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Maize ABP9 enhances tolerance to multiple stresses in transgenic Arabidopsis by modulating ABA signaling and cellular levels of reactive oxygen species.

Zhang X, Wang L, Meng H, Wen H, Fan Y, Zhao J - Plant Mol. Biol. (2011)

Bottom Line: Here we show that the expression of maize ABP9 gene, which encodes a bZIP transcription factor capable of binding to the ABRE2 motif in the maize Cat1 promoter, is induced by ABA, H(2)O(2), drought and salt.Constitutive expression of ABP9 in transgenic Arabidopsis leads to remarkably enhanced tolerance to multiple stresses including drought, high salt, freezing temperature and oxidative stresses.Taken together, these results suggest that ABP9 may play a pivotal role in plant tolerance to abiotic stresses by fine tuning ABA signaling and control of ROS accumulation.

View Article: PubMed Central - PubMed

Affiliation: Maize Gene Research and Genetic Improvement Center, Biotechnology Research Institute, National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, 100081, Beijing, People's Republic of China.

ABSTRACT
The phytohormone abscisic acid (ABA) and reactive oxygen species (ROS) play critical roles in mediating abiotic stress responses in plants. It is well known that ABA is involved in the modulation of ROS levels by regulating ROS-producing and ROS-scavenging genes, but the molecular mechanisms underlying this regulation are poorly understood. Here we show that the expression of maize ABP9 gene, which encodes a bZIP transcription factor capable of binding to the ABRE2 motif in the maize Cat1 promoter, is induced by ABA, H(2)O(2), drought and salt. Constitutive expression of ABP9 in transgenic Arabidopsis leads to remarkably enhanced tolerance to multiple stresses including drought, high salt, freezing temperature and oxidative stresses. ABP9 expressing Arabidopsis plants also exhibit increased sensitivity to exogenously applied ABA during seed germination, root growth and stomatal closure and improved water-conserving capacity. Moreover, constitutive expression of ABP9 causes reduced cellular levels of ROS, alleviated oxidative damage and reduced cell death, accompanied by elevated expression of many stress/ABA responsive genes including those for scavenging and regulating ROS. Taken together, these results suggest that ABP9 may play a pivotal role in plant tolerance to abiotic stresses by fine tuning ABA signaling and control of ROS accumulation.

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Constitutive expression of ABP9 enhances tolerance to drought, salt, cold and oxidative stresses in transgenic Arabidopsis. a, b RNA gel blot analysis of ABP9 expression in wild type (WT) and 35S-ABP9 transgenic plants (5P2 and 5P3) under normal growth and salt stress (a), ABA and PEG treatment conditions (b). Plants grown on 1/2 MS agar plates were untreated or treated with 200 mM NaCl for 1 h and 2 h, 100 μM ABA or 30% PEG for 3 h. Equal amounts (8 μg) of total RNAs separated by electrophoresis on formaldehyde-agarose gels and rRNA was used as loading control. c Drought tolerance in 35S-ABP9 transgenic plants. Intact plants were drought stressed by withholding water for 4 weeks, then were rewatered for 1 week before photograph was taken. Survival rates were calculated from the results of three independent experiments (n ≥ 30 for each experiment). Untreated plants grown under normal conditions as control were shown in the top panels. d Capacity of 35S-ABP9 transgenic plants to tolerate salt stress. The plants were treated with progressively increased concentrations of NaCl solutions ranging from 50 to 200 mM and kept irrigated with 200 mM NaCl for 12 days, then chlorophyll contents were determined. Percentage shown are chlorophyll content of salt-stresses plants relative to that of untreated ones from the results of three independent experiments with 5 intact seedlings determined for each experiment. Untreated plants grown under normal conditions as control were shown in the top panels. e Freeze tolerance of 35S-ABP9 transgenic plants. Plants were exposed to freezing temperature −4°C for 6 h and recovered for 1 week under normal growth conditions. Survival rates were counted from the results of three independent experiments (n ≥ 30 for each experiment). Untreated plants grown under normal conditions as control were shown in the top panels. f Tolerance to oxidative stress in 35S-ABP9 transgenic plants. Rosette leaves from wild-type (WT) plants and transgenic lines (5P2 and 5P3) were floated in 1/2 MS medium containing 2 μM MV for 72 h before photographs were taken. Chlorophyll contents compared to that of mocked-treated samples are shown at the bottom. Shown are representative photographs from 30 seedlings in triplicates
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Fig3: Constitutive expression of ABP9 enhances tolerance to drought, salt, cold and oxidative stresses in transgenic Arabidopsis. a, b RNA gel blot analysis of ABP9 expression in wild type (WT) and 35S-ABP9 transgenic plants (5P2 and 5P3) under normal growth and salt stress (a), ABA and PEG treatment conditions (b). Plants grown on 1/2 MS agar plates were untreated or treated with 200 mM NaCl for 1 h and 2 h, 100 μM ABA or 30% PEG for 3 h. Equal amounts (8 μg) of total RNAs separated by electrophoresis on formaldehyde-agarose gels and rRNA was used as loading control. c Drought tolerance in 35S-ABP9 transgenic plants. Intact plants were drought stressed by withholding water for 4 weeks, then were rewatered for 1 week before photograph was taken. Survival rates were calculated from the results of three independent experiments (n ≥ 30 for each experiment). Untreated plants grown under normal conditions as control were shown in the top panels. d Capacity of 35S-ABP9 transgenic plants to tolerate salt stress. The plants were treated with progressively increased concentrations of NaCl solutions ranging from 50 to 200 mM and kept irrigated with 200 mM NaCl for 12 days, then chlorophyll contents were determined. Percentage shown are chlorophyll content of salt-stresses plants relative to that of untreated ones from the results of three independent experiments with 5 intact seedlings determined for each experiment. Untreated plants grown under normal conditions as control were shown in the top panels. e Freeze tolerance of 35S-ABP9 transgenic plants. Plants were exposed to freezing temperature −4°C for 6 h and recovered for 1 week under normal growth conditions. Survival rates were counted from the results of three independent experiments (n ≥ 30 for each experiment). Untreated plants grown under normal conditions as control were shown in the top panels. f Tolerance to oxidative stress in 35S-ABP9 transgenic plants. Rosette leaves from wild-type (WT) plants and transgenic lines (5P2 and 5P3) were floated in 1/2 MS medium containing 2 μM MV for 72 h before photographs were taken. Chlorophyll contents compared to that of mocked-treated samples are shown at the bottom. Shown are representative photographs from 30 seedlings in triplicates

Mentions: To investigate the function of ABP9 in plant response to abiotic stress, transgenic Arabidopsis plants expressing the ABP9 cDNA under the control of the CaMV 35S promoter (35S-ABP9) were generated and eight independent T3 homozygous lines were obtained. Northern blot analysis revealed that ABP9 expressing transgenic plants accumulated higher levels of ABP9 mRNA under either normal growth or stress conditions with the treatment of 200 mM of NaCl (1 or 2 h), 100 μM ABA (3 h) or 30% PEG (3 h), indicating that ABP9 is constitutively expressed in these transgenic plants (Fig. 3a, b). Two representative lines (5P2 and 5P3), with medium and high expression levels of ABP9 were selected for this study.Fig. 3


Maize ABP9 enhances tolerance to multiple stresses in transgenic Arabidopsis by modulating ABA signaling and cellular levels of reactive oxygen species.

Zhang X, Wang L, Meng H, Wen H, Fan Y, Zhao J - Plant Mol. Biol. (2011)

Constitutive expression of ABP9 enhances tolerance to drought, salt, cold and oxidative stresses in transgenic Arabidopsis. a, b RNA gel blot analysis of ABP9 expression in wild type (WT) and 35S-ABP9 transgenic plants (5P2 and 5P3) under normal growth and salt stress (a), ABA and PEG treatment conditions (b). Plants grown on 1/2 MS agar plates were untreated or treated with 200 mM NaCl for 1 h and 2 h, 100 μM ABA or 30% PEG for 3 h. Equal amounts (8 μg) of total RNAs separated by electrophoresis on formaldehyde-agarose gels and rRNA was used as loading control. c Drought tolerance in 35S-ABP9 transgenic plants. Intact plants were drought stressed by withholding water for 4 weeks, then were rewatered for 1 week before photograph was taken. Survival rates were calculated from the results of three independent experiments (n ≥ 30 for each experiment). Untreated plants grown under normal conditions as control were shown in the top panels. d Capacity of 35S-ABP9 transgenic plants to tolerate salt stress. The plants were treated with progressively increased concentrations of NaCl solutions ranging from 50 to 200 mM and kept irrigated with 200 mM NaCl for 12 days, then chlorophyll contents were determined. Percentage shown are chlorophyll content of salt-stresses plants relative to that of untreated ones from the results of three independent experiments with 5 intact seedlings determined for each experiment. Untreated plants grown under normal conditions as control were shown in the top panels. e Freeze tolerance of 35S-ABP9 transgenic plants. Plants were exposed to freezing temperature −4°C for 6 h and recovered for 1 week under normal growth conditions. Survival rates were counted from the results of three independent experiments (n ≥ 30 for each experiment). Untreated plants grown under normal conditions as control were shown in the top panels. f Tolerance to oxidative stress in 35S-ABP9 transgenic plants. Rosette leaves from wild-type (WT) plants and transgenic lines (5P2 and 5P3) were floated in 1/2 MS medium containing 2 μM MV for 72 h before photographs were taken. Chlorophyll contents compared to that of mocked-treated samples are shown at the bottom. Shown are representative photographs from 30 seedlings in triplicates
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Fig3: Constitutive expression of ABP9 enhances tolerance to drought, salt, cold and oxidative stresses in transgenic Arabidopsis. a, b RNA gel blot analysis of ABP9 expression in wild type (WT) and 35S-ABP9 transgenic plants (5P2 and 5P3) under normal growth and salt stress (a), ABA and PEG treatment conditions (b). Plants grown on 1/2 MS agar plates were untreated or treated with 200 mM NaCl for 1 h and 2 h, 100 μM ABA or 30% PEG for 3 h. Equal amounts (8 μg) of total RNAs separated by electrophoresis on formaldehyde-agarose gels and rRNA was used as loading control. c Drought tolerance in 35S-ABP9 transgenic plants. Intact plants were drought stressed by withholding water for 4 weeks, then were rewatered for 1 week before photograph was taken. Survival rates were calculated from the results of three independent experiments (n ≥ 30 for each experiment). Untreated plants grown under normal conditions as control were shown in the top panels. d Capacity of 35S-ABP9 transgenic plants to tolerate salt stress. The plants were treated with progressively increased concentrations of NaCl solutions ranging from 50 to 200 mM and kept irrigated with 200 mM NaCl for 12 days, then chlorophyll contents were determined. Percentage shown are chlorophyll content of salt-stresses plants relative to that of untreated ones from the results of three independent experiments with 5 intact seedlings determined for each experiment. Untreated plants grown under normal conditions as control were shown in the top panels. e Freeze tolerance of 35S-ABP9 transgenic plants. Plants were exposed to freezing temperature −4°C for 6 h and recovered for 1 week under normal growth conditions. Survival rates were counted from the results of three independent experiments (n ≥ 30 for each experiment). Untreated plants grown under normal conditions as control were shown in the top panels. f Tolerance to oxidative stress in 35S-ABP9 transgenic plants. Rosette leaves from wild-type (WT) plants and transgenic lines (5P2 and 5P3) were floated in 1/2 MS medium containing 2 μM MV for 72 h before photographs were taken. Chlorophyll contents compared to that of mocked-treated samples are shown at the bottom. Shown are representative photographs from 30 seedlings in triplicates
Mentions: To investigate the function of ABP9 in plant response to abiotic stress, transgenic Arabidopsis plants expressing the ABP9 cDNA under the control of the CaMV 35S promoter (35S-ABP9) were generated and eight independent T3 homozygous lines were obtained. Northern blot analysis revealed that ABP9 expressing transgenic plants accumulated higher levels of ABP9 mRNA under either normal growth or stress conditions with the treatment of 200 mM of NaCl (1 or 2 h), 100 μM ABA (3 h) or 30% PEG (3 h), indicating that ABP9 is constitutively expressed in these transgenic plants (Fig. 3a, b). Two representative lines (5P2 and 5P3), with medium and high expression levels of ABP9 were selected for this study.Fig. 3

Bottom Line: Here we show that the expression of maize ABP9 gene, which encodes a bZIP transcription factor capable of binding to the ABRE2 motif in the maize Cat1 promoter, is induced by ABA, H(2)O(2), drought and salt.Constitutive expression of ABP9 in transgenic Arabidopsis leads to remarkably enhanced tolerance to multiple stresses including drought, high salt, freezing temperature and oxidative stresses.Taken together, these results suggest that ABP9 may play a pivotal role in plant tolerance to abiotic stresses by fine tuning ABA signaling and control of ROS accumulation.

View Article: PubMed Central - PubMed

Affiliation: Maize Gene Research and Genetic Improvement Center, Biotechnology Research Institute, National Key Facility for Crop Gene Resources and Genetic Improvement, Chinese Academy of Agricultural Sciences, No. 12 Zhongguancun South Street, 100081, Beijing, People's Republic of China.

ABSTRACT
The phytohormone abscisic acid (ABA) and reactive oxygen species (ROS) play critical roles in mediating abiotic stress responses in plants. It is well known that ABA is involved in the modulation of ROS levels by regulating ROS-producing and ROS-scavenging genes, but the molecular mechanisms underlying this regulation are poorly understood. Here we show that the expression of maize ABP9 gene, which encodes a bZIP transcription factor capable of binding to the ABRE2 motif in the maize Cat1 promoter, is induced by ABA, H(2)O(2), drought and salt. Constitutive expression of ABP9 in transgenic Arabidopsis leads to remarkably enhanced tolerance to multiple stresses including drought, high salt, freezing temperature and oxidative stresses. ABP9 expressing Arabidopsis plants also exhibit increased sensitivity to exogenously applied ABA during seed germination, root growth and stomatal closure and improved water-conserving capacity. Moreover, constitutive expression of ABP9 causes reduced cellular levels of ROS, alleviated oxidative damage and reduced cell death, accompanied by elevated expression of many stress/ABA responsive genes including those for scavenging and regulating ROS. Taken together, these results suggest that ABP9 may play a pivotal role in plant tolerance to abiotic stresses by fine tuning ABA signaling and control of ROS accumulation.

Show MeSH
Related in: MedlinePlus