Limits...
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.

Show MeSH

Related in: MedlinePlus

Transcripts of genes encoding anthocyanin biosynthesis enzymes. RT-PCRs were performed on RNA extracted from 4-d-old wild-type (Col-0) and gun1 seedlings grown on 0.5× MS-agar medium containing 2% sucrose. ‘Early’ anthocyanin biosynthesis genes: PAL, phenylalanine ammonia-lyase 1 (At2g37040); CHS, chalcone synthase (At5g13930); CHI, chalcone isomerase (At3g55120), F3H, flavanone 3-hydroxylase (At3g51240). ‘Late’ anthocyanin biosynthesis genes: DFR, dihydroflavonol reductase (At5g42800); LDOX, leucoanthocyanidin dioxygenase (At4g22880). Controls: ACT7, actin2/7 (At5g09810); UBQ10 ubiquitin 10 (At4g05320). The primers used are listed in Table 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig3: Transcripts of genes encoding anthocyanin biosynthesis enzymes. RT-PCRs were performed on RNA extracted from 4-d-old wild-type (Col-0) and gun1 seedlings grown on 0.5× MS-agar medium containing 2% sucrose. ‘Early’ anthocyanin biosynthesis genes: PAL, phenylalanine ammonia-lyase 1 (At2g37040); CHS, chalcone synthase (At5g13930); CHI, chalcone isomerase (At3g55120), F3H, flavanone 3-hydroxylase (At3g51240). ‘Late’ anthocyanin biosynthesis genes: DFR, dihydroflavonol reductase (At5g42800); LDOX, leucoanthocyanidin dioxygenase (At4g22880). Controls: ACT7, actin2/7 (At5g09810); UBQ10 ubiquitin 10 (At4g05320). The primers used are listed in Table 1.

Mentions: To examine the effect of the gun1 mutation on the expression of genes encoding enzymes of the anthocyanin biosynthesis pathway, PCR was carried out on the products of reverse transcription of RNA extracted from wild-type and gun1 seedlings grown on medium containing 2% sucrose for 4 d under continuous illumination (Fig. 3). Genes encoding anthocyanin biosynthesis enzymes have been shown to fall into two groups showing distinct temporal expression patterns (Kubasek et al., 1992; Pelletier et al., 1999). The first group contains genes that are expressed ‘early’ in response to light and includes genes encoding phenylalanine ammonia-lyase 1 (PAL), chalcone synthase (CHS), chalcone isomerase (CHI), and flavanone 3-hydroxylase (F3H). The second group contains genes that are expressed ‘late’ in response to light and includes the genes encoding dihydroflavonol reductase (DFR), and leucoanthocyanidin dioxygenase (LDOX) (Kubasek et al., 1992; Pelletier et al., 1999). Most of these genes are members of small gene families, but transcriptome profiling has identified the sucrose-responsive genes as At2g37040 (PAL), At5g13930 (CHS), At3g55120 (CHI), At3g51240 (F3H), At5g42800 (DFR), and At4g22870 (LDOX) (Solfanelli et al., 2006). Gene-specific PCR primers were designed for each of these genes (listed in Table 1) and the relative transcript abundance in wild-type and gun1 seedlings was determined by reference to transcripts from ACT7 or UBQ10, which did not differ between wild-type and gun1 (Fig. 3). gun1 seedlings contained fewer transcripts of the early anthocyanin biosynthesis genes than wild-type seedlings. PAL transcripts were undetectable by RT-PCR in gun1 seedlings, whereas transcripts of CHS, CHI, and F3H were present at 30%, 60%, and 45% of wild-type transcript amounts, respectively (Fig. 3). By contrast, transcripts of the late anthocyanin biosynthesis genes DFR and LDOX were slightly more abundant or unchanged in gun1 seedlings (Fig. 3). The gun1 mutation therefore results in decreased transcript abundance of genes encoding enzymes that function early in the anthocyanin biosynthesis pathway, and this may contribute to the lower amounts of anthocyanin accumulated 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)

Transcripts of genes encoding anthocyanin biosynthesis enzymes. RT-PCRs were performed on RNA extracted from 4-d-old wild-type (Col-0) and gun1 seedlings grown on 0.5× MS-agar medium containing 2% sucrose. ‘Early’ anthocyanin biosynthesis genes: PAL, phenylalanine ammonia-lyase 1 (At2g37040); CHS, chalcone synthase (At5g13930); CHI, chalcone isomerase (At3g55120), F3H, flavanone 3-hydroxylase (At3g51240). ‘Late’ anthocyanin biosynthesis genes: DFR, dihydroflavonol reductase (At5g42800); LDOX, leucoanthocyanidin dioxygenase (At4g22880). Controls: ACT7, actin2/7 (At5g09810); UBQ10 ubiquitin 10 (At4g05320). The primers used are listed in Table 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig3: Transcripts of genes encoding anthocyanin biosynthesis enzymes. RT-PCRs were performed on RNA extracted from 4-d-old wild-type (Col-0) and gun1 seedlings grown on 0.5× MS-agar medium containing 2% sucrose. ‘Early’ anthocyanin biosynthesis genes: PAL, phenylalanine ammonia-lyase 1 (At2g37040); CHS, chalcone synthase (At5g13930); CHI, chalcone isomerase (At3g55120), F3H, flavanone 3-hydroxylase (At3g51240). ‘Late’ anthocyanin biosynthesis genes: DFR, dihydroflavonol reductase (At5g42800); LDOX, leucoanthocyanidin dioxygenase (At4g22880). Controls: ACT7, actin2/7 (At5g09810); UBQ10 ubiquitin 10 (At4g05320). The primers used are listed in Table 1.
Mentions: To examine the effect of the gun1 mutation on the expression of genes encoding enzymes of the anthocyanin biosynthesis pathway, PCR was carried out on the products of reverse transcription of RNA extracted from wild-type and gun1 seedlings grown on medium containing 2% sucrose for 4 d under continuous illumination (Fig. 3). Genes encoding anthocyanin biosynthesis enzymes have been shown to fall into two groups showing distinct temporal expression patterns (Kubasek et al., 1992; Pelletier et al., 1999). The first group contains genes that are expressed ‘early’ in response to light and includes genes encoding phenylalanine ammonia-lyase 1 (PAL), chalcone synthase (CHS), chalcone isomerase (CHI), and flavanone 3-hydroxylase (F3H). The second group contains genes that are expressed ‘late’ in response to light and includes the genes encoding dihydroflavonol reductase (DFR), and leucoanthocyanidin dioxygenase (LDOX) (Kubasek et al., 1992; Pelletier et al., 1999). Most of these genes are members of small gene families, but transcriptome profiling has identified the sucrose-responsive genes as At2g37040 (PAL), At5g13930 (CHS), At3g55120 (CHI), At3g51240 (F3H), At5g42800 (DFR), and At4g22870 (LDOX) (Solfanelli et al., 2006). Gene-specific PCR primers were designed for each of these genes (listed in Table 1) and the relative transcript abundance in wild-type and gun1 seedlings was determined by reference to transcripts from ACT7 or UBQ10, which did not differ between wild-type and gun1 (Fig. 3). gun1 seedlings contained fewer transcripts of the early anthocyanin biosynthesis genes than wild-type seedlings. PAL transcripts were undetectable by RT-PCR in gun1 seedlings, whereas transcripts of CHS, CHI, and F3H were present at 30%, 60%, and 45% of wild-type transcript amounts, respectively (Fig. 3). By contrast, transcripts of the late anthocyanin biosynthesis genes DFR and LDOX were slightly more abundant or unchanged in gun1 seedlings (Fig. 3). The gun1 mutation therefore results in decreased transcript abundance of genes encoding enzymes that function early in the anthocyanin biosynthesis pathway, and this may contribute to the lower amounts of anthocyanin accumulated 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