title: An investigation of boron-toxicity in leaves of two citrus species differing in boron-tolerance using comparative proteomics.
abstract: Limited data are available on boron (B)-toxicity-responsive proteins in plants. We first applied 2-dimensional electrophoresis (2-DE) to compare the effects of B-toxicity on leaf protein profiles in B-tolerant Citrus sinensis and B-intolerant Citrus grandis seedlings, and identified 27 (20) protein species with increased abundances and 23 (25) protein species with decreased abundances from the former (latter). Generally speaking, B-toxicity increased the abundances of protein species involved in antioxidation and detoxification, proteolysis, cell transport, and decreased the abundances of protein species involved in protein biosynthesis in the two citrus species. The higher B-tolerance of C. sinensis might include following several aspects: (a) protein species related to photosynthesis and energy metabolism in C. sinensis leaves were more adaptive to B-toxicity than in C. grandis ones, which was responsible for the higher photosynthesis and for the better maintenance of energy homeostasis in the former; and (b) the increased requirement for detoxification of reactive oxygen species and cytotoxic compounds due to decreased photosynthesis was less in B-toxic C. sinensis leaves than in B-toxic C. grandis ones. B-toxicity-responsive protein species involved in coenzyme biosynthesis differed between the two species, which might also contribute to the higher B-tolerance of C. sinensis.
  
  
  CONCLUSIONS
  B-toxicity occurs in many regions all over the world, especially in arid and semiarid regions due to the raising of B-rich water tables with high B accumulated in topsoil. In China, B-toxicity often occurs in some citrus orchards. However, the mechanisms of citrus B-tolerance are still not fully understood. Here, we first used 2-DE to identify some new B-toxicity-responsive-proteins involved in carbohydrate and energy metabolism, antioxidation and detoxification, signal transduction and nucleotide metabolism. Our results showed that proteins involved in photosynthesis and energy metabolism displayed more adaptive to B-toxicity in B-tolerant C. sinensis than in B-intolerant C. grandis, which might play a key role in citrus B-tolerance. Therefore, our results reveal some new mechanisms on plant B-response and tolerance.
authors.affiliation: Institute of Horticultural Plant Physiology, Biochemistry and Molecular Biology, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Sang
authors.affiliation: College of Resource and Environmental Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Zeng-Rong
authors.initials: ZR
authors.lastname: Huang
authors.affiliation: Institute of Materia Medica, Fujian Academy of Medical Sciences, Fuzhou 350001, China.
authors.forename: Yi-Ping
authors.initials: YP
authors.lastname: Qi
authors.affiliation: Institute of Horticultural Plant Physiology, Biochemistry and Molecular Biology, Fujian Agriculture and Forestry University, Fuzhou 350002, China; College of Resource and Environmental Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Lin-Tong
authors.initials: LT
authors.lastname: Yang
authors.affiliation: Institute of Horticultural Plant Physiology, Biochemistry and Molecular Biology, Fujian Agriculture and Forestry University, Fuzhou 350002, China; College of Resource and Environmental Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Guo
authors.affiliation: Institute of Horticultural Plant Physiology, Biochemistry and Molecular Biology, Fujian Agriculture and Forestry University, Fuzhou 350002, China; College of Resource and Environmental Science, Fujian Agriculture and Forestry University, Fuzhou 350002, China; The Higher Educational Key Laboratory of Fujian Province for Soil Ecosystem Health and Regulation, Fujian Agriculture and Forestry University, Fuzhou 350002, China; Fujian Key Laboratory for Plant Molecular and Cell Biology, Fujian Agriculture and Forestry University, Fuzhou 350002, China. Electronic address: lisongchen2002@hotmail.com.
authors.forename: Li-Song
authors.initials: LS
authors.lastname: Chen
mesh_terms: D000975:Antioxidants / Q000737:chemistry; D001895:Boron / Q000737:chemistry*; D002681:China; D002957:Citrus / Q000187:drug effects / Q000235:genetics*; D032084:Citrus sinensis / Q000187:drug effects / Q000235:genetics*; D015180:Electrophoresis, Gel, Two-Dimensional; D010788:Photosynthesis; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry; D018517:Plant Roots / Q000378:metabolism; D040901:Proteomics / Q000379:methods*; D017382:Reactive Oxygen Species / Q000378:metabolism; D036226:Seedlings / Q000378:metabolism; D013045:Species Specificity
chemical_list: D000975:Antioxidants; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D001895:Boron
keywords: 2-DE; Boron; Citrus grandis; Citrus sinensis; Photosynthesis; Proteomics