State Key Laboratory of North China Crop Improvement and Regulation, Hebei Agricultural University, Baoding 071001, China.
North China Key Laboratory for Crop Germplasm Resources of the Education Ministry, Hebei Agricultural University, Baoding 071001, China.
Genes (Basel). 2022 Apr 11;13(4):670. doi: 10.3390/genes13040670.
Nitrogen is one of the essential nutrients for plant growth and development. However, large amounts of nitrogen fertilizer not only increase the production costs, but also lead to serious environmental problems. Therefore, it is particularly important to reduce the application of nitrogen fertilizer and develop maize varieties with low nitrogen tolerance. The aim of this study was to determine the phenotypic and proteomic alterations of maize affected by nitrogen deficiency and to elucidate the molecular and physiological mechanisms underpinning maize tolerance to low nitrogen. Two maize hybrids with contrasting low nitrogen tolerance were used as the experimental materials. Maize plants were grown under different nitrogen application levels (N0 and N240) and proteomic analysis performed to analyze leaf differentially abundant proteins (DAPs) under different nitrogen conditions. The results showed that under the nitrogen deficiency condition, the nitrogen content, leaf dry weight, leaf area, and leaf area index of XY335 decreased by 15.58%, 8.83%, 3.44%, and 3.44%, respectively. However, in the variety HN138, the same parameters decreased by 56.94%, 11.97%, 8.79%, and 8.79%, respectively. Through proteomic analysis, we found that the low nitrogen tolerance variety responded to low nitrogen stress through lignin biosynthesis, ubiquitin-mediated proteolysis, and stress defense proteins. Transmembrane transporters were differentially expressed in both hybrids after low nitrogen treatment, suggesting that this was a common response to low nitrogen stress. Using bioinformatics analysis, we selected the key candidate gene () that was assumed to respond to low nitrogen stress, and its function was characterized by maize mutants. The results showed that when compared with normal nitrogen treatment, the root length of the mutants under low nitrogen treatment increased by 10.1%, while that of the wild-type increased by 14.8%; the root surface area of the wild type under low nitrogen treatment increased by 9.6%, while that of the mutants decreased by 5.2%; the root surface area of the wild type was higher than that of the mutant at both nitrogen levels; and the activities of glutathione and guaiacol peroxidase enzymes in the mutant were lower than those in the wild-type under low nitrogen treatment. In summary, the mutant was less adaptable to a low nitrogen environment than the wild type. Our results provide maize genetic resources and a new direction for a further understanding of maize response to low nitrogen stress.
氮是植物生长和发育所必需的营养元素之一。然而，大量施用氮肥不仅增加了生产成本，还会导致严重的环境问题。因此，减少氮肥的施用量并开发具有低氮耐性的玉米品种尤为重要。本研究旨在确定受氮缺乏影响的玉米的表型和蛋白质组学变化，并阐明玉米对低氮耐性的分子和生理机制。本研究以两种氮耐性差异较大的玉米杂交种为实验材料，在不同氮素供应水平（N0 和 N240）下培养玉米植株，并进行蛋白质组分析，以分析不同氮条件下叶片差异丰度蛋白（DAP）。结果表明，在氮缺乏条件下，XY335 的氮含量、叶片干重、叶面积和叶面积指数分别降低了 15.58%、8.83%、3.44%和 3.44%，而在 HN138 品种中，相同参数分别降低了 56.94%、11.97%、8.79%和 8.79%。通过蛋白质组分析，我们发现低氮耐性品种通过木质素生物合成、泛素介导的蛋白水解和应激防御蛋白对低氮胁迫做出响应。在低氮处理后，两种杂交种的跨膜转运蛋白均有差异表达，这表明这是对低氮胁迫的共同响应。通过生物信息学分析，我们选择了假定对低氮胁迫做出响应的关键候选基因（），并通过玉米突变体对其功能进行了表征。结果表明，与正常氮处理相比，低氮处理下突变体的根长增加了 10.1%，而野生型增加了 14.8%；低氮处理下野生型的根表面积增加了 9.6%，而突变体的根表面积减少了 5.2%；在两种氮水平下，野生型的根表面积均高于突变体；低氮处理下，突变体的谷胱甘肽和愈创木酚过氧化物酶的活性均低于野生型。综上所述，突变体对低氮环境的适应性低于野生型。我们的研究结果为进一步了解玉米对低氮胁迫的响应提供了玉米遗传资源和新方向。
