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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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Time-course of anthocyanin accumulation in wild-type and gun1 seedlings. Anthocyanins were extracted in acidified methanol from five replicate samples of 25 seedlings of wild-type (Col-0) and gun1 seedlings grown on 0.5× MS-agar medium, ±2% sucrose (suc), ±5 μM norflurazon or ±0.5 mM lincomycin. Seedlings were harvested daily 2–8 d after germination. Anthocyanin content was determined from the absorbance of the extract at 530 nm and 657 nm, and the results 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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fig4: Time-course of anthocyanin accumulation in wild-type and gun1 seedlings. Anthocyanins were extracted in acidified methanol from five replicate samples of 25 seedlings of wild-type (Col-0) and gun1 seedlings grown on 0.5× MS-agar medium, ±2% sucrose (suc), ±5 μM norflurazon or ±0.5 mM lincomycin. Seedlings were harvested daily 2–8 d after germination. Anthocyanin content was determined from the absorbance of the extract at 530 nm and 657 nm, and the results 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: Sucrose-induced anthocyanin accumulation follows a distinct temporal pattern, with anthocyanin content reaching a maximum 5 d after germination and subsequently declining (Kubasek et al., 1992). The peak of anthocyanin content appears to coincide with the maturation of chloroplasts and the associated switch to photoautotrophic growth (Kubasek et al., 1992). To examine the effect of the gun1 mutation on the temporal pattern of anthocyanin accumulation, the anthocyanin content of whole seedlings was measured over the period 2–8 d after germination (Fig. 4). In the presence of 2% sucrose, and in the absence of inhibitors, a typical anthocyanin accumulation curve reaching a maximum at day 5 was observed for wild-type seedlings (Fig. 4, top panel). In gun1 seedlings, anthocyanin accumulation reached a maximum at day 6 and the subsequent decline in anthocyanin content was much less pronounced than in wild-type seedlings (Fig. 4, top panel). From day 3 onwards, gun1 seedlings accumulated less anthocyanin than the wild-type; the greatest difference in anthocyanin content (26%) was observed on day 5. This suggests that the gun1 mutation has perturbed the normal temporal regulation of anthocyanin accumulation during early seedling development.


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)

Time-course of anthocyanin accumulation in wild-type and gun1 seedlings. Anthocyanins were extracted in acidified methanol from five replicate samples of 25 seedlings of wild-type (Col-0) and gun1 seedlings grown on 0.5× MS-agar medium, ±2% sucrose (suc), ±5 μM norflurazon or ±0.5 mM lincomycin. Seedlings were harvested daily 2–8 d after germination. Anthocyanin content was determined from the absorbance of the extract at 530 nm and 657 nm, and the results 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

fig4: Time-course of anthocyanin accumulation in wild-type and gun1 seedlings. Anthocyanins were extracted in acidified methanol from five replicate samples of 25 seedlings of wild-type (Col-0) and gun1 seedlings grown on 0.5× MS-agar medium, ±2% sucrose (suc), ±5 μM norflurazon or ±0.5 mM lincomycin. Seedlings were harvested daily 2–8 d after germination. Anthocyanin content was determined from the absorbance of the extract at 530 nm and 657 nm, and the results 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: Sucrose-induced anthocyanin accumulation follows a distinct temporal pattern, with anthocyanin content reaching a maximum 5 d after germination and subsequently declining (Kubasek et al., 1992). The peak of anthocyanin content appears to coincide with the maturation of chloroplasts and the associated switch to photoautotrophic growth (Kubasek et al., 1992). To examine the effect of the gun1 mutation on the temporal pattern of anthocyanin accumulation, the anthocyanin content of whole seedlings was measured over the period 2–8 d after germination (Fig. 4). In the presence of 2% sucrose, and in the absence of inhibitors, a typical anthocyanin accumulation curve reaching a maximum at day 5 was observed for wild-type seedlings (Fig. 4, top panel). In gun1 seedlings, anthocyanin accumulation reached a maximum at day 6 and the subsequent decline in anthocyanin content was much less pronounced than in wild-type seedlings (Fig. 4, top panel). From day 3 onwards, gun1 seedlings accumulated less anthocyanin than the wild-type; the greatest difference in anthocyanin content (26%) was observed on day 5. This suggests that the gun1 mutation has perturbed the normal temporal regulation of anthocyanin accumulation during early seedling development.

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