The Induction of the Isoflavone Biosynthesis Pathway Is Associated with Resistance to Common Bacterial Blight in Phaseolus vulgaris L.

Abstract

Xanthomonas axonopodis infects common bean (Phaseolus vulgaris L.) causing the disease common bacterial blight (CBB). The aim of this study was to investigate the molecular and metabolic mechanisms underlying CBB resistance in P. vulgaris. Trifoliate leaves of plants of a CBB-resistant P. vulgaris recombinant inbred line (RIL) and a CBB-susceptible RIL were inoculated with X. axonopodis or water (mock treatment). Leaves sampled at defined intervals over a 48-h post-inoculation (PI) period were monitored for alterations in global transcript profiles. A total of 800 genes were differentially expressed between pathogen and mock treatments across both RILs; approximately half were differentially expressed in the CBB-resistant RIL at 48 h PI. Notably, there was a 4- to 32-fold increased transcript abundance for isoflavone biosynthesis genes, including several isoflavone synthases, isoflavone 2′-hydroxylases and isoflavone reductases. Ultra-high performance liquid chromatography-tandem mass spectrometry assessed leaf metabolite levels as a function of the PI period. The concentrations of the isoflavones daidzein and genistein and related metabolites coumestrol and phaseollinisoflavan were increased in CBB-resistant RIL plant leaves after exposure to the pathogen. Isoflavone pathway transcripts and metabolite profiles were unaffected in the CBB-susceptible RIL. Thus, induction of the isoflavone pathway is associated with CBB-resistance in P. vulgaris.

The Flavonoid Biosynthesis Network in Plants

“…Various modifications further generate specific isoflavones. Daidzein is converted to puerarin or formononetin by a specific glycosyltransferase (GT) or IOMT [ 79 , 83 ]. Malonyltransferase (MT) can act on isoflavones (genistein, daidzein, and glycitein) to generate the corresponding malonyl-isoflavones (malonylgenistein, malonyldaidzein, and malonylglycitein) [ 80 ].…”

Phenylpropanoid Metabolism in Phaseolus vulgaris during Growth under Severe Drought

“…Proposed phenylpropanoid metabolism in Phaseolus vulgaris subjected to drought. This biochemical scheme was adapted from models of isoflavone, coumestan, pterocarpan, flavonol glycoside, and phenolic acid biosynthesis pathways from previous sources [13,[17][18][19][20] and incorporates some of the corresponding metabolites that are known to occur in P. vulgaris [19,21,22]. Early phenylpropanoid biosynthesis steps that are shared between the phenolic acid, isoflavone, and flavonol pathways are represented by enzymatic steps within grey arrows.…”

“…Metabolites encased within green and brown dashed outline boxes respectively represent a pterocarpan and a phenolic acid for which their precise biosynthetic steps are not shown. Flavonol glycosides within yellow dashed outline boxes represent examples of kaempferol and quercetin glycosides that accumulate in P. vulgaris [19]. Abbreviations include: 4CL, 4-coumaroyl:coenzyme A ligase; C3H, coumarate 3-hydroxylase; C4H, cinnamate 4-hydroxylase; CHI, chalcone isomerase; CHR, chalcone reductase; CHS, chalcone synthase; F3H, flavanone 3-hydroxylase; F3 ′ H, flavonoid 3 ′hydroxylase; FLS, flavonol synthase; HI4 ′ OMT, 2-hydroxyisoflavanone 4 ′ -O-methyltransferase; HID, 2-hydroxyisoflavanone dehydratase; HTT, hydroxycinnamoyl-CoA: tartaric acid hydroxycinnamoyl transferase; IFH, isoflavone 2 ′ -hydroxylase; IFR, isoflavone reductase; IFS, isoflavone synthase; PAL, phenylalanine ammonia-lyase; UGT, UDP-glucose dependent glycosyltransferase; VR, vestitone reductase.…”

“…Prior research has shown that the isoflavones daidzein and genistein, and their derivatives coumestrol and phaseollinisoflavan, amass in the leaves of the white bean recombinant inbred line (RIL) BT6 when challenged with the causal agent of common bacterial blight (CBB), whereas this metabolic phenomenon is absent in its genetic relative BT44, a CBBsusceptible RIL [19]. Both RILs were derived from OAC Seaforth and OAC Rex, with the latter parent containing introgressively hybridized Phaseolus acutifolius (tepary bean) genes [34], including three genes that match expressed sequence tags from drought-stressed P. acutifolius leaves [35].…”

Mass Biosynthesis of Coumestrol Derivatives and Their Isomers via Soybean Adventitious Root Cultivation in Bioreactors

“…Moreover, compared with the large quantities of glyceollins produced in the seeds and leaves of soybean, low quantities of coumestan, the oxidation product of pterocarpans, have also been reported ( Figure 1 ). Although coumestan derivatives were first identified in soybean roots 40 years ago (Le-Van, 1984 ), their studies only began a decade ago (Yuk et al, 2011a ; Jeon et al, 2012 ; Yun et al, 2020 , 2021 ; Cox et al, 2021 ; Mun et al, 2021 ). Considering that plant-derived coumestan exhibits a wide range of pharmacological activities (Tu et al, 2021 ), researchers have attempted to mass-produce coumestrol (CMS), a coumestan exhibiting phytoestrogenic activity, from soybean adventitious root (AR) (Lee et al, 2020 ).…”