Nitrogen-dependent binding of the transcription factor PBF1 contributes to the balance of protein and carbohydrate storage in maize endosperm (Plant Cell)

The majority of maize endosperm is made of starch (70%) and proteins (10%) and their biosynthesis is a complex process which involves many enzymes. N-containing compounds, such as enzymes, amino acids, and nucleotides are crucial for C metabolism. Thus, when N levels are altered, the storage of proteins and starch in maize is notably affected. Several transcription factors (TFs) are involved in starch and protein metabolism in maize endosperm. Prolamin-box binding factor 1 (PBF1) it is known to be involved in the regulation of both C and N metabolism due to the presence of a conserved sequence named P-box. Variation in N supply will consequently affect the composition of starch and protein in the endosperm. Ning et al. performed an RNA-Seq to identify how the N levels affect the accumulation of starch and proteins in the endosperm. The authors observed an enrichment of the P-box sequence in the promoters of the Differentially Expressed Genes (DEGs) suggesting a possible role of PBF1. With the results of a chromatin immunoprecipitation followed by sequencing (ChIP-Seq) it was demonstrated that it is the binding pattern of PBF1 (rather than its abundance) that was altered based on N availability. These results shed light to into the development of maize varieties with improved nutritional value and stable yield. (Summary by Eva Maria Gomez Alvarez, @eva_ga96). The Plant Cell. 10.1093/plcell/koac302