POTATO ROOTS STABILIZE THE PH OF MEDIA AFFECTED BY RING-ROT CAUSAL AGENT

Different cultivars of potato (Solanum tuberosum L.) were grown in via ls together with the bacterium Clavibacter michiganensis subsp. sepedo nicum, which causes shoot wilt and tuber ring-rot. The development of disease symptoms (chlorosis and growth inhibition) is closely correlat ed with the strong acidification of the medium (to pH 2.6-3.0) caused by bacterial toxins. Root cells of the host (potato) and other plants (tomato, wheat and radish), in turn, were able to restore the pH of me dia acidified by toxin. This was apparently, pH stabilization in the a poplast. Such stabilization was correlated with resistance of a partic ular potato cultivar to bacteriosis. We conclude that the maintenance of pH-homeostasis is an important factor in nonspecific resistance to plant pathogens.