Locus prl5 improves lodging resistance of rice by delaying senescence and increasing carbohydrate reaccumulation

We investigated the reason for carbohydrate retention in the stem of rice (Oryza sativa L.) at full-ripe stage in a near-isogenic line (NIL63) carrying prl5, which confers lodging resistance without yield loss. NIL63 showed higher lodging resistance than Nipponbare (control) without reduced yield. At heading, the carbohydrate content in the NIL63 stem (culm and leaf sheathes) was the same as in Nipponbare. At 2 weeks after heading, the carbohydrate content in NIL63 was significantly higher than in Nipponbare. At 4 weeks after heading, the carbohydrate content in NIL63 had decreased to near the level in Nipponbare. At 6 weeks after heading, NIL63 showed higher carbohydrate reaccumulation. Chlorophyll degradation in the leaf blades of NIL63 was slower, and the chlorophyll content at 6 weeks after heading was higher than in Nipponbare. These results suggest that the delay in leaf senescence by prl5 results in carbohydrate reaccumulation in the stem after grain filling, increasing lodging resistance.