| Boron is essential for normal growth and development of plants, and boron deficiency causes a reduction in crop yield but also impairs the quality. Brassica napus is a representative species of dicotyledon, which has large demand for boron and is very sensitive to boron deficiency. In China the major oil rapeseed producing areas just are located in the middle and down reaches of Changjiang River, where the soil available boron is deficient or severely deficient, which is one of main limitation factors for Brassica napus growth. Boron fertilizer is widely utilized currently to deal with B-deficiency, however, it increases agricultural production cost and also bring about possible environment problem. Hence, selecting B-efficient cultivars, analyzing the adaptive mechanism to low boron of plants in physiology and genetics, and carrying out the boron nutritional genetic improvement, would be of great significance for the sustainable development of oilseed industry. Based on the previous work in our lab, in the present study we used proteome research methods to get the differential proteome profiles of B-efficient Qingyou 10 in response to boron deficiency in various degrees, and then integrated the low boron responsive pathways to give a reasonable explanation of the B-deficient tolerance mechanism. The main results were as follows:1 Optimization of protein extraction and 2-DE parameters for Brassica napus root proteomic study. Three methods (TCA/acetone, phenol extraction and phenol extraction-methanol/ammonium acetate precipitation) for protein extraction were assessed respectively with Brassica napus root, and then the protein samples were separated by SDS-PAGE and two-dimensional electrophoresis (2-DE) in turn to compare the isolation effect. Finally, we selected phenol extraction method and modified the loading volume and gel concentration to optimize the 2-DE protocol.2 Isolation and MS identification of the differential expressed proteins induced by boron deficiency. After oil rapeseed seedlings were treated by short term boron deficiency, the roots were collected at different time points to extract soluble proteins, and then separated by 2-DE. The images of control set and treatment were analyzed by PDquest software, and 78 differential spots were found, of which 46 proteins were successfully identified.3 System integration of metabolic pathway and function analysis. Taking knowledge from InterPro, NCBI, UniProt, TAIR and other bioinformatic softwares or public databases, and systematically analyzing the biological function, metabolic pathway and spatio-temporal expression of all the identified proteins, the 46 differential proteins were classified into eight groups including carbohydrate and energy metabolism, stress response, signaling and regulation, protein process, amino acid and fatty acid metabolism, cell wall structure, nucleic acid metabolism and unclassified.4 Analysis of the low boron adaptive mechanism in Qingyou 10. The carbon flux was suggested to be a putative modulating centre in charge of the response to B stress, which determining the balance between the producing of energy and reducing power by control the flow into different pathways. Cascades of MAPK were activated at first while the energy supply was not impaired. As the stress became more serious, cellular homeostasis was broke, the energy producing rate was limited to decrease the risk of oxidative damage, various signal channels were activated and different antioxidases were up-regulated to rebuild the redox equilibrium. Meanwhile, due to the shortage of nutrient and energy caused by boron deficiency in plants, many biosynthesis pathways were maintained at a relatively low level to stay up for a longer time. In addition, several genes related to cell wall synthesis were induced to stabilize the cell wall structure. |
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