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A link between magnesium-chelatase H subunit and sucrose nonfermenting 1 (SNF1)-related protein kinase SnRK2.6/OST1 in Arabidopsis guard cell signalling in response to abscisic acid.

Liang S, Lu K, Wu Z, Jiang SC, Yu YT, Bi C, Xin Q, Wang XF, Zhang DP - J. Exp. Bot. (2015)

Bottom Line: Neither mutation nor over-expression of the ABAR gene affects significantly ABA-insensitive phenotypes of stomatal movement in the OST1 knockout mutant allele srk2e.These findings suggest that ABAR shares, at least in part, downstream signalling components with PYR/PYL/RCAR receptors for ABA in guard cells; though cch and rtl1 show strong ABA-insensitive phenotypes in both ABA-induced stomatal closure and inhibition of stomatal opening, while the pyr1 pyl1 pyl2 pyl4 quadruple mutant shows strong ABA insensitivity only in ABA-induced stomatal closure.These data establish a link between ABAR/CHLH and SnRK2.6/OST1 in guard cell signalling in response to ABA.

View Article: PubMed Central - PubMed

Affiliation: Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.

No MeSH data available.


ABA-induced ROS and NO production and changes in the expression of some ROS-metabolism genes in guard cells of different genotypes. ROS production in response to ABA [10 μM (±)ABA, 20min treatment] was examined by H2DCF-DA imaging (A) and also the relative H2DCF fluorescence levels were recorded (B). NO production in response to ABA [10 μM (±)ABA, 20min treatment] was examined by diaminofluorescein (DAF) fluorescence imaging (C) and also the relative DAF fluorescence levels were recorded (D). The experiment was replicated three times with the similar results. The relative fluorescence levels are normalized relative to the control (−ABA) taken as 1. (E) and (F) show ABA-induced changes in the expression of some ROS-metabolism genes in guard cells of different genotypes. Two-week-old seedlings, sprayed with 50 μM (±)ABA or ABA-free solution (as a control), were sampled for RNA extraction 2.5h after the ABA application. The expression of the related genes was assayed by real-time PCR. Values in B, D, E, and F are means ±SE from three independent experiments, and different letters indicate significant differences at P<0.05 (Duncan’s multiple range test) when comparing values within the same ABA treatment.
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Figure 6: ABA-induced ROS and NO production and changes in the expression of some ROS-metabolism genes in guard cells of different genotypes. ROS production in response to ABA [10 μM (±)ABA, 20min treatment] was examined by H2DCF-DA imaging (A) and also the relative H2DCF fluorescence levels were recorded (B). NO production in response to ABA [10 μM (±)ABA, 20min treatment] was examined by diaminofluorescein (DAF) fluorescence imaging (C) and also the relative DAF fluorescence levels were recorded (D). The experiment was replicated three times with the similar results. The relative fluorescence levels are normalized relative to the control (−ABA) taken as 1. (E) and (F) show ABA-induced changes in the expression of some ROS-metabolism genes in guard cells of different genotypes. Two-week-old seedlings, sprayed with 50 μM (±)ABA or ABA-free solution (as a control), were sampled for RNA extraction 2.5h after the ABA application. The expression of the related genes was assayed by real-time PCR. Values in B, D, E, and F are means ±SE from three independent experiments, and different letters indicate significant differences at P<0.05 (Duncan’s multiple range test) when comparing values within the same ABA treatment.

Mentions: It is known that the pyr1 pyl1 pyl2 pyl4 quadruple mutant shows ABA insensitivity in ABA-induced ROS and NO production (Yin et al., 2013). It was observed that ABA-induced ROS and NO production was impaired in guard cells of cch and rtl1 mutants, which was similar to that in the pyr1 pyl1 pyl2 pyl4 quadruple mutant (Fig. 6A–D). The expression of some ROS metabolism-related genes was further tested. RbohD and RbohF encode two members of the NADPH oxidase family, which promote ROS production and are involved in ABA signalling likely downstream of OST1 (Kwak et al., 2003; Acharya et al., 2013). GPX1/2/5/6/7 encode five members of the glutathione peroxidase family, of which the expression is induced by environmental stresses (Sugimoto and Sakamoto, 1997; Rodriguez et al., 2003); CAT1/2/3 encode three members of the catalase family (Chevalier et al., 1992). The GPXs and CATs are responsible for ROS scavenging (Noctor et al., 2002; Smykowski et al., 2010). These enzymes are involved in maintaining ROS homeostasis in plant cells (Wang and Song, 2008). It was observed that ABA-induced expression of all these genes except for RbohD and CAT3 significantly decreased in both the pyr1 pyl1 pyl2 pyl4 and cch mutants (Fig. 6E–F), suggesting that both ROS production and scavenging processes are impaired in response to ABA in these mutants. These findings are consistent with the above-mentioned decline in the ABA sensitivity of ROS production of these mutants. Together, all the data suggest that CHLH/ABAR, like the PYR/PYL/RCAR receptors for ABA, acts upstream of ROS and NO in the ABA signalling pathway.


A link between magnesium-chelatase H subunit and sucrose nonfermenting 1 (SNF1)-related protein kinase SnRK2.6/OST1 in Arabidopsis guard cell signalling in response to abscisic acid.

Liang S, Lu K, Wu Z, Jiang SC, Yu YT, Bi C, Xin Q, Wang XF, Zhang DP - J. Exp. Bot. (2015)

ABA-induced ROS and NO production and changes in the expression of some ROS-metabolism genes in guard cells of different genotypes. ROS production in response to ABA [10 μM (±)ABA, 20min treatment] was examined by H2DCF-DA imaging (A) and also the relative H2DCF fluorescence levels were recorded (B). NO production in response to ABA [10 μM (±)ABA, 20min treatment] was examined by diaminofluorescein (DAF) fluorescence imaging (C) and also the relative DAF fluorescence levels were recorded (D). The experiment was replicated three times with the similar results. The relative fluorescence levels are normalized relative to the control (−ABA) taken as 1. (E) and (F) show ABA-induced changes in the expression of some ROS-metabolism genes in guard cells of different genotypes. Two-week-old seedlings, sprayed with 50 μM (±)ABA or ABA-free solution (as a control), were sampled for RNA extraction 2.5h after the ABA application. The expression of the related genes was assayed by real-time PCR. Values in B, D, E, and F are means ±SE from three independent experiments, and different letters indicate significant differences at P<0.05 (Duncan’s multiple range test) when comparing values within the same ABA treatment.
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Figure 6: ABA-induced ROS and NO production and changes in the expression of some ROS-metabolism genes in guard cells of different genotypes. ROS production in response to ABA [10 μM (±)ABA, 20min treatment] was examined by H2DCF-DA imaging (A) and also the relative H2DCF fluorescence levels were recorded (B). NO production in response to ABA [10 μM (±)ABA, 20min treatment] was examined by diaminofluorescein (DAF) fluorescence imaging (C) and also the relative DAF fluorescence levels were recorded (D). The experiment was replicated three times with the similar results. The relative fluorescence levels are normalized relative to the control (−ABA) taken as 1. (E) and (F) show ABA-induced changes in the expression of some ROS-metabolism genes in guard cells of different genotypes. Two-week-old seedlings, sprayed with 50 μM (±)ABA or ABA-free solution (as a control), were sampled for RNA extraction 2.5h after the ABA application. The expression of the related genes was assayed by real-time PCR. Values in B, D, E, and F are means ±SE from three independent experiments, and different letters indicate significant differences at P<0.05 (Duncan’s multiple range test) when comparing values within the same ABA treatment.
Mentions: It is known that the pyr1 pyl1 pyl2 pyl4 quadruple mutant shows ABA insensitivity in ABA-induced ROS and NO production (Yin et al., 2013). It was observed that ABA-induced ROS and NO production was impaired in guard cells of cch and rtl1 mutants, which was similar to that in the pyr1 pyl1 pyl2 pyl4 quadruple mutant (Fig. 6A–D). The expression of some ROS metabolism-related genes was further tested. RbohD and RbohF encode two members of the NADPH oxidase family, which promote ROS production and are involved in ABA signalling likely downstream of OST1 (Kwak et al., 2003; Acharya et al., 2013). GPX1/2/5/6/7 encode five members of the glutathione peroxidase family, of which the expression is induced by environmental stresses (Sugimoto and Sakamoto, 1997; Rodriguez et al., 2003); CAT1/2/3 encode three members of the catalase family (Chevalier et al., 1992). The GPXs and CATs are responsible for ROS scavenging (Noctor et al., 2002; Smykowski et al., 2010). These enzymes are involved in maintaining ROS homeostasis in plant cells (Wang and Song, 2008). It was observed that ABA-induced expression of all these genes except for RbohD and CAT3 significantly decreased in both the pyr1 pyl1 pyl2 pyl4 and cch mutants (Fig. 6E–F), suggesting that both ROS production and scavenging processes are impaired in response to ABA in these mutants. These findings are consistent with the above-mentioned decline in the ABA sensitivity of ROS production of these mutants. Together, all the data suggest that CHLH/ABAR, like the PYR/PYL/RCAR receptors for ABA, acts upstream of ROS and NO in the ABA signalling pathway.

Bottom Line: Neither mutation nor over-expression of the ABAR gene affects significantly ABA-insensitive phenotypes of stomatal movement in the OST1 knockout mutant allele srk2e.These findings suggest that ABAR shares, at least in part, downstream signalling components with PYR/PYL/RCAR receptors for ABA in guard cells; though cch and rtl1 show strong ABA-insensitive phenotypes in both ABA-induced stomatal closure and inhibition of stomatal opening, while the pyr1 pyl1 pyl2 pyl4 quadruple mutant shows strong ABA insensitivity only in ABA-induced stomatal closure.These data establish a link between ABAR/CHLH and SnRK2.6/OST1 in guard cell signalling in response to ABA.

View Article: PubMed Central - PubMed

Affiliation: Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.

No MeSH data available.