Mutations in a subfamily of abscisic acid receptor genes promote rice growth and productivity

Abscisic acid (ABA) is a key phytohormone that controls plant growth and stress responses. It is sensed by the pyrabactin resistance 1 (PYR1)/PYR1-like (PYL)/regulatory components of the ABA receptor (RCAR) family of proteins. Here, we utilized CRISPR/Cas9 technology to edit group I (PYL1-PYL6 and PYL12) and group II (PYL7-PYL11 and PYL13) PYL genes in rice. Characterization of the combinatorial mutants suggested that genes in group I have more important roles in stomatal movement, seed dormancy, and growth regulation than those in group II. Among all of the single pyl mutants, only pyl1 and pyl12 exhibited significant defects in seed dormancy. Interestingly, high-order group I mutants, but not any group II mutants, displayed enhanced growth. Among group I mutants, pyl1/4/6 exhibited the best growth and improved grain productivity in natural paddy field conditions, while maintaining nearly normal seed dormancy. Our results suggest that a subfamily of rice PYLs has evolved to have particularly important roles in regulating plant growth and reveal a genetic strategy to improve rice productivity.