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Arabidopsis mutant deficient in 3 abscisic acid-activated protein kinases reveals critical roles in growth, reproduction, and stress
Tekijät: Fujii, Hiroaki; Zhu, Jian-Kang
Kustantaja: NATL ACAD SCIENCES
Kustannuspaikka: WASHINGTON
Julkaisuvuosi: 2009
Journal: Proceedings of the National Academy of Sciences of the United States of America
Tietokannassa oleva lehden nimi: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Lehden akronyymi: P NATL ACAD SCI USA
Vuosikerta: 106
Numero: 20
Aloitussivu: 8380
Lopetussivu: 8385
Sivujen määrä: 6
ISSN: 0027-8424
DOI: https://doi.org/10.1073/pnas.0903144106
Tiivistelmä
Abscisic acid (ABA) is an important phytohormone regulating seed dormancy, germination, seedling growth, and plant transpiration. We report here an Arabidopsis triple mutant that is disrupted in 3 SNF1-related protein kinase subfamily 2 (SnRK2s) and nearly completely insensitive to ABA. These SnRK2s, SnRK2.2, SnRK2.3, and SnRK2.6 (also known as OST1), are activated by ABA and can phosphorylate the ABA-responsive element binding factor family of b-ZIP transcription factors, which are important for the activation of ABA-responsive genes. Although stomatal regulation of snrk2.6 and seed germination and seedling growth of the snrk2.2/2.3 double mutant are insensitive to ABA, ABA responses are still present in these mutants, and the growth and reproduction of these mutants are not very different from those of the WT. In contrast, the snrk2.2/2.3/2.6 triple mutant grows poorly and produces few seeds. The triple mutant plants lose water extremely fast when ambient humidity is not high. Even on 50 mu M ABA, the triple mutant can germinate and grow, whereas the most insensitive known mutants cannot develop on 10 mu M ABA. In-gel kinase assays showed that all ABA-activated protein kinase activities are eliminated in the triple mutant. Also, the expression of ABA-induced genes examined is completely blocked in the triple mutant. These results demonstrate that the protein kinases SnRK2.2, SnRK2.3, and SnRK2.6 have redundant functions, and suggest that ABA signaling is critical for plant growth and reproduction.
Abscisic acid (ABA) is an important phytohormone regulating seed dormancy, germination, seedling growth, and plant transpiration. We report here an Arabidopsis triple mutant that is disrupted in 3 SNF1-related protein kinase subfamily 2 (SnRK2s) and nearly completely insensitive to ABA. These SnRK2s, SnRK2.2, SnRK2.3, and SnRK2.6 (also known as OST1), are activated by ABA and can phosphorylate the ABA-responsive element binding factor family of b-ZIP transcription factors, which are important for the activation of ABA-responsive genes. Although stomatal regulation of snrk2.6 and seed germination and seedling growth of the snrk2.2/2.3 double mutant are insensitive to ABA, ABA responses are still present in these mutants, and the growth and reproduction of these mutants are not very different from those of the WT. In contrast, the snrk2.2/2.3/2.6 triple mutant grows poorly and produces few seeds. The triple mutant plants lose water extremely fast when ambient humidity is not high. Even on 50 mu M ABA, the triple mutant can germinate and grow, whereas the most insensitive known mutants cannot develop on 10 mu M ABA. In-gel kinase assays showed that all ABA-activated protein kinase activities are eliminated in the triple mutant. Also, the expression of ABA-induced genes examined is completely blocked in the triple mutant. These results demonstrate that the protein kinases SnRK2.2, SnRK2.3, and SnRK2.6 have redundant functions, and suggest that ABA signaling is critical for plant growth and reproduction.
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