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The Influence of Varying Light Intensities on the Photo‐transformation of Protochlorophyllide 636 in Dark Grown Wheat Leaves Treated with δ‐Aminolevulinic Acid
Author(s) -
SUNDQVIST CHRISTER
Publication year - 1973
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1973.tb04845.x
Subject(s) - protochlorophyllide , chemistry , photochemistry , light intensity , limiting , biochemistry , optics , enzyme , biosynthesis , mechanical engineering , physics , engineering
Leaves treated with δ‐aminoievulinic acid accumulate protochlorophyllide 636 in large amounts. Due to a continuous conversion of protochlorophyllide 636 (nonphototransformable) into protochlorophyllide 650 (phototransformable) in weak red light, the photoreduction of protochlorophyllide to chlorophyllide can proceed for at least 20 minutes and results in a chlorophyllide content of the leaves three times higher than that in untreated leaves. The half time for this chlorophyllide accumulation is 55 seconds. A photodestruction of the pigments takes place at high light intensities or if the content of protochlorophyllide 636 is high. The conversion of protochlorophyllide 636 to chlorophyllide is dependent on the light intensity used for phototransformation of protochlorophyllide 550 The conversion of PChlide 646 was not limiting for chlorophyllide formation within the range of the light intensity used. The extrapolation of a double reciprocal plot of chlorophyllide formation, rate versus light intensity gives a maximal value of 8.7 μg chlorophyllide per g fresh weight and min. The conversion of protochlorophyllide 363 to protochlorophyllide 650 is believed to depend on the available sites of an apophotoenzyme.