Leaf width gene LW5/D1 affects plant architecture and yield in rice by regulating nitrogen utilization efficiency

Leaves are the primary structures responsible for photosynthesis, making leaf morphology one of the most important traits of rice plant architecture. Both plant architecture and nutrient utilization jointly affect rice yield, however, their molecular association is still poorly understood. We identified a rice mutant, leaf width 5 (lw5), that displayed small grains and wide leaves and possesses characteristics typical of a small “sink” and a large “source”. Map-based cloning and CRISPR-Cas9 gene editing indicated that LW5 affects both the plant architecture and yield. It is an allele of D1, encoding the rice G protein α subunit. The loss of LW5 functioning leads to an increase in the rate of photosynthesis, vascular bundles, and chlorophyll content. However, the grain-straw ratio and the rate of grain filling decreased significantly. The detection results of 15N-ammonium nitrate and an expression analysis of genes associated with nitrogen demonstrated that LW5 serves an important role in nitrate uptake and transport. LW5 affects plant architecture and grain size by regulating nitrogen transfer. These results provide a theoretical foundation for further research surrounding the molecular mechanism of “source-sink” balance in rice and suggest novel methods of molecular design for the cultivation of breeding super rice in ideal plant types. •The plant architecture and the nutrients utilization are jointly affect rice yields.•lw5 displayed small grains and wide leaves, and possessed typical characteristics of small “sink” and large “source”.•LW5 encoded the rice G protein α subunit.•LW5 affects the plant architecture and grain size by regulating nitrogen uptake and transport.