PARENT SESSION
Posters P5C Biosynthesis and assembly: Pigments. Abstracts (643-659)

Protochlorophyllide spectral forms during plant development. Reza Amirjani¹, Krystyna Sundqvist¹, Christer Sundqvist^*,1, ¹ Botanical Institute, Göteborg, Sweden

ABSTRACT- Protochlorophyllide (Pchlide) is an intermediate in the chlorophyll biosynthetic pathway of photosynthetic organisms. Different spectral forms of Pchlide characterized by their absorption, fluorescence excitation and emission spectra accumulate in dark-grown angiosperms. In a comparative study the Pchlide spectral forms of four varieties, maize, wheat, pea and its lip1 mutant, were investigated. The effect of leaf developmental age on the Pchlide spectral forms and the expression of mRNA encoding NADPH-protochlorophyllide oxidoreductase (POR) is presented. Already in 1-day-old plants (one day after start of imbibition) short-wavelength Pchlide with a fluorescence emission at 631 nm was found. In the young developmental stage the short-wavelength Pchlide form was dominating. Long-wavelength Pchlide fluorescing mainly at 656 nm increased during continued development, which led to a relative decrease of the short-wavelength forms. The POR mRNA was first observed in 1-day-old plants of lip1 as a weak band and in 2-day-old pea and wheat and 3-day-old maize. The POR mRNA then rapidly increased. The different proportions of short- and long-wavelength Pchlide spectral forms earlier found in 7-day-old plants were thus found not to be an effect of the developmental stage but represented a true difference between plant varieties. However, the development is similar in all species starting with the formation of short-wavelength forms followed by a more or less extensive formation of long-wavelength forms.

KEY WORDS: spectral forms, etioplasts, protochlorophyllide, plastid development