Researchers at the Institute of Vegetables and Flowers (IVF), Chinese Academy of Agricultural Sciences (CAAS), have expounded the mechanism of multicopy genes and subgenomes divergence in plant polyploidy evolution. This work, in collaborated with researchers from University of California and University of Berkeley, has been published online in PNAS on March 24, 2014.

Whole-genome duplications happen repeatedly in a typical flowering plant lineage. With the rapid development of DNA sequencing, genome sequences for many plants have been released, therefore provide a good platform to reveal the process of evolutional polyploidy.

After the successful accomplishment of Brassica rapa genome sequencing in 2011, Dr Wang Xiaowu and his fellow researchers at the IVF further discovered that the B. rapa genome can be divided into three different subgenomes. And among which, one exhibits the dominant phenomenon in gene dosage and gene expression comparing with the other two. The finding also shows that transposon derived 24 nt RNAs can suppress the expression of their flanking genes, resulted in the phenomenon of dominant subgenome and subgenomes divergence. The balance of transposon position effects on genes is important for the regulation of quantity (and perhaps to solve the heterosis and C-value paradoxes).