Role of Phenylpropanoids and Flavonoids in Plant Resistance to Pests and Diseases

Abstract

Phenylpropanoids and flavonoids are specialized metabolites frequently reported as involved in plant defense to biotic or abiotic stresses. Their biosynthetic accumulation may be constitutive and/or induced in response to external stimuli. They may participate in plant signaling driving plant defense responses, act as a physical or chemical barrier to prevent invasion, or as a direct toxic weapon against microbial or insect targets. Their protective action is described as the combinatory effect of their localization during the host’s interaction with aggressors, their sustained availability, and the predominance of specific compounds or synergy with others. Their biosynthesis and regulation are partly deciphered; however, a lot of gaps in knowledge remain to be filled. Their mode of action on microorganisms and insects probably arises from an interference with important cellular machineries and structures, yet this is not fully understood for all type of pests and pathogens. We present here an overview of advances in the state of the art for both phenylpropanoids and flavonoids with the objective of paving the way for plant breeders looking for natural sources of resistance to improve plant varieties. Examples are provided for all types of microorganisms and insects that are targeted in crop protection. For this purpose, fields of phytopathology, phytochemistry, and human health were explored.

Avenanthramides, Distinctive Hydroxycinnamoyl Conjugates of Oat, Avena sativa L.: An Update on the Biosynthesis, Chemistry, and Bioactivities

“…In general, the protective action of phytoalexins is attributed to a combinatory effect of their cellular localisation during the host response to the pathogen attack, their timeous and sustained bioavailability, the upregulation of specific metabolites over others among the same subfamily, and/or putative synergistic effects between these metabolites. Accordingly, although not fully understood, their mode of action on microorganisms arises from an interference with important cellular structures and metabolism [ 52 ]. Additionally, upon infection, they can be covalently integrated into the cell wall to provide protection against breakdown, which frequently happens as a result of the enzymes released by pathogens [ 29 ].…”

Genetics and breeding of phenolic content in tomato, eggplant and pepper fruits

“…In this respect, the photoprotective role against UV-B radiation of some phenolic compounds, such as anthocyanins, flavones, caffeic acid and chlorogenic acid have been widely demonstrated in several species ( Sytar et al., 2018 ; Righini et al., 2019 ). Likewise, flavonoids and phenolic acids may act as a physical or chemical barrier to prevent invasion, or as a direct weapon against microbes and insects ( Ramaroson et al., 2022 ). In tomato leaves, increased accumulation of phenolic acids was detected in response to Pseudomonas syringae infection ( Dadáková et al., 2020 ), while higher accumulation of naringenin was associated with the resistance against Botrytis cinerea ( Szymański et al., 2020 ).…”

Influence of pectin on phenylpropanoid accumulation in buckwheat (Fagopyrum esculentum) sprout

“…Additionally, it responds significantly to stressors like high light intensity and mineral deficiency (Clemens & Weber, 2016). Additionally, it served as a mediator for interactions between plants and other creatures (Grover et al, 2022;Ramaroson et al, 2022).…”