The genetics of boron tolerance in wheat

The identification of boron tolerance genes in wheat DNA is expected to lead to the development of wheat strains in which yield is not limited by boron concentration.

Boron is an essential nutrient for plant growth but too much can be toxic and boron toxicity is a significant yield-limiting soil condition found around the globe.

The scientists, from the University of Adelaide’s Waite campus, and their German colleagues tracked specific boron tolerance genes across the complex wheat genome - from wild wheats grown in the Mediterranean region, to wheat lines brought into Australia more than a century ago, to current-day Australian commercial varieties. They found a distinct pattern of gene variant distribution that was correlated to the levels of boron in soils from different geographical regions.

Genes that affect how boron uptake is regulated in wheat were identified, and tolerance to high boron was associated with multiple genomic changes such as tetraploid introgression, gene duplication and variation in gene structure and transcript levels.

“This means the researchers now have molecular markers that can be used in breeding programs to select lines for boron tolerance with 100% accuracy,” said project leader Dr Tim Sutton from the Australian Centre for Plant Functional Genomics at the University of Adelaide.

“In southern Australia, more than 30% of soils in grain-growing regions have too high levels of boron. It’s also a global problem, particularly in drier grain-growing environments. Boron-tolerant lines of wheat, however, can maintain good root growth in boron toxic soils whereas intolerant lines will have stunted roots.”

Such genetic variation could potentially be exploited for wheat improvement in regions of the world where yield is limited by boron concentration.

This study was published in Nature.