Scientific Reports (Nov 2021)

Leaf nodule endosymbiotic Burkholderia confer targeted allelopathy to their Psychotria hosts

  • Antri Georgiou,
  • Simon Sieber,
  • Chien-Chi Hsiao,
  • Tatyana Grayfer,
  • Jacob L. Gorenflos López,
  • Karl Gademann,
  • Leo Eberl,
  • Aurélien Bailly

DOI
https://doi.org/10.1038/s41598-021-01867-2
Journal volume & issue
Vol. 11, no. 1
pp. 1 – 15

Abstract

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Abstract After a century of investigations, the function of the obligate betaproteobacterial endosymbionts accommodated in leaf nodules of tropical Rubiaceae remained enigmatic. We report that the α-d-glucose analogue (+)-streptol, systemically supplied by mature Ca. Burkholderia kirkii nodules to their Psychotria hosts, exhibits potent and selective root growth inhibiting activity. We provide compelling evidence that (+)-streptol specifically affects meristematic root cells transitioning to anisotropic elongation by disrupting cell wall organization in a mechanism of action that is distinct from canonical cellulose biosynthesis inhibitors. We observed no inhibitory or cytotoxic effects on organisms other than seed plants, further suggesting (+)-streptol as a bona fide allelochemical. We propose that the suppression of growth of plant competitors is a major driver of the formation and maintenance of the Psychotria–Burkholderia association. In addition to potential agricultural applications as a herbicidal agent, (+)-streptol might also prove useful to dissect plant cell and organ growth processes.