Light-induced starch degradation in non-dormant turions of Spirodela polyrhiza

Photochem Photobiol. 2001 Jan;73(1):77-82. doi: 10.1562/0031-8655(2001)073<0077:lisdin>2.0.co;2.

Abstract

Continuous red light controls starch degradation in turions of Spirodela polyrhiza [Dölger, K., U. K. Tirlapur and K.-J. Appenroth [1997] Photochem. Photobiol. 66, 126-127 (1997)]. This light could be replaced by repeated red light pulses with the reciprocity law fulfilled over a large range of fluence rates. The effect of red light pulses repeated every 24 or 12 h for 6 days was reversible by subsequent far-red light pulses. In contrast, hourly applied red pulses were irreversible by far-red light. This discrepancy was explained by showing the starch degradation activity of far-red pulses themselves. The investigated process was categorized as a phytochrome low fluence response with an unusual property: requirement of light treatment for several days. A partial fulfillment of this requirement was obtained with a red pulse followed by a dark period and a 24 h continuous irradiation. These results suggest the existence of two separate steps in the process of starch degradation in turions: formation of a sprout (= sink) during the pulse-induced germination, and starch degradation in the storage tissue (= source) induced by the second light treatment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Light
  • Magnoliopsida / metabolism*
  • Magnoliopsida / radiation effects*
  • Phytochrome / metabolism
  • Starch / metabolism*

Substances

  • Phytochrome
  • Starch