Biochemical Markers of Resistance to Early and Late Leaf Spot in Groundnut: Role of Phenols and Amino Acids

Abstract

Groundnut (Arachis hypogaea L.) is an important oilseed and food crop that is severely affected by early leaf spot caused by Cercospora arachidicola and late leaf spot caused by Phaeoisariopsis personata. These diseases are widely distributed and result in substantial yield losses under favourable conditions. The present investigation was undertaken to evaluate the biochemical markers associated with resistance to leaf spot diseases in groundnut genotypes. The study was conducted during 2020 at the Department of Plant Pathology, Chimanbhai Patel College of Agriculture, Sardarkrushinagar Dantiwada Agricultural University, Sardarkrushinagar. Biochemical parameters, namely total phenols and free amino acids, were estimated at two growth stages (healthy and infected) in selected groundnut genotypes. The results revealed that the concentration of both phenols and amino acids increased significantly following infection, with resistant genotypes showing a comparatively higher rate of accumulation than susceptible ones. The maximum phenol content was recorded in genotype GJG-32 (5.04 mg g⁻¹ fresh weight), while the minimum was observed in TG-37A (3.00 mg g⁻¹). Similarly, the highest amino acid content was recorded in GJG-32 (9.86 mg g⁻¹), whereas the lowest was observed in TG-37A (6.60 mg g⁻¹). Amino acid content increased initially after infection but declined at later stages. The findings indicate that enhanced accumulation of phenols and amino acids is associated with resistance to early and late leaf spot diseases in groundnut and can serve as potential biochemical markers in resistance breeding programmes.