Red region excitation spectra of protochlorophyllide in dark-grown leaves from plant species with different proportions of its spectral forms |
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Authors: | M R Amirjani C Sundqvist |
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Institution: | (1) Botanical Institute, Goteborg University, Box 461, SE-405 30 Goteborg, Sweden |
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Abstract: | Etiolated leaves of three different species, maize, wheat, and pea, as well as a pea mutant (lip1) were used to compare the excitation spectra of protochlorophyllide (Pchlide) in the red region. The species used have different
composition of short-wavelength and long-wavelength Pchlide forms. The relation between different forms was furthermore changed
through incubating the leaves in 5-aminolevulinic acid (ALA), which caused an accumulation of short-wavelength Pchlide forms,
as shown by changes in absorption and fluorescence spectra. This is the first time a comprehensive comparison is made between
excitation spectra from different species covering an emission wavelength range of 675–750 nm using fluorescence equipment
with electronic compensation for the variations in excitation irradiance. The different forms of Pchlide having excitations
peaks at 628, 632, 637, 650, and 672 nm could be best measured at 675, 700, 710, 725, and 750 nm, respectively. Measuring
emission at wavelengths between 675– 710 nm gave an exaggeration of the short-wavelength forms and measuring at longer wavelengths
gave for the pea leaves an exaggeration of the 672 nm peak. In general, an energy transfer from short-wavelength Pchlide forms
to long-wavelength Pchlide forms occurred, but such an energy transfer sometimes seemed to be limited as a result of a discrete
location of the Pchlide spectral forms. The excitation spectra resembling the absorption spectrum most were measured at an
emission wavelength of 740 nm. Measuring the excitation at 710 nm gave higher intensity of the spectra but the short-wavelength
forms were accentuated. |
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Keywords: | chlorophyllide etioplast fluorescence spectrum mutants Pisum species differences Triticum Zea |
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