Transient alteration of the flavonoid pathway: A useful tool for improving resistance of pome fruits?

The functions of phenylpropanoids and flavonoids in plants are multifaceted and their role in plant resistance is commonly accepted (Fig.). Despite of that, the application of this knowledge on a practical purpose is limited. A few reports are available which confirm the implication of phenolics in defence of plants against specialised pathogens. Evidences for the role of apple phenolics in pathogen defence are presented. The diseases include scab caused by the fungus Venturia inaequalis and fire blight caused by the bacterium Erwinia amylovora. A transient alteration of the flavonoid pathway significantly reduces susceptibility of apple cultivars. Several possibilities for influencing the biosynthesis and the accumulation of phenolics in apple and in other plants based on literature and on results of the authors are discussed.