Featured Crops Engineering Laboratory of Shandong Province, Crop Research Institute, Shandong Academy of Agricultural Sciences, Jinan 250100, China.
College of Life Science, Shandong Normal University, Jinan 250014, China.
Int J Mol Sci. 2023 Nov 14;24(22):16321. doi: 10.3390/ijms242216321.
Foxtail millet ( (L.) P. Beauv) is an important food and forage crop that is well adapted to nutrient-poor soils. However, our understanding of how different LN-tolerant foxtail millet varieties adapt to long-term low nitrogen (LN) stress at the physiological and molecular levels remains limited. In this study, two foxtail millet varieties with contrasting LN tolerance properties were investigated through analyses of physiological parameters and transcriptomics. The physiological results indicate that JG20 (high tolerance to LN) exhibited superior biomass accumulation both in its shoots and roots, and higher nitrogen content, soluble sugar concentration, soluble protein concentration, zeatin concentration in shoot, and lower soluble sugar and soluble protein concentration in its roots compared to JG22 (sensitive to LN) under LN, this indicated that the LN-tolerant foxtail millet variety can allocate more functional substance to its shoots to sustain aboveground growth and maintain high root activity by utilizing low soluble sugar and protein under LN conditions. In the transcriptomics analysis, JG20 exhibited a greater number of differentially expressed genes (DEGs) compared to JG22 in both its shoots and roots in response to LN stress. These LN-responsive genes were enriched in glycolysis metabolism, photosynthesis, hormone metabolism, and nitrogen metabolism. Furthermore, in the shoots, the glutamine synthetase gene SiGS5, chlorophyll apoprotein of photosystem II gene SiPsbQ, ATP synthase subunit gene Sib, zeatin synthesis genes SiAHP1, and aldose 1-epimerase gene SiAEP, and, in the roots, the high-affinity nitrate transporter genes SiNRT2.3, SiNRT2.4, glutamate synthase gene SiGOGAT2, fructose-bisphosphate aldolase gene SiFBA5, were important genes involved in the LN tolerance of the foxtail millet variety. Hence, our study implies that the identified genes and metabolic pathways contribute valuable insights into the mechanisms underlying LN tolerance in foxtail millet.
谷子（(L.) P. Beauv）是一种重要的粮食和饲料作物，能很好地适应养分贫瘠的土壤。然而，我们对不同耐低氮（LN）谷子品种在生理和分子水平上如何适应长期低氮（LN）胁迫的了解仍然有限。在这项研究中，通过对生理参数和转录组学的分析，研究了两种耐 LN 特性差异较大的谷子品种。生理结果表明，在 LN 条件下，JG20（对 LN 高耐受）的地上部和根生物量积累均优于 JG22（对 LN 敏感），氮含量、可溶性糖浓度、可溶性蛋白浓度、地上部玉米素浓度较高，根中可溶性糖和可溶性蛋白浓度较低，表明 LN 耐受谷子品种可将更多功能物质分配到地上部，以维持地上部生长，并通过利用 LN 条件下的低可溶性糖和蛋白质来维持高根活性。在转录组学分析中，与 JG22 相比，JG20 在其地上部和根中对 LN 胁迫的响应中表现出更多的差异表达基因（DEGs）。这些 LN 响应基因在糖酵解代谢、光合作用、激素代谢和氮代谢中富集。此外，在地上部，谷氨酰胺合成酶基因 SiGS5、光合系统 II 叶绿素脱辅基蛋白基因 SiPsbQ、ATP 合酶亚基基因 Sib、玉米素合成基因 SiAHP1 和醛糖 1-差向异构酶基因 SiAEP，以及在根部，高亲和力硝酸盐转运体基因 SiNRT2.3、SiNRT2.4、谷氨酸合酶基因 SiGOGAT2、果糖-1,6-二磷酸醛缩酶基因 SiFBA5，是谷子品种耐 LN 的重要基因。因此，本研究表明，鉴定出的基因和代谢途径为谷子耐 LN 机制提供了有价值的见解。
