Table 3.

Genes Implicated in ABA Signaling by Reverse Genetics or Expression Pattern

Locus/GeneEngineered EffectPhenotypeResponse to ABAGene ProductReferences
 Vicia faba)Dominant
   negativeNo ABA-induced stomatal closure; no ABA activation of plasma membrane anion channelsActivatedSer/Thr
   protein kinaseLi and Assmann, 1996;
 Li et al., 2000
 kinase (from
 Pisum sativum)Activation; correlated
   with stomatal closure
   & dehydrin expressionABA-activated
   myelin basic
   protein kinaseBurnett et al., 2000
ARSK1Induced by ABA or NaClRoot specific
   ser/thr kinaseHwang and Goodman,
 ATCDPK1aConstitutively active
   mutants expressed
   transiently in maize
   leaf protoplastsConstitutive activation of an ABA responsive reporter gene (HVA1-LUC)Calcium-dependent
   protein kinasesSheen, 1996
AtIP5PIIOverexpressionABA-insensitive  germination, growth  and gene expressionInositol
   5-phosphatase IISanchez and Chua, 2001
AtPLC1Antisense suppressionABA-insensitive germination, growth and gene expressionPhosphoinositide
   phospholipase CSanchez and Chua, 2001
AtPP2CWild-type and mutant proteins expressed transiently in maize leaf protoplasts; antisense suppressionOver-expression blocked ABA-inducible transcription; null mutation had little effect; dominant interfering mutant strongly repressed ABA responses. Antisense conferred increased sensitivity to ABA-induced cold-tolerance and growth inhibitionProtein
   phosphatase 2CSheen, 1998; Tahtiharju and Palva, 2001
AtRac1/Rop6Dominant-positive and dominant-negativeDominant positive blocked ABA-mediated effects on actin cytoskeleton and stomatal closure; dominant negative induced closure in absence of ABASmall GTPaseLemichez et al., 2001
Repressed; correlated with cell division activityCyclin-dependent
   kinaseHemerly et al., 1993
GPA1T-DNA insertionIncreased leaf transpiration; no ABA inhibition of guard cell K+in channels and pH-independent ABA-activation of anion channelsG protein α-subunitWang et al., 2001
Induced by ABA and NaCl; may function in stress responseGSK3/shaggy-like
   protein kinasePiao et al., 1999
ABA effect unknown; induced by osmotic stressHis kinase
   osmosensorUrao et al., 1999
ICK1Induced; may suppress cell divisionInhibitor of cyclin-
 dependent kinaseWang et al., 1998
MAPKKKABA effect unknown; induced by abiotic stressesMitogen-activated protein kinase kinase kinaseMizoguchi et al., 1996
PIP5KInduced by ABA and abiotic stressesPhosphatidylinosi-tol-4-phosphate 5-kinaseMikami et al., 1998
PKABA1Constitutive expressionSuppression of GA-inducible gene expression in aleurone; small effect on the ABA induction of a LEA geneInducedSer/Thr-protein kinase (from barley)Gómez-Cadenas et al., 1999
PLDαAntisenseDecreased ABA and ethylene promotion of senescencePhospholipase DαFan et al., 1997
ROP2Dominant negative constitutiveAltered sensitivity to germination inhibition by ABARho-type small GTPaseLi et al., 200
RPK1Induced by ABA and abiotic stresses; abiotic stress-induction not ABA-dependentReceptor-like protein kinaseHong et al., 1997
Unknown; induced by abiotic stressesRibosomal S6 kinase-likeMizoguchi et al., 1996
WAPK (from tobacco)InducedWounding-induced protein kinaseLee et al., 1998