Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2009
Publication Date: August 1, 2009
Citation: Wallace, P., Mahaffee, W.F., Press, C.M., Larsen, M.M., Neill, T.M. 2009. The relationship of biofilm production to biocontrol activity of Burkholderia pyrrocinia FP62. American Phytopathological Society Abstracts. p. 569. Technical Abstract: Foliar biocontrol agent (BCA) efficacy is often inconsistent due to poor colonization and survival on plant surfaces. Burkholderia pyrrocinia FP62, a superior leaf colonist and BCA of Botrytis cinerea, forms unsaturated biofilms on plant surfaces. To determine the relationship between biocontrol activity and biofilm formation, a mini-Tn5 mutant library was created and screened for biofilm deficiency in liquid. Mutant 55B1 has a transposon insertion in a region homologous to a trmE GTPase gene. 55B1 was complemented by marker exchange (55B1-C). Geraniums were inoculated with suspensions of washed FP62, 55B1 and 55B1-C cells. Inoculated plants were housed in a greenhouse with bottom watering for 0, 1, 3, and 7 days. Leaf populations were measured by sonicating excised leaves in phosphate buffer and plating washates on 5% yeast extract broth agar. Leaf samples were collected pre- and post-sonication, chemically fixed and viewed with scanning electron microscopy (SEM). In another experiment, 1 or 7-day treated plants were challenged with B. cinerea for 5–7 days before rating for percent disease severity. Biocontrol activity was reduced in 55B1 and restored in 55B1-C. SEM revealed that despite similar culturable populations, significantly more FP62 and 55B1-C cells remain attached to the leaf surface between plant cell junctions and trichome bases. These findings suggest that biofilm production is vital to the biocontrol activity of FP62.