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The SNF1-type serine-threonine protein kinase SAPK4 regulates stress-responsive gene expression in rice.

Diédhiou CJ, Popova OV, Dietz KJ, Golldack D - BMC Plant Biol. (2008)

Bottom Line: Induced expression of SAPK4 resulted in improved germination, growth and development under salt stress both in seedlings and mature plants.In response to salt stress, the SAPK4-overexpressing rice accumulated less Na+ and Cl- and showed improved photosynthesis.Our results show that SAPK4 regulates ion homeostasis and growth and development under salinity and suggest function of SAPK4 as a regulatory factor in plant salt stress acclimation.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physiology and Biochemistry of Plants, Faculty of Biology, University of Bielefeld, 33615 Bielefeld, Germany. calliste.diedhiou@uni-bielefeld.de

ABSTRACT

Background: Plants respond to extracellularly perceived abiotic stresses such as low temperature, drought, and salinity by activation of complex intracellular signaling cascades that regulate acclimatory biochemical and physiological changes. Protein kinases are major signal transduction factors that have a central role in mediating acclimation to environmental changes in eukaryotic organisms. In this study, we characterized the function of the sucrose nonfermenting 1-related protein kinase2 (SnRK2) SAPK4 in the salt stress response of rice.

Results: Translational fusion of SAPK4 with the green fluorescent protein (GFP) showed subcellular localization in cytoplasm and nucleus. To examine the role of SAPK4 in salt tolerance we generated transgenic rice plants with over-expression of rice SAPK4 under control of the CaMV-35S promoter. Induced expression of SAPK4 resulted in improved germination, growth and development under salt stress both in seedlings and mature plants. In response to salt stress, the SAPK4-overexpressing rice accumulated less Na+ and Cl- and showed improved photosynthesis. SAPK4-regulated genes with functions in ion homeostasis and oxidative stress response were identified: the vacuolar H+-ATPase, the Na+/H+ antiporter NHX1, the Cl- channel OsCLC1 and a catalase.

Conclusion: Our results show that SAPK4 regulates ion homeostasis and growth and development under salinity and suggest function of SAPK4 as a regulatory factor in plant salt stress acclimation. Identification of signaling elements involved in stress adaptation in plants presents a powerful approach to identify transcriptional activators of adaptive mechanisms to environmental changes that have the potential to improve tolerance in crop plants.

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(A) Transcript accumulation of SAPK4-regulated genes in wild-type rice (WT) under control conditions and under salt stress. Transcript levels were determined by RT-PCR from total RNA isolated from 8-week-old plants. The plants were grown in hydroponic culture and stressed with 150 mM NaCl for 48 h. (B) Transcript accumulation of SAPK4-regulated genes in wild-type rice (WT) and the SAPK4-over-expressing rice lines S1 and S4. Transcript levels were determined by RT-PCR from total RNA isolated from 8-week-old plants. The plants were grown in hydroponic culture and treated with 150 mM NaCl for 48 h. Actin was amplified as a loading control.
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Figure 6: (A) Transcript accumulation of SAPK4-regulated genes in wild-type rice (WT) under control conditions and under salt stress. Transcript levels were determined by RT-PCR from total RNA isolated from 8-week-old plants. The plants were grown in hydroponic culture and stressed with 150 mM NaCl for 48 h. (B) Transcript accumulation of SAPK4-regulated genes in wild-type rice (WT) and the SAPK4-over-expressing rice lines S1 and S4. Transcript levels were determined by RT-PCR from total RNA isolated from 8-week-old plants. The plants were grown in hydroponic culture and treated with 150 mM NaCl for 48 h. Actin was amplified as a loading control.

Mentions: The vacuolar ATPase, the vacuolar Na+/H+ antiporter NHX1, voltage-gated Cl- channels, and catalase are well established targets of salt-dependent regulation (Fig. 6A) and it appeared interesting to study their transcription in wild-type and transgenic rice under salt stress to identify putative target genes regulated by SAPK4. The expression levels of the vacuolar ATPase, the vacuolar Na+/H+ antiporter OsNHX1, the Cl- channel OsCLC1, and catalase isozyme A were assessed in wild-type and transgenic rice. The transcript amounts of the V-ATPase subunit B and of the catalase increased by treatment with 100 mM NaCl for 48 hours, whereas the transcript amounts of OsNHX1 and OsCLC1 decreased in response to NaCl stress (Fig. 6B). In addition, we were interested in analyzing transcription of the plasma membrane Na+/H+ antiporter SOS1 but were not able to detect its expression in both wild-type and transgenic rice.


The SNF1-type serine-threonine protein kinase SAPK4 regulates stress-responsive gene expression in rice.

Diédhiou CJ, Popova OV, Dietz KJ, Golldack D - BMC Plant Biol. (2008)

(A) Transcript accumulation of SAPK4-regulated genes in wild-type rice (WT) under control conditions and under salt stress. Transcript levels were determined by RT-PCR from total RNA isolated from 8-week-old plants. The plants were grown in hydroponic culture and stressed with 150 mM NaCl for 48 h. (B) Transcript accumulation of SAPK4-regulated genes in wild-type rice (WT) and the SAPK4-over-expressing rice lines S1 and S4. Transcript levels were determined by RT-PCR from total RNA isolated from 8-week-old plants. The plants were grown in hydroponic culture and treated with 150 mM NaCl for 48 h. Actin was amplified as a loading control.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2386468&req=5

Figure 6: (A) Transcript accumulation of SAPK4-regulated genes in wild-type rice (WT) under control conditions and under salt stress. Transcript levels were determined by RT-PCR from total RNA isolated from 8-week-old plants. The plants were grown in hydroponic culture and stressed with 150 mM NaCl for 48 h. (B) Transcript accumulation of SAPK4-regulated genes in wild-type rice (WT) and the SAPK4-over-expressing rice lines S1 and S4. Transcript levels were determined by RT-PCR from total RNA isolated from 8-week-old plants. The plants were grown in hydroponic culture and treated with 150 mM NaCl for 48 h. Actin was amplified as a loading control.
Mentions: The vacuolar ATPase, the vacuolar Na+/H+ antiporter NHX1, voltage-gated Cl- channels, and catalase are well established targets of salt-dependent regulation (Fig. 6A) and it appeared interesting to study their transcription in wild-type and transgenic rice under salt stress to identify putative target genes regulated by SAPK4. The expression levels of the vacuolar ATPase, the vacuolar Na+/H+ antiporter OsNHX1, the Cl- channel OsCLC1, and catalase isozyme A were assessed in wild-type and transgenic rice. The transcript amounts of the V-ATPase subunit B and of the catalase increased by treatment with 100 mM NaCl for 48 hours, whereas the transcript amounts of OsNHX1 and OsCLC1 decreased in response to NaCl stress (Fig. 6B). In addition, we were interested in analyzing transcription of the plasma membrane Na+/H+ antiporter SOS1 but were not able to detect its expression in both wild-type and transgenic rice.

Bottom Line: Induced expression of SAPK4 resulted in improved germination, growth and development under salt stress both in seedlings and mature plants.In response to salt stress, the SAPK4-overexpressing rice accumulated less Na+ and Cl- and showed improved photosynthesis.Our results show that SAPK4 regulates ion homeostasis and growth and development under salinity and suggest function of SAPK4 as a regulatory factor in plant salt stress acclimation.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physiology and Biochemistry of Plants, Faculty of Biology, University of Bielefeld, 33615 Bielefeld, Germany. calliste.diedhiou@uni-bielefeld.de

ABSTRACT

Background: Plants respond to extracellularly perceived abiotic stresses such as low temperature, drought, and salinity by activation of complex intracellular signaling cascades that regulate acclimatory biochemical and physiological changes. Protein kinases are major signal transduction factors that have a central role in mediating acclimation to environmental changes in eukaryotic organisms. In this study, we characterized the function of the sucrose nonfermenting 1-related protein kinase2 (SnRK2) SAPK4 in the salt stress response of rice.

Results: Translational fusion of SAPK4 with the green fluorescent protein (GFP) showed subcellular localization in cytoplasm and nucleus. To examine the role of SAPK4 in salt tolerance we generated transgenic rice plants with over-expression of rice SAPK4 under control of the CaMV-35S promoter. Induced expression of SAPK4 resulted in improved germination, growth and development under salt stress both in seedlings and mature plants. In response to salt stress, the SAPK4-overexpressing rice accumulated less Na+ and Cl- and showed improved photosynthesis. SAPK4-regulated genes with functions in ion homeostasis and oxidative stress response were identified: the vacuolar H+-ATPase, the Na+/H+ antiporter NHX1, the Cl- channel OsCLC1 and a catalase.

Conclusion: Our results show that SAPK4 regulates ion homeostasis and growth and development under salinity and suggest function of SAPK4 as a regulatory factor in plant salt stress acclimation. Identification of signaling elements involved in stress adaptation in plants presents a powerful approach to identify transcriptional activators of adaptive mechanisms to environmental changes that have the potential to improve tolerance in crop plants.

Show MeSH