Enhancing Zea mays tolerance to drought and salinity: the contribution of plant growth-promoting bacteria from arid environments

• Autor(a) principal: Cruz, Catarina da Silva
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/36257
• topic: Plant growth-promoting bacteria; Zea mays; Drought; Salinity; Sustainability; Crop production; Arid regions

The major challenges to agriculture are related to climate change, such as the occurrence of drought events, soil salinization, floods and heat waves. Both drought and salinity are proven to reduce crop productivity and development, and are expected to worsen with climate change and anthropogenic activities. Plant growth-promoting bacteria (PGPB) are soil microorganisms reported to improve plant growth and productivity, and are able to increase plant resistance to environmental factors. Thereby, in the present work were isolated PGPB from Sal Island (Cape Verde), an island with low rainfall and recurrent drought and with a high maritime influence. Plant-growth promoting traits (siderophore, IAA and alginate production and phosphate solubilization) of all the strains were evaluated. Bacteria tolerance to drought and salinity was determined and the biochemical mechanisms triggered and drought and salinity were assessed. PGPB contribution on salt and drought stress alleviation was determined on a drought tolerant variety of maize, by analyzing physiological and biochemical changes between inoculated and non-inoculated plants. Exposure to drought resulted in higher lipid and protein damage in bacteria, with increased antioxidant response and osmolyte production. Bacterial inoculation mitigated drought effects on maize plants, by reducing protein carbonylation and by inducing osmolyte production, a crucial factor contributing to plant tolerance to drought. Moreover, the influence of bacterial inoculation on the antioxidant response also contributed to increase plant tolerance to drought. Exposure of bacteria and maize to salt stress evidenced higher PGP abilities under stress and the positive influence of PGPB on root growth, contributing to nutrient and water uptake by plants. Bacterial inoculation alleviated saline stress in maize plants, through the decrease in protein damage and increase of proline and protein production. PGPB emerges as an alternative that can further increase the tolerance of drought tolerant varieties to abiotic stresses such as drought and salinity and be of major value to protect plants from water scarcity, to increase water management efficiency, and to minimize yield losses, thus contributing to food security in a climate change scenario.