Drought is one of the most serious constraints to rice cultivation, even under alternate wetting and drying (AWD), which is a water-saving management practice. In rice, enhanced root development is essential for stable shoot growth, adaptability and productivity under water deficit environments. We identified and characterized outstanding rooting1 (our1) rice mutant using hydroponics. The present study sought to examine morphological root traits of the our1 mutant and the role of the mutation gene in shoot growth and yield under AWD. Thus, we evaluated the growth performance of the our1 rice mutant in pot experiments and under field AWD conditions in Kenya. The experiments were conducted with our1 mutant, its wild type and their progenies under both AWD and continuously waterlogged (CWL) conditions. The our1 mutant possessed a well-developed root system and exhibited particularly enhanced thin root development, which was maintained from the early vegetative stage through the reproductive stage under both pot and field AWD management. This enhanced root development promoted shoot growth through increased water uptake during rewatered conditions between drought periods in AWD. In addition, the our1 mutant showed enhanced shoot growth during the reproductive stage, resulting in the maintenance of yield under AWD fields. Genotypes harbouring our1 mutation gene showed higher yields compared to wild-type genotypes which was attributed to their higher photosynthetic ability as a result of enhanced root activity. These results suggest the important role of a well-developed root system architecture and enhanced root function in stabilizing rice yields under water-limited environments. Our findings indicate that the our1 mutation gene can serve as a novel breeding material to mitigate the impact of transient drought stress on yield under AWD.

中文翻译：

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突出的rooting1突变基因通过促进缺水田间环境下水稻根系发育维持地上部生长和籽粒产量

干旱是水稻种植最严重的制约因素之一，即使在作为节水管理实践的干湿交替 (AWD) 条件下也是如此。在水稻中，增强根系发育对于在缺水环境下稳定地芽生长、适应性和生产力至关重要。我们使用水培法鉴定并表征了突出的生根1 ( our1 ) 水稻突变体。本研究旨在检查our1突变体的形态根性状以及突变基因在AWD 下的枝条生长和产量中的作用。因此，我们在肯尼亚的盆栽试验和田间 AWD 条件下评估了our1水稻突变体的生长性能。实验是用我们的1突变体、其野生型及其在 AWD 和连续淹水 (CWL) 条件下的后代。our1突变体具有发达的根系，并表现出特别增强的细根发育，在盆栽和田间 AWD 管理下，从早期营养阶段到生殖阶段都保持了这种状态。这种增强的根系发育通过在 AWD 干旱期之间的再浇水条件下增加水分吸收来促进枝条生长。此外，our1突变体在生殖阶段表现出增强的枝条生长，导致在 AWD 田间保持产量。携带我们的基因型1与野生型基因型相比，突变基因显示出更高的产量，这归因于由于根系活性增强而具有更高的光合能力。这些结果表明，发达的根系结构和增强的根系功能在限制水分的环境下稳定水稻产量方面的重要作用。我们的研究结果表明，our1突变基因可以作为一种新的育种材料来减轻瞬时干旱胁迫对 AWD 下产量的影响。