In vitro screening and biochemical profiling of green chilli fruits challenged by Colletotrichum capsici

Colletotrichum capsici causes anthracnose and continues to be a severe hindrance to the production of chillies (Capsicum annuum L.), endangering both productivity and quality after harvest. In this study, thirty green chilli genotypes were systematically evaluated under controlled conditions using an in vitro detached fruit assay to decipher resistance responses against the pathogen. Disease severity was assessed across multiple time points, revealing notable genotypic variation. Genotypes such as Bhavigva-F1 and ARD-5533-F1 showed heightened susceptibility, characterised by rapid lesion expansion and elevated percent disease index (PDI), while entries like Akhanda-23-F1, SVHA 1049 and SVHA 2222 exhibited delayed symptom progression and comparatively lower PDIs. Multivariate analysis, including principal component analysis (PCA), further highlighted the distinct pathological profiling of tested genotypes. Complementary biochemical profiling at four days post-inoculation (DPI) identified significant differences in the accumulation of total phenols, soluble sugars, reducing sugars and proteins. Notably, moderately susceptible genotypes accumulated higher phenolic and protein content, which correlated negatively with disease severity. Similarly, total soluble solids (TSS) and total reducing sugars (TRS) also showed variation among the genotypes. Together, these insights not only affirm the existence of valuable genetic variability for anthracnose resistance in chilli but also emphasise the utility of integrating biochemical markers with phenotypic screening.