Expression of stress responsive β-1,3-glucanase and chitinase genes in Arachis hypogaea seedlings against Macrophomina phaseolina

Abstract Macrophomina phaseolina is a disease known to be a destructive yield limiting factor of Arachis hypogaea L. In this study, nine genotypes of Arachis hypogaea were preliminary screened against the pathogen M. phaseolina for disease tolerance. Two genotypes, SAMNUT 21 and SAMNUT 23 were subsequently selected on the basis of their tolerance to the pathogen. Parameters like salicylic acid, polyphenols, peroxidase activity and total protein were determined to understand the overall growth of A. hypogaea under the attack of M. phaseolina. The genotype SAMNUT 21 showed an increase in the content of salicylic acid, polyphenol and peroxidase activity, thereby reducing oxidative damage of the cell membrane, while SAMNUT 23 showed significantly increased oxidative damage. Furthermore, two antifungal genes, viz., chitinase (Ah Chit) and β-1,3-glucanase (Ah Glu) were studied to understand the response to M. phaseolina attack on the selected genotypes. The expression levels of these two genes were evaluated at different time course after inoculation with the isolate of M. phaseolina. The study revealed that after inoculation, there was an inducement of Ah Glu and Ah Chit in SAMNUT 21 for 0 h and 20 h; and in SAMNUT 23 for 40 h and 20 h. Hence, Ah Glu and Ah Chit showed a significantly higher level of expression in genotype SAMNUT 21 compared to SAMNUT 23. Therefore, the results revealed that Ah Glu and Ah Chit have the potency to enhance tolerance under fungal attack.