Characterization of chlorophyll pigments in ripening canola seed (Brassica napus) |
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Authors: | Kerry Ward Rachael Scarth J K Daun C T Thorsteinson |
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Affiliation: | (1) Department of Plant Science, University of Manitoba, R3T 2N2 Winnipeg, Manitoba, Canada;(2) Grain Research Laboratory, Canadian Grain Commission, R3C 3G8 Winnipeg, Manitoba, Canada |
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Abstract: | This study characterizes the chlorophyll pigments in ripeningBrassica napus seed. Seed samples, collected weekly as the crop ripened, were analyzed by high-performance liquid chromatography to characterize
chlorophyll pigment composition. Chlorophyll A, chlorophyll B, pheophytin A and pheophytin B were the predominant pigments,
while pheophorbide A, methylpheophorbide A and pyropheophytin A were minor components. No differences in pigment composition
were observed between the three cultivars tested or between early and late seeding dates. There were differences in pigment
composition between the two years of the study, which may result either from seed aging during storage or from environmental
influences. Pigment composition was dependent on seed maturity, with physiologically mature green seeds containing both chlorophylls
and pheophytins, but fully mature seeds containing only chlorophylls. Pheophytins and the minor components appeared transiently,
presumably formed from the chlorophylls and subsequently degraded. The ratio of chlorophyll A/B increased during seed ripening,
with fully mature canola seed having a chlorophyll A/B ratio twice that of physiologically mature green seed. The “B” derivatives
degraded faster than the “A” derivatives, suggesting enzymatic reactions. The initial steps in the chlorophyll breakdown pathway
in canola seed appear to be:
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Keywords: | Canola seed chlorophyll chlorophyll analysis chlorophyll breakdown pathway chlorophyll catabolism green seed high-performance liquid chromatography pheophytin pigment ripening |
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