| 19858117 |
Sun P, Tian QY, Chen J, Zhang WH: Aluminium-induced inhibition of root elongation in Arabidopsis is mediated by ethylene and auxin. J Exp Bot. 2010;61(2):347-56. Epub 2009 Oct 25.
Aluminium (Al) is phytotoxic when solubilized into Al (3+) in acidic soils. One of the earliest and distinct symptoms of Al (3+) toxicity is inhibition of root elongation. To decipher the mechanism by which Al (3+) inhibits root elongation, the role of ethylene and auxin in Al (3+)-induced inhibition of root elongation in Arabidopsis thaliana was investigated using the wild type and mutants defective in ethylene signalling (etr1-3 and ein2-1) and auxin polar transport (aux1-7 and pin2). Exposure of wild-type Arabidopsis to AlCl (3) led to a marked inhibition of root elongation, and elicited a rapid ethylene evolution and enhanced activity of the ethylene reporter EBS:GUS in root apices. Root elongation in etr1-3 and ein2-1 mutants was less inhibited by Al (3+) than that in wild-type plants. Ethylene synthesis inhibitors, Co (2+) and aminoethoxyvinylglycine (AVG), and an antagonist of ethylene perception (Ag (+)) abolished the Al (3+)-induced inhibition of root elongation. There was less inhibition of root elongation by Al (3+) in aux1-7 and pin2 mutants than in the wild type. The auxin polar transport inhibitor, naphthylphthalamic acid (NPA), substantially alleviated the Al (3+)-induced inhibition of root elongation. The Al (3+) and ethylene synthesis precursor aminocyclopropane carboxylic acid (ACC) increased auxin reporter DR5:GUS activity in roots. The Al (3+)-induced increase in DR5:GUS activity was reduced by AVG, while the Al (3+)-induced increase in EBS:GUS activity was not altered by NPA. Al (3+) and ACC increased transcripts of AUX1 and PIN2, and this effect was no longer observed in the presence of AVG and Co (2+). These findings indicate that Al (3+)-induced ethylene production is likely to act as a signal to alter auxin distribution in roots by disrupting AUX1- and PIN2-mediated auxin polar transport, leading to arrest of root elongation. |
81(1,1,1,1) |