| Congresso Brasileiro de Microbiologia 2023 | Resumo: 13-1 | ||||
Resumo:Increasing rates of soil salinization due to anthropogenic activities and climate change imposes a threat to future food safety. Remediating salinized soils can be achieved through the cultivation of halophytes, a group of plants capable of growing under salt stress while accumulating salts in their aerial tissues, thus reducing salt content in soil. Within this group, Atriplex nummularia, popularly known as old man saltbush (or erva-sal, in Portuguese), flourishes under high drought and salinity levels, with increased phytoextraction levels. In addition to the intrinsic morphophysiological and biochemical traits of the halophytes, microbes are known to be able to confer tolerance to salinity and drought stresses in plants, representing a valuable yet underexplored avenue to increase the recovery of these areas. To better understand the effect of soil salinity on halophyte performance and microbiome composition, we performed a microcosm experiment using A. nummularia cultivated in two contrasting soil types (sandy and clay soils) at varying levels of soil salinity ranging from near absence to extreme saline levels (e.g., no NaCl addition (non-saline), 10 mS/cm (very strong salinity), and 20 mS/cm (extreme salinity)). We assessed the effect of salinity on bacterial community composition in the rhizosphere, as well as in the root and leaf endospheres using high-throughput sequencing of the bacterial 16S rRNA gene, and predicted functions related to plant growth promotion (PGP) and salinity tolerance in the rhizosphere microbiome. A. nummularia showed increased growth under salinity stress up to 20 mS/cm in two different types of soil. Along with this, rhizospheric communities were impacted by soil type and salinity, and this effect was largest in the sandy soils. Despite these major differences in rhizospheric soil, endophytic communities were no different between salinity levels, showing an environmental buffering effect, even though this plant accumulates NaCl in its tissues. We also showed that while no trends in PGP and salinity tolerance traits were found in the rhizosphere along this gradient, the subset of bacteria that responded to salinity stress enriched these functions in higher salinity levels, especially in sand soil. Altogether, these results broaden our understanding of the relationship among bacteria and plants under highly saline conditions, paving the way to effectively use microorganisms in biosaline agriculture. Palavras-chave: plant microbiome, endophytes, rhizosphere, microbiome assembly, salinity gradient Agência de fomento:ANP, CNPq, FAPERJ, CAPES | |||||