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The nucleolar GTPase nucleostemin-like 1 plays a role in plant growth and senescence by modulating ribosome biogenesis.

Jeon Y, Park YJ, Cho HK, Jung HJ, Ahn TK, Kang H, Pai HS - J. Exp. Bot. (2015)

Bottom Line: Depletion of NSN1 delayed 25S rRNA maturation and biogenesis of the 60S ribosome subunit, and repressed global translation.NSN1-deficient plants exhibited premature leaf senescence, excessive accumulation of reactive oxygen species, and senescence-related gene expression.Taken together, these results suggest that NSN1 plays a crucial role in plant growth and senescence by modulating ribosome biogenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Systems Biology, Yonsei University, Seoul 120-749, Korea.

No MeSH data available.


Related in: MedlinePlus

Premature senescence phenotypes of NSN1-deficient Arabidopsis plants. The fifth rosette leaf of seedlings grown for 14 d on (–)DEX or (+)DEX media was used for the analyses except in (B). (A) Chlorophyll content in Arabidopsis DEX-inducible NSN1 RNAi lines (RNAi-4) in response to DEX treatment. (B) Fv/Fm ratio in WT, RNAi-4, and RNAi-17 plants. Plants were grown for 2 weeks in MS medium containing either ethanol or 20 μM DEX, then transferred to soil, and sprayed with ethanol or 20 μM DEX for 3–4 d. (C) Nitro blue tetrazolium (NBT) staining to visualize superoxide production in RNAi-4 lines. (D) H2DCFDA staining to visualize H2O2 production in RNAi-4 lines. After staining, leaf protoplasts were observed under confocal microscopy (top). Relative H2DCFDA fluorescence was quantified by confocal microscopy (bottom). Data represent the means ± SD of 110 individual protoplasts. Scale bars = 50 μm. (E) RT–PCR analyses of transcript levels of senescence-related genes in WT, RNAi-4, and RNAi-17 plants. The actin 8 mRNA level was used as the control. (This figure is available in colour at JXB online.)
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Figure 8: Premature senescence phenotypes of NSN1-deficient Arabidopsis plants. The fifth rosette leaf of seedlings grown for 14 d on (–)DEX or (+)DEX media was used for the analyses except in (B). (A) Chlorophyll content in Arabidopsis DEX-inducible NSN1 RNAi lines (RNAi-4) in response to DEX treatment. (B) Fv/Fm ratio in WT, RNAi-4, and RNAi-17 plants. Plants were grown for 2 weeks in MS medium containing either ethanol or 20 μM DEX, then transferred to soil, and sprayed with ethanol or 20 μM DEX for 3–4 d. (C) Nitro blue tetrazolium (NBT) staining to visualize superoxide production in RNAi-4 lines. (D) H2DCFDA staining to visualize H2O2 production in RNAi-4 lines. After staining, leaf protoplasts were observed under confocal microscopy (top). Relative H2DCFDA fluorescence was quantified by confocal microscopy (bottom). Data represent the means ± SD of 110 individual protoplasts. Scale bars = 50 μm. (E) RT–PCR analyses of transcript levels of senescence-related genes in WT, RNAi-4, and RNAi-17 plants. The actin 8 mRNA level was used as the control. (This figure is available in colour at JXB online.)

Mentions: NSN1 deficiency caused growth retardation and gradual leaf yellowing in young Arabidopsis plants (Fig. 1E). The premature senescence phenotype of the Arabidopsis NSN1 RNAi seedlings (Fig. 8) was assessed. DEX-treated RNAi-4 seedlings had less chlorophyll than (–)DEX seedlings (Fig. 8A). This result was similar to that for NbNSN1 VIGS in N. benthamiana (Fig. 1C). The reduced chlorophyll content in DEX-treated seedlings correlated with lower photosynthetic activities as indicated by the optimum quantum yield (Fv/Fm) (Fig. 8B). The Fv/Fm ratio reflects the maximal photochemical efficiency of photosystem II. The Fv/Fm ratio in the leaves of (+)DEX RNAi lines was significantly reduced compared with that of (–)DEX controls, suggesting a reduction in functional photosystem II centres (Fig. 8B). Consistent with enhanced senescence of DEX-treated NSN1 RNAi seedlings, the seedlings also accumulated excessive amounts of reactive oxygen species (ROS) visualized by nitro blue tetrazolium (NBT) (Fig. 8C). NBT reacts with superoxide radicals to form a dark-blue formazan precipitate (Bielski et al., 1980). Excessive ROS formation in NSN1-deficient plants was further visualized by staining with H2DCFDA, which emits a green fluorescent signal in the presence of H2O2, thus indicating oxidative stress in a cell (Fig. 8D, top). Accumulation of green fluorescence in protoplasts from DEX-treated RNAi-4 seedlings was ~4.3-fold greater than in (–)DEX controls, indicating high ROS accumulation (Fig. 8D, bottom).


The nucleolar GTPase nucleostemin-like 1 plays a role in plant growth and senescence by modulating ribosome biogenesis.

Jeon Y, Park YJ, Cho HK, Jung HJ, Ahn TK, Kang H, Pai HS - J. Exp. Bot. (2015)

Premature senescence phenotypes of NSN1-deficient Arabidopsis plants. The fifth rosette leaf of seedlings grown for 14 d on (–)DEX or (+)DEX media was used for the analyses except in (B). (A) Chlorophyll content in Arabidopsis DEX-inducible NSN1 RNAi lines (RNAi-4) in response to DEX treatment. (B) Fv/Fm ratio in WT, RNAi-4, and RNAi-17 plants. Plants were grown for 2 weeks in MS medium containing either ethanol or 20 μM DEX, then transferred to soil, and sprayed with ethanol or 20 μM DEX for 3–4 d. (C) Nitro blue tetrazolium (NBT) staining to visualize superoxide production in RNAi-4 lines. (D) H2DCFDA staining to visualize H2O2 production in RNAi-4 lines. After staining, leaf protoplasts were observed under confocal microscopy (top). Relative H2DCFDA fluorescence was quantified by confocal microscopy (bottom). Data represent the means ± SD of 110 individual protoplasts. Scale bars = 50 μm. (E) RT–PCR analyses of transcript levels of senescence-related genes in WT, RNAi-4, and RNAi-17 plants. The actin 8 mRNA level was used as the control. (This figure is available in colour at JXB online.)
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Figure 8: Premature senescence phenotypes of NSN1-deficient Arabidopsis plants. The fifth rosette leaf of seedlings grown for 14 d on (–)DEX or (+)DEX media was used for the analyses except in (B). (A) Chlorophyll content in Arabidopsis DEX-inducible NSN1 RNAi lines (RNAi-4) in response to DEX treatment. (B) Fv/Fm ratio in WT, RNAi-4, and RNAi-17 plants. Plants were grown for 2 weeks in MS medium containing either ethanol or 20 μM DEX, then transferred to soil, and sprayed with ethanol or 20 μM DEX for 3–4 d. (C) Nitro blue tetrazolium (NBT) staining to visualize superoxide production in RNAi-4 lines. (D) H2DCFDA staining to visualize H2O2 production in RNAi-4 lines. After staining, leaf protoplasts were observed under confocal microscopy (top). Relative H2DCFDA fluorescence was quantified by confocal microscopy (bottom). Data represent the means ± SD of 110 individual protoplasts. Scale bars = 50 μm. (E) RT–PCR analyses of transcript levels of senescence-related genes in WT, RNAi-4, and RNAi-17 plants. The actin 8 mRNA level was used as the control. (This figure is available in colour at JXB online.)
Mentions: NSN1 deficiency caused growth retardation and gradual leaf yellowing in young Arabidopsis plants (Fig. 1E). The premature senescence phenotype of the Arabidopsis NSN1 RNAi seedlings (Fig. 8) was assessed. DEX-treated RNAi-4 seedlings had less chlorophyll than (–)DEX seedlings (Fig. 8A). This result was similar to that for NbNSN1 VIGS in N. benthamiana (Fig. 1C). The reduced chlorophyll content in DEX-treated seedlings correlated with lower photosynthetic activities as indicated by the optimum quantum yield (Fv/Fm) (Fig. 8B). The Fv/Fm ratio reflects the maximal photochemical efficiency of photosystem II. The Fv/Fm ratio in the leaves of (+)DEX RNAi lines was significantly reduced compared with that of (–)DEX controls, suggesting a reduction in functional photosystem II centres (Fig. 8B). Consistent with enhanced senescence of DEX-treated NSN1 RNAi seedlings, the seedlings also accumulated excessive amounts of reactive oxygen species (ROS) visualized by nitro blue tetrazolium (NBT) (Fig. 8C). NBT reacts with superoxide radicals to form a dark-blue formazan precipitate (Bielski et al., 1980). Excessive ROS formation in NSN1-deficient plants was further visualized by staining with H2DCFDA, which emits a green fluorescent signal in the presence of H2O2, thus indicating oxidative stress in a cell (Fig. 8D, top). Accumulation of green fluorescence in protoplasts from DEX-treated RNAi-4 seedlings was ~4.3-fold greater than in (–)DEX controls, indicating high ROS accumulation (Fig. 8D, bottom).

Bottom Line: Depletion of NSN1 delayed 25S rRNA maturation and biogenesis of the 60S ribosome subunit, and repressed global translation.NSN1-deficient plants exhibited premature leaf senescence, excessive accumulation of reactive oxygen species, and senescence-related gene expression.Taken together, these results suggest that NSN1 plays a crucial role in plant growth and senescence by modulating ribosome biogenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Systems Biology, Yonsei University, Seoul 120-749, Korea.

No MeSH data available.


Related in: MedlinePlus