Plant Biol (Stuttg) 2001; 3(3): 234-243
DOI: 10.1055/s-2001-15201
Review Article
Georg Thieme Verlag Stuttgart ·New York

Possible Mechanisms of Adaptive Leaf Senescence

K. Ono 1,3 , Y. Nishi 2,4 , A. Watanabe 1,5 , I. Terashima 2
  • 1 Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo, Bunkyo-ku, 113-0033, Japan
  • 2 Department of Biology, Graduate School of Science, Osaka University, Machikaneyama-cho, Toyonaka, 560-0043, Japan
  • 3 Present address: as 2
  • 4 Present address: BASF Japan Ltd., Nanbu Bldg., 3-3 Kioicho, Chiyoda-ku, Tokyo 102-8570, Japan
  • 5 Deceased on 22 May 2000
Further Information

Publication History

February 12, 2001

May 10, 2001

Publication Date:
31 December 2001 (online)

Abstract

Availability of nitrogen almost always limits plant growth. Therefore, efficient use of nitrogen is essential for the plants. In upright plants, especially when they form dense plant stands, old, lower leaves are shaded by young, upper leaves. Nitrogenous compounds in such shaded leaves are degraded and re-allocated to the developing young, upper leaves. These processes raise efficiency of nitrogen use in photosynthetic production of the plant. For this to occur in the most effective way, leaves would need to sense their photosynthetic status in a plant and increase, maintain or decrease their photosynthetic capacity accordingly. Hypotheses that explain how a leaf can sense its photosynthetic status in the plant are reviewed. They include systems involving phytochrome, sugar-sensing, or cytokinin. Our experimental results with Helianthus annuus and Phaseolus vulgaris plants, which were subject to various shading treatments, are examined in the light of these hypotheses. Our experimental results favoured the sugar-sensing hypothesis: A leaf can sense demand of other plant parts for photosynthates produced by it and nitrogen abundance or deficiency by monitoring its sugar concentration. Problems that are to be challenged in the near future are also pointed out.

Abbreviations

DCMU: 3-(3,4-dichlorophenyl)-1,1-dimethylurea

NL: nitrogen content per unit leaf area

Pday: daily carbon gain per unit leaf area

Pmax: light-saturated rate of net photosynthesis of the leaf on area basis

PPFD: photosynthetically active photon flux density

PS I: photosystem I

PS II: photosystem II

Rubisco: ribulose-1,5-bisphosphate carboxylase/oxygenase

VPD: vapour pressure deficit

References

K. Ono

Department of Biology
Graduate School of Science
Osaka University

1-16 Machikaneyama-cho
Toyonaka, Osaka
560-0043 Japan

Email: kiyomion@chaos.bio.sci.osaka-u.ac.jp

Section Editor: U. Lüttge

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