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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

Spatial and temporal expression of SAQR. Beta-glucuronidase activity was visualized in transgenic Arabidopsis lines containing SAQR promoter::GUS. (A)SAQR expression in cotyledon, and first true leaf at 4, 10, 17, 30, and 45 DAI. (B)SAQR expression in 56-DAI plants in second leaf and seventh leaf. (C) Cauline leaf at 45 and 56 DAI; inflorescence and flower in 45-DAI plants; siliques, stigmas, and receptacle at 5 days after flowering (DAF; a-c) and 12 DAF (d-f). White bar, 200 μm; Red bar, 500 μm; Black bar, 1 mm; Blue bar, 2 mm; Green bar, 5 mm.
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Figure 3: Spatial and temporal expression of SAQR. Beta-glucuronidase activity was visualized in transgenic Arabidopsis lines containing SAQR promoter::GUS. (A)SAQR expression in cotyledon, and first true leaf at 4, 10, 17, 30, and 45 DAI. (B)SAQR expression in 56-DAI plants in second leaf and seventh leaf. (C) Cauline leaf at 45 and 56 DAI; inflorescence and flower in 45-DAI plants; siliques, stigmas, and receptacle at 5 days after flowering (DAF; a-c) and 12 DAF (d-f). White bar, 200 μm; Red bar, 500 μm; Black bar, 1 mm; Blue bar, 2 mm; Green bar, 5 mm.

Mentions: To evaluate the spatial and temporal changes in SAQR expression during development, we fused the SAQR promoter into a construct containing the GUS tag and introduced the construct into the Arabidopsis Col-0 background (Figure 1B; SAQR::GUS lines). SAQR is expressed in the vasculature of the regions of leaves and cotyledons that are approaching senescence, and continues to increase during senescence, then reducing as the cells die (Figure 3A). SAQR expression is detected at the tips of the leaves, is strongest in the vasculature as senescence progresses, and ends in the petiole. No SAQR expression was observed in young growing tissues. No SAQR expression was detected in the root at any stage of development (not shown). In 45-DAI plants, the older leaves express SAQR toward the apical end, which is where senescence first occurs. In 56-DAI plants, a stage of the Arabidopsis lifecycle in which most leaves are senescing, SAQR expression localizes progressively from the distal to proximal portions of the leaf as these sections die (Figure 3B). SAQR is also expressed in aging cauline leaves, and stigma of flowers, funiculus and receptacle of siliques (Figure 3C).


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)

Spatial and temporal expression of SAQR. Beta-glucuronidase activity was visualized in transgenic Arabidopsis lines containing SAQR promoter::GUS. (A)SAQR expression in cotyledon, and first true leaf at 4, 10, 17, 30, and 45 DAI. (B)SAQR expression in 56-DAI plants in second leaf and seventh leaf. (C) Cauline leaf at 45 and 56 DAI; inflorescence and flower in 45-DAI plants; siliques, stigmas, and receptacle at 5 days after flowering (DAF; a-c) and 12 DAF (d-f). White bar, 200 μm; Red bar, 500 μm; Black bar, 1 mm; Blue bar, 2 mm; Green bar, 5 mm.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 3: Spatial and temporal expression of SAQR. Beta-glucuronidase activity was visualized in transgenic Arabidopsis lines containing SAQR promoter::GUS. (A)SAQR expression in cotyledon, and first true leaf at 4, 10, 17, 30, and 45 DAI. (B)SAQR expression in 56-DAI plants in second leaf and seventh leaf. (C) Cauline leaf at 45 and 56 DAI; inflorescence and flower in 45-DAI plants; siliques, stigmas, and receptacle at 5 days after flowering (DAF; a-c) and 12 DAF (d-f). White bar, 200 μm; Red bar, 500 μm; Black bar, 1 mm; Blue bar, 2 mm; Green bar, 5 mm.
Mentions: To evaluate the spatial and temporal changes in SAQR expression during development, we fused the SAQR promoter into a construct containing the GUS tag and introduced the construct into the Arabidopsis Col-0 background (Figure 1B; SAQR::GUS lines). SAQR is expressed in the vasculature of the regions of leaves and cotyledons that are approaching senescence, and continues to increase during senescence, then reducing as the cells die (Figure 3A). SAQR expression is detected at the tips of the leaves, is strongest in the vasculature as senescence progresses, and ends in the petiole. No SAQR expression was observed in young growing tissues. No SAQR expression was detected in the root at any stage of development (not shown). In 45-DAI plants, the older leaves express SAQR toward the apical end, which is where senescence first occurs. In 56-DAI plants, a stage of the Arabidopsis lifecycle in which most leaves are senescing, SAQR expression localizes progressively from the distal to proximal portions of the leaf as these sections die (Figure 3B). SAQR is also expressed in aging cauline leaves, and stigma of flowers, funiculus and receptacle of siliques (Figure 3C).

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