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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

Starch content of SAQR knockout (KO) and overexpression lines.(A)KO and OE lines are visually similar to WT controls. (B) Qualitative starch staining shows increased starch in SAQR-OE lines and decreased starch in saqr compared with WT. (C) Quantification of leaf starch levels. Data points are the mean ± SEM (standard error of the mean) of three biological replicates, with five plants per replicate. The saqr mutant, WT control and OE mutant plants were grown in a completely randomized design in the soil in pots under LD conditions, and harvested for starch determination at the end of the light period. Single-factor analysis of variance (ANOVA) with Dunnett’s method was used to compare each mutant with WT. ∗P < 0.05, ∗∗P < 0.01.
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Figure 5: Starch content of SAQR knockout (KO) and overexpression lines.(A)KO and OE lines are visually similar to WT controls. (B) Qualitative starch staining shows increased starch in SAQR-OE lines and decreased starch in saqr compared with WT. (C) Quantification of leaf starch levels. Data points are the mean ± SEM (standard error of the mean) of three biological replicates, with five plants per replicate. The saqr mutant, WT control and OE mutant plants were grown in a completely randomized design in the soil in pots under LD conditions, and harvested for starch determination at the end of the light period. Single-factor analysis of variance (ANOVA) with Dunnett’s method was used to compare each mutant with WT. ∗P < 0.05, ∗∗P < 0.01.

Mentions: Taken together, our data indicates that SAQR plays a role in stress resistance. To directly investigate the function of SAQR in Arabidopsis, we generated SAQR-OE lines driven by the 35S promoter (Figure 1B). The OE plants were verified for curtailed SAQR expression by semi-quantitative RT-PCR (Supplementary Figure S2). When grown under constant light or under LD conditions the KO and OE lines appear phenotypically similar to Col-0 control plants (Figure 5A). The SAQR-OE lines show an early-flowering phenotype (also in Luhua et al., 2008), and fewer leaves are required for flowering (Figure 6). However, saqr plants do not show any difference in flowering time when grown under SD conditions (Figure 6). When plants are treated with salt, cytokinin, or ACC, saqr and SAQR-OE mutants show a similar visual phenotype to the WT controls (Supplementary Figure S4).


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)

Starch content of SAQR knockout (KO) and overexpression lines.(A)KO and OE lines are visually similar to WT controls. (B) Qualitative starch staining shows increased starch in SAQR-OE lines and decreased starch in saqr compared with WT. (C) Quantification of leaf starch levels. Data points are the mean ± SEM (standard error of the mean) of three biological replicates, with five plants per replicate. The saqr mutant, WT control and OE mutant plants were grown in a completely randomized design in the soil in pots under LD conditions, and harvested for starch determination at the end of the light period. Single-factor analysis of variance (ANOVA) with Dunnett’s method was used to compare each mutant with WT. ∗P < 0.05, ∗∗P < 0.01.
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Related In: Results  -  Collection

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

Figure 5: Starch content of SAQR knockout (KO) and overexpression lines.(A)KO and OE lines are visually similar to WT controls. (B) Qualitative starch staining shows increased starch in SAQR-OE lines and decreased starch in saqr compared with WT. (C) Quantification of leaf starch levels. Data points are the mean ± SEM (standard error of the mean) of three biological replicates, with five plants per replicate. The saqr mutant, WT control and OE mutant plants were grown in a completely randomized design in the soil in pots under LD conditions, and harvested for starch determination at the end of the light period. Single-factor analysis of variance (ANOVA) with Dunnett’s method was used to compare each mutant with WT. ∗P < 0.05, ∗∗P < 0.01.
Mentions: Taken together, our data indicates that SAQR plays a role in stress resistance. To directly investigate the function of SAQR in Arabidopsis, we generated SAQR-OE lines driven by the 35S promoter (Figure 1B). The OE plants were verified for curtailed SAQR expression by semi-quantitative RT-PCR (Supplementary Figure S2). When grown under constant light or under LD conditions the KO and OE lines appear phenotypically similar to Col-0 control plants (Figure 5A). The SAQR-OE lines show an early-flowering phenotype (also in Luhua et al., 2008), and fewer leaves are required for flowering (Figure 6). However, saqr plants do not show any difference in flowering time when grown under SD conditions (Figure 6). When plants are treated with salt, cytokinin, or ACC, saqr and SAQR-OE mutants show a similar visual phenotype to the WT controls (Supplementary Figure S4).

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