Transcription factors ZmNF-YA1 and ZmNF-YB16 regulate plant growth and drought tolerance in maize.

ABSTRACT

The identification of drought stress regulatory genes is crucial for the genetic improvement of maize (Zea mays L.) yield. Nuclear factors Y (NF-Ys) are important transcription factors, but their roles in the drought stress tolerance of plants and underlying molecular mechanisms are largely unknown. In this work, we used yeast two-hybrid screening to identify potential interactors of ZmNF-YB16 and confirmed the interaction between ZmNF-YA1 and ZmNF-YB16-YC17 and between ZmNF-YA7 and ZmNF-YB16-YC17. ZmNF-YB16 interacted with ZmNF-YC17 via its histone fold domain to form a heterodimer in the cytoplasm and then entered the nucleus to form a heterotrimer with ZmNF-YA1 or ZmNF-YA7 under osmotic stress. Overexpression of ZmNF-YA1 improved drought and salt stress tolerance and root development of maize, whereas zmnf-ya1 mutants exhibited drought and salt stress sensitivity. ZmNF-YA1-mediated transcriptional regulation, especially in JA signaling, histone modification, and chromatin remodeling, could underlie the altered stress tolerance of zmnf-ya1 mutant plants. ZmNF-YA1 bound to promoter CCAAT motifs and directly regulated the expression of multiple genes that play important roles in stress responses and plant development. Comparison of ZmNF-YB16- and ZmNF-YA1-regulated genes showed that ZmNF-YA1 and ZmNF-YB16 have similar biological functions in stress responses but varied functions in other biological processes. Taken together, ZmNF-YA1 is a positive regulator of plant drought and salt stress responses and is involved in the root development of maize, and ZmNF-Y complexes with different subunits may have discrepant functions.