Oxalic Acid From Sesbania rostrata Seed Exudates Mediates the Chemotactic Response of Azorhizobium caulinodans ORS571 Using Multiple Strategies

Abstract

Chemotaxis toward seed exudates is important in the establishment of microbe–plant associations. The objective of this work was to explore whether organic acids from the seed exudates of Sesbania rostrata play a role in recruiting Azorhizobium caulinodans ORS571 in the plant rhizosphere. High-performance liquid chromatography (HPLC) was used to analyze the organic acid content in seed exudates of S. rostrata and to further determine their roles in A. caulinodans growth and chemotactic response. Succinic, acetic, citric, oxalic, and lactic acids were the most abundant, and, except for oxalic acid, they could support A. caulinodans growth as the sole carbon source. TlpA1, a transmembrane chemoreceptor, was found to be involved in the chemotactic response to these organic acids. Oxalic acid played a direct role in the chemotactic response, but it also played an indirect role by promoting or inhibiting the chemotactic response toward other chemoeffectors. Furthermore, the indirect role of oxalic acid on other chemoeffectors was concentration-dependent. The effect of oxalic acid at different concentrations on host root colonization was also determined. By using different strategies, oxalic acid appears to play a major role in the early steps of the association of A. caulinodans and its host plant.

Effects of organic acids on the chemotaxis profiles and biocontrol traits of antagonistic bacterial endophytes against root-rot disease in Panax notoginseng

“…Furthermore, our results were highly consistent with earlier reports that some bene cial bacteria associated with plants exhibit chemotaxis toward OAs in a dose-dependent manner (Liu et al 2019;Zhang et al 2013;Zhang et al 2014). As expected, the qRT-PCR on cheA relative gene expression levels in YP1 demonstrated that FA at 50 µM induced the highest increase in cheA gene transcript expression of all the OA treatments at that concentration (Fig.…”

“…Effects of OAs on the growth of the representative P. notoginseng-associated CAEB strain in vitro An assay was designed to evaluate the effect of exogenous OAs at different concentrations on the growth of representative CAEB as previously described (Liu et al 2019). The bacterial cells were incubated overnight in 10 mL NB medium and then adjusted to an OD 600 of 0.1.…”

The Effect of Banana Rhizosphere Chemotaxis and Chemoattractants on Bacillus velezensis LG14-3 Root Colonization and Suppression of Banana Fusarium Wilt Disease

“…Moreover, the addition of exogenous glycine or citric acid can increase the colonization of LG14-3 in the banana rhizosphere. Some carbon metabolites in plant root exudates can serve as food and as an energy source for rhizosphere microorganisms [5,47,48]. Similarly, citric acid supports the growth of LG14-3.…”

Excessive Oxalic Acid Secreted by Sparassis latifolia Inhibits the Growth of Mycelia during Its Saprophytic Process

“…Quantitative analysis of OA secreted by S. latifolia in culture was carried out using high-pressure liquid chromatography (HPLC) (Agilent 1260 Infinity II Prime, Agilent, Santa Clara, CA, USA) [ 20 ]. S. latifolia mycelial discs were placed in the center of a sterile cellophane sheet overlayed on top of PDPA plates and incubated at 24 °C.…”