Morphometric analysis of root shape

Authors


Author for correspondence: A. Grabov Tel: +44 207 594 2748 Fax: +44 207 594 2640 E-mail: a.grabov@imperial.ac.uk

Summary

  • • Alterations in the root shape in plant mutants indicate defects in hormonal signalling, transport and cytoskeleton function.
  • • To quantify the root shape, we introduced novel parameters designated vertical growth index (VGI) and horizontal growth index (HGI). VGI was defined as a ratio between the root tip ordinate and the root length. HGI was the ratio between the root tip abscissa and the root length.
  • • To assess the applicability of VGI and HGI for quantification of root shape, we analysed root development in agravitropic Arabidopsis mutants. Statistical analysis indicated that VGI is a sensitive morphometric parameter enabling detection of weak gravitropic defects. VGI dynamics were qualitatively similar in auxin-transport mutants aux1, pin2 and trh1, but different in the auxin-signalling mutant axr2. Analysis of VGI and HGI of roots grown on tilted plates showed that the trh1 mutation affected downstream cellular responses rather than perception of the gravitropic stimulus.
  • • All these tests indicate that the VGI and HGI analysis is a versatile and sensitive method for the study of root morphology.

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