Red region excitation spectra of protochlorophyllide in dark-grown leaves from plant species with different proportions of its spectral forms

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.

A Versatile Probe for Caffeine Detection in Real-Life Samples via Excitation-Triggered Alteration in the Sensing Behavior of Fluorescent Organic Nanoaggregates

“…The time-resolved emission spectra of compound 2 (λ ex = 300 nm) revealed the existence of a long-lived excited state with multiexponential decay (λ av = 1.18 ns) at 470 nm band and a short-lived excited state with single exponential decay at 370 nm (Figure a). This suggested that the emission at the 470 nm band was originated from the fluorescent nanoaggregates, whereas monomeric compound showed emission at the 370 nm band. , Now, upon scanning the entire emission range, we found two distinctive excitation spectra for compound 2 , indicating their origin from two different photoexcited species (see Figure S16 in the Supporting Information). , The excitation spectra correspond to the lower emission wavelengths (350 and 370 nm) that are exhibited by the carbazole monomers, whereas broad excitation spectra observed at higher emission wavelengths (420, 450, and 470 nm) correspond to the nanoaggregates in water.…”

“…42,43 Now, upon scanning the entire emission range, we found two distinctive excitation spectra for compound 2, indicating their origin from two different photoexcited species (see Figure S16 in the Supporting Information). 44,45 The excitation spectra correspond to the lower emission wavelengths (350 and 370 nm) that are exhibited by the carbazole monomers, whereas broad excitation spectra observed at higher emission wavelengths (420, 450, and 470 nm) correspond to the nanoaggregates in water.…”

High salt stress in wheat leaves causes retardation of chlorophyll accumulation due to a limited rate of protochlorophyllide formation

“…The short-wavelength forms have fluorescence emission peaks between 631 and 643 nm and the main long-wavelength form has a fluorescence emission peak at 656 nm. Small variations in the peak position of the long-wavelength Pchlide form were found to be species dependent (Bö ddi et al 1992, Amirjani andSundqvist 2006). Factors such as phytohormones, drought and leaf age influence the proportion between long-wavelength and short-wavelength Pchlide forms (Bengtson et al 1977, 1978, Schoefs and Franck 1993, Schoefs et al 2000.…”

Protochlorophyllide and POR development in dark‐grown plants with different proportions of short‐wavelength and long‐wavelength protochlorophyllide spectral forms†

“…The low‐temperature (77 K) fluorescence emission spectra of Pchlide in leaves have typical peaks at about 633 and 656 nm. The exact peak positions and the ratio between their heights can vary with plant varieties and excitation wavelength (Amirjani and Sundqvist 2004, 2006, Solymosi et al 2004). The short‐wavelength band is heterogeneous and composed of four emission bands located at 625, 631, 637 and 643 nm (Schoefs et al 2000).…”