Plant Growth Promotion Driven by a Novel Caulobacter Strain

• DOI: 10.1094/mpmi-12-18-0347-r
• Publication Date: 2019-04-01T21:46:36Z
• Authors: Dexian Luo; Sarah Langendries; Sonia Garcia Mendez; Joren De Ryck; Derui Liu; Stien Beirinckx; Anne Willems; Eugenia Russinova; Jane Debode; Sofie Goormachtig
• Keywords: EXPRESSION; 2. Zero hunger; NITRIC-OXIDE; Biology and Life Sciences; RHIZOSPHERE; Plant Roots; Zea mays; molecular signaling; LEAF DEVELOPMENT; microscopy and imaging; Caulobacter; genetics and gene regulation; SP NOV.; BACTERIA; Host-Pathogen Interactions; genomics; ARABIDOPSIS-THALIANA; AUXIN TRANSPORT; rhizosphere and phyllosphere ecology KeyWords Plus:INDUCED SYSTEMIC RESISTANCE; RHIZOBACTERIA

Soil microbial communities hold great potential for sustainable and ecologically compatible agriculture. Although numerous plant-beneficial bacterial strains from a wide range of taxonomic groups have been reported, very little evidence is available on the plant-beneficial role of bacteria from the genus Caulobacter. Here, the mode of action of a Caulobacter strain, designated RHG1, which had originally been identified through a microbial screen for plant growth-promoting (PGP) bacteria in maize (Zea mays), is investigated in Arabidopsis thaliana. RHG1 colonized both roots and shoots of Arabidopsis, promoted lateral root formation in the root, and increased leaf number and leaf size in the shoot. The genome of RHG1 was sequenced and was utilized to look for PGP factors. Our data revealed that the bacterial production of nitric oxide, auxins, cytokinins, or 1-aminocyclopropane-1-carboxylate deaminase as PGP factors could be excluded. However, the analysis of brassinosteroid mutants suggests that an unknown PGP mechanism is involved that impinges directly or indirectly on the pathway of this growth hormone.