Genome-Wide Analysis of the Cyclin Gene Family and Their Expression Profile in .

Cyclins, together with highly conserved cyclin-dependent kinases (CDKs), play an important role in the process of cell cycle in plants, but less is known about the functions of cyclins in legume plants, especially . Our genome-wide analysis identified 58, 103, and 51 cyclin members in the , , and genomes. Phylogenetic analysis suggested that these cyclins could be classified into 10 types, and the CycB-like types (CycBL1-BL8) were the specific subgroups in , which was one reason for the expansion of the B-type in . All putative cyclin genes were mapped onto their own chromosomes of each genome, and 9 segmental duplication gene pairs involving 20 genes were identified in cyclins. Determined by quantitative real-time PCR, the expression profiling suggested that 57 cyclins in were differentially expressed in 9 different tissues, while a few genes were expressed in some specific tissues. Using the publicly available RNAseq data, the expression of Mtcyclins in the wild-type strain A17 and three nodule mutants during rhizobial infection showed that 23 cyclins were highly upregulated in the nodulation (Nod) factor-hypersensitive mutant () mutant after 12 h of rhizobium inoculation. Among these cyclins, six cyclin genes were also specifically expressed in roots and nodules, which might play specific roles in the various phases of Nod factor-mediated cell cycle activation and nodule development. Our results provide information about the gene family in legume plants, serving as a guide for further functional research on plant cyclins.