Cadmium (Cd) contamination is a growing threat to food safety, and rice is one of the most vulnerable crops. Because rice plants can accumulate cadmium from contaminated soils more readily than many other staples, Cd can become a major dietary exposure route for large parts of the world’s population. Yet attempts to lower cadmium often create trade-offs—reducing uptake of essential nutrients or weakening plant performance.

A new study from Okayama University, Japan, and collaborating researchers in China reports a precision-editing strategy designed to avoid those trade-offs. The team focused on the rice metal transporter gene OsNramp5, which is known to move metals such as manganese and cadmium, and used base-editing to search for a beneficial point mutation within the gene rather than disabling it.

Using adenine and cytosine base editors, the researchers generated more than 1,600 genome-edited rice lines and screened them for reduced cadmium accumulation. Their saturation mutagenesis approach targeted OsNramp5 to identify variants that kept normal plant physiology while limiting Cd buildup in grain.

The key breakthrough was the I441T substitution: changing isoleucine to threonine at amino acid position 441. This single change reduced cadmium levels in both shoots and brown rice without altering gene expression, protein abundance, or the subcellular localization of the transporter.

Importantly, the mutation did not come at the cost of micronutrients. Field trials on cadmium-contaminated soil showed a 48% decrease in cadmium concentration in brown rice, from 0.14 mg/kg in wild type to 0.07 mg/kg in the edited plants, while iron, manganese, and zinc levels remained essentially unchanged.

The researchers then explored the mechanism behind the selective effect. Although OsNramp5 transports multiple metals, the I441T mutation shifted its selectivity—enhancing zinc transport preference. Increased zinc accumulation in root cells promoted competitive inhibition against cadmium during root-to-shoot movement.

Instead of completely blocking cadmium uptake, the edited transporter selectively limited cadmium translocation, reducing grain contamination while preserving essential mineral delivery. The team supported these conclusions with physiological assessments, gene and protein analyses, yeast transport assays, and agronomic evaluation.

Overall, the work demonstrates how precision genome editing can address a long-standing breeding challenge: lowering toxic metal accumulation without disrupting nutrient homeostasis. The researchers propose that the OsNramp5^I441T allele could accelerate development of safer rice varieties for mildly contaminated regions.

Subject of Research: Not applicable
Article Title: Genome-edited rice variety with low-cadmium accumulation in the grain
News Publication Date: 18-Jun-2026
Web References: http://dx.doi.org/10.1073/pnas.2610609123
References: DOI: 10.1073/pnas.2610609123 (Proceedings of the National Academy of Sciences)
Image Credits: Credit: Professor Jian Feng Ma from Okayama University, Japan

Keywords: cadmium, rice, OsNramp5, base editing, genome editing, metal transporters, food safety, micronutrients, zinc competition, plant breeding

Nitrogen is an essential building block of proteins, amino acids, and DNA. Without nitrogen, cells can’t function or reproduce. Nitrogen is abundant in the atmosphere as dinitrogen gas, but plants and animals can’t access atmospheric nitrogen. Instead, we rely on biologically available forms like ammonia and nitrate. 

Specialized microbes can transform atmospheric nitrogen into ammonia via a process called biological nitrogen fixation. Nitrogen-fixing soil bacteria have a unique protein complex, the nitrogenase complex, that facilitates this nitrogen transformation. The nitrogenase complex is activated by a group of genes known as nif genes. 

Legume plants like peanuts, peas, and beans have nitrogen-fixing bacteria in the soil zone around their roots, called the rhizosphere. The symbiotic relationship between nitrogen-fixing soil bacteria and legume plants supplies most of the biologically available nitrogen to life on Earth.

However, one piece of the puzzle remains unexplored: the role of soil viruses in these nitrogen transformations, referred to as the nitrogen cycle. Viruses are microscopic particles made up of genetic material and proteins, but they can’t reproduce without a host cell. Scientists consider viruses to be biological entities that are halfway between living and non-living.

To reproduce, viruses contact a host cell and inject their genetic material into it. The virus’s genetic material takes over the host cell’s genome and forces the cell to produce proteins that assemble into new viruses. As new viruses are created, they can incorporate genes from the host cell into their own genetic material. Genes that are transferred from a host cell to a virus are known as auxiliary metabolic genes (AMGs). Viruses can carry AMGs and pass them to other hosts or use them to increase their own ecological fitness. 

Scientists from China, Spain, and the Czech Republic set out to investigate whether viruses from legume roots could increase local soil nitrogen fixation by expressing nif AMGs or by transferring nif genes to other bacteria. First, they determined the global distribution of viral nitrogen-fixing genes by analyzing about 8.6 million viral genomes from the Integrated Microbial Genomes/Virus database. They looked for the DNA sequences of known nitrogen-fixing genes and the locations where the viruses were sampled. They found that only 0.003% of the viruses in the database had at least 1 nitrogen-fixing gene, but they clustered in the same locations as nitrogen-fixing bacteria. 

The team also found 3 types of viruses that most commonly carried nitrogen-fixing genes: Kyanoviridae, Nudiviridae, and Bronfenbrennervirinae. Kyanoviridae viruses carried a nif gene called nifU. The researchers used a computer program called DRAM-v to confirm that nifU was a fully functional gene and a real tool that viruses could use. 

Next, the team collected soil samples from a cowpea field in Nanjing, China, to test whether the cowpea roots influenced the abundance of viruses using nitrogen-fixing genes. They collected soil from the cowpea rhizospheres and soil away from the plants. They analyzed both viral and bacterial RNA in the soil samples to identify active genes, using a sequencing process called metatranscriptomics. They found that the viral nifU gene was actively expressed in the cowpea rhizosphere samples more than in the non-crop soil. Although about 96% of nifU genes were being expressed by bacteria, viruses contributed about 4%. 

The researchers then assessed whether rhizospheric viruses changed the amount of nitrogen being fixed in these soils. They set up small, enclosed containers of sterile soil and added either bacteria or a mixture of bacteria and viruses extracted from the cowpea rhizospheres. They found that soil with viruses had higher total nitrogen (36 milligrams per kilogram, or mg/kg) than soil without viruses (17 mg/kg). 

Finally, they adjusted the air in each container to have a different form of dinitrogen gas. Atoms of the same element that have different atomic masses are known as isotopes. Nitrogen has 2 stable isotopes: lighter nitrogen-14 and heavier nitrogen-15. Bacteria or viruses that fix nitrogen at natural isotope abundances will take up nitrogen-14. But scientists can track who in the population fixes nitrogen by adding nitrogen-15 to the air, a process called nitrogen-15 stable isotope probing. Nitrogen-fixers will incorporate the heavy nitrogen-15 into their biomass over time and increase their weight, allowing researchers to separate and identify them.

The team grew the bacteria and viruses with nitrogen-15 for 35 days, then used stable isotope probing to separate the nitrogen fixers. They detected viral nifU AMGs among the heavier biomass, confirming that rhizospheric viruses were fixing nitrogen. 

The team concluded that rhizospheric viruses and the viral nifU AMG can increase nitrogen fixation in cowpea soils. The team suggested that although viruses with nitrogen-fixing genes are rare, they can influence the soil nitrogen cycle. They recommended that future researchers further test the contribution of viral nifU genes to plant nitrogen fixation with controlled infection experiments.

The post Viruses help plants obtain nitrogen appeared first on Sciworthy.

Europe has relaxed its gene-editing rules after years of debate but kept strict checks on herbicide-tolerant crops. India eased its rules too but dropped an early warning about the trait, even as illegal seeds spread across cotton-growing States.

A whole-genome analysis of Beefalo, a hybrid bison-cattle breed, suggests very few individuals have any bison DNA at all, a new study reports.

Corn sweat (noun, “KORN SWET”)

Corn sweat is moisture released by cornfields during summer heat, particularly in the central United States. The scientific term for corn sweat is evapotranspiration. This process combines evaporation and transpiration. Those are both ways that water moves from the land into the air during Earth’s water cycle.

Evaporation happens when liquid water turns into water vapor and rises into the air. In the case of corn sweat, water evaporates from the surface of the soil in farm fields.

Transpiration is the movement of water from a plant’s roots to its surfaces. There, water vapor escapes through tiny holes on the stems and leaves. These tiny holes are known as stomata. Releasing water vapor through transpiration is an essential function for plants.

The amount of water that plants add to the atmosphere varies. But in places with lots of cornfields, corn sweat can cause a spike in local humidity. The U.S. Department of Agriculture estimates that corn sweat releases about 13,000 to 19,000 liters (3,500 to 5,000 gallons) of water per acre per day. That’s about a quarter of the water held in most swimming pools.

Corn sweat is often blamed for muggy summer weather. But the water released by crops during heat waves is only an estimated 2 to 5 percent of the total humidity.

In a sentence

Humidity from crops is often attributed to corn sweat, but soybeans transpire too.

Check out the full list of Scientists Say.

Salty soil, one of the greatest threats to agriculture, may have a new remedy in the form of naturally occurring soil bacteria that allow plants to thrive under harsh conditions.

An international team led by Dr. Yanfen Zheng at the Chinese Academy of Agricultural Sciences presented their findings on increasing plant survivability in inhospitable environments in a recent paper published in Science Advances.

In their research, the international team demonstrated that maize, tomato, and rapeseed thrived in soil that would typically be unusable due to a previously unknown mechanism in these microbes, in a breakthrough for agriculture.

Salt and Agriculture

“The build-up of salt in farmland is a major and worsening problem – driven by climate change, irrigation and rising sea levels,” said co-author Prof Jonathan Todd, from the University of East Anglia’s School of Biological Sciences and the Quadram Institute on the Norwich Research Park. “Salt chokes plant growth, damages roots, and severely impacts entire harvests – putting global food supplies at risk.”

Agricultural scientists have long known that root microbiomes, the community of microbes living among a plant’s roots, are important for dealing with environmental stresses, yet they remained uncertain of the mechanics involved.

“We found that plants appear to recruit beneficial bacteria in salty soil conditions, which in turn trigger internal changes that strengthen their physical structure and resilience,” Todd continued. “If scientists can harness this natural process, it could mark the beginning of a new era in climate-resilient agriculture.”

Investigating Plant Root Microbiomes

The international team examined a variety of plant root microbiomes across different soil types and plant species, identifying pseudomonads, a type of naturally occurring soil bacterium, that are drawn to the roots of maize, tomato, and rapeseed in heavily salted environments. By noting the commonality of high salt content across a variety of crops, the researchers concluded that this was more than a mere coincidence and decided to analyze the genetic mechanisms behind the bacterium’s behavior.

“Compared to other microbes, pseudomonads carry specialised genes that help them tolerate high salt levels, including sodium transport systems and other stress resistance mechanisms,” Todd said.

Next, the researchers introduced various pseudomonad strains to soybean plants in laboratory and real-world soil experiments and observed that the bacteria colonized plant roots, resulting in increased growth in harsh, salty environments. Those soybean plants that received the bacteria demonstrated stronger root systems, more advanced development, and higher yields than those without.

“The most surprising thing was finding out how the bacteria helped plants cope,” Todd said. “For decades, it was thought that plants survive salinity by controlling sodium levels – essentially keeping harmful salt out. But we found no evidence that bacteria influenced sodium transport or ion balance.”

Lignin and Salt

“Instead of helping plants manage salt directly, the bacteria stimulated the plant to produce more of a substance called lignin,” Todd continued. “Roots of bacteria-treated plants showed a significant increase in lignin content, with some measurements rising by over 30 percent under salt stress.”

The tough, wood-like lignin acted as a shield against the salt, strengthening delicate tissues to endure a challenging environment. Unfortunately, in plants that couldn’t produce lignin, the pseudomonads produced no benefit. Building on the discovery, the researchers identified the genes in the plants involved in lignin synthesis and artificially overexpressed them to successfully confer salt resilience.

“We hope this discovery opens up new possibilities for agriculture,” Todd concluded. “With vast areas of farmland already affected by salinity and more under threat, microbial solutions could become an essential tool for maintaining crop yields and ensuring food security.”

The paper, “Pseudomonads Associated with Salt-Stressed Plants Facilitate Stress Adaptation of Soybean through Enhanced Lignin Biosynthesis,” appeared in Science Advances on June 24, 2026.

Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.