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Loss of the Arabidopsis thaliana P₄-ATPase ALA3 reduces adaptability to temperature stresses and impairs vegetative, pollen, and ovule development.

McDowell SC, López-Marqués RL, Poulsen LR, Palmgren MG, Harper JF - PLoS ONE (2013)

Bottom Line: We also demonstrate that ala3 mutants have reduced fecundity resulting from a combination of decreased ovule production and pollen tube growth defects.In-vitro pollen tube growth assays showed that ala3 pollen germinated ∼2 h slower than wild-type and had approximately 2-fold reductions in both maximal growth rate and overall length.Together, these results support a model in which ALA3 functions to modify endomembranes in multiple cell types, enabling structural changes, or signaling functions that are critical in plants for normal development and adaptation to varied growth environments.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Nevada, United States of America.

ABSTRACT
Members of the P4 subfamily of P-type ATPases are thought to help create asymmetry in lipid bilayers by flipping specific lipids between the leaflets of a membrane. This asymmetry is believed to be central to the formation of vesicles in the secretory and endocytic pathways. In Arabidopsis thaliana, a P4-ATPase associated with the trans-Golgi network (ALA3) was previously reported to be important for vegetative growth and reproductive success. Here we show that multiple phenotypes for ala3 knockouts are sensitive to growth conditions. For example, ala3 rosette size was observed to be dependent upon both temperature and soil, and varied between 40% and 80% that of wild-type under different conditions. We also demonstrate that ala3 mutants have reduced fecundity resulting from a combination of decreased ovule production and pollen tube growth defects. In-vitro pollen tube growth assays showed that ala3 pollen germinated ∼2 h slower than wild-type and had approximately 2-fold reductions in both maximal growth rate and overall length. In genetic crosses under conditions of hot days and cold nights, pollen fitness was reduced by at least 90-fold; from ∼18% transmission efficiency (unstressed) to less than 0.2% (stressed). Together, these results support a model in which ALA3 functions to modify endomembranes in multiple cell types, enabling structural changes, or signaling functions that are critical in plants for normal development and adaptation to varied growth environments.

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The size of ala3 rosettes relative to wild-type varies with growth conditions.Representative examples and quantitative analysis of strong (left) and weak (right) presentations of the ala3 rosette size phenotype. The growth conditions shown in the panels on the left are the same as those used by Poulsen et al. [22] to report the reduced rosette size phenotype of ala3 mutants. Rosette size was measured at the time of bolting as the average length of the three longest rosette leaves. Rosette sizes were normalized to the wild-type mean and are reported as mean ± SE. Genotypes significantly different from wild-type (p<0.05, Welch’s t-test) appear in gray. Column label abbreviations are as follows: WT represents the wild-type controls; 3-1 and 3-4 represent ala3-1 and ala3-4 mutants, respectively; and R represents ala3 plants rescued by the expression of full length ALA3. Representative results are shown for three independent experiments, n = 7–9 plants for each genotype/condition combination.
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pone-0062577-g002: The size of ala3 rosettes relative to wild-type varies with growth conditions.Representative examples and quantitative analysis of strong (left) and weak (right) presentations of the ala3 rosette size phenotype. The growth conditions shown in the panels on the left are the same as those used by Poulsen et al. [22] to report the reduced rosette size phenotype of ala3 mutants. Rosette size was measured at the time of bolting as the average length of the three longest rosette leaves. Rosette sizes were normalized to the wild-type mean and are reported as mean ± SE. Genotypes significantly different from wild-type (p<0.05, Welch’s t-test) appear in gray. Column label abbreviations are as follows: WT represents the wild-type controls; 3-1 and 3-4 represent ala3-1 and ala3-4 mutants, respectively; and R represents ala3 plants rescued by the expression of full length ALA3. Representative results are shown for three independent experiments, n = 7–9 plants for each genotype/condition combination.

Mentions: To further investigate the reproducibility of the reduced rosette size phenotype [22][26], ala3 and wild-type plants were grown in parallel under four different combinations of soil (SMB-238 and LB-2) and temperature (20°C and 24°C) conditions. Rosette sizes were measured at the time of bolting as the average length of the three longest rosette leaves. We observed a reduction in ala3 rosette size that varied independently with both temperature and soil between 40% (20°C, LB-2 soil) and 80% (24°C, SMB-238 soil) that of wild-type (Figure 2, Figure S1). This condition-dependent variation in the ala3 rosette size phenotype provides a possible explanation for the discrepancy between the results of Zhang and Oppenheimer [26] and Poulsen et al. [22]. Nevertheless, the average size of ala3 rosettes was significantly smaller than that of wild-type under all conditions tested (p<0.05, Welch’s t-test).


Loss of the Arabidopsis thaliana P₄-ATPase ALA3 reduces adaptability to temperature stresses and impairs vegetative, pollen, and ovule development.

McDowell SC, López-Marqués RL, Poulsen LR, Palmgren MG, Harper JF - PLoS ONE (2013)

The size of ala3 rosettes relative to wild-type varies with growth conditions.Representative examples and quantitative analysis of strong (left) and weak (right) presentations of the ala3 rosette size phenotype. The growth conditions shown in the panels on the left are the same as those used by Poulsen et al. [22] to report the reduced rosette size phenotype of ala3 mutants. Rosette size was measured at the time of bolting as the average length of the three longest rosette leaves. Rosette sizes were normalized to the wild-type mean and are reported as mean ± SE. Genotypes significantly different from wild-type (p<0.05, Welch’s t-test) appear in gray. Column label abbreviations are as follows: WT represents the wild-type controls; 3-1 and 3-4 represent ala3-1 and ala3-4 mutants, respectively; and R represents ala3 plants rescued by the expression of full length ALA3. Representative results are shown for three independent experiments, n = 7–9 plants for each genotype/condition combination.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3646830&req=5

pone-0062577-g002: The size of ala3 rosettes relative to wild-type varies with growth conditions.Representative examples and quantitative analysis of strong (left) and weak (right) presentations of the ala3 rosette size phenotype. The growth conditions shown in the panels on the left are the same as those used by Poulsen et al. [22] to report the reduced rosette size phenotype of ala3 mutants. Rosette size was measured at the time of bolting as the average length of the three longest rosette leaves. Rosette sizes were normalized to the wild-type mean and are reported as mean ± SE. Genotypes significantly different from wild-type (p<0.05, Welch’s t-test) appear in gray. Column label abbreviations are as follows: WT represents the wild-type controls; 3-1 and 3-4 represent ala3-1 and ala3-4 mutants, respectively; and R represents ala3 plants rescued by the expression of full length ALA3. Representative results are shown for three independent experiments, n = 7–9 plants for each genotype/condition combination.
Mentions: To further investigate the reproducibility of the reduced rosette size phenotype [22][26], ala3 and wild-type plants were grown in parallel under four different combinations of soil (SMB-238 and LB-2) and temperature (20°C and 24°C) conditions. Rosette sizes were measured at the time of bolting as the average length of the three longest rosette leaves. We observed a reduction in ala3 rosette size that varied independently with both temperature and soil between 40% (20°C, LB-2 soil) and 80% (24°C, SMB-238 soil) that of wild-type (Figure 2, Figure S1). This condition-dependent variation in the ala3 rosette size phenotype provides a possible explanation for the discrepancy between the results of Zhang and Oppenheimer [26] and Poulsen et al. [22]. Nevertheless, the average size of ala3 rosettes was significantly smaller than that of wild-type under all conditions tested (p<0.05, Welch’s t-test).

Bottom Line: We also demonstrate that ala3 mutants have reduced fecundity resulting from a combination of decreased ovule production and pollen tube growth defects.In-vitro pollen tube growth assays showed that ala3 pollen germinated ∼2 h slower than wild-type and had approximately 2-fold reductions in both maximal growth rate and overall length.Together, these results support a model in which ALA3 functions to modify endomembranes in multiple cell types, enabling structural changes, or signaling functions that are critical in plants for normal development and adaptation to varied growth environments.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Nevada, United States of America.

ABSTRACT
Members of the P4 subfamily of P-type ATPases are thought to help create asymmetry in lipid bilayers by flipping specific lipids between the leaflets of a membrane. This asymmetry is believed to be central to the formation of vesicles in the secretory and endocytic pathways. In Arabidopsis thaliana, a P4-ATPase associated with the trans-Golgi network (ALA3) was previously reported to be important for vegetative growth and reproductive success. Here we show that multiple phenotypes for ala3 knockouts are sensitive to growth conditions. For example, ala3 rosette size was observed to be dependent upon both temperature and soil, and varied between 40% and 80% that of wild-type under different conditions. We also demonstrate that ala3 mutants have reduced fecundity resulting from a combination of decreased ovule production and pollen tube growth defects. In-vitro pollen tube growth assays showed that ala3 pollen germinated ∼2 h slower than wild-type and had approximately 2-fold reductions in both maximal growth rate and overall length. In genetic crosses under conditions of hot days and cold nights, pollen fitness was reduced by at least 90-fold; from ∼18% transmission efficiency (unstressed) to less than 0.2% (stressed). Together, these results support a model in which ALA3 functions to modify endomembranes in multiple cell types, enabling structural changes, or signaling functions that are critical in plants for normal development and adaptation to varied growth environments.

Show MeSH
Related in: MedlinePlus