Ice-Nucleation Activity of Pseudomonas Syringae on Phaseolus Vulgaris Leaflets

Abstract

Frost hazard to a plant canopy is a function of both the population size of ice nucleation active (INA) bacteria and the nucleation frequency (i.e., ratio of ice nuclei to INA bacteria cells) of these bacteria (Lindow et al., Plant Physiol. 70:1090, 1982). Nucleation frequency of INA bacteria in vitro is dependent on genotype, cultural conditions (e.g., medium composition, temperature during growth), and the test temperature itself. To understand the relationship between INA bacteria and frost injury, it is important to determine the nucleation frequency of these bacteria on frost sensitive plants under field conditions. The objective of this study, therefore, was to examine the relationship between population size of INA bacteria, predominantly P. syringae, on individual snap bean leaflets and the temperature at which nucleation occurred on each of those leaflets.