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Back-to-the-Past Journey to Trace History and Movement of Barley – the Beer Source

Andet forskningsprojekt | 13/12/2017

Abiotic stress experiments with barley cultivars grown at controlled environments in a climate chamber.

By D.Sc., Professor Birger Lindberg Møller

Barley is an important and old crop, domesticated about 10,000 years ago. Domestication and intended selection of barley have led to the loss of genetic diversity and thus reduced capacity to adapt to different growth conditions. Genes lost over the millennia might have changed grain quality and stress-tolerance, so a comparison to the presence of genes in an ancient cereal genome could offer new breeding opportunities in barley to mitigate the negative effects of climate change and shed some light onto the barley movement routes in the course of time. To carry out the project, key expertise within bioinformatics was established at the Carlsberg Research Laboratory by new recruitments. Gene sequencing and bioinformatics enable monitoring of the genetic changes introduced in the barley genome as a result of random mutations that may have resulted in the recruitment of new functions or loss of functions. Even more interesting is to elucidate the changes that are the result of human selection for desired characteristics such as higher yield, grain size and drought resistance. The availability of an accurate genome sequence of a modern barley cultivar is a prerequisite for assignment of differences to the ancient barleys. The project has contributed to such an improved barley genome sequence as recently published in Nature. 

Why Barley?

Barley’s crucial role in Neolithic and present-day agriculture makes it a model plant to study the genetic path of turning into a domesticated crop. Barley was gathered long before the domestication with the first evidence of human use of wild barley as a food source discovered on the shore of the Sea of Galilee in Israel. The barley grains found there were dated as 23,000-year-old. Thus, it is one of the first cereals to be cultivated. By the quantity produced, barley currently ranks as the fourth most important grain in the world, left behind only by corn, rice and wheat. Its varieties are divided into those used for food (high protein levels, carbohydrate source) and those suitable for malting (low protein content). Barley is widely used to produce malt and the grains provide an excellent carbohydrate source in beer production.

What Do We Know About Domestication?

There are different theories about origins of barley cultivation. The Fertile Crescent is thought to be a place where hunter-gatherers turned into farmers. This process took place between 12,000 and 9,500 years Before Present. Crop domestication is a complex process and a glimpse of what might have happened may be obtained by characterisation of the crops cultivated nowadays and comparison with non-cultivated related wild species. What lacks in such an approach is that the result obtained narrows down the view to the final effect of the millennia-long evolution. The disappearance of ancestral species and breeds makes the analysis highly complex.

What Could We Find Out and Why Do We Want to Do That?

Spotting and recovering “gone” barley genes, lost over generations and possibly responsible for grain quality and stress-tolerance, is a detective investigation of the interplay between highly complex networks of genes, the lives of ancient people, the routes and movements of people in the course of history and the cereals they possibly carried with them. With the climatic changes and stresses, lost genes could be a key for possible modifications of modern barley plants. Comparing the genome of modern barley, recently sequenced, with an ancient cereal genome could give some new important solutions to nowadays agriculture.

Active engagement with the do-it-yourself communities is given high priority.

How Would We Do That?

The methodological differences in restoring data from the ancient DNA (aDNA) in comparison with the isolation of the DNA from fresh tissues are quite significant. aDNA is usually immensely fragmented into small pieces of 70-100 nucleotides and contains some chemical modifications. However, the recent progress in aDNA studies renders comparison of the whole genomes of contemporary crops with aDNA sequences from ancient specimens possible. Special bioinformatics and molecular biological skills are required as well as the experience in working with such material. The research group in the Australian Centre for Ancient DNA has a specially constructed laboratory for ancient DNA work and is a participant in the project. An additional aim is to analyse the metabolite composition of the barley grain as an alternative way to track changes in genes involved in abiotic and biotic stress tolerance. Grains collected from the Areni-1 cave in Armenia are used as experimental material.

The unique combination of high-end experimental approaches, rare expertise and exclusive material are key to the project and help, eventually, to improve abiotic stress tolerance in future breeding programs.

Occurrence and distribution of defense compounds belonging to the class of hydroxynitrile glucosides in barley (Hordeum vulgare) and the genes involved in their biosynthesis (The Plant Journal 88: 247–256 (2016).

Birger Lindberg Møller has participated in several radio programs:

Lone Frank, Radio24syv: 24 Spørgsmål til Professoren

Peter Lund Madsen DR Hjernekassen på P1: Planter for fremtiden

Resulting Publications

T. Kutchan, J. Gershenzon, B.L. Møller, D. Gang: Chapter 24: Natural Products (Secondary Metabolites). In: Biochemistry & Molecular Biology of Plants (Eds: Buchanan, Gruissem, Jones) American Society of Plant Physiologists, 2.nd Edition, pp. 1132-1206 (2015)

E. Knoch, M.S. Motawia, C.E. Olsen, B.L. Møller, M.F. Lyngkjær:  Biosynthesis of the leucine derived α-, β- and γ-hydroxynitrile glucosides in barley (Hordeum vulgare L.). Plant Journal, 88(2): 247-256 (2016)

Mascher, M., Gundlach, H., Himmelbach, A., et al.:  A chromosome conformation capture ordered sequence of the barley genome. Nature544(7651):427-433 (2017)