Dissecting negative effects of two root-associated bacteria on the growth of an invasive weed

• Published in: FEMS microbiology ecology 2024-09, Vol.100 (10)
• Main Authors: Liu, Xiangyu, Fernandes, Hocelayne Paulino, Ossowicki, Adam, Vrieling, Klaas, Lommen, Suzanne T E, Bezemer, Thiemo Martijn
• Format: Article
• Language: English
• Subjects: Germination; Introduced Species; Plant Roots - growth & development; Plant Roots - microbiology; Plant Weeds - growth & development; Plant Weeds - microbiology; Pseudomonas - growth & development; Seedlings - growth & development; Seedlings - microbiology; Serratia - growth & development; Serratia - metabolism; Volatile Organic Compounds - metabolism; Weed Control - methods
• ISSN: 1574-6941; 1574-6941
• DOI: 10.1093/femsec/fiae116

Plant-associated microorganisms can negatively influence plant growth, which makes them potential biocontrol agents for weeds. Two Gammaproteobacteria, Serratia plymuthica and Pseudomonas brassicacearum, isolated from roots of Jacobaea vulgaris, an invasive weed, negatively affect its root growth. We examined whether the effects of S. plymuthica and P. brassicacearum on J. vulgaris through root inoculation are concentration-dependent and investigated if these effects were mediated by metabolites in bacterial suspensions. We also tested whether the two bacteria negatively affected seed germination and seedling growth through volatile emissions. Lastly, we investigated the host specificity of these two bacteria on nine other plant species. Both bacteria significantly reduced J. vulgaris root growth after root inoculation, with S. plymuthica showing a concentration-dependent pattern in vitro. The cell-free supernatants of both bacteria did not affect J. vulgaris root growth. Both bacteria inhibited J. vulgaris seed germination and seedling growth via volatiles, displaying distinct volatile profiles. However, these negative effects were not specific to J. vulgaris. Both bacteria negatively affect J. vulgaris through root inoculation via the activity of bacterial cells, while also producing volatiles that hinder J. vulgaris germination and seedling growth. However, their negative effects extend to other plant species, limiting their potential for weed control.