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A receptor-like kinase gene (GbRLK) from Gossypium barbadense enhances salinity and drought-stress tolerance in Arabidopsis.

Zhao J, Gao Y, Zhang Z, Chen T, Guo W, Zhang T - BMC Plant Biol. (2013)

Bottom Line: Transgenic Arabidopsis with constitutive overexpression of GbRLK exhibited a reduced rate of water loss in leaves in vitro, along with improved salinity and drought tolerance and increased sensitivity to ABA compared with non-transgenic Col-0 Arabidopsis.Overexpression of GbRLK may improve stress tolerance by regulating stress-responsive genes to reduce water loss.Further studying of GbRLK will help elucidate abiotic stress signaling pathways.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Key Laboratory of Crop Genetics & Germplasm Enhancement, MOE Hybrid Cotton R&D Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, Jiangsu Province, China.

ABSTRACT

Background: Cotton (Gossypium spp.) is widely cultivated due to the important economic value of its fiber. However, extreme environmental degradation impedes cotton growth and production. Receptor-like kinase (RLK) proteins play important roles in signal transduction and participate in a diverse range of processes in response to plant hormones and environmental cues. Here, we introduced an RLK gene (GbRLK) from cotton into Arabidopsis and investigated its role in imparting abiotic stress tolerance.

Results: GbRLK transcription was induced by exogenously supplied abscisic acid (ABA), salicylic acid, methyl jasmonate, mock drought conditions and high salinity. We cloned the promoter sequence of this gene via self-formed adaptor PCR. Sequence analysis revealed that the promoter region contains many cis-acting stress-responsive elements such as ABRE, W-Box, MYB-core, W-Box core, TCA-element and others. We constructed a vector containing a 1,890-bp sequence in the 5' region upstream of the initiation codon of this promoter and transformed it into Arabidopsis thaliana. GUS histochemical staining analysis showed that GbRLK was expressed mainly in leaf veins, petioles and roots of transgenic Arabidopsis, but not in the cotyledons or root hairs. GbRLK promoter activity was induced by ABA, PEG, NaCl and Verticillium dahliae. Transgenic Arabidopsis with constitutive overexpression of GbRLK exhibited a reduced rate of water loss in leaves in vitro, along with improved salinity and drought tolerance and increased sensitivity to ABA compared with non-transgenic Col-0 Arabidopsis. Expression analysis of stress-responsive genes in GbRLK Arabidopsis revealed that there was increased expression of genes involved in the ABA-dependent signaling pathway (AtRD20, AtRD22 and AtRD26) and antioxidant genes (AtCAT1, AtCCS, AtCSD2 and AtCSD1) but not ion transporter genes (AtNHX1, AtSOS1).

Conclusions: GbRLK is involved in the drought and high salinity stresses pathway by activating or participating in the ABA signaling pathway. Overexpression of GbRLK may improve stress tolerance by regulating stress-responsive genes to reduce water loss. GbRLK may be employed in the genetic engineering of novel cotton cultivars in the future. Further studying of GbRLK will help elucidate abiotic stress signaling pathways.

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Analysis of wild-type and 35S::GbRLK transgenic Arabidopsis lines subjected to salt and drought treatment. (a) The response of transgenic Arabidopsis to salt and drought stress. Wild-type (Col-0) and transgenic Arabidopsis were grown in pots containing soil mixture (rich soil: vermiculite = 2:1, v/v) and maintained in a growth chamber at 22°C on a 16-h light/8-hr dark regimen. For drought stress treatment, the photograph was taken after withholding water for 42 days. For salt stress treatment, the photograph was taken after treatment with a 150 mM NaCl solution for 35 days at 22°C. The experiments were repeated three times with similar results. (b) and (c) represent the survival ratios of transgenic Arabidopsis lines and Col-0 (CK) under drought-stress treatment for 42 days and salt-stress treatment for 35 days, respectively. (d) Water loss rate in transgenic and non-transgenic plants; standard deviations (bars) are indicated. Comparisons were made between wild-type and individual transgenic lines under control or drought-stress conditions using the paired t-test. ** indicates significant differences compared with the control at P < 0.01.
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Figure 4: Analysis of wild-type and 35S::GbRLK transgenic Arabidopsis lines subjected to salt and drought treatment. (a) The response of transgenic Arabidopsis to salt and drought stress. Wild-type (Col-0) and transgenic Arabidopsis were grown in pots containing soil mixture (rich soil: vermiculite = 2:1, v/v) and maintained in a growth chamber at 22°C on a 16-h light/8-hr dark regimen. For drought stress treatment, the photograph was taken after withholding water for 42 days. For salt stress treatment, the photograph was taken after treatment with a 150 mM NaCl solution for 35 days at 22°C. The experiments were repeated three times with similar results. (b) and (c) represent the survival ratios of transgenic Arabidopsis lines and Col-0 (CK) under drought-stress treatment for 42 days and salt-stress treatment for 35 days, respectively. (d) Water loss rate in transgenic and non-transgenic plants; standard deviations (bars) are indicated. Comparisons were made between wild-type and individual transgenic lines under control or drought-stress conditions using the paired t-test. ** indicates significant differences compared with the control at P < 0.01.

Mentions: The analysis of the transgenic plants tolerance to drought revealed that the wild-type plants showed more severe symptoms than the transgenic plants (Figure 4a). Only 10% of the WT plants survived to maturity, whereas 58%, 51%, 47% and 36% of the transgenic plants survived in lines K-2, K-3, K-5 and K-6, respectively (Figure 4b). For analysis of high-salt tolerance, 3-week-old seedlings of transgenic and wild-type Arabidopsis grown in pots (with 4–5 leaves per plant ) were irrigated with a solution containing 200 mM NaCl once a week for 5 weeks. As shown in Figure 3a, both the transgenic and wild-type plants showed etiolation and yellowing, but the leaves of the WT plants wilted, and some of the WT plants died. The survival rate was approximately 27% in the WT compared to 80%, 65%, 64% and 49%, respectively in the four transgenic lines (Figure 4c). Additionally, there were also significant differences in fresh weight (FW), rosette diameter, anthocyanin accumulation, chlorophyll content and level of leaf chlorosis between the transgenic and the WT plants suffered drought and salt stresses (Tables 1 and2). It is concluded that the transgenic Arabidopsis lines are more tolerant to drought and salt stresses compared to the WT, and among these transgenic lines, K-2 showed the highest tolerance, consistent with the expression level of the GbRLK. Overall, the WT plants showed more serious symptoms than the transgenic plants.


A receptor-like kinase gene (GbRLK) from Gossypium barbadense enhances salinity and drought-stress tolerance in Arabidopsis.

Zhao J, Gao Y, Zhang Z, Chen T, Guo W, Zhang T - BMC Plant Biol. (2013)

Analysis of wild-type and 35S::GbRLK transgenic Arabidopsis lines subjected to salt and drought treatment. (a) The response of transgenic Arabidopsis to salt and drought stress. Wild-type (Col-0) and transgenic Arabidopsis were grown in pots containing soil mixture (rich soil: vermiculite = 2:1, v/v) and maintained in a growth chamber at 22°C on a 16-h light/8-hr dark regimen. For drought stress treatment, the photograph was taken after withholding water for 42 days. For salt stress treatment, the photograph was taken after treatment with a 150 mM NaCl solution for 35 days at 22°C. The experiments were repeated three times with similar results. (b) and (c) represent the survival ratios of transgenic Arabidopsis lines and Col-0 (CK) under drought-stress treatment for 42 days and salt-stress treatment for 35 days, respectively. (d) Water loss rate in transgenic and non-transgenic plants; standard deviations (bars) are indicated. Comparisons were made between wild-type and individual transgenic lines under control or drought-stress conditions using the paired t-test. ** indicates significant differences compared with the control at P < 0.01.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 4: Analysis of wild-type and 35S::GbRLK transgenic Arabidopsis lines subjected to salt and drought treatment. (a) The response of transgenic Arabidopsis to salt and drought stress. Wild-type (Col-0) and transgenic Arabidopsis were grown in pots containing soil mixture (rich soil: vermiculite = 2:1, v/v) and maintained in a growth chamber at 22°C on a 16-h light/8-hr dark regimen. For drought stress treatment, the photograph was taken after withholding water for 42 days. For salt stress treatment, the photograph was taken after treatment with a 150 mM NaCl solution for 35 days at 22°C. The experiments were repeated three times with similar results. (b) and (c) represent the survival ratios of transgenic Arabidopsis lines and Col-0 (CK) under drought-stress treatment for 42 days and salt-stress treatment for 35 days, respectively. (d) Water loss rate in transgenic and non-transgenic plants; standard deviations (bars) are indicated. Comparisons were made between wild-type and individual transgenic lines under control or drought-stress conditions using the paired t-test. ** indicates significant differences compared with the control at P < 0.01.
Mentions: The analysis of the transgenic plants tolerance to drought revealed that the wild-type plants showed more severe symptoms than the transgenic plants (Figure 4a). Only 10% of the WT plants survived to maturity, whereas 58%, 51%, 47% and 36% of the transgenic plants survived in lines K-2, K-3, K-5 and K-6, respectively (Figure 4b). For analysis of high-salt tolerance, 3-week-old seedlings of transgenic and wild-type Arabidopsis grown in pots (with 4–5 leaves per plant ) were irrigated with a solution containing 200 mM NaCl once a week for 5 weeks. As shown in Figure 3a, both the transgenic and wild-type plants showed etiolation and yellowing, but the leaves of the WT plants wilted, and some of the WT plants died. The survival rate was approximately 27% in the WT compared to 80%, 65%, 64% and 49%, respectively in the four transgenic lines (Figure 4c). Additionally, there were also significant differences in fresh weight (FW), rosette diameter, anthocyanin accumulation, chlorophyll content and level of leaf chlorosis between the transgenic and the WT plants suffered drought and salt stresses (Tables 1 and2). It is concluded that the transgenic Arabidopsis lines are more tolerant to drought and salt stresses compared to the WT, and among these transgenic lines, K-2 showed the highest tolerance, consistent with the expression level of the GbRLK. Overall, the WT plants showed more serious symptoms than the transgenic plants.

Bottom Line: Transgenic Arabidopsis with constitutive overexpression of GbRLK exhibited a reduced rate of water loss in leaves in vitro, along with improved salinity and drought tolerance and increased sensitivity to ABA compared with non-transgenic Col-0 Arabidopsis.Overexpression of GbRLK may improve stress tolerance by regulating stress-responsive genes to reduce water loss.Further studying of GbRLK will help elucidate abiotic stress signaling pathways.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Key Laboratory of Crop Genetics & Germplasm Enhancement, MOE Hybrid Cotton R&D Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, Jiangsu Province, China.

ABSTRACT

Background: Cotton (Gossypium spp.) is widely cultivated due to the important economic value of its fiber. However, extreme environmental degradation impedes cotton growth and production. Receptor-like kinase (RLK) proteins play important roles in signal transduction and participate in a diverse range of processes in response to plant hormones and environmental cues. Here, we introduced an RLK gene (GbRLK) from cotton into Arabidopsis and investigated its role in imparting abiotic stress tolerance.

Results: GbRLK transcription was induced by exogenously supplied abscisic acid (ABA), salicylic acid, methyl jasmonate, mock drought conditions and high salinity. We cloned the promoter sequence of this gene via self-formed adaptor PCR. Sequence analysis revealed that the promoter region contains many cis-acting stress-responsive elements such as ABRE, W-Box, MYB-core, W-Box core, TCA-element and others. We constructed a vector containing a 1,890-bp sequence in the 5' region upstream of the initiation codon of this promoter and transformed it into Arabidopsis thaliana. GUS histochemical staining analysis showed that GbRLK was expressed mainly in leaf veins, petioles and roots of transgenic Arabidopsis, but not in the cotyledons or root hairs. GbRLK promoter activity was induced by ABA, PEG, NaCl and Verticillium dahliae. Transgenic Arabidopsis with constitutive overexpression of GbRLK exhibited a reduced rate of water loss in leaves in vitro, along with improved salinity and drought tolerance and increased sensitivity to ABA compared with non-transgenic Col-0 Arabidopsis. Expression analysis of stress-responsive genes in GbRLK Arabidopsis revealed that there was increased expression of genes involved in the ABA-dependent signaling pathway (AtRD20, AtRD22 and AtRD26) and antioxidant genes (AtCAT1, AtCCS, AtCSD2 and AtCSD1) but not ion transporter genes (AtNHX1, AtSOS1).

Conclusions: GbRLK is involved in the drought and high salinity stresses pathway by activating or participating in the ABA signaling pathway. Overexpression of GbRLK may improve stress tolerance by regulating stress-responsive genes to reduce water loss. GbRLK may be employed in the genetic engineering of novel cotton cultivars in the future. Further studying of GbRLK will help elucidate abiotic stress signaling pathways.

Show MeSH
Related in: MedlinePlus