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Keywords:

  • acid soil;
  • aluminium resistance;
  • aluminium tolerance;
  • rhizosheath;
  • root hairs;
  • roots;
  • toxicity;
  • wheat

Summary

  • We found significant genetic variation in the ability of wheat (Triticum aestivum) to form rhizosheaths on acid soil and assessed whether differences in aluminium (Al3+) tolerance of root hairs between genotypes was the physiological basis for this genetic variation.
  • A method was developed to rapidly screen rhizosheath size in a range of wheat genotypes. Backcrossed populations were generated from cv Fronteira (large rhizosheath) using cv EGA-Burke (small rhizosheath) as the recurrent parent.
  • A positive correlation existed between rhizosheath size on acid soil and root hair length. In hydroponic experiments, root hairs of the backcrossed lines with large rhizosheaths were more tolerant of Al3+ toxicity than the backcrossed lines with small rhizosheaths.
  • We conclude that greater Al3+ tolerance of root hairs underlies the larger rhizosheath of wheat grown on acid soil. Tolerance of the root hairs to Al3+ was largely independent of the TaALMT1 gene which suggests that different genes encode the Al3+ tolerance of root hairs. The maintenance of longer root hairs in acid soils is important for the efficient uptake of water and nutrients.