OsSTP1介导蔗糖分配调控水稻氮响应

OsSTP1 mediates sucrose allocation to regulate rice responses to different nitrogen supply levels

摘要:

提高水稻氮肥的利用效率是增加产量的有效途径，而维持碳氮平衡是促进水稻正常生长发育的保障。为探究蔗糖转运蛋白OsSTP1对水稻氮素吸收的影响，本研究以野生型TB309为背景材料，构建了蔗糖转运蛋白OsSTP1的过表达转基因株系OsSTP1-OE1、OsSTP1-OE2和突变体转基因株系osstp1-1、osstp1-2。采用水培试验，设置不供氮(free nitrogen,FN,0 mg/L)、低氮(low nitrogen,LN,10 mg/L)、正常氮(normal nitrogen,NN,40 mg/L)和高氮(high nitrogen,HN,80 mg/L)四个供氮水平，研究各株系苗期对不同供氮水平的响应。结果发现，相对于野生型和突变体，OsSTP1过表达材料在低氮水平下，生物量、根长、株高显著增加，叶片可溶性糖含量显著降低，而根部的可溶性糖含量显著增加。表明其叶片光合作用产生的可溶性糖通过韧皮部转运到根系中，从而促进根系的生长来吸收更多的氮素促进地上部生物量增加。本研究证明水稻糖转运蛋白基因OsSTP1通过影响水稻碳水化合物在源库端的长距离运输来促进水稻的根系生长，最终影响水稻对氮素的吸收与积累，提高了水稻氮素利用率，为氮肥减施提供了参考。

Abstract:

Improving the nitrogen use efficiency is an effective way to increase the yield of rice, and maintaining carbon-nitrogen balance is essential for the normal growth and development of rice. To investigate the impact of the sucrose transporter protein OsSTP1 on nitrogen absorption in rice, in this study, we constructed transgenic lines overexpressing the sucrose transporter gene OsSTP1 (OsSTP1-OE1, OsSTP1-OE2) and mutant transgenic lines (osstp1-1, osstp1-2) from the wild type TB309. Further, we conducted a hydroponic experiment with four nitrogen supply levels of free nitrogen (FN, 0 mg/L), low nitrogen (LN, 10 mg/L), normal nitrogen (NN, 40 mg/L), and high nitrogen (HN, 80 mg/L) to study the responses of each line to different nitrogen supply levels during the seedling stage. The results showed that compared with the wild type and mutant lines in the LN group, the OsSTP1-overexpressing lines exhibited significantly increased biomass, root length, and plant height, decreased soluble sugar content in the leaves, and increased soluble sugar content in the roots. The results indicate that the soluble sugars produced by leaf photosynthesis are transported to the roots through the phloem to promote root growth and nitrogen uptake, thus increasing the aboveground biomass. This study has identified that OsSTP1 can affect the long-distance transport of carbohydrates from source to sink to promote root growth, ultimately influencing rice’s absorption and accumulation of nitrogen, improving nitrogen use efficiency and providing reference for reducing nitrogen fertilizer application.