| Boron is an essential microelement for normal growth and development of plants, which is involved in a series of physiological functions, including cell wall synthesis and structure, membrane integrity and function, cell division, phenol metabolism, nitrogen fixation, pollen germination and growth of pollen tube. As the most important oilseed crop in China, Barssica napus is one the most sensitive crops in response to B-deficiency, lacking of available boron takes the major responsibility for reduced output of oilseed rape. At present, utilization of boron fertilizer is the mainly solution to deal with B-deficiency. However, it dramatically increased agricultural production cost, caused environmental pollution, and will speed boron resource exhaustion. Hence, deciphering the tolerant mechanism of B-deficiency in plants, and carrying out boron nutritional genetic improvement in plants, would be an important pathway to solve the problem of boron limitation. This study took boron-efficient Brassica napu cultivar "Qingyou 10" as research material to isolate and identify the differentially expressed proteins induced by B-deficiency by proteome research methods.As a rsult, a protein profile of Brassica napus in responses to boron-deficiency was conducted, and the physiological responses and tolerant mechanism of Brassica napus in responses to boron-deficiency was illustrated further. The main results were as follows:1.Optimized technical system of two-dimensional electrophoresis (2-DE) including the gel strength, pH range and length of IPG strip, technical parameters in IEF and SDS-PAGE was screeded, and a 2-DE system was finally set up for proteome research of Brassica napus root:18 cm, liner pH 5-8 IPG strips were adopted in IEF,12% gels concentration was used in SDS-PAGE, the SDS-PAGE was performed in a low voltage of 50 V firstly to ensure protein sample getting into gels, then changed to 120 V for protein separation.2.Separating total protein from Brassica napus root under different B-treatments, and 59 differentially expressed proteins in response to B-deficiency were determined. Through MALDI-TOF/TOF-MS and LTQ-ESI-MS/MS analysis,46 of them were successfully identified, and then a protein profile of Brassica napus in responses to boron-deficiency was conducted.3.By integrating various of bioinformatic softwares and public databases including WEGO, InterProScan, KEGG and UniProt, along with the analyzed molecular function, metabolic pathway and cellular location of the boron-deficiency responsed proteins, the identified 46 proteins were classified into 9 groups including antioxidant and detoxification mechanism, defense related proteins, signaling and regulation, carbohydrate and energy metabolism, amino acid and fatty acid metabolism, protein translation and degradation, cell wall structure, transporter, and function unknown.4.By combining protein function, metabolic pathway and physiological function of boron, one physiological and chemical pathway of Brassica napus in responses to boron-deficiency was illustrated. Under B-deficient stress, redox homeostasis in plants was impaired and results in oxidative burst, which in turn causes damages to cellular component and may influence a series of physiological pathways and biochemical reactions such as protein processing, amino acid metabolism and fatty acid synthesis. Membrane system was affected by oxyradical, and transmembrane transport of ion was disrupted. Carbohydrate metabolism was also affected and pentose phosphate pathway was enhanced. To resist B-deficiency stress, proteins involved in antioxidant and detoxification were over-expressed, and defense mechanism was triggered against the detriment of cellular components, and repairing the affected homeostasis in plants.
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