CHARACTERISTICS OF PATHOGENESIS-RELATED PROTEINS INDUCED IN PHASEOLUS-VULGARIS CV PINTO FOLLOWING VIRAL-INFECTION

Ten acidic and eight basic pathogenesis-related (PR) proteins were ind uced in primary leaves of Phaseolus vulgaris is cv. Pinto following in fection with southern bean mosaic virus (SBMV), a virus that induces c ircular, brown necrotic local lesions. These PR proteins included: fou r, 17 kDa, serologically related, acidic proteins of unknown functions ; two chitinases, one acidic (29 kDa) and one basic (32 kDa) possessin g antifungal activities; and four (21 kDa, 28 kDa, 29 kDa, 36 kDa) ser ologically related, acidic glucanases. The production of PR proteins w as minimal during the period of active SBMV multiplication; greatest i ncrease of PR proteins occurred after SBMV had reached a maximum level . Several of these PR proteins, including the 29 kDa acidic chitinase and two acidic glucanases (21 kDa and 36 kDa) accumulated in the inter cellular space fluid. Similar PR proteins were synthesized in Pinto be an primary leaves infects with any of three other viruses that formed lesions of divergent phenotypes. However, the proportion of some of th e PR proteins in the various lesion-types differed considerably. These results indicate that PR proteins play no active role in viral locali zation or inactivation and that their production is a metabolic adjust ment to endogenous stress.