Thu Sep 06 15:58:35 CEST 2018
After 13 years of meticulous effort, 200 scientists from 20 countries managed to decode the genome of wheat, one of the most common crops in agriculture. The results, reached with a significant participation of experts from the Institute of Experimental Botany of the Czech Academy of Sciences, will facilitate a faster breeding of wheat varieties with better qualities, as well as help people with allergy to gluten.
Due to its enormous size, decoding hereditary information of common wheat had long been deemed impossible. It consists of 17 milliard letters and is, therefore, five times larger than the human one. This is because it consists of three similar subgenomes and also because most of the genome is made up of parts of DNA that repeat themselves multiple times. According to Martin Vágner, director of the Institute of Experimental Botany, the work published in the Science magazine, accomplished with a significant participation of Czech scientists from Olomouc, aspires to be this year’s most important breakthrough in plant biology.
The scientists from Olomouc presented the ground-breaking results on August 20, 2018 in the Centre of Plant Structural and Functional Genomics of the Institute of Experimental Botany of the CAS.
The scientists’ work was further complicated by the fact that they had to read the hereditary information only in small pieces at a time. Jaroslav Doležel, supervisor of the Centre of Plant Structural and Functional Genomics of the Institute of Experimental Botany explains that this makes its correct assembly quite difficult: “It’s like we cut up three editions of the same book in very similar languages into segments no longer than a single sentence, then mix them up and try to assemble the books into their original forms. I am truly glad we managed to do so with such a sizable genome like the one of wheat.”
The green revolution from Olomouc
In 2003, the Olomouc institute of the Czech Academy of Sciences was one of the co-founders of the International Wheat Genome Sequencing Consortium (IWGSC). The Czech institute played a key part in the international project because the research of the wheat genome was based on the method of sorting chromosomes using the so-called flow cytometry which had been developed and routinely used only in one place in the world: the institute in Olomouc.
The unique procedure allowed scientists to divide the complicated hereditary information into smaller parts, i.e. chromosomes. This made easier reading the DNA and subsequent arrangement of the decoded parts. The laboratory in Olomouc then handed the DNA of various chromosomes over to institutes in various parts of the world.
The scientists from Olomouc also prepared the so-called BAC libraries. Thanks to these libraries, longer parts of the text of hereditary information could be read which also simplified the assembly of the genome. The Czech scientists also brought other modern methods, such as optical mapping, to the research.
In special freezing boxes, 2.5 million clones of wheat DNA are kept at temperature of –80°C. Jaroslav Doležel shows frozen plates with BAC libraries of wheat chromosomes.
Decoded genome will help breeders as well as further research
Thanks to this major breakthrough, breeders will have new options of solving problems connected with food safety. This is especially important because wheat is a basic foodstuff for more than one third of the world’s population. “Wheat is grown on the largest part of all agricultural land, it provides more than one fifth of calories and proteins and its role in the nourishment of humanity is currently irreplaceable,” confirms Jaroslav Doležel.
The knowledge of the wheat genome will enable the breeders to identify the genes responsible for the quality of the grain and its resistance against diseases and pests, as well as those which might allow wheat to better withstand dry months.
Currently, the scientists are faced with new challenges. So far, they have mainly studied the genome as a linear string of letters of the hereditary code, but in reality, the hereditary information carried by the DNA molecules is arranged in a three-dimensional space of cell nucleus with a diameter of several thousandths of millimetre, and some of its parts interact with each other. “This arrangement can be compared to a ball of yarn composed of 42 threads 30 centimetres long. Finding the parts of the threads which affect each other is difficult, but we have already worked out procedures of finding them and characterizing them more closely,” concludes Jaroslav Doležel.
Original Czech text prepared by: Luděk Svoboda, Division of External Relations of the CAO of the CAS
Photo: Luděk Svoboda and Pavlína Jáchimová, Division of External Relations of the CAO of the CAS, Institute of Experimental Botany of the CAS