Plastid development in germinating wheat (Triticum aestivum) is enhanced by gibberellic acid and delayed by gabaculine |
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Authors: | Suhaila Younis Margareta Ryberg Christer Sundqvist |
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Institution: | Botanical Institute, Dept of Plant Physiology, Univ. of Göteborg, Carl Skottsbergs Gata 22, S-413 19 Göteborg, Sweden. |
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Abstract: | Etioplast development and protochlorophyllide (Pchlide) accumulation was studied in wheat seedlings ( Triticum aestivum L. cv. Walde, Weibull) grown in darkness on gibberellic acid (GA3), gabaculine (3-amino-2,3-dihydrobenzoic acid), or on a combination of the two. The results were compared with the features of seedlings grown on water only. GA3 enhanced shoot growth and promoted etioplast development. A correlation was observed between the appearance of prolamellar bodies (PLBs) and of phototransformable Pchlide. Gabaculine, a known tetrapyrrole biosynthesis inhibitor, delayed growth, slowed down the rate of PLB formation and caused structural alterations of the etioplasts up to 48 h of germination. Gabaculine also delayed the formation of phototransformable Pchlide as well as overall Pchlide biosynthesis, as determined by low-temperature fluorescence emission in vivo. The spectral blue-shift of newly formed chlorophyllide (Chlide) was delayed in irradiated dark-grown gabaculine-grown seedlings, indicating an inhibited dissociation of Chlide and NADPH-Pchlide oxidoreductase (Pchlide reductase: EC 1.3.1.33). Thus there is a close correlation between accumulation of Pchlide and etioplast development, also under conditions when development is enhanced or delayed. |
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Keywords: | Chlorophyllide etioplast fluorescence gabaculine gibberellic acid phototransformation plastid development prolamellar body protochlorophyllide Triticum aestivum ultrastructure wheat |
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