PHS gene prevents wheat from sprouting: Fewer crop losses anticipated

Preharvest sprouting can cause significant losses in wheat crops, particularly in white wheat crops. Credit: Kansas State University Photo Services

A new study about the common problem of preharvest sprouting, or PHS, in wheat is nipping the crop-killing issue in the bud.

Researchers at Kansas State University and the U.S. Department of Agriculture-Agricultural Research Service, or USDA-ARS, found and cloned a gene in wheat named PHS that prevents the plant from preharvest sprouting. Preharvest sprouting happens when significant rain causes the wheat grain to germinate before harvest and results in significant crop losses.

"This is great news because preharvest sprouting is a very difficult trait for wheat breeders to handle through breeding alone," said Bikram Gill, university distinguished professor of plant pathology and director of the Wheat Genetics Resource Center. "With this study, they will have a gene marker to expedite the breeding of wheat that will not have this problem."

Gill conducted the study with Guihau Bai, a researcher with the Hard Winter Wheat Genetics Research Unit of the USDA-ARS, adjunct professor of agronomy at Kansas State University and the study's lead author. Also involved were Harold Trick, professor of plant pathology; Shubing Liu, research associate in agronomy; Sunish Sehgal, senior scientist in plant pathology; Jiarui Li, research assistant professor; and Meng Lin, doctoral student in agronomy, all from Kansas State University; and Jianming Yu, Iowa State University.

Their study, "Cloning and Characterization of a Critical Regulator for Pre-Harvest Sprouting in Wheat," appears in a recent issue of the scientific journal Genetics.

The finding will to be most beneficial to white wheat production, which loses $1 billion annually to preharvest sprouting, according to Gill.

He said consumers prefer white wheat to the predominant red wheat because white wheat lacks the more bitter flavor associated with red wheat. Millers also prefer white wheat to red because it produces more flour when ground. The problem is that white wheat is very susceptible to preharvest sprouting.

"There has been demand for white wheat in Kansas for more than 30 years," Gill said. "The very first year white wheat was grown in the state, though, there was rain in June and then there was preharvest sprouting and a significant loss. The white wheat industry has not recovered since and has been hesitant to try again. I think that this gene is a big step toward establishing a white wheat industry in Kansas."

Gill said identifying the PHS gene creates a greater assurance before planting a crop that it will be resistant to preharvest sprouting once it grows a year later. Wheat breeders can now bring a small tissue sample of a wheat plant into a lab and test whether it has the preharvest sprouting resistance gene rather than finding out once the crop grows.

Much of the work to isolate the PHS gene came from Gill and his colleagues' efforts to fully sequence the genome -- think genetic blueprint -- of common wheat. Wheat is the only major food plant not to have its genome sequenced. The genome of wheat is nearly three times the size of the human genome.

Researchers were able to study sequenced segments of the common wheat genome and look for a naturally occurring resistance gene. Gill said without the sequenced segments, finding the PHS gene would have been impossible.

Source: Kansas State University

Improving taste of alcohol-free beer with aromas from regular beer

Some aromatic substances from alcoholic beer can be extracted and added to alcohol-free varieties.

Consumers often complain that alcohol-free beer is tasteless, but some of the aromas it is lacking can be carried across from regular beer. Researchers from the University of Valladolid (Spain) have developed the technique and a panel of tasters has confirmed its effectiveness.

The alcohol in beer acts as a solvent for a variety of aromatic compounds; therefore, when it is eliminated, as in non-alcoholic beers, the final product loses aromas and some of its taste. It is difficult to recover these compounds, but researchers from the University of Valladolid have done just this using a pervaporation process.

"This technique consists in using a semipermeable membrane to separate two fractions from alcoholic beer: one liquid phase in which alcohol is retained, and another gaseous phase, where the aromatic compounds come in," Carlos A. Blanco, one of the authors explains. "Then, this gaseous phase can be condensed, the aromatic compounds extracted and added to non-alcoholic beer."

To conduct the study, the scientists used a special beer (with 5.5% alcohol) and another reserve beer (6.5%) from which they extracted three aromatic compounds: ethyl acetate, isoamyl acetate and isobutyl alcohol. They then added these substances to two 'almost' alcohol-free beers on the market: low-alcohol beer (less than 1% ABV) and alcohol-free beer (less than 0.1% ABV)..

A panel of experts tasted them. 90% of tasters preferred enriched low-alcohol beer instead of their original factory counterparts, and this percentage rose to 80% for alcohol-free beer. The figures have been published in the 'Journal of Food Engineering'.

"In light of these results, we conclude that the taste is improved, and thus the quality of this 'alcohol-free' beer, as the majority of panellists preferred the beer with aromas to the original," Blanco confirms.

The researchers recognise that this technique cannot yet capture all the aromas and tastes associated with alcoholic beer, but it does show progress in making 'alcohol-free' varieties more palatable for the consumer.

Spain is the primary producer and consumer of alcohol-free beer in the European Union. Around 13% of the beer sold in this country is alcohol-free, consumption of which has increased in recent years due to driving restrictions and for health reasons.

Source: Plataforma SINC