title: Iron deficiency stress can induce MxNRAMP1 protein endocytosis in M. xiaojinensis.
abstract: BACKGROUND
  Iron deficiency is one of the most common nutritional disorders in plants, especially in fruit trees grown in calcareous soil. Iron deficiency stress can induce a series of adaptive responses in plants, the cellular and molecular mechanisms of which remain unclear. NRAMPs (natural resistance-associated macrophage proteins) play an important role in divalent metal ion transportation.
  
  
  RESULTS
  In this study, we cloned MxNRAMP1, an NRAMP family gene from a highly iron-efficient apple genotype, Malus xiaojinensis. Further research showed that iron deficiency stress could induce MxNRAMP1 expression in roots and leaves. A protoplast transient expression system and immune electron microscopy localization techniques were used to prove that MxNRAMP1 mainly exists in the plasma membrane and vesicles. Interestingly, iron deficiency stress could induce the MxNRAMP protein to transport iron ions to specific organelles (lysosome and chloroplast) through vesicle endocytosis. Stable transgenic tobacco showed that MxNRAMP1 over-expression could promote iron absorption and accumulation in plants, and increase the plant's resistance against iron deficiency stress.
  
  
  CONCLUSIONS
  These results showed that, in M. xiaojinensis, MxNRAMP1 not only plays an important role in iron absorption and transportation, it can also produce adaptive responses against iron deficiency through endocytosis.
authors.affiliation: China Agricultural University, Beijing 100193, China; Key Laboratory of Genetic improvement and Ecophysiology of Horticultural Crop, Anhui Province, Institute of Horticulture, Anhui Academy of Agricultural Sciences, Hefei 230031, Anhui, China.
authors.forename: Haifa
authors.initials: H
authors.lastname: Pan
authors.affiliation: China Agricultural University, Beijing 100193, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.affiliation: China Agricultural University, Beijing 100193, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zha
authors.affiliation: China Agricultural University, Beijing 100193, China.
authors.forename: Mudan
authors.initials: M
authors.lastname: Yuan
authors.affiliation: China Agricultural University, Beijing 100193, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Yin
authors.affiliation: China Agricultural University, Beijing 100193, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Wu
authors.affiliation: China Agricultural University, Beijing 100193, China.
authors.forename: Xinzhong
authors.initials: X
authors.lastname: Zhang
authors.affiliation: China Agricultural University, Beijing 100193, China.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Xu
authors.affiliation: China Agricultural University, Beijing 100193, China.
authors.forename: Zhenhai
authors.initials: Z
authors.lastname: Han
mesh_terms: D000595:Amino Acid Sequence; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D017124:Conserved Sequence; D004705:Endocytosis; D018506:Gene Expression Regulation, Plant; D000090463:Iron Deficiencies; D027845:Malus / Q000378:metabolism*; D008969:Molecular Sequence Data; D010935:Plant Diseases; D018515:Plant Leaves / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D011523:Protoplasts / Q000378:metabolism; D013312:Stress, Physiological; D014026:Nicotiana; D015533:Transcriptional Activation; D003313:Zea mays
chemical_list: D027682:Cation Transport Proteins; D010940:Plant Proteins
keywords: Iron deficiency stress; M. xiaojinensis; MxNRAMP1; Subcellular localization; Tobacco; Transporter