Lamichhane Suman, Murata Chiaki, Griffey Carl A, Thomason Wade E, Fukao Takeshi
School of Plant and Environmental Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
Texas A&M Agrilife Research, Beaumont, TX 77713, USA.
Plants (Basel). 2021 Jan 17;10(1):165. doi: 10.3390/plants10010165.
A sufficient nitrogen (N) supply is pivotal for high grain yield and desired grain protein content in wheat ( L.). Elucidation of physiological and molecular mechanisms underlying nitrogen use efficiency (NUE) will enhance our ability to develop new N-saving varieties in wheat. In this study, we analyzed two soft red winter wheat genotypes, VA08MAS-369 and VA07W-415, with contrasting NUE under limited N. Our previous study demonstrated that higher NUE in VA08MAS-369 resulted from accelerated senescence and N remobilization in flag leaves at low N. The present study revealed that VA08MAS-369 also exhibited higher nitrogen uptake efficiency (NUpE) than VA07W-415 under limited N. VA08MAS-369 consistently maintained root growth parameters such as maximum root depth, total root diameter, total root surface area, and total root volume under N limitation, relative to VA07W-415. Our time-course N content analysis indicated that VA08MAS-369 absorbed N more abundantly than VA07W-415 after the anthesis stage at low N. More efficient N uptake in VA08MAS-369 was associated with the increased expression of genes encoding a two-component high-affinity nitrate transport system, including four s and three s, in roots at low N. Altogether, these results demonstrate that VA08MAS-369 can absorb N efficiently even under limited N due to maintained root development and increased function of N uptake. The ability of VA08MAS-369 in N remobilization and uptake suggests that this genotype could be a valuable genetic material for the improvement of NUE in soft red winter wheat.
充足的氮素供应对于小麦（Triticum aestivum L.）实现高产和理想的籽粒蛋白质含量至关重要。阐明氮素利用效率（NUE）的生理和分子机制将增强我们培育小麦新的节氮品种的能力。在本研究中，我们分析了两种软红冬小麦基因型VA08MAS - 369和VA07W - 415，它们在低氮条件下氮素利用效率存在差异。我们之前的研究表明，VA08MAS - 369较高的氮素利用效率源于低氮条件下旗叶加速衰老和氮素再转运。本研究表明，在低氮条件下，VA08MAS - 369的氮素吸收效率（NUpE）也高于VA07W - 415。相对于VA07W - 415，在氮素限制条件下，VA08MAS - 369始终保持着如最大根深度、总根直径、总根表面积和总根体积等根系生长参数。我们的氮含量时间进程分析表明，在低氮条件下，VA08MAS - 369在开花期后比VA07W - 415更大量地吸收氮素。VA08MAS - 369更高效的氮素吸收与低氮条件下根系中编码双组分高亲和硝酸盐转运系统的基因（包括四个NRT2s和三个NAR2s）表达增加有关。总之，这些结果表明，由于根系发育的维持和氮素吸收功能的增强，VA08MAS - 369即使在低氮条件下也能高效吸收氮素。VA08MAS - 369在氮素再转运和吸收方面的能力表明，该基因型可能是改良软红冬小麦氮素利用效率的宝贵遗传材料。
