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The Arabidopsis plastid-signalling mutant gun1 (genomes uncoupled1) shows altered sensitivity to sucrose and abscisic acid and alterations in early seedling development.

Cottage A, Mott EK, Kempster JA, Gray JC - J. Exp. Bot. (2010)

Bottom Line: Norflurazon and lincomycin, which induce retrograde signalling, further decreased the anthocyanin content of sucrose-treated seedlings, and altered the temporal pattern of anthocyanin accumulation.Lincomycin treatment altered the spatial pattern of sucrose-induced anthocyanin accumulation, suggesting that plastids provide information for the regulation of anthocyanin biosynthesis in Arabidopsis seedlings.Growth and development of gun1 seedlings was more sensitive to exogenous 2% sucrose than wild-type seedlings and, in the presence of lincomycin, cotyledon expansion was enhanced in gun1 seedlings compared to the wild type. gun1 seedlings were more sensitive than wild-type seedlings to the inhibition of seedling growth and development by abscisic acid.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK.

ABSTRACT
Developing seedlings of the Arabidopsis gun1 (genomes uncoupled1) mutant, which is defective in retrograde plastid-to-nucleus signalling, show several previously unrecognized mutant phenotypes. gun1 seedlings accumulated less anthocyanin than wild-type seedlings when grown in the presence of 2% (w/v) sucrose, due to lower amounts of transcripts of early anthocyanin biosynthesis genes in gun1. Norflurazon and lincomycin, which induce retrograde signalling, further decreased the anthocyanin content of sucrose-treated seedlings, and altered the temporal pattern of anthocyanin accumulation. Lincomycin treatment altered the spatial pattern of sucrose-induced anthocyanin accumulation, suggesting that plastids provide information for the regulation of anthocyanin biosynthesis in Arabidopsis seedlings. The temporal pattern of accumulation of LHCB1 transcripts differed between wild-type and gun1 seedlings, and gun1 seedlings were more sensitive to sucrose suppression of LHCB1 transcript accumulation than wild-type seedlings. Growth and development of gun1 seedlings was more sensitive to exogenous 2% sucrose than wild-type seedlings and, in the presence of lincomycin, cotyledon expansion was enhanced in gun1 seedlings compared to the wild type. gun1 seedlings were more sensitive than wild-type seedlings to the inhibition of seedling growth and development by abscisic acid. These observations clearly implicate GUN1 and plastid signalling in the regulation of seedling development and anthocyanin biosynthesis, and indicate a complex interplay between sucrose and plastid signalling pathways.

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Effect of sucrose, norflurazon, and lincomycin on anthocyanin accumulation in wild-type and gun1 seedlings. The upper part of the figure shows 1 cm × 1 cm images of representative wild-type (Col-0) and gun1 seedlings grown for 4 d on 0.5× MS-agar medium, ±2% sucrose (suc), ±0.5 mM lincomycin (Linc), or ±5 μM norflurazon (NF). The top row of images shows seedlings grown in the presence of sucrose (+suc), with the bottom row showing seedlings grown in the absence of sucrose (–suc). The lower part of the figure shows the anthocyanin content of the seedlings, with the bars numbered corresponding to the numbered images above. Anthocyanins were extracted from five replicate samples of 25 seedlings from each treatment by homogenization in acidified methanol. The anthocyanin content was determined from the absorbance of the extract at 530 nm and 657 nm, and expressed as 1000×A530–A637 per seedling. The results are shown as mean ±standard errors for each set of five replicates. The experiment was repeated four times with essentially identical results.
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fig1: Effect of sucrose, norflurazon, and lincomycin on anthocyanin accumulation in wild-type and gun1 seedlings. The upper part of the figure shows 1 cm × 1 cm images of representative wild-type (Col-0) and gun1 seedlings grown for 4 d on 0.5× MS-agar medium, ±2% sucrose (suc), ±0.5 mM lincomycin (Linc), or ±5 μM norflurazon (NF). The top row of images shows seedlings grown in the presence of sucrose (+suc), with the bottom row showing seedlings grown in the absence of sucrose (–suc). The lower part of the figure shows the anthocyanin content of the seedlings, with the bars numbered corresponding to the numbered images above. Anthocyanins were extracted from five replicate samples of 25 seedlings from each treatment by homogenization in acidified methanol. The anthocyanin content was determined from the absorbance of the extract at 530 nm and 657 nm, and expressed as 1000×A530–A637 per seedling. The results are shown as mean ±standard errors for each set of five replicates. The experiment was repeated four times with essentially identical results.

Mentions: To confirm our preliminary observation that gun1 seedlings accumulated less anthocyanin than wild-type seedlings, seedlings were grown in the presence or absence of 2% sucrose, 0.5 mM lincomycin or 5 μM norflurazon in continuous light for 4 d following stratification. Different treatments produced marked differences in the anthocyanin content of the seedlings (Fig. 1). The anthocyanin content was quantified spectrophotometrically following extraction in acidic methanol. The anthocyanin content of seedlings grown in the absence of sucrose was fairly low and there were only small differences between gun1 and wild-type seedlings. However, in the presence of sucrose there was a marked induction of anthocyanin accumulation in both wild-type and gun1 seedlings in all treatments. The anthocyanin content was 18–25-fold higher in wild-type and gun1 seedlings grown on 2% sucrose, compared with those grown in the absence of sucrose, although the gun1 seedlings accumulated about 20% less anthocyanin than wild-type seedlings. A similar pattern was observed with seedlings grown in the presence of norflurazon or lincomycin, although the differences between the wild-type and gun1 seedlings were more easily visible to the naked eye, due to the absence of chlorophyll (Fig. 1). The gun1 seedlings accumulated only ∼50% of the amount of anthocyanins in wild-type seedlings grown on sucrose and norflurazon or lincomycin. These results suggest that sucrose-induced anthocyanin accumulation is perturbed in gun1 seedlings.


The Arabidopsis plastid-signalling mutant gun1 (genomes uncoupled1) shows altered sensitivity to sucrose and abscisic acid and alterations in early seedling development.

Cottage A, Mott EK, Kempster JA, Gray JC - J. Exp. Bot. (2010)

Effect of sucrose, norflurazon, and lincomycin on anthocyanin accumulation in wild-type and gun1 seedlings. The upper part of the figure shows 1 cm × 1 cm images of representative wild-type (Col-0) and gun1 seedlings grown for 4 d on 0.5× MS-agar medium, ±2% sucrose (suc), ±0.5 mM lincomycin (Linc), or ±5 μM norflurazon (NF). The top row of images shows seedlings grown in the presence of sucrose (+suc), with the bottom row showing seedlings grown in the absence of sucrose (–suc). The lower part of the figure shows the anthocyanin content of the seedlings, with the bars numbered corresponding to the numbered images above. Anthocyanins were extracted from five replicate samples of 25 seedlings from each treatment by homogenization in acidified methanol. The anthocyanin content was determined from the absorbance of the extract at 530 nm and 657 nm, and expressed as 1000×A530–A637 per seedling. The results are shown as mean ±standard errors for each set of five replicates. The experiment was repeated four times with essentially identical results.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2921207&req=5

fig1: Effect of sucrose, norflurazon, and lincomycin on anthocyanin accumulation in wild-type and gun1 seedlings. The upper part of the figure shows 1 cm × 1 cm images of representative wild-type (Col-0) and gun1 seedlings grown for 4 d on 0.5× MS-agar medium, ±2% sucrose (suc), ±0.5 mM lincomycin (Linc), or ±5 μM norflurazon (NF). The top row of images shows seedlings grown in the presence of sucrose (+suc), with the bottom row showing seedlings grown in the absence of sucrose (–suc). The lower part of the figure shows the anthocyanin content of the seedlings, with the bars numbered corresponding to the numbered images above. Anthocyanins were extracted from five replicate samples of 25 seedlings from each treatment by homogenization in acidified methanol. The anthocyanin content was determined from the absorbance of the extract at 530 nm and 657 nm, and expressed as 1000×A530–A637 per seedling. The results are shown as mean ±standard errors for each set of five replicates. The experiment was repeated four times with essentially identical results.
Mentions: To confirm our preliminary observation that gun1 seedlings accumulated less anthocyanin than wild-type seedlings, seedlings were grown in the presence or absence of 2% sucrose, 0.5 mM lincomycin or 5 μM norflurazon in continuous light for 4 d following stratification. Different treatments produced marked differences in the anthocyanin content of the seedlings (Fig. 1). The anthocyanin content was quantified spectrophotometrically following extraction in acidic methanol. The anthocyanin content of seedlings grown in the absence of sucrose was fairly low and there were only small differences between gun1 and wild-type seedlings. However, in the presence of sucrose there was a marked induction of anthocyanin accumulation in both wild-type and gun1 seedlings in all treatments. The anthocyanin content was 18–25-fold higher in wild-type and gun1 seedlings grown on 2% sucrose, compared with those grown in the absence of sucrose, although the gun1 seedlings accumulated about 20% less anthocyanin than wild-type seedlings. A similar pattern was observed with seedlings grown in the presence of norflurazon or lincomycin, although the differences between the wild-type and gun1 seedlings were more easily visible to the naked eye, due to the absence of chlorophyll (Fig. 1). The gun1 seedlings accumulated only ∼50% of the amount of anthocyanins in wild-type seedlings grown on sucrose and norflurazon or lincomycin. These results suggest that sucrose-induced anthocyanin accumulation is perturbed in gun1 seedlings.

Bottom Line: Norflurazon and lincomycin, which induce retrograde signalling, further decreased the anthocyanin content of sucrose-treated seedlings, and altered the temporal pattern of anthocyanin accumulation.Lincomycin treatment altered the spatial pattern of sucrose-induced anthocyanin accumulation, suggesting that plastids provide information for the regulation of anthocyanin biosynthesis in Arabidopsis seedlings.Growth and development of gun1 seedlings was more sensitive to exogenous 2% sucrose than wild-type seedlings and, in the presence of lincomycin, cotyledon expansion was enhanced in gun1 seedlings compared to the wild type. gun1 seedlings were more sensitive than wild-type seedlings to the inhibition of seedling growth and development by abscisic acid.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK.

ABSTRACT
Developing seedlings of the Arabidopsis gun1 (genomes uncoupled1) mutant, which is defective in retrograde plastid-to-nucleus signalling, show several previously unrecognized mutant phenotypes. gun1 seedlings accumulated less anthocyanin than wild-type seedlings when grown in the presence of 2% (w/v) sucrose, due to lower amounts of transcripts of early anthocyanin biosynthesis genes in gun1. Norflurazon and lincomycin, which induce retrograde signalling, further decreased the anthocyanin content of sucrose-treated seedlings, and altered the temporal pattern of anthocyanin accumulation. Lincomycin treatment altered the spatial pattern of sucrose-induced anthocyanin accumulation, suggesting that plastids provide information for the regulation of anthocyanin biosynthesis in Arabidopsis seedlings. The temporal pattern of accumulation of LHCB1 transcripts differed between wild-type and gun1 seedlings, and gun1 seedlings were more sensitive to sucrose suppression of LHCB1 transcript accumulation than wild-type seedlings. Growth and development of gun1 seedlings was more sensitive to exogenous 2% sucrose than wild-type seedlings and, in the presence of lincomycin, cotyledon expansion was enhanced in gun1 seedlings compared to the wild type. gun1 seedlings were more sensitive than wild-type seedlings to the inhibition of seedling growth and development by abscisic acid. These observations clearly implicate GUN1 and plastid signalling in the regulation of seedling development and anthocyanin biosynthesis, and indicate a complex interplay between sucrose and plastid signalling pathways.

Show MeSH
Related in: MedlinePlus