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A Clade-Specific Arabidopsis Gene Connects Primary Metabolism and Senescence.

Jones DC, Zheng W, Huang S, Du C, Zhao X, Yennamalli RM, Sen TZ, Nettleton D, Wurtele ES, Li L - Front Plant Sci (2016)

Bottom Line: In contrast, under experimentally induced senescence, SAQR expression increases in vasculature of cotyledons but not in true leaves.In SAQR KO line, the transcript level of the dirigent-like disease resistance gene (AT1G22900) is increased, while that of the Early Light Induced Protein 1 gene (ELIP1, AT3G22840) is decreased.Taken together, these data indicate that SAQR may function in the QQS network, playing a role in integration of primary metabolism with adaptation to internal and environmental changes, specifically those that affect the process of senescence.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, Development and Cell Biology, Iowa State University, Ames IA, USA.

ABSTRACT
Nearly immobile, plants have evolved new components to be able to respond to changing environments. One example is Qua Quine Starch (QQS, AT3G30720), an Arabidopsis thaliana-specific orphan gene that integrates primary metabolism with adaptation to environment changes. SAQR (Senescence-Associated and QQS-Related, AT1G64360), is unique to a clade within the family Brassicaceae; as such, the gene may have arisen about 20 million years ago. SAQR is up-regulated in QQS RNAi mutant and in the apx1 mutant under light-induced oxidative stress. SAQR plays a role in carbon allocation: overexpression lines of SAQR have significantly decreased starch content; conversely, in a saqr T-DNA knockout (KO) line, starch accumulation is increased. Meta-analysis of public microarray data indicates that SAQR expression is correlated with expression of a subset of genes involved in senescence, defense, and stress responses. SAQR promoter::GUS expression analysis reveals that SAQR expression increases after leaf expansion and photosynthetic capacity have peaked, just prior to visible natural senescence. SAQR is expressed predominantly within leaf and cotyledon vasculature, increasing in intensity as natural senescence continues, and then decreasing prior to death. In contrast, under experimentally induced senescence, SAQR expression increases in vasculature of cotyledons but not in true leaves. In SAQR KO line, the transcript level of the dirigent-like disease resistance gene (AT1G22900) is increased, while that of the Early Light Induced Protein 1 gene (ELIP1, AT3G22840) is decreased. Taken together, these data indicate that SAQR may function in the QQS network, playing a role in integration of primary metabolism with adaptation to internal and environmental changes, specifically those that affect the process of senescence.

No MeSH data available.


Related in: MedlinePlus

Senescence-Associated and QQS-Related expression is altered by diverse stresses. Beta-glucuronidase activity was visualized in transgenic Arabidopsis lines containing SAQR promoter::GUS. (A)SAQR expression in cotyledon and true leaf of seedlings under environmental stresses. Seedlings grown in soil under constant light to 15 DAI (Control); seedlings grown in soil under constant light for 7 days, placed in the dark for 5 days, and exposed to light for 3 days (Light); seedlings grown to 15 DAI in soil under constant light in unwatered pots (Drought); and seedlings grown to 12 DAI in soil under constant light and then treated for 4 days by watering with 200 mM NaCl (Salt). (B)SAQR expression in cotyledon and true leaf of seedlings under chemical treatments. Seedlings grown in soil under constant light to 12 DAI were moved and placed for 4 days under constant light in: water (Control), or water plus 1 μM kinetin (Cytokinin), 50 μM of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), 500 μM hydrogen peroxide (Oxidative stress), or 10 μM methyl jasmonate (MeJA).
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Figure 4: Senescence-Associated and QQS-Related expression is altered by diverse stresses. Beta-glucuronidase activity was visualized in transgenic Arabidopsis lines containing SAQR promoter::GUS. (A)SAQR expression in cotyledon and true leaf of seedlings under environmental stresses. Seedlings grown in soil under constant light to 15 DAI (Control); seedlings grown in soil under constant light for 7 days, placed in the dark for 5 days, and exposed to light for 3 days (Light); seedlings grown to 15 DAI in soil under constant light in unwatered pots (Drought); and seedlings grown to 12 DAI in soil under constant light and then treated for 4 days by watering with 200 mM NaCl (Salt). (B)SAQR expression in cotyledon and true leaf of seedlings under chemical treatments. Seedlings grown in soil under constant light to 12 DAI were moved and placed for 4 days under constant light in: water (Control), or water plus 1 μM kinetin (Cytokinin), 50 μM of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), 500 μM hydrogen peroxide (Oxidative stress), or 10 μM methyl jasmonate (MeJA).

Mentions: To investigate which conditions of senescence might increase SAQR expression and to identify the spatial patterns of expression, we examined patterns of SAQR-promoter-driven GUS expression under induced senescence (Figure 4). Because various methods of inducing senescence activate different genes (van der Graaff et al., 2006), we used three diverse methods to induce senescence. (1) Young seedlings were placed in darkness for 5 days and then exposed to constant light for 3 days (“light stress”; Weaver and Amasino, 2001). (2) Fully expanded true leaves attached to the plant were covered for 3 days (“dark stress”). (3) Fully expanded true leaves were detached and floated in water in the dark for 3 days (“dark stress of detached leaves”; van der Graaff et al., 2006).


A Clade-Specific Arabidopsis Gene Connects Primary Metabolism and Senescence.

Jones DC, Zheng W, Huang S, Du C, Zhao X, Yennamalli RM, Sen TZ, Nettleton D, Wurtele ES, Li L - Front Plant Sci (2016)

Senescence-Associated and QQS-Related expression is altered by diverse stresses. Beta-glucuronidase activity was visualized in transgenic Arabidopsis lines containing SAQR promoter::GUS. (A)SAQR expression in cotyledon and true leaf of seedlings under environmental stresses. Seedlings grown in soil under constant light to 15 DAI (Control); seedlings grown in soil under constant light for 7 days, placed in the dark for 5 days, and exposed to light for 3 days (Light); seedlings grown to 15 DAI in soil under constant light in unwatered pots (Drought); and seedlings grown to 12 DAI in soil under constant light and then treated for 4 days by watering with 200 mM NaCl (Salt). (B)SAQR expression in cotyledon and true leaf of seedlings under chemical treatments. Seedlings grown in soil under constant light to 12 DAI were moved and placed for 4 days under constant light in: water (Control), or water plus 1 μM kinetin (Cytokinin), 50 μM of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), 500 μM hydrogen peroxide (Oxidative stress), or 10 μM methyl jasmonate (MeJA).
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4940393&req=5

Figure 4: Senescence-Associated and QQS-Related expression is altered by diverse stresses. Beta-glucuronidase activity was visualized in transgenic Arabidopsis lines containing SAQR promoter::GUS. (A)SAQR expression in cotyledon and true leaf of seedlings under environmental stresses. Seedlings grown in soil under constant light to 15 DAI (Control); seedlings grown in soil under constant light for 7 days, placed in the dark for 5 days, and exposed to light for 3 days (Light); seedlings grown to 15 DAI in soil under constant light in unwatered pots (Drought); and seedlings grown to 12 DAI in soil under constant light and then treated for 4 days by watering with 200 mM NaCl (Salt). (B)SAQR expression in cotyledon and true leaf of seedlings under chemical treatments. Seedlings grown in soil under constant light to 12 DAI were moved and placed for 4 days under constant light in: water (Control), or water plus 1 μM kinetin (Cytokinin), 50 μM of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), 500 μM hydrogen peroxide (Oxidative stress), or 10 μM methyl jasmonate (MeJA).
Mentions: To investigate which conditions of senescence might increase SAQR expression and to identify the spatial patterns of expression, we examined patterns of SAQR-promoter-driven GUS expression under induced senescence (Figure 4). Because various methods of inducing senescence activate different genes (van der Graaff et al., 2006), we used three diverse methods to induce senescence. (1) Young seedlings were placed in darkness for 5 days and then exposed to constant light for 3 days (“light stress”; Weaver and Amasino, 2001). (2) Fully expanded true leaves attached to the plant were covered for 3 days (“dark stress”). (3) Fully expanded true leaves were detached and floated in water in the dark for 3 days (“dark stress of detached leaves”; van der Graaff et al., 2006).

Bottom Line: In contrast, under experimentally induced senescence, SAQR expression increases in vasculature of cotyledons but not in true leaves.In SAQR KO line, the transcript level of the dirigent-like disease resistance gene (AT1G22900) is increased, while that of the Early Light Induced Protein 1 gene (ELIP1, AT3G22840) is decreased.Taken together, these data indicate that SAQR may function in the QQS network, playing a role in integration of primary metabolism with adaptation to internal and environmental changes, specifically those that affect the process of senescence.

View Article: PubMed Central - PubMed

Affiliation: Department of Genetics, Development and Cell Biology, Iowa State University, Ames IA, USA.

ABSTRACT
Nearly immobile, plants have evolved new components to be able to respond to changing environments. One example is Qua Quine Starch (QQS, AT3G30720), an Arabidopsis thaliana-specific orphan gene that integrates primary metabolism with adaptation to environment changes. SAQR (Senescence-Associated and QQS-Related, AT1G64360), is unique to a clade within the family Brassicaceae; as such, the gene may have arisen about 20 million years ago. SAQR is up-regulated in QQS RNAi mutant and in the apx1 mutant under light-induced oxidative stress. SAQR plays a role in carbon allocation: overexpression lines of SAQR have significantly decreased starch content; conversely, in a saqr T-DNA knockout (KO) line, starch accumulation is increased. Meta-analysis of public microarray data indicates that SAQR expression is correlated with expression of a subset of genes involved in senescence, defense, and stress responses. SAQR promoter::GUS expression analysis reveals that SAQR expression increases after leaf expansion and photosynthetic capacity have peaked, just prior to visible natural senescence. SAQR is expressed predominantly within leaf and cotyledon vasculature, increasing in intensity as natural senescence continues, and then decreasing prior to death. In contrast, under experimentally induced senescence, SAQR expression increases in vasculature of cotyledons but not in true leaves. In SAQR KO line, the transcript level of the dirigent-like disease resistance gene (AT1G22900) is increased, while that of the Early Light Induced Protein 1 gene (ELIP1, AT3G22840) is decreased. Taken together, these data indicate that SAQR may function in the QQS network, playing a role in integration of primary metabolism with adaptation to internal and environmental changes, specifically those that affect the process of senescence.

No MeSH data available.


Related in: MedlinePlus