Wild rice GL12 synergistically improves grain length and salt tolerance in cultivated rice.

The abounding variations in wild rice provided potential reservoirs of beneficial genes for rice breeding. Maintaining stable and high yields under environmental stresses is a long-standing goal of rice breeding but is challenging due to internal trade-off mechanisms. Here, we report wild rice GL12 improves grain length and salt tolerance in both indica and japonica genetic backgrounds. GL12 alters cell length by regulating grain size related genes including GS2, and positively regulates the salt tolerance related genes, such as NAC5, NCED3, under salt stresses. We find that a G/T variation in GL12 promoter determined its binding to coactivator GIF1 and transcription factor WRKY53. GIF1 promotes GL12 expression in young panicle and WRKY53 represses GL12 expression under salt stresses. The G/T variation also contributes to the divergence of indica and japonica subspecies. Our results provide useful resources for modern rice breeding and shed insights for understanding yield and salt tolerance trade-off mechanism.