Efficacy of Phloxine B as a Bactericidal Agent in Plants

Abstract

Agrobacterium tumefaciens cells were killed upon illumination when treated with submicromolar concentrations of phloxine B. Phloxine B could be distributed systemically through a plant by amending the water supply or delivered directly to specific locations through topical applications in 0.1% adjuvant (Kinetic HV). Sweet basil (Ocimum basilicum L.), jimsonweed (Datura stramonium L.), and soybean (Glycine max L.) were infected with A. tumefaciens to establish a marker for a systemic pathogenic bacteria. There was a >90% reduction in the plants' population of A. tumefaciens when watered daily with a 1 micromolar phloxine B solution. Furthermore, the plants treated with phloxine B were asymptomatic to the pathogenic challenge. Leaf tissue, collected from basil and soybean, also expressed a reduction in the population of A. tumefaciens by >90% when treated under greenhouse conditions for 24 h with 10 μM phloxine B in 0.1% Kinetic HV. The possible use of phloxine B as an agent to control bacterial diseases in plants is suggested. Keywords: Photodynamic action; singlet oxygen; phloxine B; xanthene dyes