Plant Biol (Stuttg) 2005; 7(5): 495-500
DOI: 10.1055/s-2005-865853
Research Paper

Georg Thieme Verlag Stuttgart KG · New York

Bacterial Leaf Nodule Symbiosis in Ardisia (Myrsinaceae): Does it Contribute to Seedling Growth Capacity?

C. D. Nakahashi1 , K. Frole1 , L. Sack1
  • 1Department of Botany, University of Hawai'i at Mānoa, 3190 Maile Way, Honolulu, Hawai'i 96822, USA
Weitere Informationen

Publikationsverlauf

Received: November 30, 2004

Accepted: June 6, 2005

Publikationsdatum:
15. September 2005 (online)

Abstract

Numerous species of Ardisia (shrubs in the Myrsinaceae) possess conspicuous bacterial nodules in their leaf margins. This is an obligate, life-cycle symbiosis: the bacteria are maintained in the bud, and re-infect each new leaf primordium, as well as flowers and seeds, and are transmitted vertically to the next generation. Previous studies have shown that treatments which kill the bacteria in the buds lead to death of the plant. This study is the first to test for a net cost or benefit of the nodules in seedling growth capacity. A net benefit of the symbiosis would be expected from the elaborate nodule structure, and also from evolutionary theory. Seedlings of two symbiotic species (A. crenata and A. virens) and two non-symbiotic species (A. elliptica and A. sieboldii) were grown comparatively. For the symbiotic species, performance was assessed for intact plants, for plants with nodules clipped off, and for control plants in which the lamina was clipped between the nodules. The nodules did not contribute to, or detract from, seedling performance in high resource supply. Although plants increased ca. 4- to 6-fold in dry mass, nodule removal had no significant impact on plant growth, gas exchange, biomass allocation, or on foliar concentrations of chlorophyll or of 11 nutrients. No significant advantage was observed for the two symbiotic species over the two non-symbiotic species. The nodules might contribute to growth capacity during other life stages, during resource shortage, or during exposure to specific herbivores or pathogens.

References

L. Sack

Department of Botany
University of Hawai'i at Mãnoa

3190 Maile Way

Honolulu, Hawai'i 96822

USA

eMail: lsack@hawaii.edu

Editor: H. Papen

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