title: Accumulation and cellular toxicity of aluminum in seedling of Pinus massoniana.
abstract: BACKGROUND
  Masson pine (Pinus massoniana) is one of the most important timber species with adaptable, fast growing, versatile advantages in southern China. Despite considerable research efforts, the cellular and molecular mechanisms of A1 toxicity and resistance in P. massoniana are still poorly understood. The effects of Al on uptake and translocation of Al and other minerals, cell division and nucleolus in P. massoniana were investigated.
  
  
  RESULTS
  The results indicated that Al accumulated mainly in the roots, and small amounts were transported to aboveground organs. In the presence of Al, the contents of Mg and Fe in stems increased and decreased in roots. Accumulation of Mn in the organs was inhibited significantly. Evidence from cellular experiments showed that Al had an inhibitory effect on the root growth at all concentrations (10⁻⁵ - 10⁻² M) used. Chromosome fragments, chromosome bridges, C-mitosis and chromosome stickiness were induced during mitosis in the root tip cells. Al induced the formation of abnormal microtubule (MT) arrays, consisting of discontinuous wavy MTs or short MT fragments at the cell periphery. MT organization and function of the mitotic spindle and phragmoplast were severely disturbed. The nucleolus did not disaggregate normally and still remained its characteristic structure during metaphase. Nucleolar particles containing argyrophilic proteins were accumulated and leached out from the nucleus to the cytoplasm. Evidence confirmed that these proteins contained nucleophosmin (B23), nucleolin (C23) and fibrillarin. Western immunoblot analysis revealed that the contents of three nucleolar proteins increased significantly.
  
  
  CONCLUSIONS
  Based on the information provided in this article, it is concluded that root tips of plants are the most sensitive organ to environmental stresses and the accumulation of Al ions primarily is in roots of P. massoniana, and small amounts of Al are transported to aboveground. Root apical meristems play a key role in the immediate reaction to stress factors by activating signal cascades to the other plant organs. Al induces a series of the cellular toxic changes concerning with cell division and nucleolus. The data presented above can be also used as valuable and early markers in cellular changes induced by metals for the evaluation of metal contamination.
authors.forename: Huanhuan
authors.initials: H
authors.lastname: Zhang
authors.forename: Ze
authors.initials: Z
authors.lastname: Jiang
authors.forename: Rong
authors.initials: R
authors.lastname: Qin
authors.forename: Huaning
authors.initials: H
authors.lastname: Zhang
authors.forename: Jinhua
authors.initials: J
authors.lastname: Zou
authors.forename: Wusheng
authors.initials: W
authors.lastname: Jiang
authors.forename: Donghua
authors.initials: D
authors.lastname: Liu
mesh_terms: D000535:Aluminum / Q000378:metabolism* / Q000633:toxicity; D002455:Cell Division / Q000187:drug effects; D002466:Cell Nucleolus / Q000187:drug effects; D032461:Chromosomes, Plant / Q000187:drug effects; D003599:Cytoskeleton / Q000187:drug effects; D007501:Iron / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism; D008345:Manganese / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D028223:Pinus / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development; D036226:Seedlings / Q000187:drug effects / Q000378:metabolism
chemical_list: D009687:Nuclear Proteins; D010940:Plant Proteins; D008345:Manganese; D000535:Aluminum; D007501:Iron; D008274:Magnesium