Evaluation of Differences Among Vigna aconitifolia Varieties for Acquired Thermotolerance

Abstract

The induction of thermotolerance using the efficacy of heat acclimation was analyzed in nine varieties of moth bean (Vigna aconitifolia Jacq.), including those derived through mutation breeding. Seedlings maintained at 27 _C were exposed to lethal temperature with or without heat-acclimation treatment. All the nine varieties sustained an abrupt rise in temperature up to 42 _C; however, 47 _C proved detrimental to all the varieties used, with CZM-99, RMB-75, and RMO-40 showing resistance. Heat acclimation followed by lethal temperature induced acquired thermo-tolerance in all the varieties except RMO-225 and RMO-435. An increase in the protein level was observed up to 37 _C, while no alteration recorded in protein content at heat-acclimation and lethal temperature. The maximum and significant increase in the level of proline content was observed in CZM-99, RMB-75, and RMO-40. Acquired thermotolerance was also found to be associated with the induction of peroxidase (POX), ascorbic peroxidase (APOX), and catalase (CAT) activities. Maximum activities of enzymes were recorded for POX at heat-acclimation temperature (42 _C), and for CAT and APOX at sub-optimal temperature (37 _C). Among all the studied enzymes, only CAT showed greater activity at lethal temperature in all the accessions except var. Jwala.