in the healthy leaves than in the infected ones. The study concluded that Alternaria blight infection caused a significant reduction in chlorophyll and sugar contents, while simultaneously triggering an increase in the production of stress-related bio-chemicals, specifically phenol and proline, in Indian mustard leaves.