With barley shortage affecting the industry, sometimes, with unexpected rainfall, sprouting barley can also cause several issues, including low market value prices.

CRISPR decided to try something new. Pre-harvest sprouting can be avoided by prolonged grain dormancy through genetic manipulation. However, such dormancy can interfere with malt production and can also cause non-uniform germination upon sowing so finding a balance between the two is of vital importance.

Led by Associate Professor Dr. Hiroshi Hisano from Okayama University, Japan, a team of scientists have attempted to achieve the ‘perfect’ barley, looking to the latest gene manipulation technology—CRISPR/Cas9-based gene editing. “We recognized the need to strategically manipulate crops to weather the effects of steadily exacerbating climate change. Since our collaborative research group had already developed expertise in precision genome editing of barley, we decided to go with the same initially. Also, previous studies have pinpointed specific grain and seed dormancy genes in barley, called Qsd1, and Qsd2. Hence, our modus operandi was pretty clear,” said Dr. Hisano.

Dr. Hisano and his team genetically manipulated samples of ‘Golden Promise’ barley using CRISPR/Cas9 targeted mutagenesis, to be either single mutants (qsd1, or qsd2), or double mutants (qsd1 and qsd2). Then, they proceeded to perform germination assays on all mutants and non-mutated samples.

Subsequently, the results they obtained for mutants, when compared to non-mutants, was extremely interesting. All the mutants showed delayed germination, but there were mutant-specific or conditional properties. Germination of mutants was promoted by 3% hydrogen peroxide treatment; exposure of all mutants to cold temperatures largely promoted germination, indicating that the grains of the mutants were not dead but had been dormant longer. The qsd1 mutation in single mutants partially reduced long grain dormancy, owing to qsd2; and qsd2 mutants could germinate in the dark, but not in the light. Also, all mutants showed abscisic acid build-up, consistent with conditions observed with delayed germination. Notably, this abscisic acid build-up in itself cannot maintain long-term grain dormancy, the latter being important for high-quality barley production.

“We could successfully produce mutant barley that was resistant to pre-harvest sprouting, using the CRISPR/Cas9 technology. Also, our study has not only clarified the roles of qsd1 and qsd2 in grain germination or dormancy, but has also established that qsd2 plays a more significant role,” explains Dr. Hisano.

Photo courtesy of Dr. Hiroshi Hisano from Okayama University