Scientists discover new drought-resilient wheat gene, suitable for drier soil conditions

A new drought-resilient semi-dwarf wheat gene which can be grown in drier soil conditions, discovered by an international team of scientists, has given new hopes of sowing the crop in water-limited environments.

Scientists at the John Innes Centre, in collaboration with an international team of researchers, discovered the new ‘reduced height’ or semi-dwarf gene called Rht13.

Reduced height gene means that seeds can be planted deeper in the soil, giving access to moisture, without the adverse effect on seedling emergence seen with existing wheat varieties.

The researchers published a study in the Proceedings of the National Academy of Sciences (PNAS) journal November 23, 2022. The study said varieties of wheat with the Rht13 gene could be rapidly bred into wheat varieties to enable farmers to grow reduced-height wheat in drier soil conditions.

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Since the 1960s and the Green Revolution, reduced height genes have increased global wheat yields because the short-stemmed wheat they produce puts more investment into the grains rather than into the stems and has improved standing ability.

However, these genes bred into wheat also have a significant disadvantage of not working in drought-like conditions. When these varieties are planted deeper to access moisture in water-limited environments, they can fail to reach the surface of the soil, the authors said.

The newly discovered gene overcomes this problem of seedling emergence because the gene acts in tissues higher-up in the wheat stem.

So, the dwarfing mechanism only takes effects once the seedling has fully emerged. This gives farmers a significant advantage when planting deeper in dry conditions.

“We have found a new mechanism that can make reduced-height wheat varieties without some of the disadvantages associated with the conventional semi-dwarfing genes. The discovery of the gene, its effects and exact location on the wheat genome, means that we can give breeders a perfect genetic marker to allow them to breed more climate-resilient wheat,” Philippa Borrill, John Innes Centre group leader and corresponding author of the study, said.

Experiments testing the effects of the gene in a range of transgenic wheat plants confirmed that the Rht13 variation represents a new class of reduced height gene—more commonly associated with disease resistance as opposed to widely used Green Revolution genes (Rht-B1b and Rht-D1b) which are associated with hormones and therefore affect overall growth.

“In dry environments, the alternative reduced height gene will allow farmers to sow seeds at depth—and not have to gamble on the seedlings emerging. We think the stiffer stems could result in less lodging—where stems fall over,” Borrill said.

The next step for this research will be to test how this gene works in diverse agronomic environments from the UK to Australia. Additionally, the study found that the new semi-dwarfing gene may be able to withstand stormier weather too. 

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