Adaption of roots to nitrogen deficiency revealed by 3-D quantification and proteomic analysis
- Plant Physiology期刊
- Rapeseed (Brassica napus L.) 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 3-D in situ quantification. Root proteome responses to N deficiency were analyzed by the tandem mass tag (TMT)-based proteomics method, and related proteins were further characterized. 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 (DEPs) 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 were also 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 thaliana plants demonstrated that the two root-related DEPs contribute to the enhanced root growth under N-deficiency conditions. These results provide insights into 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.