It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Thursday, November 06, 2025
Genetic variants fine-tune grain dormancy and crop resilience in barley
Summary author: Walter Beckwith
American Association for the Advancement of Science (AAAS)
New research reveals how genetic changes in the barley MKK3 gene fine-tune seed dormancy, determining whether grains stay dormant or sprout too soon. The findings offer breeders new genetic tools to balance seed dormancy and crop resilience under changing climate conditions. The rise of agriculture was driven by the intentional selection of crops with improved traits. One key trait under selection, particularly in cereal crops, is grain dormancy – the period before which a seed can germinate. In wild cereals, grain dormancy helps ensure plant survival under unpredictable conditions. During domestication, human selection shortened dormancy enabling quick and uniform crop establishment and greater yield. However, shorter dormancy also makes modern cereals like barley more vulnerable to pre-harvest sprouting (PHS), where grains germinate prematurely during warm, wet weather, which can lead to major agricultural losses. As global temperatures rise and extreme weather becomes more frequent, the incidence of PHS and associated crop loss will likely increase.
Despite the importance of grain dormancy to global food security, the evolutionary and molecular mechanisms underlying this trait remain poorly understood. Previous research has shown that variation in the Mitogen-activated protein kinase kinase 3 (MKK3) gene plays a major role in controlling grain dormancy. Morten Jøgensen and colleagues investigated genetic variation in MKK3 across wild and domesticated barley and found that slight amino acid changes in the MKK3 protein lead to big differences in dormancy and PHS resistance. Detailed genetic and molecular analyses revealed that domesticated barley, unlike its wild ancestor, often carries multiple copies of the MKK3 gene, and that this copy number variation in combination with amino acid changes that alter kinase activity is what fine-tunes grain dormancy traits in barley. According to the findings, distinct MKK3 haplotypes have evolved around the world in response to local climates and agricultural practices. For example, hyperactive variants emerged in northern Europe, where barley with low dormancy was favored for malting and beer brewing, while more dormant types persisted in humid and monsoon-prone regions of East Asia to prevent PHS. Although certain MKK3 haplotypes have become regionally prominent by enhancing productivity and grain quality for certain uses and within certain growing conditions, their genetic complexity poses challenges for traditional crossbreeding programs. Jørgensen et al. note that this illustrates the value of pangenomic approaches in identifying variants that could, when introduced into modern genotypes, promote sustainable and resilient crops under changing climate conditions.
Models that inform how magma moves and volcanic eruptions unfold may need an update, according to a new study. It reports that gas bubbles in magmas can form through the mechanical forces of shear as magmas flow and deform– a new physical mechanism for magma bubble nucleation that challenges conventional degassing models. The formation of gas bubbles within magma – also known as nucleation – is a fundamental process that shapes how volcanic eruptions unfold. The timing and rate at which these bubbles appear and expand influences key magma features, including its buoyancy, viscosity, and explosive potential. Understanding nucleation is therefore vital for building accurate models of magma movement and predicting eruptive styles. Traditionally, bubble nucleation has been attributed mainly to depressurization as magma rises to the surface, which causes dissolved gases like water vapor and carbon dioxide (CO2) to separate from the mix. Although these bubbles can form spontaneously, it’s thought that they usually form more easily on tiny mineral crystals within the magma, which act as microscopic catalysts for nucleation within magmatic reservoirs and conduits.
Here, Olivier Roche and colleagues investigated a new way that gas bubbles might form in magma. Instead of focusing on decompression as the trigger, Roche et al. propose that the mechanical energy from shear forces, created as magmas move, can also drive bubble nucleation. In a series of laboratory experiments, the authors observed bubble formation in a pressurized molten polymer infused with dissolved CO2 – an analog for magma – as different shear rates were applied to the liquid. They found that, while some bubbles formed naturally, most bubbles formed after shear was applied, especially in regions where shear stress was the strongest, and that the required shear stress needed to trigger nucleation decreased as dissolved CO2 content within the liquid increased. Overall, the findings demonstrate that viscous shear – a mechanical force common in flowing magmas – can supply the energy needed to trigger bubble formation without a reduction in pressure. Moreover, sudden mechanical shocks to the liquid resulted in rapid, widespread nucleation, further illustrating that deformation and motion within magma can actively drive bubble formation. Roche et al. use theoretical and computational models to show that shear-induced nucleation can occur naturally in volcanic conduits, especially in high-viscosity magmas, and that it may be enhanced by magma decompression during ascent. According to the authors, shear could promote efficient degassing and explain why highly-viscous, gas-rich magmas can sometimes erupt quietly and effusively, and without explosive fragmentation.
Ice coverage in the Arctic sea is rapidly declining, which causes the remaining ice to melt faster and alters nutrient availability. In a University of Washington-led study, researchers show how particles from space can help recreate ice conditions over the past 30,000 years.
Arctic sea ice has declined by more than 42% since 1979, when regular satellite monitoring began. As the ice grows thinner and recedes, more water is exposed to sunlight. Ice reflects sunlight but dark water absorbs it, advancing warming and accelerating ice loss. Climate models indicate that the Arctic will see ice-free summers within the coming decades, and scientists still aren’t sure what this will mean for life on Earth.
Researchers have known for some time that fine-grained dust from space blankets the surface of Earth, falling from the cosmos at a constant rate and settling into ocean sediments. A study published Nov. 6 in Science shows that tracking where cosmic dust has fallen — and where it hasn’t – can reveal how sea ice coverage has changed over millennia.
“If we can project the timing and spatial patterns of ice coverage decline in the future, it will help us understand warming, predict changes to food webs and fishing, and prepare for geopolitical shifts,” said Frankie Pavia, a UW assistant professor of oceanography, who led the study.
Cosmic dust swirls through space after stars explode and comets collide. Passing the sun, cosmic dust is implanted with a rare form of helium — helium-3. Scientists measure helium-3 to distinguish cosmic dust from earthly debris.
“It’s like looking for a needle in a haystack,” Pavia said. “You’ve got this small amount of cosmic dust raining down everywhere, but you’ve also got Earth sediments accumulating pretty fast.”
In this study, Pavia was more interested in the absence of cosmic dust.
“During the last ice age, there was almost no cosmic dust in the Arctic sediments,” he said.
The researchers hypothesized that cosmic dust could stand as a proxy for ice before there were satellites to monitor changes in coverage. Ice at the sea surface blocks cosmic dust from reaching the seafloor, while open water allows cosmic dust to settle into sediment. By analyzing the amount of cosmic dust in sediment cores from three sites, researchers reconstructed the history of sea ice for the past 30,000 years.
The three sites featured in the study “span a gradient of modern ice coverage,” Pavia said. The first, located near the North Pole, is covered year-round. The second borders the edge of the ice during its annual low in September, and the third was ice-bound in 1980 but is now seasonally ice-free.
The researchers found that year-round ice coverage corresponded with less cosmic dust in the sediment. This was also observed during the last ice age, around 20,000 years ago. As Earth began to thaw, cosmic dust once again appeared in samples.
The researchers then matched ice coverage to nutrient availability, showing that nutrient consumption peaked when sea ice was low and decreased as ice built up.
The data on nutrient cycling comes from tiny shells once occupied by nitrogen digesters called foraminifera. Chemical analysis of these organisms’ shells shows what percentage of the total available nutrients were consumed when they were alive.
“As ice decreases in the future, we expect to see increased consumption of nutrients by phytoplankton in the Arctic, which has consequences for the food web,” Pavia said.
Additional research is needed to show what is driving changes in nutrient availability. One hypothesis suggests that sea ice decline increases the amount of nutrients used by surface organisms because there is more photosynthesis, but another argues that nutrients are diluted by ice melting.
Both scenarios present as more consumption, but only the first indicates an increase in marine productivity.
Ice coverage in the Arctic sea is rapidly declining, which causes the remaining ice to melt faster and alters nutrient availability. In a University of Washington-led study, researchers show how particles from space can help recreate ice conditions over the past 30,000 years.
Ice coverage in the Arctic sea is rapidly declining, which causes the remaining ice to melt faster and alters nutrient availability. In a University of Washington-led study, researchers show how particles from space can help recreate ice conditions over the past 30,000 years.
Ice coverage in the Arctic sea is rapidly declining, which causes the remaining ice to melt faster and alters nutrient availability. In a University of Washington-led study, researchers show how particles from space can help recreate ice conditions over the past 30,000 years.
A new record of Arctic sea-ice coverage – informed by the slow and steady sedimentation of cosmic dust on the sea floor – reveals that ancient ice waxed and waned with atmospheric warming, not ocean heat, over the last 300,000 years. The findings provide rare insights into how modern melting in the region could reshape the Arctic’s nutrient balance and biological productivity. The Arctic is warming more rapidly than any other region on Earth, driving a precipitous decline in sea ice coverage. This loss not only affects the region’s marine ecosystems and coastal communities, but it also has far-reaching implications on global climate and economics. However, predicting when the Arctic Ocean will become perennially ice-free remains uncertain due in large part to the general lack of long-term sea ice records and the fact that the processes controlling ice loss are not fully understood.
To address this gap and measure the abundance of sea ice over the past 300,000 years, Frank Pavia and colleagues developed a new geochemical technique using two naturally occurring isotopes – extraterrestrial helium-3 (3HeET) and thorium-230 (230Thxs,0) – preserved in Arctic Ocean sediments. Under ice-free conditions, both isotopes settle onto the seafloor at steady, predictable rates, but they originate from very different sources. Helium-3 arrives from space, delivered uniformly to Earth’s surface by a constant influx of cosmic dust particles. In contrast, thorium-231 is produced consistently within the ocean as dissolved uranium decays. During open water conditions, both isotopes accumulate together. However, during periods of sea-ice cover, the deposition of helium-3 is blocked, altering the ratio of the two isotopes accumulating on the sea floor. Pavia et al. use the ratio of these two isotopes in Arctic sediment cores to measure when and where ocean surface was covered by ice in the past. The record shows that during the last ice age, the central Arctic Ocean remained covered by sea ice year-round. As the Arctic began to warm ~15,000 years ago, ice started to retreat, leading to mostly seasonal sea ice during the warm early Holocene. Later, as the global climate cooled again, sea-ice cover expanded once more. According to the authors, these changes were driven mostly by atmospheric warming, rather than ocean temperatures, challenging assumptions that oceanic inflows of warm water dominated past Arctic sea-ice extent. What’s more, Pavia et al. found that sea ice variation was closely coupled with biological nutrient use, suggesting that as sea ice retreats, surface productivity increases. These findings indicate that future reductions in Arctic sea ice are likely to enhance biological nutrient consumption, with implications for long-term marine productivity in a warming Arctic Ocean.
