Xanthophyll-cycle dynamics and rapid induction of anthocyanin synthesis in Eucalyptus nitens seedlings transferred to photoinhibitory conditions.
The effects of rapid induction and subsequent relaxation of cold-induced photo-inhibition on pigment chemistry of Eucalyptus nitens (Deane and Maiden) Maiden seedling leaves was assessed. The seedlings were subjected to four treatments in a nursery, fertilised or non-fertilised and shaded or non-shaded, before induction of photoinhibition in a growth chamber. Within 2 days, growth chamber conditions decreased photochemical efficiency (Fv/Fm) and increased xanthophyll-cycle conversion ratio. This was associated with decreased levels of total chlorophyll and increased levels of xanthophyll-cycle pigments. After 8 days, Fv/Fm of all treatments rose. Anthocyanin Levels gradually increased until day eight, except in non-shaded, non-fertilised seedlings, which had high levels before the induction of photoinhibition. Visible spectroscopy indicated increased absorption between 500 and 590nm, indicative of anthocyanin absorption. Electron transport rate after xanthophyll-cycle relaxation was half that measured before induction of photoinhibition. The findings indicate that anthocyanins may provide a photoprotective role in E. nitens seedlings under conditions of photoinhibition.
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Dugald C
DC
Cooperative Research Centre for Sustainable Production Forestry, University of Tasmania, Hobart 7001, Autralia. dugald.close@ffp.csiro.au
Beadle
Chris L
CL
D000872:Anthocyanins / Q000096:biosynthesis*; D002734:Chlorophyll / Q000378:metabolism; D004579:Electron Transport; D005052:Eucalyptus / Q000378:metabolism*; D005308:Fertilizers; D008027:Light; D013057:Spectrum Analysis; D013696:Temperature; D013997:Time Factors; D024341:Xanthophylls / Q000378:metabolism*
D000872:Anthocyanins; D005308:Fertilizers; D024341:Xanthophylls; D002734:Chlorophyll