On December 3，2018 Nature Genetics online published an article of the HZAU CottonGen team titled “Reference Genome Sequences of Two Cultivated Allotetraploid Cottons, Gossypium Hirsutum & Gossypium Barbadense.” The corresponding authors are Prof. Zhang Xianlong and Prof. Lin Zhongxu from HZAU, Prof. Keith Lindsey from University of Durham and Prof. Joshua A.Udall from Iowa State University. And the joint first authors are Wang Maojun, a doctoral candidate, Prof. Tu Lili and Associate Professor Yuan Daojun of HZAU. The research is funded by the National Natural Science Foundation of China, National GM Program and other major Projects.
These two allotetraploid cotton species (G. barbadense and G. hirsutum ) are mainly used in cotton production. G. hirsutum has high yield and strong adaptability, while G. barbadense has low yield, but more quality fiber than the former. It has long been the goal of the team at HZAU to introduce favorable chromosome segments from G. barbadense to G. hirsutum for fiber quality improvement. However, the previous draft genome sequences of both species are available but highly fragmented, thus making it hard for the researchers to draw comparisons at the genomic level.
In order to obtain fine genome sequences, the team adopted the third generation single-molecule real-time sequencing (PacBioRS II), BioNano optical mapping and Hi-C (High-throughput/resolution chromosome conformation capture) techniques. Compared with previous assembled draft genomes, these genome sequences show considerable improvements in contiguity and completeness for regions with high content of repeats such as centromeres. Comparative genomics analyses of these two allotetraploid cotton species identified that extensive structural variations occurred after polyploidization in them. And it is worth noting that the study has found large paracentric/pericentric inversions in 14 chromosomes of the two cotton species.
The team also constructed an introgression line population between the two cottons and identified 13 quantitative trait loci associated with superior fiber quality. Furthermore, it explored the mechanism of expression and regulation of these loci based on the transcriptome data of developing cotton fiber. These resources will accelerate evolutionary and functional genomic studies in cotton and benefit future breeding programs for fiber improvement.
Source：http://news.hzau.edu.cn/2018/1204/53233.shtml
Translated by : Jiang Jingjing
Supervised by: Guo Haiyan
