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Gene knockout study reveals that cytosolic ascorbate peroxidase 2(OsAPX2) plays a critical role in growth and reproduction in rice under drought, salt and cold stresses.

Zhang Z, Zhang Q, Wu J, Zheng X, Zheng S, Sun X, Qiu Q, Lu T - PLoS ONE (2013)

Bottom Line: Loss of function in OsAPX2 affected the growth and development of rice seedlings, resulting in semi-dwarf seedlings, yellow-green leaves, leaf lesion mimic and seed sterility.H2O2 and MDA levels were high in Osapx2 mutants but low in OsAPX2-OX transgenic lines relative to wild-type plants after stress treatments.Taken together, the cytosolic ascorbate peroxidase OsAPX2 plays an important role in rice growth and development by protecting the seedlings from abiotic stresses through scavenging reactive oxygen species.

View Article: PubMed Central - PubMed

Affiliation: Biotechnology Research Institute, Chinese Academy of Agricultural Sciences/National Key facility for Gene Resources And Genetic Improvement, Beijing, China.

ABSTRACT
Plant ascorbate peroxidases (APXs), enzymes catalyzing the dismutation of H2O2 into H2O and O2, play an important role in reactive oxygen species homeostasis in plants. The rice genome has eight OsAPXs, but their physiological functions remain to be determined. In this report, we studied the function of OsAPX2 gene using a T-DNA knockout mutant under the treatment of drought, salt and cold stresses. The Osapx2 knockout mutant was isolated by a genetic screening of a rice T-DNA insertion library under 20% PEG-2000 treatment. Loss of function in OsAPX2 affected the growth and development of rice seedlings, resulting in semi-dwarf seedlings, yellow-green leaves, leaf lesion mimic and seed sterility. OsAPX2 expression was developmental- and spatial-regulated, and was induced by drought, salt, and cold stresses. Osapx2 mutants had lower APX activity and were sensitive to abiotic stresses; overexpression of OsAPX2 increased APX activity and enhanced stress tolerance. H2O2 and MDA levels were high in Osapx2 mutants but low in OsAPX2-OX transgenic lines relative to wild-type plants after stress treatments. Taken together, the cytosolic ascorbate peroxidase OsAPX2 plays an important role in rice growth and development by protecting the seedlings from abiotic stresses through scavenging reactive oxygen species.

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Characterization of wild-type, Osapx2, complementation and OsAPX2-OX plants.A,C: The phenotype of wild-type (WT), Osapx2, complementation (cp) plants and OsAPX2-OX plants at mature stage. B: The leaves of wild-type (WT), Osapx2 (m) and complementation plants (cp) during the vegetative development stage. D: The comparison of the height and the flag leaf angle between wild-type and Osapx2 mutant plants at the mature stage. E: Comparison of anther morphology and pollen viability stained with KI among wild-type (WT), Osapx2 and complementation plants (cp). Bar = 20.0 µm.
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pone-0057472-g004: Characterization of wild-type, Osapx2, complementation and OsAPX2-OX plants.A,C: The phenotype of wild-type (WT), Osapx2, complementation (cp) plants and OsAPX2-OX plants at mature stage. B: The leaves of wild-type (WT), Osapx2 (m) and complementation plants (cp) during the vegetative development stage. D: The comparison of the height and the flag leaf angle between wild-type and Osapx2 mutant plants at the mature stage. E: Comparison of anther morphology and pollen viability stained with KI among wild-type (WT), Osapx2 and complementation plants (cp). Bar = 20.0 µm.

Mentions: Not only were the seeds of the Osapx2 mutant smaller than the wild-type plants, but also the mutant plants were shorter than the wild-type plants. At the heading stage, the height of the mutant seedlings was about two-third of the wild-type Nipponbare (63 cm compared with 110 cm of wild-type) (Figure 4-A,D). The angle of flag leaf was increased in the mutant plants (Figure 4-D). Seedlings of the Osapx2 mutants grown both in greenhouse and paddy field showed a lesion mimic phenotype in the middle of the leaf blade during the tillering stage. After the tillering stage, the lesion spots spreaded to the whole leaves in the mutant plants (Figure 4-B). The mutant plants were completely sterile which was supported by abnormal anther morphology and defective pollen viabiligy (Figure 4-E). Genetic analyses of T1 heterozygous progeny revealed that a segregation ration of wild-type (145):sterility (55) phenotype was 3∶1 (χ2 = 0.67< χ20.01,1), suggesting that the mutated phenotype was controlled by a single recessive nuclear locus.


Gene knockout study reveals that cytosolic ascorbate peroxidase 2(OsAPX2) plays a critical role in growth and reproduction in rice under drought, salt and cold stresses.

Zhang Z, Zhang Q, Wu J, Zheng X, Zheng S, Sun X, Qiu Q, Lu T - PLoS ONE (2013)

Characterization of wild-type, Osapx2, complementation and OsAPX2-OX plants.A,C: The phenotype of wild-type (WT), Osapx2, complementation (cp) plants and OsAPX2-OX plants at mature stage. B: The leaves of wild-type (WT), Osapx2 (m) and complementation plants (cp) during the vegetative development stage. D: The comparison of the height and the flag leaf angle between wild-type and Osapx2 mutant plants at the mature stage. E: Comparison of anther morphology and pollen viability stained with KI among wild-type (WT), Osapx2 and complementation plants (cp). Bar = 20.0 µm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585366&req=5

pone-0057472-g004: Characterization of wild-type, Osapx2, complementation and OsAPX2-OX plants.A,C: The phenotype of wild-type (WT), Osapx2, complementation (cp) plants and OsAPX2-OX plants at mature stage. B: The leaves of wild-type (WT), Osapx2 (m) and complementation plants (cp) during the vegetative development stage. D: The comparison of the height and the flag leaf angle between wild-type and Osapx2 mutant plants at the mature stage. E: Comparison of anther morphology and pollen viability stained with KI among wild-type (WT), Osapx2 and complementation plants (cp). Bar = 20.0 µm.
Mentions: Not only were the seeds of the Osapx2 mutant smaller than the wild-type plants, but also the mutant plants were shorter than the wild-type plants. At the heading stage, the height of the mutant seedlings was about two-third of the wild-type Nipponbare (63 cm compared with 110 cm of wild-type) (Figure 4-A,D). The angle of flag leaf was increased in the mutant plants (Figure 4-D). Seedlings of the Osapx2 mutants grown both in greenhouse and paddy field showed a lesion mimic phenotype in the middle of the leaf blade during the tillering stage. After the tillering stage, the lesion spots spreaded to the whole leaves in the mutant plants (Figure 4-B). The mutant plants were completely sterile which was supported by abnormal anther morphology and defective pollen viabiligy (Figure 4-E). Genetic analyses of T1 heterozygous progeny revealed that a segregation ration of wild-type (145):sterility (55) phenotype was 3∶1 (χ2 = 0.67< χ20.01,1), suggesting that the mutated phenotype was controlled by a single recessive nuclear locus.

Bottom Line: Loss of function in OsAPX2 affected the growth and development of rice seedlings, resulting in semi-dwarf seedlings, yellow-green leaves, leaf lesion mimic and seed sterility.H2O2 and MDA levels were high in Osapx2 mutants but low in OsAPX2-OX transgenic lines relative to wild-type plants after stress treatments.Taken together, the cytosolic ascorbate peroxidase OsAPX2 plays an important role in rice growth and development by protecting the seedlings from abiotic stresses through scavenging reactive oxygen species.

View Article: PubMed Central - PubMed

Affiliation: Biotechnology Research Institute, Chinese Academy of Agricultural Sciences/National Key facility for Gene Resources And Genetic Improvement, Beijing, China.

ABSTRACT
Plant ascorbate peroxidases (APXs), enzymes catalyzing the dismutation of H2O2 into H2O and O2, play an important role in reactive oxygen species homeostasis in plants. The rice genome has eight OsAPXs, but their physiological functions remain to be determined. In this report, we studied the function of OsAPX2 gene using a T-DNA knockout mutant under the treatment of drought, salt and cold stresses. The Osapx2 knockout mutant was isolated by a genetic screening of a rice T-DNA insertion library under 20% PEG-2000 treatment. Loss of function in OsAPX2 affected the growth and development of rice seedlings, resulting in semi-dwarf seedlings, yellow-green leaves, leaf lesion mimic and seed sterility. OsAPX2 expression was developmental- and spatial-regulated, and was induced by drought, salt, and cold stresses. Osapx2 mutants had lower APX activity and were sensitive to abiotic stresses; overexpression of OsAPX2 increased APX activity and enhanced stress tolerance. H2O2 and MDA levels were high in Osapx2 mutants but low in OsAPX2-OX transgenic lines relative to wild-type plants after stress treatments. Taken together, the cytosolic ascorbate peroxidase OsAPX2 plays an important role in rice growth and development by protecting the seedlings from abiotic stresses through scavenging reactive oxygen species.

Show MeSH
Related in: MedlinePlus