Plant Biol (Stuttg) 2004; 6(6): 708-714
DOI: 10.1055/s-2004-830385
Research Paper

Georg Thieme Verlag Stuttgart KG · New York

Rejuvenation of Ageing Bean Leaves under the Effect of Low-Dose Stressors

P. Nyitrai1 , K. Bóka2 , L. Gáspár1 , É. Sárvári1 , Á. Keresztes2
  • 1Department of Plant Physiology, Eötvös University, 1518, Budapest, P.O.B. 120, Hungary
  • 2Department of Plant Anatomy, Eötvös University, 1518, Budapest, P.O.B. 120, Hungary
Further Information

Publication History

Received: March 19, 2004

Accepted: September 10, 2004

Publication Date:
29 November 2004 (online)

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Abstract

The effect of low concentrations of some stress-inducing compounds like Cd, Pb, Ni, and Ti salts and DCMU on the senescence of chloroplasts was investigated in detached primary leaves of bean. After the petioles of ageing leaves had developed roots, these low-dose stressors stimulated chlorophyll synthesis and photosynthetic activity, as compared to the control, thus causing rejuvenation in treated leaves. The amount of photosystem I (lowest in DCMU-treated leaves) and light-harvesting complex II increased, while that of photosystem II decreased or remained unchanged. Fluorescence induction parameters indicated unchanged electron transport (except for DCMU treatment). CO2 fixation and, in some cases, starch accumulation was stimulated. In parallel, the occurrence of large plastoglobuli seemed to decrease in plastids of heavy metal-treated leaves. A cytokinin bioassay of leaf extracts confirmed the cytokinin-mediated effect of low-dose stressors, as the slopes of Chl and cytokinin curves were similar during the rejuvenation process. It is assumed that these stressors generate non-specific alarm reactions, which involve changes in the hormonal balance by increasing the synthesis of cytokinins.

References

P. Nyitrai

P.O.B. 120

1518, Budapest

Hungary

Email: pnyiti@ludens.elte.hu

Editor: M. Riederer