Chloroplast biogenesis 88. Protochlorophyllide b occurs in green but not in etiolated plants.
It has recently been reported that protochlorophyllide (Pchlide) b is an abundant pigment in barley etioplasts but is rather unstable, as it is rapidly converted to Pchlide a by 7-formyl reductase during pigment extraction with conventional 80% acetone (Reinbothe, S., Pollmann, S., and Reinbothe, C. (2003) J. Biol. Chem. 278, 800-806). It has also been claimed that extraction of barley etioplasts with 100% acetone containing 0.1% diethyl pyrocarbonate prevents the conversion of Pchlide b to Pchlide a and leads to the detection of large amounts of Pchlide b in the isolated etioplasts. In this work the extraction protocol of Reinbothe et al. is compared with the more conventional 80% aqueous acetone extraction method. No Pchlide b was detected either in etiolated barley leaves or isolated barley etioplasts irrespective of the extraction protocol. On the other hands, small amounts of Pchlide b were detected in green barley leaves and isolated chloroplasts, extracted either with 80% acetone or 100% acetone containing 0.1% diethyl pyrocarbonate. It is concluded that the proposed occurrence of a light-harvesting POR-Pchlide-a,b complex in etiolated plant tissues is untenable, and its ensuing consequences and implications, for the greening process, are irrelevant.
Kolossov
Vladimir L
VL
Laboratory of Plant Biochemistry and Photobiology, Natural Resources and Environmental Sciences, University of Illinois, Urbana, Illinois 61801, USA.
Rebeiz
Constantin A
CA
D000096:Acetone / Q000737:chemistry / Q000494:pharmacology; D002734:Chlorophyll / Q000737:chemistry; D002736:Chloroplasts / Q000378:metabolism*; D004047:Diethyl Pyrocarbonate / Q000494:pharmacology; D001467:Hordeum / Q000378:metabolism; D008027:Light; D018462:Photobiology; D010860:Pigments, Biological / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry; D018521:Plant Physiological Phenomena; D010940:Plant Proteins / Q000737:chemistry; D018087:Plastids / Q000737:chemistry; D011521:Protochlorophyllide / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
D010860:Pigments, Biological; D010940:Plant Proteins; D000096:Acetone; D002734:Chlorophyll; D011521:Protochlorophyllide; C037184:chlorophyll b; D004047:Diethyl Pyrocarbonate