Plant growth enhancement is not a conserved feature in the Caulobacter genus

Genes related to redox and cell curvature facilitate interactions between Caulobacter strains and Arabidopsis

“…RHG1 cells localize to regions of lateral root formation in Arabidopsis and increase root length and lateral root formation compared to the roots of uninoculated plants. Similarly, we previously identified six Caulobacter strains that could increase plant weight and root length relative to control conditions [ 22 ], and our results suggested that common PGP factors did not explain the plant growth enhancement that we observed in our system.…”

“…Thus, we investigated Caulobacter cell shape in the context of plant-microbe interactions and hypothesized that the crescent shape of C . crescentus cells may contribute to the Caulobacter -mediated plant growth enhancement that we previously observed [ 22 ].…”

“…Nonetheless, functional genetics approaches that seek to resolve the function of redox related activities in the context of PGPB assays have not been communicated and many reports consider only correlative data involving common PGP factors (1-aminocyclopropane deaminase (ACC deaminase), cytokinin biosynthesis, indole-3-acetic acid (IAA) production, nitrogen fixation, and phosphate solubilization) as proxies to assess the potential of a bacterial strain to enhance plant growth [ 20 , 21 ]. However, common PGP factors can also negatively correlate with plant fitness [ 22 ].…”

“…The genus Caulobacter , a member of the class Alphaproteobacteria , possesses many strains that have been isolated from the endosphere and rhizosphere of Arabidopsis , Citrullus , Lavandula and Zea mays [ 23 – 26 ], which in part implicates members of the Caulobacter genus as representative microbial hub species [ 27 ]. Moreover, select Caulobacter strains have been shown to increase plant biomass and alter root architecture relative to uninoculated conditions [ 22 – 24 ]. Functional roles that explain Caulobacter -mediated plant growth enhancement, however, have not been reported [ 22 – 24 ].…”

“…Moreover, select Caulobacter strains have been shown to increase plant biomass and alter root architecture relative to uninoculated conditions [ 22 – 24 ]. Functional roles that explain Caulobacter -mediated plant growth enhancement, however, have not been reported [ 22 – 24 ]. A recent report from Luo et al (2019) [ 23 ] demonstrated that Caulobacter sp.…”