The WD40-repeat proteins nfc101 and nfc102 regulate different aspects of maize development through chromatin modification mechanisms

The maize (Zea mays) nucleosome remodeling factor complex component 101 and 102 (nfc101/nfc102) are putative paralogs encoding WD-repeat proteins that exhibit homology with plant and mammalian components of various chromatin modifying complexes. In this study, we generated transgenic lines with simultaneous nfc101 and nfc102 down-regulation and analyzed phenotypic alterations, along with effects on RNA levels, the binding of nfc101/nfc102 and Rpd3- type histone deacetylases (HDACs), and histone modifications at selected targets. Direct nfc101/nfc102 binding and negative correlation with mRNA levels were reported for key activators of the floral transition, such as indeterminate 1 (id1) and the florigen ZCN8. In addition, the abolition of nfc101/nfc102 association with repetitive sequences of different transposable elements (TEs) resulted in tissue-specific up-regulation of transcripts produced by these regions. All direct nfc101/nfc102 targets showed histone modification patterns linked to active chromatin in nfc101/nfc102 down-regulation lines. However, different mechanisms may be involved because nfc101/nfc102 proteins mediate HDACs recruitment at id1 and TE repeats, but not at ZCN8. These results, along with the pleiotropic effects observed in nfc101/nfc102 down-regulation lines, suggest that nfc101 and nfc102 are components of distinct chromatin modifying complexes, which operate in different pathways and influence diverse aspects of maize development