Flavonoids are polyphenolic secondary metabolites with various in vivo and
in vitro structure-related benefits that are ubiquitously found in plants. In addition to
their role in many physiological activities, flavonoids play major roles as phytoalexins
and phytoanticipins in protecting plants from potent pathogens. Since the first
discovery of such defense roles, their routes of biosynthesis induced upon pathogen
infection and mechanisms of action have attracted the attention of researchers in
various fields. The ultimate goal of the study of plant-pathogen interactions is to
develop biotechnological applications that enhance crop production in an
environmentally friendly manner, with the outcome of engineering highly pathogen-resistant genotypes. Steady progress has been made previously in this regard.
Inoculation of potential pathogens in plant tissues, followed by the systematic analysis
of various targeted biochemical changes, including investigations into flavonoid
variations, has become an appealing methodological approach. In this chapter, the role
of flavonoids as defense mechanisms in plant-pathogen interactions is discussed with
respect to the latest findings. In addition, we emphasize research trends observed in this
regard. In light of the most recent studies, including those conducted by some of the
authors of this chapter, key findings in flavonoid variations upon pathogen infection are
highlighted comprehensively, focusing on fungal inoculation and liquid
chromatography-tandem mass spectrometry analysis for reasons described in later
sections.
Keywords: Defense, Flavonoid, Flavonoid variation, Liquid chromatography,
Pathogen, Phytoalexin, Phytoanticipins, Tandem mass spectrometry.
