Shenzhen, China – A research group led by Chinese scientists reported the 3.89-Gb draft genome of Tibetan hulless barley with 36,151 protein-coding genes today on PNAS. These scientists are from Tibet Academy of Agricultural and Animal Husbandry Sciences, Chengdu Institute of Biology, BGI, Israel Sapir Academic College and other institutes. Following the physical map of barley, the draft genome of hexaploid wheat as well as its diploid A-genome and D-genome progenitors, this project is another milestone in the evolutionary research and crop improvement in the Triticeae tribes.
Barley is one of the earliest domesticated crops and the world’s fourth most abundant cereal. Tibet and its vicinity is one of the domestication and diversity centers for cultivated barley, which is named Tibetan hulless barley “Qingke” in Chinese and “Ne” in Tibetan. It is famous for the naked caryopsis without grain cover. The Tibetan hulless barley is the staple food for Tibetans and an important livestock feed in the Qinghai-Tibet Plateau for about 3,500-4,000 years. Scientists in this project constructed a high-quality draft genome of the Tibetan hulless barley, to help decipher its adaptation to extreme environmental conditions on highland and to facilitate crop improvement,.
Using the whole-genome shotgun strategy, the researchers built a 3.89-Gb genome of a landrace Lasa Goumang, and predicted 36,151 protein-coding genes. Based on this, they investigated the divergent time among hulless barley and other important Poaceae crops. It showed that hulless barley separated from Ae. tauschii, T. urartu, and T. aestivum about 17 million years ago. They also compared gene families among these species, finding that ~18,849 gene families were similar to those of Ae. tauschii,T. urartu, and B. Distachyon,.
By re-sequencing 10 wild and cultivated hulless barley, the authors found that the wild accessions possessed nearly twice SNPs than the cultivated ones, indicating genetic bottlenecks during domestication and the authors uncovered a series of gene families under specific selection. Notably, some gene families expanded significantly in hulless barley, including some important genes on transcription factors. These defense responses to stressful environments will enable the flexibility to regulate the adaptation to high altitudes. Besides, genes involved in pathways related to environmental responses and adaptation, such as plant hormone signal transduction, replication and repair, plant-pathogen interaction were also found positively selected in Tibetan hulless barley. These results will facilitate crop improvement on the highland towards sustainable supplies of food, feed, and industry resources.
Shancen Zhao, a senior research scientist of BGI in this project, commented, “The draft genome of Tibetan hulless barley provides a robust framework to better understand Poaceae evolution. The project uncovered the plant adaptation to harsh environments on the highland and will facilitate future genetic improvement of hulless barley”.
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