Azospirillum brasilense Az39 restricts cadmium entrance into wheat plants and mitigates cadmium stress

VAZQUEZ, ANALÍA; ZAWOZNIK MS; BENAVIDES MP; GROPPA MD

PLANT SCIENCE

ELSEVIER IRELAND LTD

Lugar: Amsterdam; Año: 2021 vol. 312 p. 1 - 10

0168-9452

In this work, we tested if inoculation with the plant growth-promoting rhizobacteria Azospirillum brasilense strainAz39 alleviates Cd2+ stress in wheat seedlings grown under controlled conditions. Growth, total N, N-relatedmetabolites/enzymes, and oxidative stress parameters were measured. Additionally, the usefulness of a real-timePCR protocol to screen the preferred colonization site of the introduced microorganism was evaluated. Inoculatedplants demonstrated mitigation of cadmium-induced adverse effects on plant growth and less reactiveoxygen species accumulation in their roots by the end of the experiment, 28 days after sowing. Cd additionresulted in lower NO3􀀀 content in the leaves and higher NO3􀀀 content in the roots, and a significant rise in NH4+concentration in both organs in uninoculated plants; in inoculated plants, NH4+ content in the roots did not vary.A. brasilense Az39 enhanced NO levels in wheat root tips, and more adventitious roots and root hairs wereobserved in inoculated plants. Despite having a more developed root system, inoculated plants showed lower Cdlevels in their roots compared to non-inoculated plants. Inoculation with this PGPR favored ion homeostasis inthe roots of metal-exposed plants, decreasing Cd/Fe ratio. We corroborated A. brasilense Az39 preference forwheat exorhizosphere using a real-time PCR-based method targeting the nifA gene