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New ABA-hypersensitive Arabidopsis mutants are affected in loci mediating responses to water deficit and Dickeya dadantii infection.

Plessis A, Cournol R, Effroy D, Silva Pérez V, Botran L, Kraepiel Y, Frey A, Sotta B, Cornic G, Leung J, Giraudat J, Marion-Poll A, North HM - PLoS ONE (2011)

Bottom Line: The has2 mutant also exhibited increased germination inhibition by ABA, while ABA-inducible gene expression was not modified on dehydration, indicating the mutated gene affects early ABA-signalling responses that do not modify transcript levels.In contrast, weak ABA-hypersensitivity relative to mutant developmental phenotypes suggests that HAS3 regulates drought responses by both ABA-dependent and independent pathways. has1 mutant phenotypes were only apparent on stress or ABA treatments, and included reduced water loss on rapid dehydration.In contrast to has2, has1 exhibited only minor changes in susceptibility to Dickeya dadantii despite similar ABA-hypersensitivity, indicating that crosstalk between ABA responses to this pathogen and drought stress can occur through more than one point in the signalling pathway.

View Article: PubMed Central - PubMed

Affiliation: Institut Jean-Pierre Bourgin, UMR1318, INRA, AgroParisTech, Versailles, France.

ABSTRACT
On water deficit, abscisic acid (ABA) induces stomata closure to reduce water loss by transpiration. To identify Arabidopsis thaliana mutants which transpire less on drought, infrared thermal imaging of leaf temperature has been used to screen for suppressors of an ABA-deficient mutant (aba3-1) cold-leaf phenotype. Three novel mutants, called hot ABA-deficiency suppressor (has), have been identified with hot-leaf phenotypes in the absence of the aba3 mutation. The defective genes imparted no apparent modification to ABA production on water deficit, were inherited recessively and enhanced ABA responses indicating that the proteins encoded are negative regulators of ABA signalling. All three mutants showed ABA-hypersensitive stomata closure and inhibition of root elongation with little modification of growth and development in non-stressed conditions. The has2 mutant also exhibited increased germination inhibition by ABA, while ABA-inducible gene expression was not modified on dehydration, indicating the mutated gene affects early ABA-signalling responses that do not modify transcript levels. In contrast, weak ABA-hypersensitivity relative to mutant developmental phenotypes suggests that HAS3 regulates drought responses by both ABA-dependent and independent pathways. has1 mutant phenotypes were only apparent on stress or ABA treatments, and included reduced water loss on rapid dehydration. The HAS1 locus thus has the required characteristics for a targeted approach to improving resistance to water deficit. In contrast to has2, has1 exhibited only minor changes in susceptibility to Dickeya dadantii despite similar ABA-hypersensitivity, indicating that crosstalk between ABA responses to this pathogen and drought stress can occur through more than one point in the signalling pathway.

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Reduced rosette size and root length of has2 and has3 mutants.Wild-type has1, has2 and has3 A, rosettes grown in long-day photoperiod for 14–18 days. B, rosettes grown in short-day photoperiod for 55 to 73 days. C, primary root length of 13 d old seedlings grown in long-day photoperiod. WT, wild-type. Error bars represent SE values (b, n = 4; c, n = 24). Similar results were obtained in 2 independent experiments. Student t-test p<1%, ** or p<0.1%, ***.
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pone-0020243-g004: Reduced rosette size and root length of has2 and has3 mutants.Wild-type has1, has2 and has3 A, rosettes grown in long-day photoperiod for 14–18 days. B, rosettes grown in short-day photoperiod for 55 to 73 days. C, primary root length of 13 d old seedlings grown in long-day photoperiod. WT, wild-type. Error bars represent SE values (b, n = 4; c, n = 24). Similar results were obtained in 2 independent experiments. Student t-test p<1%, ** or p<0.1%, ***.

Mentions: When plants bolted, the rosettes of has2 and has3 mutants grown in long-day photoperiods were slightly smaller than those of wild-type (Figure 4A) although at maturity these differences in rosette size were less evident. This size reduction was also observed for plants grown in a short-day photoperiod (Figure 4B) and for 14 d-old drought-stressed plants (Figure 1 B, C, E and F). Furthermore, has2 and has3 had a reduced number of rosette leaves at flowering (wild-type: 20±0.7; has1: 19.3±0.9; has2: 16.3±0.7; has3: 16.75±1.0). Flowering time was, however, not affected in has1 and has2 in long- and short-day conditions or for has3 in long-day conditions. Interestingly, in short-day conditions, bolting of floral stems was earlier in the has3 mutant (wild-type: 62.3 days±0.9; has3: 55.7±0.7), indicating that in certain circumstances has3 is an early-flowering mutant. Primary root length was also reduced in the has2 and has3 mutants, in accordance with the reduced rosette size (Figure 4C).


New ABA-hypersensitive Arabidopsis mutants are affected in loci mediating responses to water deficit and Dickeya dadantii infection.

Plessis A, Cournol R, Effroy D, Silva Pérez V, Botran L, Kraepiel Y, Frey A, Sotta B, Cornic G, Leung J, Giraudat J, Marion-Poll A, North HM - PLoS ONE (2011)

Reduced rosette size and root length of has2 and has3 mutants.Wild-type has1, has2 and has3 A, rosettes grown in long-day photoperiod for 14–18 days. B, rosettes grown in short-day photoperiod for 55 to 73 days. C, primary root length of 13 d old seedlings grown in long-day photoperiod. WT, wild-type. Error bars represent SE values (b, n = 4; c, n = 24). Similar results were obtained in 2 independent experiments. Student t-test p<1%, ** or p<0.1%, ***.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3102102&req=5

pone-0020243-g004: Reduced rosette size and root length of has2 and has3 mutants.Wild-type has1, has2 and has3 A, rosettes grown in long-day photoperiod for 14–18 days. B, rosettes grown in short-day photoperiod for 55 to 73 days. C, primary root length of 13 d old seedlings grown in long-day photoperiod. WT, wild-type. Error bars represent SE values (b, n = 4; c, n = 24). Similar results were obtained in 2 independent experiments. Student t-test p<1%, ** or p<0.1%, ***.
Mentions: When plants bolted, the rosettes of has2 and has3 mutants grown in long-day photoperiods were slightly smaller than those of wild-type (Figure 4A) although at maturity these differences in rosette size were less evident. This size reduction was also observed for plants grown in a short-day photoperiod (Figure 4B) and for 14 d-old drought-stressed plants (Figure 1 B, C, E and F). Furthermore, has2 and has3 had a reduced number of rosette leaves at flowering (wild-type: 20±0.7; has1: 19.3±0.9; has2: 16.3±0.7; has3: 16.75±1.0). Flowering time was, however, not affected in has1 and has2 in long- and short-day conditions or for has3 in long-day conditions. Interestingly, in short-day conditions, bolting of floral stems was earlier in the has3 mutant (wild-type: 62.3 days±0.9; has3: 55.7±0.7), indicating that in certain circumstances has3 is an early-flowering mutant. Primary root length was also reduced in the has2 and has3 mutants, in accordance with the reduced rosette size (Figure 4C).

Bottom Line: The has2 mutant also exhibited increased germination inhibition by ABA, while ABA-inducible gene expression was not modified on dehydration, indicating the mutated gene affects early ABA-signalling responses that do not modify transcript levels.In contrast, weak ABA-hypersensitivity relative to mutant developmental phenotypes suggests that HAS3 regulates drought responses by both ABA-dependent and independent pathways. has1 mutant phenotypes were only apparent on stress or ABA treatments, and included reduced water loss on rapid dehydration.In contrast to has2, has1 exhibited only minor changes in susceptibility to Dickeya dadantii despite similar ABA-hypersensitivity, indicating that crosstalk between ABA responses to this pathogen and drought stress can occur through more than one point in the signalling pathway.

View Article: PubMed Central - PubMed

Affiliation: Institut Jean-Pierre Bourgin, UMR1318, INRA, AgroParisTech, Versailles, France.

ABSTRACT
On water deficit, abscisic acid (ABA) induces stomata closure to reduce water loss by transpiration. To identify Arabidopsis thaliana mutants which transpire less on drought, infrared thermal imaging of leaf temperature has been used to screen for suppressors of an ABA-deficient mutant (aba3-1) cold-leaf phenotype. Three novel mutants, called hot ABA-deficiency suppressor (has), have been identified with hot-leaf phenotypes in the absence of the aba3 mutation. The defective genes imparted no apparent modification to ABA production on water deficit, were inherited recessively and enhanced ABA responses indicating that the proteins encoded are negative regulators of ABA signalling. All three mutants showed ABA-hypersensitive stomata closure and inhibition of root elongation with little modification of growth and development in non-stressed conditions. The has2 mutant also exhibited increased germination inhibition by ABA, while ABA-inducible gene expression was not modified on dehydration, indicating the mutated gene affects early ABA-signalling responses that do not modify transcript levels. In contrast, weak ABA-hypersensitivity relative to mutant developmental phenotypes suggests that HAS3 regulates drought responses by both ABA-dependent and independent pathways. has1 mutant phenotypes were only apparent on stress or ABA treatments, and included reduced water loss on rapid dehydration. The HAS1 locus thus has the required characteristics for a targeted approach to improving resistance to water deficit. In contrast to has2, has1 exhibited only minor changes in susceptibility to Dickeya dadantii despite similar ABA-hypersensitivity, indicating that crosstalk between ABA responses to this pathogen and drought stress can occur through more than one point in the signalling pathway.

Show MeSH
Related in: MedlinePlus