Erwinia amylovora infection of hawthorn blossom. 2. The stigma
1989
Wilson, M. (Manchester Univ. (UK). Dept of Cell and Structural Biology) | Epton, H.A.S. | Sigee, D.C.
The stigmas of hawthorn flowers on detached branches were inoculated with ca 5 x 10(4) colony forming units (cfu) of E. amylovora and the population development followed by viable counts and light and electron microscopy. The population developed in a biphasic manner, with an epiphytic phase up to 48 h after inoculation, (in which bacteria were restricted to the intercellular spaces between the papillae) followed by an invasive phase (where bacteria invaded the secretory tissue below the papillae). In the epiphytic phase the bacteria multiplied rapidly, with doubling-times approaching those observed for in vitro multiplication, reaching a population of ca. 10(6) cfu/flower. After the second phase of multiplication the population attained a final level of ca. 10(8) cfu/flower. At no stage was the style invaded by bacteria. Stigma infection does not appear to lead directly to blossom-blight in hawthorn, but bacteria were carried down the style in stigmatic secretions, where they may cause infection of the nectarial surface and susequent disease
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