Genome-wide analysis of the nuclear factor Y (NF-Y) gene family in bermudagrass (Cynodon dactylon L.) identified an NF-Y heterotrimer comprising CdNF-YA-1A1/CdNF-YB-7B2/CdNF-YC-1A2

Nuclear factor Y (NF-Y) transcription factors are important regulators of plant growth, development, and stress responses. However, the functions of NF-Ys in bermudagrass (Cynodon dactylon L.), a warm-season turfgrass species with wide applications and great value, have not yet been elucidated. In this study, 88 CdNF-Y genes, including 32 CdNF-YAs, 31 CdNF-YBs, and 25 CdNF-YCs, were successfully identified in the bermudagrass genome. Sequence analyses revealed that three subfamilies of CdNF-Y genes exhibited different gene structure and protein domain characteristics. Expression profiling indicated that eight CdNF-Y genes were constitutively expressed in all samples, whereas other CdNF-Y genes were preferentially expressed in a few organs or induced by specific stresses. RT-qPCR indicated that three CdNF-Y genes, CdNF-YA-1A1, CdNF-YB-7B2, and CdNF-YC-1A2, have similar tissue expression profiles. Moreover, their expression abundances were all reduced under heat stress treatment. Subcellular localization analysis indicated that CdNF-YA-1A1 was located in the nucleus, while CdNF-YB-7B2 and CdNF-YC-1A2 were both simultaneously located in the nucleus and cytoplasm. Yeast two-hybrid assay, yeast three-hybrid assay, and bimolecular fluorescence complementation assay collectively indicated that CdNF-YB-7B2 and CdNF-YC-1A2 could interact to form a heterodimer, which then interacts with CdNF-YA-1A1 to form a heterotrimer. Results of this study greatly expanded our understanding of NF-Y genes and NF-Y protein complexes in bermudagrass.