Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences/Key Laboratory of Biology and Genetics Improvement of Oil Crops of the Ministry of Agriculture, Wuhan 430062, China.
Tropotech LLC, St. Louis, Missouri 63141.
Plant Physiol. 2019 Jan;179(1):329-347. doi: 10.1104/pp.18.00716. Epub 2018 Nov 19.
Rapeseed () is an important oil crop worldwide. However, severe inhibition of rapeseed production often occurs in the field due to nitrogen (N) deficiency. The root system is the main organ to acquire N for plant growth, but little is known about the mechanisms underlying rapeseed root adaptions to N deficiency. Here, dynamic changes in root architectural traits of N-deficient rapeseed plants were evaluated by 3D in situ quantification. Root proteome responses to N deficiency were analyzed by the tandem mass tag-based proteomics method, and related proteins were characterized further. Under N deficiency, rapeseed roots become longer, with denser cells in the meristematic zone and larger cells in the elongation zone of root tips, and also become softer with reduced solidity. A total of 171 and 755 differentially expressed proteins were identified in short- and long-term N-deficient roots, respectively. The abundance of proteins involved in cell wall organization or biogenesis was highly enhanced, but most identified peroxidases were reduced in the N-deficient roots. Notably, peroxidase activities also were decreased, which might promote root elongation while lowering the solidity of N-deficient roots. These results were consistent with the cell wall components measured in the N-deficient roots. Further functional analysis using transgenic Arabidopsis () plants demonstrated that the two root-related differentially expressed proteins contribute to the enhanced root growth under N deficiency conditions. These results provide insights into the global changes of rapeseed root responses to N deficiency and may facilitate the development of rapeseed cultivars with high N use efficiency through root-based genetic improvements.
油菜（）是一种重要的油料作物，在全世界范围内广泛种植。然而，由于氮（N）素缺乏，油菜在田间常受到严重抑制。根系是植物生长获取 N 的主要器官，但人们对油菜根系适应 N 缺乏的机制知之甚少。在这里，通过 3D 原位定量评估了 N 缺乏油菜植株根系结构特征的动态变化。采用串联质量标签（tandem mass tag，TMT）蛋白质组学方法分析了 N 缺乏下油菜根系的蛋白质组响应，并对相关蛋白进行了进一步的分析。在 N 缺乏条件下，油菜根变得更长，根尖分生区细胞更密集，伸长区细胞更大，根变软，刚性降低。在短期和长期 N 缺乏的根中分别鉴定到 171 和 755 个差异表达蛋白。参与细胞壁组织或生物发生的蛋白质丰度显著增加，但大多数鉴定出的过氧化物酶在 N 缺乏的根中减少。值得注意的是，过氧化物酶活性也降低，这可能促进了根的伸长，同时降低了 N 缺乏根的刚性。这些结果与 N 缺乏根中测量的细胞壁成分一致。利用转基因拟南芥（）植物进行的进一步功能分析表明，这两个与根相关的差异表达蛋白有助于在 N 缺乏条件下增强根的生长。这些结果为油菜根系对 N 缺乏的响应的全面变化提供了深入的了解，并可能通过基于根系的遗传改良促进高氮利用效率油菜品种的发展。
