ZmbZIP22 regulates 27-kD γ-zein transcription during maize endosperm development (Plant Cell)

Zeins are maize seed storage proteins, but are notoriously low in the amino acids lycine and tryptophan. Therefore, to improve maize’s nutritional properties, efforts have been made to decrease zein levels. However, such efforts often lead to abnormal (opague) kernels. Previous work has demonstrated that the 27-kD γ-zein gene is extremely highly expressed in the maize endosperm, and several transcription factors that are involved in its expression have been identified. However, even when all of these are mutated, the gene is still expressed, suggesting that other transcription factors contribute. Li et al. set about identifying and characterizing this missing partner, ZmbZIP22. Using a combination of tranditional (gel shift) and modern (CRISPR/Cas9, RNA-seq, ChIP-seq) methods, the identified cis-elements bound by ZmbZIP22 and genes it is involved in regulating. (Summary by Mary Williams) Plant Cell 10.1105/tpc.18.00422