Counteracting action of Bacillus stratosphericus and Staphylococcus succinus strains against deleterious salt effects on Zea mays L

Gianmaria Oliva; Giovanni Vigliotta; Mattia Terzaghi; Francesco Guarino; Angela Cicatelli; Antonio Montagnoli; Stefano Castiglione

doi:10.3389/fmicb.2023.1171980

Counteracting action of Bacillus stratosphericus and Staphylococcus succinus strains against deleterious salt effects on Zea mays L

Front Microbiol. 2023 May 25:14:1171980. doi: 10.3389/fmicb.2023.1171980. eCollection 2023.

Authors

Gianmaria Oliva¹, Giovanni Vigliotta¹, Mattia Terzaghi^{1

2}, Francesco Guarino¹, Angela Cicatelli¹, Antonio Montagnoli³, Stefano Castiglione¹

Affiliations

¹ Department of Chemistry and Biology "A. Zambelli", University of Salerno, Fisciano, SA, Italy.
² Department of Biosciences, Biotechnologies and Environment, University of Bari "Aldo Moro", Bari, BA, Italy.
³ Department of Biotechnologies and Life Sciences (DBSV), University of Insubria, Varese, Italy.

Abstract

The salinization of soil is the process of progressive accumulation of salts such as sulfates, sodium, or chlorides into the soil. The increased level of salt has significant effects on glycophyte plants, such as rice, maize, and wheat, which are staple foods for the world's population. Consequently, it is important to develop biotechnologies that improve crops and clean up the soil. Among other remediation methods, there is an environmentally friendly approach to ameliorate the cultivation of glycophyte plants in saline soil, namely, the use of microorganisms tolerant to salt with growth-promoting features. Plant growth-promoting rhizobacteria (PGPR) can improve plant growth by colonizing their roots and playing a vital role in helping plants to establish and grow in nutrient-deficient conditions. Our research aimed to test in vivo halotolerant PGPR, isolated and characterized in vitro in a previous study conducted in our laboratory, inoculating them on maize seedlings to improve their growth in the presence of sodium chloride. The bacterial inoculation was performed using the seed-coating method, and the produced effects were evaluated by morphometric analysis, quantization of ion contents (sodium, potassium), produced biomass, both for epigeal (shoot) and hypogeal (root) organs, and by measuring salt-induced oxidative damage. The results showed an increase in biomass and sodium tolerance and even a reduction of oxidative stress in seedlings pretreated with a PGPR bacterial consortium (Staphylococcus succinus + Bacillus stratosphericus) over the control. Moreover, we observed that salt reduces growth and alters root system traits of maize seedlings, while bacterial treatment improves plant growth and partially restores the root architecture system in saline stress conditions. Therefore, the PGPR seed-coating or seedling treatment could be an effective strategy to enhance sustainable agriculture in saline soils due to the protection of the plants from their inhibitory effect.

Keywords: PGPR; ROS; antioxidant enzymes; root system; seed coating; soil salinization; sustainable agriculture.

Grants and funding

This research was funded by the University of Salerno/Department of Chemistry and Biology “A. Zambelli”. The titles of the financed projects are (Fondi di Ateneo per la Ricerca di Base-FARB): Effetti di consorzi batterici promotori della crescita delle piante su semenzali di mais e pomodoro coltivati in condizioni di elevate concentrazioni di sale (NaCl); Regolazione del metabolismo energetico in batteri ambientali di interesse biotecnologico; Studi omici (epigenomica e trascrittomica) in specie vegetali modello e di interesse agrario in risposta a stress abiotici e/o alle interazioni biotiche con batteri promotori della crescita (PGPR).