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Shorter wheat gene offers benefits over Green Revolution varieties

Research Digest

A new mechanism that can reduce the height in wheat, without the disadvantages of the genes currently used, has been discovered by an international team of researchers, led by the John Innes Centre (JIC).

Dr Philippa BorrillGroup Leader Designing Future Wheat, Genes in the Environment
Dr Philippa Borrill, Group Leader, Designing Future Wheat, Genes in the Environment

Reduced height genes have increased global wheat yields because the plant puts more investment into the grains rather than into the stems, and the shorter stems also improve standing ability. The disadvantage is that if these varieties are planted deeper to access moisture in water limited environments, they can fail to reach the surface of the soil.

The newly discovered Rht13 dwarf gene overcomes this problem. The gene acts in tissues higher up in the wheat stem, so, the dwarfing mechanism only takes effect once the seedling has fully emerged. This gives farmers a significant advantage when planting deeper in dry conditions.

Other benefits of the new semi-dwarfing gene may include stiffer stems, making it better able to withstand stormier weather.

Perfect genetic marker for breeders

Varieties of wheat with the Rht13 gene could be rapidly bred into wheat varieties and give breeders a perfect genetic marker to allow them to breed more climate-resilient wheat according to  group leader Dr Philippa Borrill corresponding author of the study, which appears in the Proceedings of the National Academy of Sciences (PNAS).

The discovery of the Rht13 dwarfing gene was made possible by recent advances in wheat genomic research, principally the publication in 2020 of the Pan Genome, an atlas of 15 wheat genomes collected from around the world.

Earlier studies had identified the Rht13 locus – the region of DNA – as located on chromosome 7B on the wheat genome but the underlying gene had not been identified.

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.

Drought resilience improved by new wheat gene

“This is an exciting discovery because it opens a new way to use these autoactive NB-LRR genes in breeding in agriculture,” explains Dr Borrill. “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 – and the upregulation of a pathogen related dwarfing gene may help to enhance resistance response to certain pathogens.”

Next steps

The next step for this research will be to test how this gene works in diverse agronomic environments from the UK to Australia. The research team are also investigating how the mechanism works and are exploring the hypothesis that it may be down to molecular restrictions on the cell wall preventing elongation.

The paper ‘An autoactive NB-LRR wheat gene causes Rht13 dwarfism in wheat’ appears in PNAS.

The paper

An autoactive NB-LRR gene causes Rht13 dwarfism in wheat – Philippa Borrill, Rohit Mago, Tianyuan Xu, Wolfgang Spielmeyer – Proceedings of the National Academy of Sciences (PNAS) November 23, 2022