Tomato root growth, gravitropism, and lateral development: correlation with auxin transport

Plant Physiol Biochem. Mar-Apr 1994;32(2):193-203.


Tomato (Lycopersicon esculentum, Mill.) roots were analyzed during growth on agar plates. Growth of these roots was inhibited by the auxin transport inhibitors naphthylphthalamic acid (NPA) and semicarbazone derivative I (SCB-1). The effect of auxin transport inhibitors on root gravitropism was analyzed by measurement of the angle of gravitropic curvature after the roots were reoriented 90 degrees from the vertical. NPA and SCB-1 abolished both the response of these roots to gravity and the formation of lateral roots, with SCB-1 being the more effective at inhibition. Auxins also inhibited root growth. Both auxins tested has a slight effect on the gravity response, but this effect is probably indirect, since auxins reduced the growth rate. Auxins also stimulated lateral root growth at concentration where primary root growth was inhibited. When roots were treated with both IAA and NPA simultaneously, a cumulative inhibition of root growth was found. When both compounds were applied together, analysis of gravitropism and lateral root formation indicated that the dominant effect was exerted by auxin transport inhibitors. Together, these data suggest a model for the role of auxin transport in controlling both primary and lateral root growth.

Publication types

  • Comparative Study

MeSH terms

  • Biological Transport / drug effects
  • Biological Transport / physiology
  • Gravitropism / drug effects*
  • Gravitropism / radiation effects
  • Herbicides / pharmacology
  • Indoleacetic Acids / antagonists & inhibitors
  • Indoleacetic Acids / metabolism*
  • Indoleacetic Acids / pharmacology
  • Light
  • Lycopersicon esculentum / drug effects
  • Lycopersicon esculentum / growth & development*
  • Lycopersicon esculentum / radiation effects
  • Naphthaleneacetic Acids / pharmacology
  • Phthalimides / pharmacology
  • Plant Growth Regulators / antagonists & inhibitors
  • Plant Growth Regulators / metabolism*
  • Plant Growth Regulators / pharmacology
  • Plant Roots / drug effects
  • Plant Roots / growth & development*
  • Plant Roots / radiation effects
  • Semicarbazones / pharmacology


  • Herbicides
  • Indoleacetic Acids
  • Naphthaleneacetic Acids
  • Phthalimides
  • Plant Growth Regulators
  • Semicarbazones
  • alpha-naphthylphthalamic acid
  • 1-naphthaleneacetic acid
  • indoleacetic acid