ZmIBH1-1 regulates plant architecture in maize

Leaf angle (LA) is a critical agronomic trait which affects grain yield through planting density in maize. Much research has been conducted in recent years to investigate the genes responsible for LA variation and a few genes were identified through map-based cloning. Here we cloned the ZmIBH1-1 gene, which is a bHLH transcription factor with both a basic binding region and a Helix-Loop-Helix domain; and qRT-PCR results showed that ZmIBH1-1 is a negative regulator of LA in maize. Histological analysis showed that the change in LA was mainly caused by differential cell wall lignification and cell elongation in the ligular region. To reveal the regulatory framework of ZmIBH1-1, we conducted RNA-Seq and DAP-Seq analysis. Overlay of the RNA-Seq and DAP-Seq results revealed 59 ZmIBH1-1 modulated target genes with annotation, and they were mainly cell wall related, cell development or hormone related genes. We have built a new regulatory model of ZmIBH1-1 gene controlling plant architecture in maize.