Evaluation of virulence potential of Aspergillus tubingensis and subsequent biochemical and enzymatic defense response of cotton.

Aspergillus tubingensis is a causative known pathogen of various important crops, worldwide. The existing study was aimed to examine the virulence potential of A. tubingensis on resistant (NIA-Sadori) and susceptible (CIM-573) cultivars of cotton. For this purpose, both cultivars were inoculated with pathogen and altered morphology of diseased leaves was observed with light and scanning electron microscope. Disease severity was measured and estimated to be 68.7 and 27.1% in susceptible and resistant cultivars, respectively. To understand and compare defense mechanism of resistant and susceptible cultivars, different biochemical and enzymatic changes were observed. After the infection of A. tubingensis, increase in the concentrations of sugar, total protein, proline, phenol, and phenylalanine ammonia lyase (PAL) was more prominent in resistant cultivar, than the susceptible one. Moreover, due to increased number of dead cells, significantly higher electrolyte leakage was detected in susceptible cultivar. Principal component analysis confirmed the effect of A. tubingensis on growth attributes and various physiological and biochemical activities of cotton. These findings help us to suggest a possible role of proline content, protein content, and PAL activity in resistance mechanism of Cotton plant.