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Sugar regulation of SUGAR TRANSPORTER PROTEIN 1 (STP1) expression in Arabidopsis thaliana.

Cordoba E, Aceves-Zamudio DL, Hernández-Bernal AF, Ramos-Vega M, León P - J. Exp. Bot. (2014)

Bottom Line: STP1 transcript levels decrease more rapidly after the addition of low concentrations of sugars than the levels of other repressed genes, such as DIN6 (DARK-INDUCED 6).We found that this regulation is exerted at the transcriptional level and is initiated by phosphorylatable sugars.Putative cis-acting elements involved in this response were identified.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, Cuernavaca, Morelos. México. C.P. 62210, Mexico eliza@ibt.unam.mx patricia@ibt.unam.mx.

No MeSH data available.


Related in: MedlinePlus

Sugar regulates STP1 expression at a transcriptional level. Total RNA was isolated from 12-day-old plants from independent homozygous transgenic lines containing pSTP1-2.4::GUS. Prior to the treatment, the plants were grown for 2 days in media depleted of sugar (–) or supplemented with 150mM Glc (+) and then transferred to media without (–) or with 150mM Glc (+) for 6h. Each lane contains 10 µg of total RNA, and the blot was hybridized with the STP1 and GUS probes. The rRNA of the methylene blue-stained membrane is shown as a loading control. Membranes shown here are representative of three biologically independent experiments.
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Figure 6: Sugar regulates STP1 expression at a transcriptional level. Total RNA was isolated from 12-day-old plants from independent homozygous transgenic lines containing pSTP1-2.4::GUS. Prior to the treatment, the plants were grown for 2 days in media depleted of sugar (–) or supplemented with 150mM Glc (+) and then transferred to media without (–) or with 150mM Glc (+) for 6h. Each lane contains 10 µg of total RNA, and the blot was hybridized with the STP1 and GUS probes. The rRNA of the methylene blue-stained membrane is shown as a loading control. Membranes shown here are representative of three biologically independent experiments.

Mentions: Our previous northern analysis demonstrated that the STP1 transcript practically disappears after 1h of Glc addition (Fig. 1B), thus the activity of GUS was followed in the transgenic plants after the addition of 150mM Glc. In contrast to the RNA analyses noticeable differences in GUS accumulation in the Glc-treated plants were not observed prior to 12h of Glc exposure (data not shown). After 12h of Glc treatment a reduction in the GUS activity was observed in all the transgenic lines (Fig. 5B and E). This response is specific for Glc as it is not observed with isosmotic concentrations of Mtl (Fig. 5C and F), which display an undistinguishable GUS level compared to the one observed without the carbon source (Fig. 5A). The decrease in GUS expression in response to the presence of Glc was most prominent in the stomata and trichomes, where the defined patterns observed in these structures were basically lost (Fig. 5E and H). However, even after 12h of Glc treatment, considerable GUS activity was detected in the sugar-treated transgenic plants (Fig. 5) in contrast to the endogenous STP1 RNA response. This apparent discrepancy might be explained because it has been shown that GUS activity persists for long periods beyond its actual promoter activity (Kavita and Burma, 2008). Thus, to unequivocally demonstrate whether the STP1 promoter in these transgenic plants contains the elements responsible for regulation by sugar observed with the endogenous STP1 gene, the expression of GUS and STP1 endogenous transcripts in these lines was analysed by northern blotting. As shown in Fig. 6, high levels of the GUS transcript were detected in the transgenic plants that were transferred to media without sugar (–); this high expression was independent of the initial growing media prior to the transfer (with or without sugar). In contrast, the GUS transcript was barely detectable when these plants were transferred to media containing 150mM Glc (Fig. 6). This regulation was very similar to the one observed for the STP1 endogenous transcript (Figs 1C and 6). From this analysis, we concluded that the cis-acting elements responsible for Glc regulation of the STP1 gene are contained in the 2.4kb fragment, at least under the conditions analysed.


Sugar regulation of SUGAR TRANSPORTER PROTEIN 1 (STP1) expression in Arabidopsis thaliana.

Cordoba E, Aceves-Zamudio DL, Hernández-Bernal AF, Ramos-Vega M, León P - J. Exp. Bot. (2014)

Sugar regulates STP1 expression at a transcriptional level. Total RNA was isolated from 12-day-old plants from independent homozygous transgenic lines containing pSTP1-2.4::GUS. Prior to the treatment, the plants were grown for 2 days in media depleted of sugar (–) or supplemented with 150mM Glc (+) and then transferred to media without (–) or with 150mM Glc (+) for 6h. Each lane contains 10 µg of total RNA, and the blot was hybridized with the STP1 and GUS probes. The rRNA of the methylene blue-stained membrane is shown as a loading control. Membranes shown here are representative of three biologically independent experiments.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4265152&req=5

Figure 6: Sugar regulates STP1 expression at a transcriptional level. Total RNA was isolated from 12-day-old plants from independent homozygous transgenic lines containing pSTP1-2.4::GUS. Prior to the treatment, the plants were grown for 2 days in media depleted of sugar (–) or supplemented with 150mM Glc (+) and then transferred to media without (–) or with 150mM Glc (+) for 6h. Each lane contains 10 µg of total RNA, and the blot was hybridized with the STP1 and GUS probes. The rRNA of the methylene blue-stained membrane is shown as a loading control. Membranes shown here are representative of three biologically independent experiments.
Mentions: Our previous northern analysis demonstrated that the STP1 transcript practically disappears after 1h of Glc addition (Fig. 1B), thus the activity of GUS was followed in the transgenic plants after the addition of 150mM Glc. In contrast to the RNA analyses noticeable differences in GUS accumulation in the Glc-treated plants were not observed prior to 12h of Glc exposure (data not shown). After 12h of Glc treatment a reduction in the GUS activity was observed in all the transgenic lines (Fig. 5B and E). This response is specific for Glc as it is not observed with isosmotic concentrations of Mtl (Fig. 5C and F), which display an undistinguishable GUS level compared to the one observed without the carbon source (Fig. 5A). The decrease in GUS expression in response to the presence of Glc was most prominent in the stomata and trichomes, where the defined patterns observed in these structures were basically lost (Fig. 5E and H). However, even after 12h of Glc treatment, considerable GUS activity was detected in the sugar-treated transgenic plants (Fig. 5) in contrast to the endogenous STP1 RNA response. This apparent discrepancy might be explained because it has been shown that GUS activity persists for long periods beyond its actual promoter activity (Kavita and Burma, 2008). Thus, to unequivocally demonstrate whether the STP1 promoter in these transgenic plants contains the elements responsible for regulation by sugar observed with the endogenous STP1 gene, the expression of GUS and STP1 endogenous transcripts in these lines was analysed by northern blotting. As shown in Fig. 6, high levels of the GUS transcript were detected in the transgenic plants that were transferred to media without sugar (–); this high expression was independent of the initial growing media prior to the transfer (with or without sugar). In contrast, the GUS transcript was barely detectable when these plants were transferred to media containing 150mM Glc (Fig. 6). This regulation was very similar to the one observed for the STP1 endogenous transcript (Figs 1C and 6). From this analysis, we concluded that the cis-acting elements responsible for Glc regulation of the STP1 gene are contained in the 2.4kb fragment, at least under the conditions analysed.

Bottom Line: STP1 transcript levels decrease more rapidly after the addition of low concentrations of sugars than the levels of other repressed genes, such as DIN6 (DARK-INDUCED 6).We found that this regulation is exerted at the transcriptional level and is initiated by phosphorylatable sugars.Putative cis-acting elements involved in this response were identified.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, Cuernavaca, Morelos. México. C.P. 62210, Mexico eliza@ibt.unam.mx patricia@ibt.unam.mx.

No MeSH data available.


Related in: MedlinePlus