Characteristic symptoms of photosynthesis inhibition by herbicides are expressed in photomixotrophic tissue cultures of Nicotiana |
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Authors: | Á Csépl? P Medgyesy |
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Institution: | (1) Institute of Plant Physiology, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary |
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Abstract: | A photomixotrophic tissue culture system for Nicotiana plumbaginifolia and N. tabacum has been developed in which a primary symptom (bleching) of the inhibition of photosynthetic electron transport by herbicides can be observed. Photomixotrophic cultures were initiated and maintained in the light on medium containing 0.2–0.3% sucrose or glucose (low-sugar medium) as sole source of respirable carbohydrate. The usual medium for growing heterotrophic cultures contains 2–3% sucrose or glucose (high-sugar medium). Callus grown on low-sugar medium achieved a fresh weight three to four times greater in the light than in the dark and reached about half that of callus grown on high-sugar medium. Carbon-dioxide fixation rates were an order of magnitude higher in cultures grown on low-sugar medium in the light than in those grown on high-sugar medium or in any of the dark-grown cultures. The lightdependent growth and CO2-fixation rates of cultures grown on low-sugar medium indicated that a major proportion of the weight increase resulted from photosynthesis. Under these photomixotrophic conditions it was found that a number of photosystem-II herbicides, at concentrations which inhibit photosynthetic electron transport, also inhibited the light-dependent component of callus growth, and caused bleaching. These effects could not be demonstrated on high-sugar medium.Abbreviations PSII
photosystem II
For common names of the herbicides the reader is referred to Weed Res. 19, 401–406 (1979) |
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Keywords: | Carbohydrate supply Herbicide Nicotiana (herbicide effects) Photosynthesis inhibition Tissue culture (photomixotrophic) |
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