Ultraviolet irradiation effects on serotinous shape Leucadendron laureolum seeds: altered seed physiology and ultrastructure, and seedling performance.

 

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dc.contributor.author Musil, C
dc.contributor.author Newton, R
dc.contributor.author Farrant, J
dc.date.accessioned 2016-07-29T09:11:40Z
dc.date.available 2016-07-29T09:11:40Z
dc.date.issued 1998
dc.identifier http://dx.doi.org/10.1023/A:1009750404120
dc.identifier.citation Musil, C. F., Newton, R. J., & Farrant, J. M. (1998). Ultraviolet irradiation effects on serotinous shape Leucadendron laureolum seeds: altered seed physiology and ultrastructure, and seedling performance. Plant Ecology, 139(1), 25-34. en_ZA
dc.identifier.issn 1385-0237 en_ZA
dc.identifier.uri http://hdl.handle.net/11427/21011
dc.description.abstract Dry seeds of Leucadendron laureolum (Lam.) Fourc. (Proteaceae) were exposed for different intervals (range: 7 to 84 days) to visible, UV-A and UV-B radiation of different biologically effective dose (range: 0 to 11.43 kJ m-2 d-1). Changes in seed germination, physiology and ultrastructure, and residual UV effects on seedling performance, were examined. Germination was depressed in seeds following short (7-day) exposures to UV radiation. This depression was intensified with increased UV exposure dose, and most pronounced at shorter UV-B wavelengths. Also glutathione reductase (GR) activities increased in seeds exposed to shorter UV-B wavelengths, but these were unaffected by irradiation dose level in the UV-B range. Electrolyte leakage rates from UV-irradiated seeds were unaltered, which indicated that germination depression did not result from intrinsic membrane damage. The reversal of germination depression (UV-induced dormancy) in UV-irradiated seeds by red light pointed to the possible involvement of phytochrome in this photo-response. Germination depression disappeared in seeds after 56-days irradiation, possibly due to photoreceptor damage by excess UV light. At this stage, all UV irradiated seeds, irrespective of treatment wavelength or dose level, exhibited increased electrolyte leakage rates, which indicated membrane perturbation. Also, increased GR activities were observed in irradiated seeds, but these were proportionately smaller in seeds exposed to shorter wavelength UV-B radiation (9.1 to 35.8% increase) than longer wavelength UV-A (73.4% increase) and visible (97.7% increase) radiation. This implied a metabolic limitation for scavenging of free radicals and peroxides in aging seeds exposed to UV-B radiation, which pointed to accelerated seed deterioration. It was indirectly supported by ultrastructural evidence of sub-cellular damage (lipid coagulation and plasmalemma withdrawal from cell walls) in embryonic tissues of seeds after 84 days UV-B exposure, and reflected in decreased leaf numbers, photochemical efficiencies, and foliar chlorophyll a and carotenoid levels in seedlings cultured from these seeds. en_ZA
dc.language eng en_ZA
dc.publisher Springer en_ZA
dc.source Plant Ecology en_ZA
dc.source.uri http://link.springer.com/journal/11258
dc.subject.other Electrolyte leakage, Germination, Glutathione reductase, Growth, Photochemistry
dc.title Ultraviolet irradiation effects on serotinous shape Leucadendron laureolum seeds: altered seed physiology and ultrastructure, and seedling performance. en_ZA
dc.type Journal Article en_ZA
dc.date.updated 2016-07-29T09:01:41Z
uct.type.publication Research en_ZA
uct.type.resource Article en_ZA
dc.publisher.institution University of Cape Town
uct.type.filetype Text
uct.type.filetype Image
dc.identifier.apacitation Musil, C., Newton, R., & Farrant, J. (1998). Ultraviolet irradiation effects on serotinous shape Leucadendron laureolum seeds: altered seed physiology and ultrastructure, and seedling performance. <i>Plant Ecology</i>, http://hdl.handle.net/11427/21011 en_ZA
dc.identifier.chicagocitation Musil, C, R Newton, and J Farrant "Ultraviolet irradiation effects on serotinous shape Leucadendron laureolum seeds: altered seed physiology and ultrastructure, and seedling performance." <i>Plant Ecology</i> (1998) http://hdl.handle.net/11427/21011 en_ZA
dc.identifier.vancouvercitation Musil C, Newton R, Farrant J. Ultraviolet irradiation effects on serotinous shape Leucadendron laureolum seeds: altered seed physiology and ultrastructure, and seedling performance. Plant Ecology. 1998; http://hdl.handle.net/11427/21011. en_ZA
dc.identifier.ris TY - Journal Article AU - Musil, C AU - Newton, R AU - Farrant, J AB - Dry seeds of Leucadendron laureolum (Lam.) Fourc. (Proteaceae) were exposed for different intervals (range: 7 to 84 days) to visible, UV-A and UV-B radiation of different biologically effective dose (range: 0 to 11.43 kJ m-2 d-1). Changes in seed germination, physiology and ultrastructure, and residual UV effects on seedling performance, were examined. Germination was depressed in seeds following short (7-day) exposures to UV radiation. This depression was intensified with increased UV exposure dose, and most pronounced at shorter UV-B wavelengths. Also glutathione reductase (GR) activities increased in seeds exposed to shorter UV-B wavelengths, but these were unaffected by irradiation dose level in the UV-B range. Electrolyte leakage rates from UV-irradiated seeds were unaltered, which indicated that germination depression did not result from intrinsic membrane damage. The reversal of germination depression (UV-induced dormancy) in UV-irradiated seeds by red light pointed to the possible involvement of phytochrome in this photo-response. Germination depression disappeared in seeds after 56-days irradiation, possibly due to photoreceptor damage by excess UV light. At this stage, all UV irradiated seeds, irrespective of treatment wavelength or dose level, exhibited increased electrolyte leakage rates, which indicated membrane perturbation. Also, increased GR activities were observed in irradiated seeds, but these were proportionately smaller in seeds exposed to shorter wavelength UV-B radiation (9.1 to 35.8% increase) than longer wavelength UV-A (73.4% increase) and visible (97.7% increase) radiation. This implied a metabolic limitation for scavenging of free radicals and peroxides in aging seeds exposed to UV-B radiation, which pointed to accelerated seed deterioration. It was indirectly supported by ultrastructural evidence of sub-cellular damage (lipid coagulation and plasmalemma withdrawal from cell walls) in embryonic tissues of seeds after 84 days UV-B exposure, and reflected in decreased leaf numbers, photochemical efficiencies, and foliar chlorophyll a and carotenoid levels in seedlings cultured from these seeds. DA - 1998 DB - OpenUCT DP - University of Cape Town J1 - Plant Ecology LK - https://open.uct.ac.za PB - University of Cape Town PY - 1998 SM - 1385-0237 T1 - Ultraviolet irradiation effects on serotinous shape Leucadendron laureolum seeds: altered seed physiology and ultrastructure, and seedling performance TI - Ultraviolet irradiation effects on serotinous shape Leucadendron laureolum seeds: altered seed physiology and ultrastructure, and seedling performance UR - http://hdl.handle.net/11427/21011 ER - en_ZA


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