by Pat Hayes, OSU Barley Breeding Rock Star
The answer today is most likely “no”. But it could well be a resounding “yes” in a few years. So cheers, and here’s how to be in the know when the opportunity comes.
Let’s start with the word “facultative”, since it is tied directly to the looming specter of our times: climate change, and its evil henchman climate volatility. As you’ve all experienced these last few years, the weather is increasingly moody. That wreaks havoc on barley planting, growth and harvest. And when the barley isn’t what it should be, the barley-malt-beer/spirits supply chain breaks down. Barley can do a lot of great things in terms of providing for human health and happiness, but fixing climate change isn’t one of them. That one’s too big even for barley. But at least we can at least give our farmers tools for dealing with volatility.
Planting date options give growers tools to deal with volatility. Too wet to plant in the fall? Plant your facultative variety in the spring. Late thaw? Fall plant that facultative. Mid-winter thaw? No-till in February! The beauty of it all is that with a facultative it is the same variety, planted whenever, and the maltster /brewer/distiller know what to expect.
How can you plant the same variety fall or spring, you may ask, since spring barley varieties will die over the winter from cold while winter varieties won’t flower if planted in the spring, due to vernalization requirement. (Vernalization requirement refers to “cold units” required to progress from a vegetative to a reproductive state.) That’s where facultative varieties come in: they have the genetic circuitry to be cold tolerant, but they don’t require vernalization to flower. Instead, they are sensitive to the number of hours of daylight per day. They won’t flower until there are around 11 hours of daylight (the exact number of hours can be variety dependent). Even with climate change, daylength won’t change. Vernalization requirement, on the other hand, was a useful tool for keeping plants in a vegetative condition when it got cold and stayed cold. But anymore, we have episodes of cold and thaw. The worst case scenario: the vernalization requirement is met by January; a thaw comes, the barley thinks it is spring and transitions to flowering, only to be hammered by below zero temperatures in February. The facultative with photperiod sensitivity, on the other hand, remains vegetative until later in the season, when the greatest risk from low temperature injury is past.
Breeding for facultative growth habit in barley is relatively straightforward, given knowledge of the underlying genetics. A natural deletion of a gene in the vernalization pathway, plus a naturally occurring variant at a photoperiod sensitivity gene, plus a complete and inducible low temperature tolerance pathway is all it takes. But even with complete genetic information at hand, it still helps to accelerate the breeding process. That’s where doubled haploids come into the picture.
Doubled haploids are sex cells, e.g. pollen grains, turned into plants. The technique requires skill and tissue culture facilities but is worth every bit of effort due to the time savings achieved in developing new varieties. Here’s an example of how it works. Say you want to combine the cold tolerance of a winter variety (example Violetta) with the agronomic performance and flavor of a spring variety (example Full Pint). You make a cross by removing the anthers from the flowers of one variety (say Violetta) to turn it into a female and transfer pollen from Full Pint (the male). The resulting seed is called the “F1” generation (which stand for first filial, not formula one). Each F1 plant will produce around 300 anthers, each of which contains thousands of pollen grains (the haploid generation). The F1 anthers are transferred to a series of tissue culture media and along the way the chromosome number spontaneously doubles, producing doubled haploids. Each doubled haploid plant is completely homozygous (true breeding) and each doubled haploid plant is genetically unique and distinct from its brothers and sisters.
Among the doubled haploids produced from the cross of Violetta x Full Pint, one could select a semi-dwarf, high yielding, facultative variety with Full Pint flavor. In fact, we are in the process of doing just that. The doubled haploids were started from the F1 of Violetta x Full Pint in the fall of 2012; they were in head rows harvested in 2013 and in yield trial plots harvested in 2014. Malting quality data, as well as heaps of information on facultative barley and doubled haploids, are posted at www.barleyworld.org. The first pilot brews could come from the Oregon State University malt lab and brewery in 2016. Stay tuned for the “Full Violet” flavorful facultative barley malt. Coming soon to a pint near you.