Decoding and sequencing the wheat genome

In an international study published in the prestigious journal SCIENCE with the participation of researchers from the University of Haifa, Tel Aviv and the high-tech company NRGene. Decoding the genome will allow the cultivation of wheat varieties that are resistant to diseases, yield more, are better adapted to changing environmental conditions, and more. As more than 20% of the world's protein and calorie consumption comes from wheat - this is especially important news for the well-being of all humanity

More than 200 researchers from twenty countries, including Israel, and 73 research institutions managed to do what was considered impossible until a few years ago - to crack and sequence the genome of the cultivated wheat, the bread wheat. Cracking the genome, published in the prestigious journal SCIENCE. The large scientific consortium included three Israeli teams, from the University of Haifa, Tel Aviv University and the high-tech company NRGene, which played a central part in the achievement.

Cultured wheat, from which many foods are produced (breads, pitas, sweet and savory pastries, cakes, etc.), is a central component of the global diet, with over 20% of global calorie and protein consumption coming from it, much more than any other food plant. According to Prof. Fahima, head of the Institute of Evolution at the University of Haifa and a partner in the study, according to all estimates, in order to meet the projected food consumption for 2050, when the world's population will be approximately 10 billion people, wheat production must be increased by approximately 1.6% each year. But in recent years we have been able to increase production by half of that. The meaning is simple: the possibility of a future hunger crisis, or finding ways of genetic improvement that will increase the yield in the same areas that exist today.

However, efforts to genetically improve wheat have so far encountered an almost impossible wall to crack: the wheat genome consists of approximately 16 billion letters, on 21 chromosomes divided into three subgenomes (the human genome, for comparison, consists of approximately 3 billion letters). To deal with the impossible task, most of the world's wheat researchers have joined together in the International Wheat Genome Sequencing Consortium (IWGSC - International Wheat Genome Sequencing Consortium), which includes over 2400 researchers and cultivators from 68 countries. Each research group focused on a small part of one of the 21 chromosomes - with the overarching goal being to eventually connect all the pieces to form the complete puzzle. But even in this way, progress was slow and the end date was hardly in sight.

An important milestone during the project was that of Prof. Avraham Korol, from the Institute of Evolution of the University of Haifa. Prof. Korol developed a method that is three times more effective for physical mapping of the chromosomes - the mapping that allows scientists to associate the DNA segments they are studying with specific sites on the surface of the chromosomes.

But this method did not help speed up the central process of deciphering each and every section - and only allowed short sections to be joined together. At this point the company NRGene entered the picture, a high-tech company from the private market, which consists of graduates of the 8200 unit, which presented its own algorithms for decoding the genome. "The method was so advanced and efficient that it increased the decoding efficiency by more than 10 times, until at first the international consortium refused to believe that the method was indeed reliable," said Dr. Gil Ronan, CEO of NRGene. Only after researchers from Tel Aviv University, Haifa University and other institutions around the world teamed up with the NRGene people in decoding the genome of wild wheat, and published the research about a year ago also in SCIENCE, were the members of the consortium convinced and invited them to work with them on the truly great challenge - the genome of bread wheat.

"After seeing the high quality of the wild wheat genome decoding, we were able to convince the IWGSC to follow the same path and even allowed the international community access to the databases with the sequences, even before the official publication," said Prof. Assaf Distelfeld from the Cereal Institute at Tel Aviv University, partner added to the study. "The groundbreaking technology of the partners from Israel allowed us to advance our research in the improvement of wheat by giant steps" says Dr. Curtis Pozniak, a wheat researcher and breeder from the University of Saskatchewan in Canada, who visited Israel in 2016 and also funded a large part of the research.

The new collaboration allowed the consortium to decipher the 16 billion letters within a year and for another year the researchers worked to understand what was written in those letters. As published in the study, the cultivated wheat genome includes about 107 thousand genes, which make up only about 2 percent of the genome. 85% of the genome are sequences of viruses, which joined the genome of wheat during millions of years of evolution, and took an important part in shaping the structure and function of the genome, but generally, most of them do not have a great impact on the daily functioning of the wheat plant.

"Until the genome was deciphered, we were like navigators in the dark, without a map. It took me 25 years to find a few genes with important functions, such as disease resistance or increasing the nutritional quality of wheat. I now believe that this process can be shortened to only about three to five years. This is a discovery of extraordinary importance for the future of humanity," said Prof. Fahima.

The challenge now facing the researchers is to find in the 107 genes those whose manipulation will yield wheat varieties with a greater grain yield, those that grow faster, that have higher nutritional values, that can grow in extreme conditions of cold or heat, with less water, in more saline soil, and more. "With the help of the new methods, we can now rapidly sequence the hundreds and thousands of varieties of cultivated wheat and compare them to different species and varieties of wild wheat species. Now that we have the complete sequence of the cultivated wheat genome as a basis for comparison, the process of sequencing other varieties becomes less complicated. Once we identify the beneficial genes, we will also know where to look for these genes in the other varieties - and thus we may only have to sequence a few percent of the genome of the wild varieties until we find the appropriate gene with which we can cultivate wheat that yields more kernels per square meter. There is no doubt that now only the sky is the limit for us", Prof. Fahima concluded.