Biochemical Changes in Eggplant Cultivars Due to Infection with Alternaria alternata (Fr.) Keissler) Causing Early Blight Disease

Abstract

The study aimed to evaluate the biochemical responses of brinjal (Solanum melongena L.) genotypes to Alternaria alternata infection. Five genotypes - resistant (Uttra), moderately resistant (Pant Rituraj), moderately susceptible (Pusa Upkar), susceptible (Pusa Shymala) and highly susceptible (BR-112) were assessed for total amino acids, total sugars, reducing and non-reducing sugars and phenolic content at 45 and 60 days after sowing. Total soluble sugars were estimated using the anthrone method, reducing sugars by Nelson’s method, amino acids by the ninhydrin reaction and phenols by the Folin–Ciocalteu method. The data revealed significant biochemical variation among genotypes: resistant genotypes exhibited lower sugar and amino acid levels but higher phenolic content, whereas susceptible genotypes showed elevated sugar and amino acid levels with lower phenolic content. Maximum phenolic content was recorded in Uttra (8.83 mg/g), and the minimum in BR-112 (4.72 mg/g) at 60 DAS. These findings suggest that enhanced phenolic metabolism, along with regulated sugar and amino acid levels, contributes to brinjal resistance, offering valuable markers for screening and breeding programs.