title: Reduced tolerance to abiotic stress in transgenic Arabidopsis overexpressing a Capsicum annuum multiprotein bridging factor 1.
abstract: BACKGROUND
  The pepper fruit is the second most consumed vegetable worldwide. However, low temperature affects the vegetative development and reproduction of the pepper, resulting in economic losses. To identify cold-related genes regulated by abscisic acid (ABA) in pepper seedlings, cDNA representational difference analysis was previously performed using a suppression subtractive hybridization method. One of the genes cloned from the subtraction was homologous to Solanum tuberosum MBF1 (StMBF1) encoding the coactivator multiprotein bridging factor 1. Here, we have characterized this StMBF1 homolog (named CaMBF1) from Capsicum annuum and investigated its role in abiotic stress tolerance.
  
  
  RESULTS
  Tissue expression profile analysis using quantitative RT-PCR showed that CaMBF1 was expressed in all tested tissues, and high-level expression was detected in the flowers and seeds. The expression of CaMBF1 in pepper seedlings was dramatically suppressed by exogenously supplied salicylic acid, high salt, osmotic and heavy metal stresses. Constitutive overexpression of CaMBF1 in Arabidopsis aggravated the visible symptoms of leaf damage and the electrolyte leakage of cell damage caused by cold stress in seedlings. Furthermore, the expression of RD29A, ERD15, KIN1, and RD22 in the transgenic plants was lower than that in the wild-type plants. On the other hand, seed germination, cotyledon greening and lateral root formation were more severely influenced by salt stress in transgenic lines compared with wild-type plants, indicating that CaMBF1-overexpressing Arabidopsis plants were hypersensitive to salt stress.
  
  
  CONCLUSIONS
  Overexpression of CaMBF1 in Arabidopsis displayed reduced tolerance to cold and high salt stress during seed germination and post-germination stages. CaMBF1 transgenic Arabidopsis may reduce stress tolerance by downregulating stress-responsive genes to aggravate the leaf damage caused by cold stress. CaMBF1 may be useful for genetic engineering of novel pepper cultivars in the future.
authors.forename: Wei-Li
authors.initials: WL
authors.lastname: Guo
authors.forename: Ru-Gang
authors.initials: RG
authors.lastname: Chen
authors.forename: Xiao-Hua
authors.initials: XH
authors.lastname: Du
authors.forename: Zhen
authors.initials: Z
authors.lastname: Zhang
authors.forename: Yan-Xu
authors.initials: YX
authors.lastname: Yin
authors.affiliation: College of Horticulture, Northwest A&F University, Yangling, Shaanxi, P R China. zhgong@nwsuaf.edu.cn.
authors.forename: Zhen-Hui
authors.initials: ZH
authors.lastname: Gong
authors.forename: Guang-Yin
authors.initials: GY
authors.lastname: Wang
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development / Q000502:physiology*; D002212:Capsicum / Q000235:genetics / Q000378:metabolism*; D003080:Cold Temperature; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D004573:Electrolytes; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006360:Heat-Shock Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D010641:Phenotype; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D030821:Plants, Genetically Modified; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020156:Salicylic Acid / Q000494:pharmacology; D036226:Seedlings / Q000187:drug effects / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics
chemical_list: D018076:DNA, Complementary; D004573:Electrolytes; D006360:Heat-Shock Proteins; D010940:Plant Proteins; D012333:RNA, Messenger; D012965:Sodium Chloride; D020156:Salicylic Acid