Effect of climate parameters on induced resistance in strawberry powdery mildew
Abstract: Induced disease resistance in plants is a physiological state of enhanced defensivecapacity elicited by specific stimuli, whereby the plant’s innate defences are potentiated againstsubsequent challenges. This enhanced state of resistance is effective against a broad range ofpathogens and parasites, including fungi, bacteria, viruses, and nematodes. The two most clearlydefined forms of induced resistance are Systemic Acquired Resistance (SAR) and InducedSystemic Resistance (ISR). The changing environmental conditions may lead to changes in theactivity and survival of organisms. Powdery mildew (Podosphaera aphanis) is one of the majorfungal diseases of strawberry world-wide and is expected to increase its distribution underchanging climatic conditions. In the present research we study induced resistance in strawberryplants under the changing environmental conditions that are expected due to global warming.Inducers that are tested in the present study include Trichoderma harzianum T39, acibenzolar-Smethyl(Bion), a new SCNB2 inducer and isolates of a bacterium and a yeast. These agents notonly effectively suppressed powdery mildew on leaves when sprayed on the canopy, but alsoinduced systemic resistance when applied to the root zone while disease was evaluated on theleaves. Similarly lower leaf application resulted in upper leaf disease suppression. Plant growthwas enhanced in the presence of the biological inducers in the root zone, especially under limitedirrigation conditions. The effect of different temperatures and water stress conditions on inducedresistance is further studied. Furthermore, the effect of the climate parameters on the expressionof induced resistance genes will be studied.