INDUCTION OF RESISTANCE IN PLANTS: A NOVEL STRATEGY TO CONTROL DISEASES IN AFRICAN HORTICULTURE?
Induction of resistance (IR) requires the use of abiotic or biotic non- or less toxic compounds, to activate plant defense, this before any infection occurs. Acibenzolar-S-methyl (ASM), Phytogard® (K2HPO3), α-(ABA), β-(BABA) and γ-amino-n-butyric acid (GABA) (3 isomers of aminobutyric acid) and three disease resistance inducers under development and named X, Y and Z were evaluated for their ability to protect the target crops in the pathosystems cauliflower/downy mildew, lettuce/downy mildew, tomato/grey mould and broccoli/head soft rot. Avirulent isolates of P. parasitica were also tested for their ability to induce resistance in cauliflower, broccoli and cabbages against virulent ones. Direct toxicity of the inducers against the pathogens was evaluated in vitro. Systemicy and curative or preventive effects of the IR, efficiency against virulent and avirulent isolates and the length of the protection it provides were also tested. ASM (at 0.1 g L-1), Phytogard® (7 ml L-1), BABA (20 mM) and X induced efficient resistances under laboratory conditions and lasted up to 30 days after application of the inducers. ASM, BABA and X did not show any direct toxic activity against the pathogens tested but Phytogard® did. Field trials also gave some significant disease reductions. It is thus suggested to re-apply the inducers 3 weeks after the first application. ASM strongly induced β-1,3 glucanase and the corresponding PR-2 but not chitinase and their corresponding PR-3Q and PR3-C. Analysis of other acidic proteins namely Q 1C, PR-5S, PR-8 and one basic (PR-6) showed that only PR-1 and PR-5 were slightly and slowly induced (4±5 days after treatment), but this induction was more pronounced after inoculation with P. parasitica. BABA did not induce any PR proteins in the treated plants. However, PR-2 was strongly induced after the treated plants were challenged with the pathogen and confirmed its priming action. Phytogard® did not induce PR proteins.
Monot, C., Pajot, E., Aveline, N., Penguilly, D., Guerrand, J., Le Corre, D. and Silué, D. (2011). INDUCTION OF RESISTANCE IN PLANTS: A NOVEL STRATEGY TO CONTROL DISEASES IN AFRICAN HORTICULTURE? . Acta Hortic. 911, 251-258
localized (LIR), systemic induced resistance (SIR), pathogenesis related proteins, downy mildew, lettuce, brassicas, sustainable disease control