Divergent evolutionary paces among eudicot plants revealed by simultaneously duplicated genes produced thousand millions of years ago

Yao Wang Jiangli Wang Yingjie Li ^* Yongchao Jin ^* Xiyin Wang ^*

• North China University of Science and Technology, Tangshan, China

Polyploidization often occurs more than once along an evolutionary lineage to form extant plants. Major core eudicot plants shared a whole-genome triplication (ceWGT), thousands of simultaneously duplicated genes produced by which were retained in extant genomes, providing a precious starting line to check the difference in their evolutionary paces. Here, by characterizing the synonymous nucleotide substitutions (Ks) between these duplicates from 28 representative plants from 21 families, we found up to 68.04% difference in evolutionary rates among the selected plants. A statistical correlation analysis (correlation coefficient = 0.57, at significant level = 0.01) indicated that plants affected by extra polyploidies have evolved faster than plants without such extra polyploidies, showing (additional) polyploidization has resulted in elevated genetic diversity. Comparing the plants affected by additional polyploidization and plants without it, the duplicated genes produced by the ceWGT and retained in extant genomes have gathered 4.75% more nucleotide substitutions in the former plants. By identifying the fast-and slowly-evolving genes, we showed that genes evolving at divergent rates were often related to different evolutionary paths. By performing correction to evolutionary rates using a genome-scale approach, we revised the estimated timing of key evolutionary events. The present effort exploited the simultaneously duplicated genes produced by the shared polyploidization and help deepen the understanding of the role of polyploidization, especially its long-term effect in plant evolution and biological innovation.