Plant Growth-Promoting Rhizobacterial Mediated Protection in Tomato Against Tomato mottle virus

ABSTRACT Tomato plants treated with plant growth-promoting rhizobacteria (PGPR), applied as an industrially formulated seed treatment, a spore preparation mixed with potting medium (referred to as powder), or a combined seed-powder treatment, were evaluated under field conditions for induced resistance to Tomato mottle virus (ToMoV). The PGPR strains used, based on their ability to induce resistance in previous experiments, included Bacillus amyloliquefaciens 937a, B. subtilis 937b, and B. pumilus SE34. Experiments were conducted in the fall of 1997 and the spring and fall of 1998 at the University of Florida's Gulf Coast Research & Education Center, Bradenton. All plants were rated for symptoms and analyzed for the presence of ToMoV DNA at 40 days after transplant (dat). Whitefly densities were determined on individual plants in each trial, and marketable fruit yields were determined at least two times during each trial. The highest level of protection occurred in the fall 1997 trial when, at 40 dat, ToM...