EN 
PT_BR 
A study conducted by Embrapa in partnership with Brandeis University In the United States, researchers discovered that extremophilic archaea (a group of microorganisms distinct from bacteria and adapted to extreme conditions) can increase corn's tolerance to excessive soil salinity, allowing plants to grow vigorously even under saline stress conditions. The researchers demonstrated that the archaea colonize the rhizosphere, the region of soil surrounding the roots, characterized by intense chemical and biological exchanges. The study was published in the journal Environmental Microbiome. .
The microorganisms were isolated from the plant's roots. Triplex nummularia , naturally adapted to salinity and used in the phytoremediation of saline soils. After cultivation in the laboratory, they were evaluated in corn plants. This crop is strategic for food production and highly sensitive to soil salinity, which compromises plant growth and reduces productivity.
In experiments conducted under controlled conditions, researchers observed that, under saline stress, archaea reduced the toxic effects of salt, allowing corn to maintain more vigorous growth and greater physiological tolerance than plants that were not treated with archaea.
Analysis by qPCR (a molecular technique to detect the quantity of microorganisms present in a sample) of the archaeal-specific 16S rRNA gene confirmed successful colonization. The abundance of microorganisms in the maize rhizosphere increased proportionally to the increase in soil salinity.
Complete genome sequencing has identified genes associated with the production of phytohormones (plant hormones), such as auxins, and osmoprotectants, substances that help maintain cellular water balance in saline environments. The discovery highlights the potential of archaea to interact with the plant and mitigate osmotic stress caused by salt. In experiments, the presence of microorganisms increased biomass and maintained chlorophyll levels even under high salt concentrations.
The results highlight the technology's potential to increase the stability of food production in areas affected by salinization. Unlike bacteria, which are the best-known organisms, archaea belong to their own domain of living organisms and are notable for their high resistance to extreme chemical conditions.
Potential of biotechnology
Second Itamar Melo , researcher at Embrapa Environment The researcher who coordinated the study stated that salinized soils are frequently excluded from agricultural production and become a significant environmental liability, given the limited number of effective technologies for their recovery. He emphasizes that major commercial crops are sensitive to excessive salinity, further limiting the use of these areas.
According to him, the use of these microorganisms adapted to saline environments, which co-evolved with halophytic plants (plants naturally tolerant to salt), emerges as an alternative to reduce the damage caused by salinity and enable cultivation in soils previously considered unproductive. “The problem is not limited to the Brazilian Semi-Arid region, where approximately 30% of irrigated areas are affected by salinization. It is present in various regions of Brazil and the world.”
Melo points out that the situation worsens in areas with high evaporation rates and inadequate management practices, such as irrigation with brackish water. "In this context, microbial inoculants based on archaea represent a promising innovation in the field of bio-inputs and can open new possibilities for agriculture in degraded areas."
Researcher João Paulo Ventura, affiliated with Embrapa Meio Ambiente, where he completed his doctorate, led the research, conducting the experiments and analyzing the study's data. According to him, the findings could change the way science views these microorganisms.
According to Ventura, the study demonstrates that archaea are not only capable of surviving in extreme environments, but can also become strategic allies for sustainable agriculture. Until now, the interactions between plants and archaea were poorly understood and rarely studied, largely due to the difficulties involved in cultivating these microorganisms in the laboratory.
The researcher states that experiments have shown that, when inoculated, archaea establish a competitive and successful colonization of corn roots. "The abundance of these microorganisms increases as soil salinity levels increase, indicating their adaptability to adverse conditions and their potential use in salinity-affected areas."
According to him, the discoveries redefine the role of these organisms. "Previously considered microbiological curiosities associated with extreme environments, archaea are now beginning to be seen as practical biotechnological tools with the potential to support agricultural productivity and contribute to food security in areas affected by salinization and climate change," he states.
Practical applications in the field
In the short term, the results suggest potential for testing under real production conditions. Bioinoculants produced from archaea isolated from naturally saline environments or from microbial consortia adapted to this stress could be evaluated for application to seeds or directly to the soil before sowing.
The hypothesis is that the strategy will help crops such as corn, beans, and vegetables maintain their productive performance in areas irrigated with brackish water, a common situation in the semi-arid Northeast of Brazil. When integrated with already established management practices—such as crop rotation with halophytes (species adapted to high salinity environments), no-till farming, and balanced fertilization, for example—microbial inoculation can reduce the effects of salinization on crops, increase the resilience of agricultural systems, and contribute to food security and rural income.
