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A mechanism of growth inhibition by abscisic acid in germinating seeds of Arabidopsis thaliana based on inhibition of plasma membrane H+-ATPase and decreased cytosolic pH, K+, and anions.

Planes MD, Niñoles R, Rubio L, Bissoli G, Bueso E, García-Sánchez MJ, Alejandro S, Gonzalez-Guzmán M, Hedrich R, Rodriguez PL, Fernández JA, Serrano R - J. Exp. Bot. (2014)

Bottom Line: Concerning the latter effect, several mutants of Arabidopsis thaliana with improved capability for H(+) efflux (wat1-1D, overexpression of AKT1 and ost2-1D) are less sensitive to inhibition by ABA than the wild type.The mechanism of inhibition of the H(+)-ATPase by ABA and its effects on cytosolic pH and membrane potential in roots were different from those in guard cells.ABA did not affect the in vivo phosphorylation level of the known activating site (penultimate threonine) of H(+)-ATPase in roots, and SnRK2.2 phosphorylated in vitro the C-terminal regulatory domain of H(+)-ATPase while the guard-cell kinase SnRK2.6/OST1 did not.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, Camino de Vera, 46022 Valencia, Spain.

No MeSH data available.


Related in: MedlinePlus

Effect of ABA on cytosolic pH (pHc) of root epidermal cells measured with microelectrodes in wild type Col-0, the wat1-1D mutant, and the sextuple knockout in ABA receptors mutant 112458 pyr/pyl (pyr/pyl). (A) Time course of a typical experiment with wild type (continuous line), wat1-1D (short dashes), and pyr/pyl (long dashes). (B) Statistical data from four to six independent experiments as in (A). The average cytosolic pH±standard error is given. * indicates significant difference (P<0.05 by Student’s t-test) compared with wild type without ABA.
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Figure 5: Effect of ABA on cytosolic pH (pHc) of root epidermal cells measured with microelectrodes in wild type Col-0, the wat1-1D mutant, and the sextuple knockout in ABA receptors mutant 112458 pyr/pyl (pyr/pyl). (A) Time course of a typical experiment with wild type (continuous line), wat1-1D (short dashes), and pyr/pyl (long dashes). (B) Statistical data from four to six independent experiments as in (A). The average cytosolic pH±standard error is given. * indicates significant difference (P<0.05 by Student’s t-test) compared with wild type without ABA.

Mentions: As the PM H+-ATPase is the major proton extrusion pump of plant cells (Gaxiola et al., 2007; Duby and Boutry, 2009; Haruta and Sussman, 2012), its inhibition by ABA could result in acidification of cytosolic pH. In guard cells, however, metabolic effects of the hormone result in overall alkalinization (Blatt, 2000; Suhita et al., 2004). We measured the effect of ABA on the cytosolic pH of root epidermal cells impaled with pH-sensitive microelectrodes. As indicated in a typical time-course experiment of Fig. 5A, treatment with ABA in the wild type induced, after a lag of about 3min, a small (0.06 pH units) and transient (7min) cytosolic alkalinization followed by a permanent and more pronounced (0.3 pH units) acidification. ABA did not induce cytosolic acidification in either the wat1-1D or 112458 pyr/pyl mutant (Fig. 5A). In the first case, this is because the wat1-1D mutant has increased capability for proton extrusion to counteract intracellular acidification (Niñoles et al., 2013) and only the metabolic alkalinization effect of the hormone is observed. The sextuple mutant in PYR/PYL ABA receptors is very insensitive to the hormone, both in guard cells and in other tissues (Gonzalez-Guzmán et al., 2012). This mutant exhibited a cytosolic pH that was more alkaline than that of the wild type in the absence of exogenous ABA, and the addition of the hormone had no effect. The statistical data of the effects of ABA on cytosolic pH of the different genotypes are presented in Fig. 5B.


A mechanism of growth inhibition by abscisic acid in germinating seeds of Arabidopsis thaliana based on inhibition of plasma membrane H+-ATPase and decreased cytosolic pH, K+, and anions.

Planes MD, Niñoles R, Rubio L, Bissoli G, Bueso E, García-Sánchez MJ, Alejandro S, Gonzalez-Guzmán M, Hedrich R, Rodriguez PL, Fernández JA, Serrano R - J. Exp. Bot. (2014)

Effect of ABA on cytosolic pH (pHc) of root epidermal cells measured with microelectrodes in wild type Col-0, the wat1-1D mutant, and the sextuple knockout in ABA receptors mutant 112458 pyr/pyl (pyr/pyl). (A) Time course of a typical experiment with wild type (continuous line), wat1-1D (short dashes), and pyr/pyl (long dashes). (B) Statistical data from four to six independent experiments as in (A). The average cytosolic pH±standard error is given. * indicates significant difference (P<0.05 by Student’s t-test) compared with wild type without ABA.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4321545&req=5

Figure 5: Effect of ABA on cytosolic pH (pHc) of root epidermal cells measured with microelectrodes in wild type Col-0, the wat1-1D mutant, and the sextuple knockout in ABA receptors mutant 112458 pyr/pyl (pyr/pyl). (A) Time course of a typical experiment with wild type (continuous line), wat1-1D (short dashes), and pyr/pyl (long dashes). (B) Statistical data from four to six independent experiments as in (A). The average cytosolic pH±standard error is given. * indicates significant difference (P<0.05 by Student’s t-test) compared with wild type without ABA.
Mentions: As the PM H+-ATPase is the major proton extrusion pump of plant cells (Gaxiola et al., 2007; Duby and Boutry, 2009; Haruta and Sussman, 2012), its inhibition by ABA could result in acidification of cytosolic pH. In guard cells, however, metabolic effects of the hormone result in overall alkalinization (Blatt, 2000; Suhita et al., 2004). We measured the effect of ABA on the cytosolic pH of root epidermal cells impaled with pH-sensitive microelectrodes. As indicated in a typical time-course experiment of Fig. 5A, treatment with ABA in the wild type induced, after a lag of about 3min, a small (0.06 pH units) and transient (7min) cytosolic alkalinization followed by a permanent and more pronounced (0.3 pH units) acidification. ABA did not induce cytosolic acidification in either the wat1-1D or 112458 pyr/pyl mutant (Fig. 5A). In the first case, this is because the wat1-1D mutant has increased capability for proton extrusion to counteract intracellular acidification (Niñoles et al., 2013) and only the metabolic alkalinization effect of the hormone is observed. The sextuple mutant in PYR/PYL ABA receptors is very insensitive to the hormone, both in guard cells and in other tissues (Gonzalez-Guzmán et al., 2012). This mutant exhibited a cytosolic pH that was more alkaline than that of the wild type in the absence of exogenous ABA, and the addition of the hormone had no effect. The statistical data of the effects of ABA on cytosolic pH of the different genotypes are presented in Fig. 5B.

Bottom Line: Concerning the latter effect, several mutants of Arabidopsis thaliana with improved capability for H(+) efflux (wat1-1D, overexpression of AKT1 and ost2-1D) are less sensitive to inhibition by ABA than the wild type.The mechanism of inhibition of the H(+)-ATPase by ABA and its effects on cytosolic pH and membrane potential in roots were different from those in guard cells.ABA did not affect the in vivo phosphorylation level of the known activating site (penultimate threonine) of H(+)-ATPase in roots, and SnRK2.2 phosphorylated in vitro the C-terminal regulatory domain of H(+)-ATPase while the guard-cell kinase SnRK2.6/OST1 did not.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Biología Molecular y Celular de Plantas, Universidad Politécnica de Valencia-Consejo Superior de Investigaciones Científicas, Camino de Vera, 46022 Valencia, Spain.

No MeSH data available.


Related in: MedlinePlus