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

Laura D Cox,Honghui Zhu,Karl Peter Pauls,Seth Munholland,William L Crosby,Lili Mats,Gale G Bozzo,Lewis Lukens

doi:10.3390/metabo11070433

Laura D Cox, Honghui Zhu + Show 6 more

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https://doi.org/10.3390/metabo11070433

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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.

Highlights

Introduction published maps and institutional affilCommon bean (Phaseolus vulgaris L.) is one of the most highly cultivated edible legumes, with global production in 2019 at 28.9 million tonnes [1]
recombinant inbred line (RIL), both of which were previously derived from a cross between the CBBCBB-susceptible RIL, both of which were previously derived from a cross between the CBBresistant white whitebean beancultivar cultivar‘OAC
The molecular and metabolic determinants of common bacterial blight (CBB)-resistance were investigated in two RILs derived from the CBB-susceptible parent ‘OAC Seaforth’ and CBB-resistant parent ‘OAC Rex’ [8]

Summary

Introduction

Common bean (Phaseolus vulgaris L.) is one of the most highly cultivated edible legumes, with global production in 2019 at 28.9 million tonnes [1]. Most bean producing regions are quite susceptible to common bacterial blight (CBB), a disease caused by the bacterium Xanthomonas axonopodis and its fuscans relative [2]. Most P. vulgaris cultivars are susceptible to CBB [7]. The white bean cultivar ‘OAC Rex’ is resistant to CBB, as it carries resistance loci from a member of its pedigree that was derived from an interspecific cross with Phaseolus acutifolius A. Alleles linked to/associated with CBB resistance are highly conserved between the ‘OAC Rex’ genome and that of the Andean P. vulgaris iations

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