Effect of drought stress on proline accumulation in peanut genotypes

The changes in the concentration of total protein, total free amino acids and free proline in the leaves of drought susceptible and drought tolerant varieties of peanut was studied under various durations of drought stress. In addition, the relative water content in the leaves was also analyzed. Under drought stress, the concentration of total protein was found to decrease in both drought susceptible and drought tolerant varieties and the degree of decrease was found to be higher in drought susceptible variety compared to drought tolerant variety. Whereas, the content of free amino acids was found to be higher in both the varieties and the increase in drought tolerant variety was found to be more significant than drought susceptible variety. The concentration of proline (a major osmolyte) was found to be significantly higher in the drought tolerant variety compared to drought susceptible variety. Further, the increase in the proline content under increasing drought stress (21 days) was found to be more than 2 folds in the tolerant variety when compared with susceptible variety. The relative water content was found to be inversely proportional to the proline accumulation. The results are discussed in the light of proline, acting as an osmolyte, facilitating the development of drought tolerance.