Plant Chemical Defenses: Are all Constitutive Antimicrobial Metabolites Phytoanticipins?

Abstract

A critical perspective on phytoanticipins, constitutive plant secondary metabolites with defensive roles against microbes is presented. This mini-review focuses on the chemical groups and structural types of defensive plant metabolites thus far not reviewed from the phytoanticipin perspective: i) fatty acid derivatives and polyketides, ii) terpenoids, iii) shikimates, phenylpropanoids and derivatives, and iv) benzylisoquinoline and pyrrolizidine alkaloids. The more traditional groups of phytoanticipins are briefly summarized, with particular focus on the latest results: i) benzoxazinoids, ii) cyanogenic glycosides, iii) glucosinolates and their metabolic products, and iv) saponins. Current evidence suggests that a better understanding of the functions of plant metabolites will drive their application to protect crops against microbial diseases.

Biotic elicitation as a tool to improve strawberry and raspberry extract potential on metabolic syndrome‐related enzymes in vitro

“…34 The decrease in phenols and anthocyanins may be due to bacterial activation of the biosynthetic pathway beyond anthocyanins because these compounds have been shown to play a role in plant defense either directly, behaving as phytoalexins, or as precursors of the real phytoalexins. 35,36 Although anthocyanins have a strong antioxidant capacity, the newly formed products may not show this ability, which is consistent with the loss of antioxidant capacity that was detected. Nevertheless, a beneficial effect on other targets should not be ruled out yet, because health benefits may be achieved by a more specific mechanism than the basic mechanism of reactive oxigen species (ROS) removal from the system.…”

“…Only P. fluorescens spring samples caused a significant decrease in total phenolics and anthocyanin concentrations, in parallel with a decrease in antioxidant capacity, supporting the relationship between these compounds and antioxidant capacity . The decrease in phenols and anthocyanins may be due to bacterial activation of the biosynthetic pathway beyond anthocyanins because these compounds have been shown to play a role in plant defense either directly, behaving as phytoalexins, or as precursors of the real phytoalexins . Although anthocyanins have a strong antioxidant capacity, the newly formed products may not show this ability, which is consistent with the loss of antioxidant capacity that was detected.…”

Ecological Roles of Tryptanthrin, Indirubin and N‐Formylanthranilic Acid in Isatis indigotica: Phytoalexins or Phytoanticipins?

“…Indeed, in spite of significant endeavors to clarify definitions, [9,10,12] many secondary or specialized plant metabolites that would be more appropriately considered phytoanticipins are reported as phytoalexins. [13] Not surprisingly, like for many other classifications, there are gray areas and cases where the distinction between phytoanticipins and phytoalexins is not so obvious. In such cases, examination of biosynthetic intermediates might be required to more accurately classify those plant metabolites as phytoanticipins or phytoalexins.…”

“…NMR spectra were recorded on Bruker Avance 500 MHz spectrometers. For 1 H-NMR (500 MHz) and 13 C-NMR (125.8 MHz) spectra, the chemical shifts (δ) are reported in parts per million (ppm) relative to TMS. MS data (high resolution (HR)) were obtained on a Jeol AccuToF GCv 4G mass spectrometer (field desorption (FD)) or on a Qstar XL MS/MS System (ESI) by direct insertion.…”

“…[9][10][11] By contrast, phytoanticipins are antimicrobial metabolites constitutively produced in amounts that usually increase under stress. [12,13] These two groups of metabolites have ecological roles that include involvement in molecular plant defense mechanisms against microbial pathogens. [10,11] Cruciferous phytoalexins encompass a Supporting information for this article is available on the WWW under https://doi.org/10.1002/cbdv.201800579 group of alkaloids derived from L-tryptophan such as the brassinins and camalexins, [11] or from L-phenylalanine such as the nasturlexins (Figure 2).…”