AUTHOR=Malviya Deepti , Varma Ajit , Singh Udai B. , Singh Shailendra , Saxena Anil K. 

TITLE=Unraveling the mechanism of sulfur nutrition in pigeonpea inoculated with sulfur-oxidizing bacteria

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.927702

DOI=10.3389/fmicb.2022.927702

ISSN=1664-302X

ABSTRACT=<p>An investigation was carried out to understand the mechanism(s) involved in the uptake of sulfur (S) as sulfate in pigeonpea following single inoculation of two sulfur-oxidizing bacteria (SOB), <italic>Stenotrophomonas maltophilia</italic> and <italic>Stenotrophomonas pavanii</italic> in the treatments amended with either elemental sulfur (S<sup>0</sup>) or sulfate (S<sup>6</sup>). Colonization potential and biofilm formation were analyzed through confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM). Furthermore, the effect of seed inoculation on root architecture, expression of genes involved in sulfur oxidation (<italic>sox</italic>) in bacterial inoculants, and genes involved in sulfate transport in pigeonpea (<italic>PpSULTR</italic>) were analyzed to correlate with the higher uptake of S in roots and shoots of pigeonpea. Both the SOB exhibited a good colonization potential and biofilm formation on the roots of pigeonpea. Among the 11 <italic>sox</italic> genes targeted in rhizosphere of pigeonpea, expression was achieved for seven genes, which showed 2-fold increase in treatments inoculated with <italic>S. maltophilia</italic> and amended with either S<sup>6</sup> or S<sup>0</sup>. The inoculation of <italic>S. maltophilia</italic> and amendment of S<sup>0</sup> led to increased expression of <italic>PpSULTR</italic> genes by several folds in roots. The inoculation of SOB had a significant influence on non-enzymatic (osmolytes like proline) and enzymatic (PAL, peroxidase, superoxide dismutase, and catalase) levels. The results revealed a significant increase in sulfur uptake in roots and shoots in treatment inoculated with <italic>S. maltophilia</italic> and amended with S<sup>6</sup>. The investigation showed that the SOB-mediated over-expression of <italic>PpSULTR</italic> genes in roots of pigeonpea and <italic>sox</italic> genes in the rhizosphere were acting synergistically in facilitating higher uptake and translocation of S in roots and shoots of pigeonpea plants.</p>