Association ofPseudomonas syringaepv.lachrymansand Other Bacterial Pathogens with Roots

Abstract

P. syringae pv. lachrymans (Psl) spread, with attendant multiplication, from inoculated cucumber seeds or radicles to seedling roots growing on water agar. Pathogen cells were motile in the water bordering young roots; as roots became older, areas next to them were packed with static bacterial cells. High populations were associated with hair roots. Three unidentified bacteria and a yeast from cucumber seeds spread from radicles to distal parts of cucumber roots on agar, as did Agrobacterium tumefaciens, Erwinia carotovora pv. carotovora, E. stewartii, P. solanacearum, P. syringae pv. glycinea, P. syringae pv. phaseolicola, P. syringae pv. syringae, P. syringae pv. tomato, Xanthomonas campestris pv. campestris, X. campestris pv. nigromaculans and X. campestris pv. phaseoli. Some microorganisms from some lots of cucumber seeds and from soil interfered with the spread of Psl with cucumber roots on agar. When Psl was inoculated on cucumber radicles and planted in an unsterilized soil mix that was watered by capillarity in greenhouse pot tests, or in growth room pot tests with another unsterilized soil mix kept at 2 levels of high water content, the pathogen was detected on distal roots of 44 and > 50% of the seedlings, respectively. With inoculated seeds, the percentages were lower.