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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 ABA sensitivity and water-conserving capacity of 35S-ABP9 transgenic Arabidopsis plants. a Germination rates of wild-type (WT) and 35S-ABP9 seeds (5P2 and 5P3) exposed to 0, 0.25, 0.5, 0.75, and 1 μM ABA at 72 h after stratification. Data represent means ± SD of three independent experiments with 40 seeds per genotype and experiment. Asterisks indicate significant differences between the WT and 5P2 or 5P3 plants (*P < 0.05, **P < 0.01, Students t test). b Primary root growth of WT, 5P2 and 5P3 seedlings. The germinated seeds plated in ABA-free MS medium for 48 h after stratification were transferred to plates supplemented with 0, 3, 7, 10 and 20 μM ABA and root elongation was scored after 10 days. Each value is the mean ± SD of at least 30 seedlings from three independent experiments. Asterisks indicate significant differences between the WT and 5P2 or 5P3 plants (**P < 0.01, Students t test). c Stomatal aperture measurements of wild-type (WT) and 35S-ABP9 transgenic lines (5P2 and 5P3) in response to 0 and 10 μM ABA. Values are means ± SD of 75 stomata from three independent experiments. Asterisks indicate significant differences between the WT and 5P2 or 5P3 plants (**P < 0.01, Students t test). d Percentage of  ABA-induced stomatal closure in (c) of wild-type (WT) and 35S-ABP9 transgenic plants (5P2 and 5P3). Asterisks indicate significant differences between the WT and 5P2 or 5P3 plants (*P < 0.05, **P < 0.01, Students t test). e Transpirational water loss in wild-type (WT) and 35S-ABP9 transgenic plants (5P2 and 5P3). Leaf weight is expressed as the percentage of initial fresh weight (FW). Each data point represents the mean of duplicate measurements (5 detached leaves for each measurement)
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Fig4: Constitutive expression of ABP9 enhances ABA sensitivity and water-conserving capacity of 35S-ABP9 transgenic Arabidopsis plants. a Germination rates of wild-type (WT) and 35S-ABP9 seeds (5P2 and 5P3) exposed to 0, 0.25, 0.5, 0.75, and 1 μM ABA at 72 h after stratification. Data represent means ± SD of three independent experiments with 40 seeds per genotype and experiment. Asterisks indicate significant differences between the WT and 5P2 or 5P3 plants (*P < 0.05, **P < 0.01, Students t test). b Primary root growth of WT, 5P2 and 5P3 seedlings. The germinated seeds plated in ABA-free MS medium for 48 h after stratification were transferred to plates supplemented with 0, 3, 7, 10 and 20 μM ABA and root elongation was scored after 10 days. Each value is the mean ± SD of at least 30 seedlings from three independent experiments. Asterisks indicate significant differences between the WT and 5P2 or 5P3 plants (**P < 0.01, Students t test). c Stomatal aperture measurements of wild-type (WT) and 35S-ABP9 transgenic lines (5P2 and 5P3) in response to 0 and 10 μM ABA. Values are means ± SD of 75 stomata from three independent experiments. Asterisks indicate significant differences between the WT and 5P2 or 5P3 plants (**P < 0.01, Students t test). d Percentage of ABA-induced stomatal closure in (c) of wild-type (WT) and 35S-ABP9 transgenic plants (5P2 and 5P3). Asterisks indicate significant differences between the WT and 5P2 or 5P3 plants (*P < 0.05, **P < 0.01, Students t test). e Transpirational water loss in wild-type (WT) and 35S-ABP9 transgenic plants (5P2 and 5P3). Leaf weight is expressed as the percentage of initial fresh weight (FW). Each data point represents the mean of duplicate measurements (5 detached leaves for each measurement)

Mentions: In the absence of exogenously applied ABA, the germination percentage of 35S-ABP9 seeds was similar to that of wild-type seeds when scored at 72 h on MS medium. However, compared to wild-type seeds, germination of 35S-ABP9 seed is more sensitive to exogenously applied ABA (concentrations ranging from 0.25 to 1 μM), and the sensitivity is dependent on the level of ABP9 expression (Fig. 4a). Measurement of root length showed that the ABP9 transgenic plants exhibited a greater reduction in response to exogenously applied ABA, in comparison with wild-type plants (Fig. 4b).Fig. 4


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 ABA sensitivity and water-conserving capacity of 35S-ABP9 transgenic Arabidopsis plants. a Germination rates of wild-type (WT) and 35S-ABP9 seeds (5P2 and 5P3) exposed to 0, 0.25, 0.5, 0.75, and 1 μM ABA at 72 h after stratification. Data represent means ± SD of three independent experiments with 40 seeds per genotype and experiment. Asterisks indicate significant differences between the WT and 5P2 or 5P3 plants (*P < 0.05, **P < 0.01, Students t test). b Primary root growth of WT, 5P2 and 5P3 seedlings. The germinated seeds plated in ABA-free MS medium for 48 h after stratification were transferred to plates supplemented with 0, 3, 7, 10 and 20 μM ABA and root elongation was scored after 10 days. Each value is the mean ± SD of at least 30 seedlings from three independent experiments. Asterisks indicate significant differences between the WT and 5P2 or 5P3 plants (**P < 0.01, Students t test). c Stomatal aperture measurements of wild-type (WT) and 35S-ABP9 transgenic lines (5P2 and 5P3) in response to 0 and 10 μM ABA. Values are means ± SD of 75 stomata from three independent experiments. Asterisks indicate significant differences between the WT and 5P2 or 5P3 plants (**P < 0.01, Students t test). d Percentage of  ABA-induced stomatal closure in (c) of wild-type (WT) and 35S-ABP9 transgenic plants (5P2 and 5P3). Asterisks indicate significant differences between the WT and 5P2 or 5P3 plants (*P < 0.05, **P < 0.01, Students t test). e Transpirational water loss in wild-type (WT) and 35S-ABP9 transgenic plants (5P2 and 5P3). Leaf weight is expressed as the percentage of initial fresh weight (FW). Each data point represents the mean of duplicate measurements (5 detached leaves for each measurement)
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Fig4: Constitutive expression of ABP9 enhances ABA sensitivity and water-conserving capacity of 35S-ABP9 transgenic Arabidopsis plants. a Germination rates of wild-type (WT) and 35S-ABP9 seeds (5P2 and 5P3) exposed to 0, 0.25, 0.5, 0.75, and 1 μM ABA at 72 h after stratification. Data represent means ± SD of three independent experiments with 40 seeds per genotype and experiment. Asterisks indicate significant differences between the WT and 5P2 or 5P3 plants (*P < 0.05, **P < 0.01, Students t test). b Primary root growth of WT, 5P2 and 5P3 seedlings. The germinated seeds plated in ABA-free MS medium for 48 h after stratification were transferred to plates supplemented with 0, 3, 7, 10 and 20 μM ABA and root elongation was scored after 10 days. Each value is the mean ± SD of at least 30 seedlings from three independent experiments. Asterisks indicate significant differences between the WT and 5P2 or 5P3 plants (**P < 0.01, Students t test). c Stomatal aperture measurements of wild-type (WT) and 35S-ABP9 transgenic lines (5P2 and 5P3) in response to 0 and 10 μM ABA. Values are means ± SD of 75 stomata from three independent experiments. Asterisks indicate significant differences between the WT and 5P2 or 5P3 plants (**P < 0.01, Students t test). d Percentage of ABA-induced stomatal closure in (c) of wild-type (WT) and 35S-ABP9 transgenic plants (5P2 and 5P3). Asterisks indicate significant differences between the WT and 5P2 or 5P3 plants (*P < 0.05, **P < 0.01, Students t test). e Transpirational water loss in wild-type (WT) and 35S-ABP9 transgenic plants (5P2 and 5P3). Leaf weight is expressed as the percentage of initial fresh weight (FW). Each data point represents the mean of duplicate measurements (5 detached leaves for each measurement)
Mentions: In the absence of exogenously applied ABA, the germination percentage of 35S-ABP9 seeds was similar to that of wild-type seeds when scored at 72 h on MS medium. However, compared to wild-type seeds, germination of 35S-ABP9 seed is more sensitive to exogenously applied ABA (concentrations ranging from 0.25 to 1 μM), and the sensitivity is dependent on the level of ABP9 expression (Fig. 4a). Measurement of root length showed that the ABP9 transgenic plants exhibited a greater reduction in response to exogenously applied ABA, in comparison with wild-type plants (Fig. 4b).Fig. 4

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