AUTHOR=Blume Rostyslav , Yemets Alla , Korkhovyi Vitaliy , Radchuk Volodymyr , Rakhmetov Dzhamal , Blume Yaroslav 

TITLE=Genome-wide identification and analysis of the cytokinin oxidase/dehydrogenase (ckx) gene family in finger millet (Eleusine coracana)

JOURNAL=Frontiers in Genetics

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2022.963789

DOI=10.3389/fgene.2022.963789

ISSN=1664-8021

ABSTRACT=<p>Cytokinin dehydrogenase/oxidase (CKX) enzymes play a key role in regulating cytokinin (CK) levels in plants by degrading the excess of this phytohormone. <italic>CKX</italic> genes have proven an attractive target for genetic engineering, as their silencing boosts cytokinin accumulation in various tissues, thereby contributing to a rapid increase in biomass and overall plant productivity. We previously reported a similar effect in finger millet (<italic>Eleusine coracana</italic>) somaclonal lines, caused by downregulation of <italic>EcCKX1</italic> and <italic>EcCKX2</italic>. However, the <italic>CKX</italic> gene family has numerous representatives, especially in allopolyploid crop species, such as <italic>E. coracana</italic>. To date, the entire <italic>CKX</italic> gene family of <italic>E. coracana</italic> and its related species has not been characterized. We offer here, for the first time, a comprehensive genome-wide identification and analysis of a panel of <italic>CKX</italic> genes in finger millet. The functional genes identified in the <italic>E. coracana</italic> genome are compared with the previously-identified genes, <italic>EcCKX1</italic> and <italic>EcCKX2</italic>. Exon-intron structural analysis and motif analysis of FAD- and CK-binding domains are performed. The phylogeny of the <italic>EcCKX</italic> genes suggests that <italic>CKX</italic> genes are divided into several distinct groups, corresponding to certain isotypes. Finally, the phenotypic effect of <italic>EcCKX1</italic> and <italic>EcCKX2</italic> in partially silencing the SE7 somaclonal line is investigated, showing that lines deficient in <italic>CKX</italic>-expression demonstrate increased grain yield and greater bushiness, enhanced biomass accumulation, and a shorter vegetation cycle.</p>