Abstract：
Rice direct seeding technology has been considered as a promising alternative to traditional transplanting because of its advantages in saving labor and water. However, the poor emergence and seedling growth caused by chill stress are the main bottlenecks in wide-scale adoption of direct-seeded rice in Heilongjiang Province, China. Here, we found that natural plant growth regulator guvermectin (GV) effectively improved rice seed germination and seedling growth under chilling stress. Results from 2 year field trials showed that seed-soaking with GV not only enhanced the emergence rate and seedling growth but also increased the panicle number per plant and grain number per panicle, resulting in 9.0 and 6.8% increase in the yield of direct-seeded rice, respectively. Integrative physiological, transcriptomic, and metabolomic assays revealed that GV promoted seed germination under chilling stress mainly by enhancing the activities of α-amylase and antioxidant enzymes (superoxide dismutase, peroxidase, and catalase), increasing the contents of soluble sugar and soluble protein, improving the biosynthesis of glutathione and flavonoids, as well as activating gibberellin-responsive transcription factors and inhibiting the abscisic acid signaling pathway. These findings indicate that seed-soaking with GV has good potential to improve seedling establishment and yield of direct-seeded rice even under chilling stress.
摘要：
水稻直播技术因其具有省力、省水等优点,被认为是传统移栽的有希望的替代方案。然而,寒冷胁迫导致的出苗和幼苗生长不良是黑龙江省直播水稻大规模采用的主要瓶颈，中国。这里,研究发现,在低温胁迫下,天然植物生长调节剂古维菌素(guvermectin,GV)可有效促进水稻种子萌发和幼苗生长。2年田间试验结果表明，GV浸种不仅提高了出苗率和幼苗生长，而且增加了单株穗数和单穗粒数，使直播稻的产量分别提高了9.0%和6.8%,分别。综合生理，转录组，和代谢组学分析表明，GV主要通过增强α-淀粉酶和抗氧化酶（超氧化物歧化酶，过氧化物酶,和过氧化氢酶)，增加可溶性糖和可溶性蛋白质的含量，改善谷胱甘肽和类黄酮的生物合成，以及激活赤霉素应答转录因子和抑制脱落酸信号通路。这些发现表明，即使在低温胁迫下，用GV浸种也具有改善直播水稻幼苗建立和产量的良好潜力。
