AOBPreview originally published online on January 21, 2008
Annals of Botany 2008 101(4):573-578; doi:10.1093/aob/mcm324
Suppression of Host Photosynthesis by the Parasitic Plant Rhinanthus minor
1 School of Biological Science (Plant and Soil Science), University of Aberdeen, Cruickshank Building, St Machar Drive, Old Aberdeen AB24 3UU, UK
2 Ecole Nationale Supérieure Agronomique de Montpellier, 2 Place Pierre Viala, F-34060, Monpellier Cedex 1, France
* For correspondence. Present address: Department of Biological Science, Graduate School of Science, Osaka University, 1,1-Machikaneyama-cho, Toyonaka, Osaka 560 0043, Japan. E-mail ljirving{at}gmail.com
Received: 5 September 2007 Returned for revision: 15 October 2007 Accepted: 20 November 2007 Published electronically: 21 January 2008
Background and Aims: Parasitism is well understood to have wide-ranging deleterious effects on host performance in species thus far characterized. Photosynthetic performance reductions have been noted in the Striga–Zea mays association; however, no such information exists for facultative hemiparasitic plants and their hosts, nor are the effects of host species understood.
Methods: Chlorophyll fluorimetry was used to study the effects of parasitism by the hemiparasite Rhinanthus minor on the grass Phleum bertolinii and the forb Plantago lanceolata, and the effects of host species on the photosynthetic apparatus of R. minor.
Key Results: Parasitism by Rhinanthus led to a significant decrease in the host, and total (host + parasite) biomass in Phleum; however, in Plantago, no significant repression of growth was noted. Maximum quantum yield (Fv/Fm) was reduced in parasitized Plantago, relative to control plants, but not in Phleum. Fv/Fm was significantly lower in R. minor parasitizing Phleum than Plantago, suggesting Phleum to be a superior host to Plantago for R. minor. Steady-state quantum yield (
PSII) was significantly depressed in parasitized Phleum, but only at low irradiances in Plantago. PSII was very low for R. minor grown on Plantago, but not Phleum.
Conclusions: Shown here is the first evidence of the suppression of host photosynthesis by a facultative hemiparasitic plant, which has significant effects on total biomass production. Host identity is a significant factor in parasite success, with the forb Plantago lanceolata exhibiting apparent chemical as well as previously identified physical defences to parasitism. It is proposed that the electron transport rate (as denoted by PSII) represents the limiting factor for biomass accumulation in this system, and that Plantago is able to suppress the growth of Rhinanthus by suppressing the electron transport rate.
Key words: Parasitic plant, Rhinanthus minor, photosynthesis, facultative hemiparasite, chlorophyll fluorescence, ABA, Rubisco
Present address: Department of Animal and Plant Sciences, University of Sheffield, Alfred Denny Building, Western Bank, Sheffield S10 2TN, UK.
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