AUTHOR=Xu Weijie , Zhao Yiyang , Chen Sisi , Xie Jianbo , Zhang Deqiang 

TITLE=Evolution and Functional Divergence of the Fructokinase Gene Family in Populus

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.00484

DOI=10.3389/fpls.2020.00484

ISSN=1664-462X

ABSTRACT=<p>New kinase has emerged throughout evolution, but how new kinase evolve while maintaining their functions and acquiring new functions remains unclear. Fructokinase (FRK), the gateway kinase to fructose metabolism, plays essential roles in plant development, and stress tolerance. Here, we explored the evolution of <italic>FRK</italic> gene family in 20 plant species (from green algae to angiosperms) and their functional roles in <italic>Populus</italic>. We identified 125 putative <italic>FRK</italic> genes in the 20 plant species with an average of 6 members per species. Phylogenetic analysis separated these 125 genes into 8 clades including 3 conserved clades and 5 specific clades, the 5 of which only exist in green algae or angiosperms. Evolutionary analysis revealed that <italic>FRK</italic> genes in ancient land plants have the largest number of functional domains with the longest amino acid sequences, and the length of <italic>FRK</italic> genes became shorter during the transition to vascular plants. This was accompanied by loss, acquisition, and diversification of functional domains. In <italic>Populus</italic>, segmental duplication appears to be the main mechanism for the expansion of <italic>FRK</italic> genes. Specially, most <italic>FRK</italic> genes duplicated in salicoids are regulated by <italic>Populus</italic>-specific microRNAs. Furthermore, compared with common <italic>FRKs, Populus</italic>-specific <italic>FRK</italic>s have showed higher expression specificity and are associated with fewer growth and wood property traits, which suggests that these <italic>FRKs</italic> may have undergone functional divergence. Our study explores the specific roles of <italic>FRKs</italic> in the <italic>Populus</italic> genome and provides new insights for functional investigation of this gene family.</p>