The TaNHLP1-TaRACK1A module regulates tillering via abscisic acid signaling in wheat.

Wheat tillering is an important agronomic trait influencing grain yield. Here, we identify an NHL repeat-containing protein, TaNHLP1, which positively regulates tiller number in wheat. We discovered that the core components of the abscisic acid (ABA) signaling pathway, type 2C protein phosphatase TaPP2C and SNF1-related protein kinase TaSnRK2, interact with TaNHLP1 to regulate its abundance. Furthermore, TaNHLP1 interacts with the Receptor for Activated C Kinase 1 (TaRACK1A), an ABA pathway negative regulator, and influences its subcellular localization. Importantly, both the TaNHLP1 and TaRACK1A mutations promote ABA accumulation in the shoot bases and tiller buds. Notably, the NHLP1-RACK1 module is conserved across monocots and eudicots, and natural variations in the promoter of TaNHLP1-A enhance its transcriptional activity, leading to increased tiller number and yield. Collectively, these findings elucidate the genetic mechanism of NHLP1-mediated tillering regulation and highlight its potential as a target for improving crop plant architecture.