Aspartic protease in leaves of common bean (Phaseolus vulgaris L.) and cowpea (Vigna unguiculata L. Walp): enzymatic activity, gene expression and relation to drought susceptibility

Four cultivars of related species, common bean and cowpea, which exhibit di fferent degrees of drought resistance, were submitted to water stress by wi thholding irrigation, Drought induced an increase in endoproteolytic activi ty, being higher in susceptible cultivars (bean) than in tolerant ones (cow pea). An aspartic protease activity was found to be strongly induced especi ally in bean. From a cowpea leaf cDNA library, a full length aspartic prote ase precursor cDNA was obtained. Transcript accumulation in response to wat er stress indicated that the expression of the gene mas constitutive in cow pea and transcriptionally up-regulated in bean, The results showed that dro ught-tolerant and drought-susceptible bean plants differ regarding aspartic protease precursor gene expression. (C) 2001 Federation of European Bioche mical Societies. Published by Elsevier Science B.V. All rights reserved.