Resistance responses induced by the plant growth retardant prohexadione-Ca in apple against scab infections
2008
Bini, F. | Ragaini, A. | Bazzi, C.
The efficacy of the dioxygenase inhibitor prohexadione-Ca (ProCa) as an inducer of resistance responses against apple scab (Venturia inaequalis/Spilocaea pomi) was evaluated in two sets of experiments under glasshouse conditions. ProCa (200 ppm) was applied on seedlings of open-pollinated Malus domestica L. cv. Golden Delicious, and 10 days after application, a group of seedlings was inoculated with a conidial suspension of S. pomi. Total RNA was extracted from leaf samples collected at different times from both inoculated and noninoculated seedlings, and expression of the pathogenesis-related proteins PR-1, PR-2, PR-5, PR-8, PR-10 and chitinase was studied by reverse transcription-polymerase chain reaction and Northern blot hybridisation. Disease severity was significantly lower on seedlings treated with ProCa than on the water-treated control seedlings. ProCa triggered a general increase in gene expression of almost all the PR genes; only the level of chitinase and PR-10 did not show a detectable increase. A strong upregulation of all the assayed genes was observed in leaves of apple seedlings first treated with ProCa and then inoculated with the pathogen, whereas no expression and/or a constitutive signal was found in samples from the control seedlings.
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