INDUCTION OF WATER-SOAKING IN PLANT-LEAVES BY EXTRACELLULAR POLYSACCHARIDES FROM PHYTOPATHOGENIC PSEUDOMONADS AND XANTHOMONADS

Extracellular polysaccharides (EPS) were obtained and partially purified from culture filtrates of Pseudomonas glycinea, P. lachrymans, P. phaseolicola, P. pisi, Xanthomonas malvacearum and X. translucens f. sp cerealis. These preparations induced persistent water-soaked spots after infiltration into leaves of those plant species which were hosts of the respective EPS-producing bacteria. Treatment of non-host plants did not result in persistent water-soaking. EPS from P. fluorescens did not induce persistent water-soaked spots in any of the plants tested. Only the susceptible cultivars of a host, but not the resistant ones, were affected by the EPS of the corresponding bacterial species. Active EPS were also obtained from halo-blight-infected bean leaves. © 1979.