Characterisation of a protein from Venturia inaequalis that induces necrosis in Malus carrying the Vm resistance gene
Apple scab (black spot) is caused by the fungus, Venturia inaequalis. Race 1 isolates of this fungus are avirulent on Malus hosts carrying the resistance gene V m . Detached leaves from a V m host (resistant, differential host 5) and ‘Royal Gala’ (susceptible, host 1) were inoculated with a conidial...
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Veröffentlicht in: | Physiological and molecular plant pathology 2003-04, Vol.62 (4), p.193-202 |
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Sprache: | eng |
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Zusammenfassung: | Apple scab (black spot) is caused by the fungus,
Venturia inaequalis. Race 1 isolates of this fungus are avirulent on
Malus hosts carrying the resistance gene
V
m
. Detached leaves from a
V
m
host (resistant, differential host 5) and ‘Royal Gala’ (susceptible, host 1) were inoculated with a conidial suspension of
V. inaequalis. In the resistant reaction, a hypersensitive response (HR), characterised by necrosis and the accumulation of autofluorescent materials in epidermal and mesophyll cells, was observed at the site of fungal penetration. No HR was observed in the susceptible host.
V. inaequalis grown in vitro produced an elicitor that induced necrosis, similar to the HR, when infiltrated into leaves of the resistant
V
m
host. No response, however, was observed in the susceptible host. The elicitor was proteinaceous and a fraction with elicitor activity was isolated using ultra-filtration, acetone precipitation and ion-exchange chromatography. The elicitor activity was resistant to boiling but it was abolished by digestion with proteinase K. The protein fraction contained three major proteins all with low isoelectric points (p
I 3·0–4·5). The fraction also elicited necrosis in the differential host 4, but not in any of the other resistant hosts tested, including differential hosts 2, 3, and 6. Therefore, the fraction may contain elicitors with more than one host specificity. |
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ISSN: | 0885-5765 1096-1178 |
DOI: | 10.1016/S0885-5765(03)00061-4 |