The source–sink relationship determines the overall agronomic performance of rice. Cloning and characterizing key genes involved in the regulation of source and sink dynamics is imperative for improving rice yield. However, few source genes with potential application in rice have been identified. Glucan, Water-Dikinase 1 (GWD1) is an essential enzyme that plays a pivotal role in the first step of transitory starch degradation in source tissues. In the present study, we successfully generated gwd1 weak mutants by promoter editing using CRISPR/Cas9 system, and also leaf-dominant overexpression lines of GWD1 driven by Osl2 promoter. Analysis of the gwd1 plants indicated that promoter editing mediated down-regulation of GWD1 caused no observable effects on rice growth and development, but only mildly modified its grain transparency and seed germination. However, the transgenic pOsl2::GWD1 overexpression lines showed improvements in multiple key traits, including rice yield, grain shape, rice quality, seed germination and stress tolerance. Therefore, our study shows that GWD1 is not only involved in transitory starch degradation in source tissues, but also plays key roles in the seeds, which is a sink tissue. In conclusion, we find that GWD1 is an ideal biotechnological target with promising potential for the breeding of elite rice cultivars via genetic engineering.

中文翻译：

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葡聚糖、水二激酶 1 (GWD1) 是潜在提高水稻产量和品质的理想生物技术靶点

源库关系决定了水稻的整体农艺性能。克隆和表征参与源库动态调节的关键基因对于提高水稻产量至关重要。然而，很少有在水稻中具有潜在应用的源基因被确定。葡聚糖，水二激酶 1 (GWD1) 是一种必需酶，在源组织中瞬时淀粉降解的第一步中起关键作用。在本研究中，我们通过使用CRISPR/Cas9系统的启动子编辑成功地产生了gwd1弱突变体，以及由Osl2启动子驱动的GWD1的叶片优势过表达系。对gwd1植物的分析表明，启动子编辑介导了GWD1的下调对水稻生长发育没有明显影响，只是轻微改变了其籽粒透明度和种子发芽率。然而，转基因pOsl2::GWD1过表达系在多个关键性状方面表现出改善，包括水稻产量、粒形、水稻品质、种子萌发和胁迫耐受性。因此，我们的研究表明，GWD1不仅参与源组织中的瞬时淀粉降解，而且在种子中起着关键作用，种子是一种库组织。总之，我们发现GWD1是一个理想的生物技术靶点，具有通过基因工程培育优良水稻品种的潜力。