Multiplication of Xanthomonas campestris pv. Phaseoli and Intercellular Enzyme Activities in Resistant and Susceptible Beans

Abstract

In order to assess resistance to common bean blight, populations of two isolates of Xanthomonas campestris pv. phaseoli were monitored in leaves of two Phaseolus vulgaris breeding lines, BLT87‐2 (susceptible) and OAC88‐1 (partially resistant) and a resistant tepary bean accession, P. acutifolius P. I. 440795. The breeding line OAC88‐1 possesses resistance to common bacterial blight which was incorporated from P. acutifolius by an interspecific cross. In susceptible, leaves, bacterial populations increased to 108 CFU/g leaf at 3 wk after inoculation whereas, in resistant leaves, bacterial populations declined to 101 ‐ 103 CFU/g leaf. In partially resistant leaves the population first declined similar to that in resistant P. acutifolius but later increased, and typical bacterial blight symptoms appeared. Cellulase, protease and amylase activities were monitored in culture and intercellular leaf spaces. Only cellulase activity was, clearly related to bacterial growth in the susceptible host; other enzyme activities were variable in their relationship to host resistance and bacterial growth. Differences between strains in cellulase activity inside partially resistant leaves corresponded to their ability to secrete cellulase in culture. Measuring cellulase activity in intercellular wash fluids may be a simple and sensitive method for determining X. c. phaseoli populations in leaves.

Inhibition of photosynthesis and export in geranium grown at two CO2 levels and infected with Xanthomonas campestris pv. Pelargonii

“…7b). The activity of bacterial amylase could also have reduced the total extractable starch levels in the leaves (Goodwin, Sopher, & Michaels 1995). Export in a dark chase period did not compensate for decreased export in the light.…”

Breeding Common Bean for Resistance to Diseases: A Review

“…Common bacterial blight susceptible genotypes accumulate larger bacterial populations in the leaves that move faster systemically through vascular tissues than resistant and partially resistant genotypes (Goodwin et al, 1995). Furthermore, resistant (or partially resistant dry bean breeding line BAC 6) genotypes did not have internal seed infection (Aggour et al, 1989).…”

Breeding Common Bean for Resistance to Common Blight: A Review

“…However, among the inoculated primary and trifoliolate leaves and pods in the greenhouse common blight was more severe on the trifoliolate leaf and the least on pods (Viteri et al, 2014a). Common blight susceptible genotypes accumulate larger bacterial populations in the leaves that move faster systemically through vascular tissues than resistant and partially resistant genotypes (Goodwin et al, 1995).…”

“…Bacteria, under warm temperature, multiply asymptomatically on common bean leaves ( Jacques et al, 2005;Weller and Saettler, 1980a), and the disease is seed transmitted Weller and Saettler, 1980b). Common blight susceptible genotypes accumulate larger bacterial populations in the leaves that move faster systemically through vascular tissues than resistant and partially resistant genotypes (Goodwin et al, 1995). Under favorable weather conditions, epiphytic bacteria, after reaching a threshold population density (see below), attack all aerial plant parts of susceptible cultivars including leaves, stems, flower buds, pods, and seeds Harveson and Schwartz, 2007;Saettler, 1989;Schuster et al, 1983;Singh and Muñoz, 1999).…”