过量表达OsNRT2.1对水稻日本晴生长和氮素利用效率的影响

The Effects of Os NRT2.1 Over-expression on Plant Growth and Nitrogen use Efficiency in Rice Nipponbare(Oryza sativa L.ssp.japonica)

为了提高水稻的氮素利用效率,我们用农杆菌介导ubiquitin(Ubi)启动子在水稻日本晴中过量表达高亲和的硝酸盐转运蛋白Os NRT2.1。田间实验发现,与野生型相比,过量表达株系总分蘖数增加约70%,生物量提高约27%,整个生育期的生长速率都显著提高,在齐穗期和成熟期的氮素积累总量提高约20%和18%。过量表达株系生物量和总氮含量主要集中在茎秆和叶,由于Os NRT2.1伴侣蛋白Os NAR2.1的表达没有提高,在生殖生长阶段,往穗子中的氮素转运效率减少了约35%,导致过量表达株系的氮素收获指数、生理氮素利用效率和农学氮素利用效率分别降低约30%、34%和20%,最终导致单株产量降低13%~26%。研究表明,一般的组成型强启动子单独过量表达Os NRT2.1并不能达到提高水稻最终产量的目的。

Inorder to improve nitrogen use efficiency, Agrobacterium-mediated ubiquitin(Ubi) promoter was used to over express Os NRT2.1, a high-affinity NO3-transporter in Nipponbare. The field experiments showed that,compared to the wild type of rice, the total tillers of over-expression lines were increased by about 70%, and their biomass increased by about 27%, the growth rate during whole growth period was increased significantly. The total content of nitrogen accumulation was increased by about 20% in the anthesis stage and 18% in the maturity stage. The biomass and total nitrogen content of overexpression lines mainly concentrated in the stems and leafs.Because the expression of Os NRT2.1's chaperone protein Os NAR2.1 was not improved, nitrogen translocation efficiency decreased by about 35% in the stage of reproductive growth. So, nitrogen harvest index, nitrogen use efficiency and agronomic nitrogen use efficiency decreased by about 30%, 20% and 34% respectively, and finally the yield per plant decreased by 13% ~26%. The results indicated that the over-expression of Os NRT2.1 by the usually constitutive strong promoter singly could not increase the final yield of rice.