Rice Research Institute, Guangdong Academy of Agricultural Sciences/Guangdong Rice Engineering Laboratory/ Guangdong Key Laboratory of New Technology in Rice Breeding /Key Laboratory of Genetics and Breeding of High Quality Rice in Southern China (Co-construction by Ministry and Province), Ministry of Agriculture and Rural Affairs, Guangzhou, 510640, PR China.
Rice Research Institute, Guangdong Academy of Agricultural Sciences/Guangdong Rice Engineering Laboratory/ Guangdong Key Laboratory of New Technology in Rice Breeding /Key Laboratory of Genetics and Breeding of High Quality Rice in Southern China (Co-construction by Ministry and Province), Ministry of Agriculture and Rural Affairs, Guangzhou, 510640, PR China.
J Plant Physiol. 2023 May;284:153976. doi: 10.1016/j.jplph.2023.153976. Epub 2023 Mar 25.
Nitrogen (N) is a principal macronutrient and plays a paramount role in mineral nutrition of rice plants. Mixed provision of ammonium- and nitrate-nitrogen (MPAN) at a moderate level could enhance N uptake and translocation and promote growth of rice, but current understanding of their molecular mechanisms is still insufficient. Two rice lines of W6827 and GH751, with contrasting ability of N uptake, were subjected to four levels of MPAN (NH/NO = 100:0, 75:25, 50:50, 25:75) in hydroponic experiments. In terms of plant height, growth rate and shoot biomass, growth of GH751 tended to increase firstly and then decrease with enhancement in NO-N ratio. It attained maximal level under 75:25 MPAN, with an 8.3% increase in shoot biomass. In general, W6827 was comparatively less responsive to MPAN. For GH751, the uptake rate of N, phosphor (P) and potassium (K) under 75:25 MPAN was enhanced by 21.1%, 20.8% and 16.1% in comparison with that of control (100:0 MPAN). Meanwhile, the translocation coefficient and content in shoots of N, P and K were all increased significantly. In contrast to transcriptomic profile under control, 288 differentially expressed genes (DEGs) were detected to be up-regulated and 179 DEGs down-regulated in transcription under 75:25 MPAN. Gene Ontology analysis revealed that some DEGs were up-regulated under 75:25 MPAN and they code for proteins mainly located in membrane and integral component of membrane and involved in metal ion binding, oxidoreductase activity and other biological processes. KEGG pathway enrichment analysis indicated that DEGs related to nitrogen metabolism, carbon fixation in photosynthetic organisms, photosynthesis, starch and sucrose metabolism, and zeatin biosynthesis were up- or down-regulated in transcription under 75:25 MPAN, and they are responsible for improved nutrient uptake and translocation and enhanced growth of seedlings.
氮（N）是主要的大量营养素，在水稻植株的矿物质营养中起着至关重要的作用。适度提供铵态氮和硝态氮（MPAN）可以促进水稻对氮的吸收和转运，促进其生长，但目前对其分子机制的理解仍然不足。本研究选用具有不同氮吸收能力的两个水稻品种 W6827 和 GH751，在水培条件下进行 4 个 MPAN 处理（NH/NO=100:0、75:25、50:50、25:75）。就株高、生长速率和地上部生物量而言，GH751 的生长趋势为先增加后减少，随着 NO-N 比例的增加而增加。在 75:25MPAN 处理下，GH751 的地上部生物量最大，比对照（100:0MPAN）增加了 8.3%。总体而言，W6827 对 MPAN 的响应相对较小。对于 GH751，75:25MPAN 处理下氮、磷和钾的吸收速率分别比对照提高了 21.1%、20.8%和 16.1%。同时，氮、磷和钾在地上部的转运系数和含量均显著增加。与对照的转录组谱相比，在 75:25MPAN 处理下检测到 288 个差异表达基因（DEGs）上调，179 个下调。GO 分析表明，在 75:25MPAN 处理下，一些 DEGs 上调，它们编码的蛋白质主要位于膜和膜的整合成分中，参与金属离子结合、氧化还原酶活性和其他生物过程。KEGG 途径富集分析表明，与氮代谢、光合生物固碳、光合作用、淀粉和蔗糖代谢、玉米素生物合成相关的 DEGs 在转录水平上上调或下调，这些基因负责促进养分吸收和转运，从而促进幼苗生长。
