The synthetic deoxymugineic acid proline-2′-deoxymugineic acid enhances plant resilience to high-temperature stress. Image courtesy of Nature Communications (2025).
As rising temperatures become more common across wheat-growing regions, growers have seen firsthand how sustained heat can slow plant growth, bleach young leaves, and reduce yields. A recent study examining wheat and related cool-season grasses offers new insight into what drives this decline and where breeders and seed suppliers may find opportunities to improve heat resilience.
The research looked at wheat alongside Brachypodium distachyon, a model grass closely related to wheat. The work focused on moderate but prolonged heat similar to what many producers are experiencing during warmer growing seasons. Instead of short bursts of extreme heat, the plants were grown for weeks at daytime temperatures around 32 to 35 degrees Celsius.
Under these conditions, wheat seedlings showed slower growth and pale yellow young leaves. The study found that this response was tied to iron availability in the plant. Even though iron is present in most soils, wheat relies on a specific iron uptake system that becomes more strained under heat stress. When temperatures remained high for several weeks, the wheat plants had about half the iron in their leaves compared to plants grown under cooler conditions. This reduced iron limited photosynthesis and plant development, leading to lower biomass.
To better understand how some grasses tolerate heat better than others, the researchers compared two accessions of Brachypodium that differ in their response to high temperatures. The heat-tolerant type maintained better growth and greener leaves under high temperatures. It also released more of a natural compound from its roots that helps capture iron from soil. This compound, known as deoxymugineic acid, forms a complex with iron that the plant can then pull into the roots. The tolerant plants had stronger activation of genes involved in producing and releasing this compound, helping them maintain iron levels even when stressed.
The study identified a gene called TOM1 as a major factor in this heat response. The tolerant plants had a TOM1 version that provided more effective iron acquisition under heat. Plants lacking a functional TOM1 struggled to grow even under normal temperatures, but growth was restored when researchers supplied a synthetic version of the iron-chelating compound.
The researchers tested whether applying this synthetic chelating compound could help plants under heat stress. When wheat seedlings were treated during prolonged heat, they showed greener leaves, higher photosynthetic activity, and improved iron content. However, the study also cautioned that supplying too much available iron under sustained heat may trigger damaging oxidative reactions in the plant. The work suggests that the key is maintaining balanced iron levels rather than simply adding more iron fertilizer.
As heat stress becomes a more common concern in wheat production, this research points toward an approach that focuses on nutrient balance rather than only heat tolerance. For seed companies, selecting lines with improved iron uptake traits may play an important role in maintaining yields. For growers, it reinforces that nutrient efficiency under stress may be just as important as fertilizer supply itself.
The full study can be accessed here.