Spectral and dose dependence of light-induced ion flux responses from maize leaves and their involvement in leaf expansion growth

Plant Cell Physiol. 2007 Apr;48(4):598-605. doi: 10.1093/pcp/pcm032. Epub 2007 Feb 28.

Abstract

Two types of segments (intact leaf tissue and isolated mesophyll tissue respectively) were isolated from basal (still growing) and tip (non-growing) maize leaf regions. The leaf segments were exposed to different light qualities (blue or red light) and quantities, and net fluxes of K+, Ca2+ and H+ were measured non-invasively using ion-selective vibrating microelectrodes (the MIFE technique). A clear dose dependency of all ion flux responses on both red (RL) and blue (BL) light fluence rate was found. We provide evidence that light-induced K+ flux kinetics are different between growing and non-growing tissues and attribute this difference to the direct involvement of RL-induced K+ flux in turgor-driven leaf expansion growth controlled by the epidermis, as well as to the charge-balancing role of K+ in the leaf mesophyll. Generally, BL was much more efficient in stimulating K+ uptake in the growing basal region compared with RL. We also show a much stronger influence of RL on Ca2+ fluxes in the basal region compared with BL, which argues in favor of the importance of RL in Ca2+ signaling during leaf growth.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Calcium / metabolism
  • Dose-Response Relationship, Radiation
  • Ion Transport / radiation effects*
  • Light*
  • Plant Leaves / growth & development*
  • Plant Leaves / metabolism
  • Plant Leaves / radiation effects*
  • Potassium / metabolism
  • Protons
  • Zea mays / metabolism*

Substances

  • Protons
  • Potassium
  • Calcium