The Promise of Hop and Barley Breeding

World opinion about climate change has shifted dramatically since the turn of the millennium. While only a decade ago there were still many politicians and even scientists who insisted that climate change was a hoax and not happening, there is now a near universal consensus that climate change is already upon us and that it presents a serious threat to the survival of all wild and domesticated flora and fauna on earth. Species extinctions are now rapidly accelerating, because environments are changing faster than the very plants and creatures that have lived there for centuries can adapt; and many habitats are becoming simply too inhospitable to support life as we know it... unless humans change their carbon-powered modern lifestyle immediately, which appears not very likely. 

The role of modern genetics in the breeding of crops

Climate change, therefore, is jeopardizing the entire human food chain; and that includes our agricultural raw materials for beer making; and many climate prognoses seem rather dire nowadays. However, there is one ray of hope; and that is our ability to breed new, climate-hardy crops based on cutting-edge technologies. These have become available only recently because of enormous advances in genetics. Fortunately, we still have access to a huge variety of genes that reside in modern domesticated crops and in several revived heirloom varieties. In addition, we can use genes of their wild progenitors and even of extinct species whose genetic materials are preserved and carefully kept viable in seed banks around the world. These sources provide a repository of genetic diversity that allows us to develop new cultivars with enhanced resistances to various new stresses from the weather and parasites. We are also lucky that the number of genes that plants carry in their genomes usually range in the thousands. The strawberry genome ranks at the very top, with more than 100,000 genes, while a typical hop variety contains an estimated 75,000 genes; and a barley genome, around 30,000 to 45,000 genes.

Geneticists are now making dramatic progress not only in identifying and naming all of these genes but also in linking many of them to specific, observable phenotypical traits, that is, to their gene expression. In addition, they have been able to pinpoint the precise locations of many genes within the structure of a plant’s genetic material. Given the fact that many species, including hops and barley, have evolved into many species in many terroirs—either through deliberate human selection, through natural mutations and adaptations, or through both—the opportunity for crossbreeding new varieties with particular traits through targeted, marker-guided hybridizations is sheer infinite. Faced with climate change, therefore, the goal of breeders is to create new plants with greater nutrient efficiency, drought resistance, and pathogen tolerance, while also ensuring high agronomic yields.

Nature, Targeted Hybridization, and Generic Modification: A Clarification

Technically, one can argue that all these efforts amount to genetic engineering. However, there seem to be differences in the ethical and political-legal evaluation of the results, mostly based on the processes employed to create them. Simple hybrids, for instance, tend not to be considered problematic, because such crosses can also occur in nature without any human participation. But the issue becomes more problematic, some argue, when breeders move beyond hybridizations to selectively add desirable genes or delete undesirable ones, instead of mixing entire gene sets from several sources in hopes of obtaining a favorable gene combination in the offsprings. But legislatures around the world have generally shied away from regulating the farming and use of such plants. The next level of genetic manipulation, however, the creation of so-called genetically modified organisms (GMOs), has become a political and philosophical flashpoint, in part because they can include the development of organisms that could not possibly have been produced by nature.

Not surprisingly, governments are struggling to find the right approach to GMOs. In the Unites States, for instance, law makers have adopted a relatively relaxed view, arguing that the composition of such organisms is not fundamentally different from that of conventional ones. The European Union, on the other hand, takes a much more restrictive approach, arguing that the potential risks of GMOs to the environment and to human health cannot be completely known. Thus, the process of creating GMOs in the EU is strictly regulated. It requires that breeders and users of new organisms, which they have on the genetic “drawing boards,” need to err on the side of caution. Thus, they must provide regulators with proof in advance that the organisms are safe, especially if they are intended for the human food chain.

The Process of Developing a New Hop Variety

It is generally understood that the hop bine originated in eastern Asia and that it migrated from there into several directions, where it adapted to different terroirs. Thus, there is a wild variety, H. lupulus cordifolius, that is native to Japan. Likewise, with the emergence of Beringia—the temporary land bridge between Asia and North America—Humulus crossed into the New World and diverged there into three native varieties. These are H. lupulus neomexicanus with its primary habitat in the Cordillera Mountain chain along the Pacific Coast of Canada the United Sates; H. lupulus pubescens, which took up residence in the midwestern United States and the Canadian Prairies; and H. lupulus lupuloides, which settled in central and eastern North America. Finally, a fifth branch, H. lupulus lupulus, migrated from Asia westward through the Caucasus Mountains to Europe, where it became the progenitor of most of the hop cultivars we now use for brewing. 

While none of the wild offshoots of Humulus are suitable for beer making because of their unpleasant bitterness and aroma, they contain nonetheless many useful resistance genes that are not found in our domesticated varieties. This turns them into attractive gene pools for composing new climate-hardy varieties. This, however, is nothing new because crossings between wild and domesticated hop varieties have occurred in nature for centuries. Cluster, for instance, is a hop still used by brewers today. Most experts believe that it is the result of a pollination by indigenous wild hops of a European variety cultivated by English and Dutch settlers.

The Suntory Global Innovation Center in conjunction with the Czech Hop Research Institute published the first genome blueprint of a hop variety, Saaz, in 2015; and progress in genome-sequencing of many other varieties has been brisk since then. While it is not clear how many wild, feral, and domesticated hop varieties exist today, there is agreement that some 250 to 300 hop varieties are currently commercially available; and each has its own specific gene set. Thus, the number of genetic hybrids that hop breeders can create is theoretically endless and is limited in practice only by the high cost of crossing, testing, and selecting new foundation rhizomes over successive plant generations. As experience has shown, it currently takes an average of a decade to move a new variety from the lab to commercial cultivation.

The Process of Developing a New Hop Barley Variety

Work on the first genome sequencing of barley was started by the International Barley Genome Sequencing Consortium in 2006, and it is still a work in progress. Nonetheless, just as in hops, breeders are rapidly acquiring an increasingly sophisticated set of tools to precisely locate and identify the genes of an estimated 4,000 barley varieties worldwide and to assess their characteristics and functions. This will enhance our ability to purposefully assemble new genomes of new plants that we hope will defy the challenges of climate change while also ensuring the continued quality of our beer.

BrauBeviale 2024

Visitors interested in the topic of developing new barley varieties to ensure future supplies are encouraged to attend a moderated expert discussion about cutting-edge barley breeding methods during the 2024 BrauBeviale in Nuremberg, on Thursday, November 28, from 12:00 noon to 13:30 p.m., at the Forum Raw materials, in Hall 1, Stand 1-150. 

Elva Ellen Kowald is co-author of this article.