Differential Contribution of Plant-Beneficial Functions from Pseudomonas kilonensis F113 to Root System Architecture Alterations in Arabidopsis thaliana and Zea mays

Fluorescent pseudomonads are playing key roles in plant-bacteria symbiotic interactions due to the multiple plant-beneficial functions (PBFs) they are harboring. The relative contributions of PBFs to plant-stimulatory effects of the well-known plant growth-promoting rhizobacteria Pseudomonas kilonensis F113 (formerly P. fluorescens F113) were investigated using a genetic approach. To this end, several deletion mutants were constructed, simple mutants ΔphlD (impaired in the biosynthesis of 2,4-diacetylphloroglucinol [DAPG]), ΔacdS (deficient in 1-aminocyclopropane-1-carboxylate deaminase activity), Δgcd (glucose dehydrogenase deficient, impaired in phosphate solubilization), and ΔnirS (nitrite reductase deficient), and a quadruple mutant (deficient in the four PBFs mentioned above). Every PBF activity was quantified in the wild-type strain and the five deletion mutants. This approach revealed few functional interactions between PBFs in vitro. In particular, biosynthesis of glucose dehydrogenase severely re...