Table I.

Rationale for selection of mutants analyzed

Cellular ProcessEvidence for Involvement in Heat ResponsesPrevious Mutants Tested/ConditionMutants Tested in This StudyReferences
ABA signaling/biosynthesisPretreatment with ABA increases basal thermotoleranceabi1, abi2, defective in basal thermotolerance, 10 daba1-3, aba2-1, aba3-1, abi1-1, abi2-1, abi3-1, and ade1-1Robertson et al. (1994); Gong et al. (1998); Larkindale and Knight (2002); Larkindale and Huang (2004)
SA signalingPretreatment with SA increases basal thermotoleranceNahG transgenic line (unable to accumulate SA) and npr1 defective in basal thermotolerance, 10 dNahG and npr1-1Dat et al. (1998a, 1998b); Larkindale and Knight (2002); Clarke et al. (2004); Larkindale and Huang (2004)
Ethylene signalingPretreatment with ACCa (ethylene precursor) increases basal thermotoleranceetr1 defective in basal thermotolerance, 10 detr1-1 and ein2-1Larkindale and Huang (2004); Larkindale and Knight (2002)
AOS signalingPretreatment with H2O2 increases basal thermotoleranceNoneatrbohA, atrbohB, atrbohC, atrbohD, atrbohE, atrbohF, atrbohG, and atrbohHDat et al. (1998b); Larkindale and Huang (2004)
Membrane fatty acid compositionReducing trienoic fatty acid levels by chemical treatment or mutation results in increased stability of photosynthesis and increased tolerance to chronic heat stressfad7/fad8 double mutant showed increased tolerance to chronic heat stressfad2-1, fad2-2, fad3-1, fad4-1, fad5-1, fad6-1, fad7-1, fad 7-2, fad7-1/8-1, and fab2-1Horváth et al. (1998); Murakami et al. (2000); Alfonso et al. (2001); Sangwan et al. (2002)
Antioxidant pathwayHeat stress causes photooxidative damage and results in increased antioxidant productionNonenpq1-2, cad2-1, vtc1-1, vtc2-1, and cat1/3Dat et al. (1998a, 1998b); Gong et al. (1998); Larkindale and Knight (2002)
Ubiquitin pathwayUbiquitin-mediated cytoplasmic proteolysis can compensate for the absence of HSPs in yeastubp1, ubp2, and ubp1/2 were defective in prevention of damage due to protein aggregationubp1-1, ubp2-1, and ubp1-1/2-1Yan et al. (2000); Friant et al. (2003); Riezman (2004)
Programmed cell deathHigh temperature treatments induce programmed cell death in plantsNoneacd2-2Swidzinski et al. (2002); Vacca et al. (2004)
UV-sensitive mutantsUV stress and heat stress might be expected to cause similar kinds of damageuvh6 has previously been shown to be defective in chronic heat toleranceuvh1-1, uvh3-1, and uvh6-1Jenkins et al. (1997)
OtherThis or similar mutants have previously been shown to be sensitive to high temperaturestsl4 and the auxin resistant mutant TU8 were shown to be sensitive to chronic heat stressrns1, tsl4, and axr1-3Bariola et al. (1999); Ludwig-Muller et al. (2000); Berardini et al. (2001); C. Somerville, unpublished data
  • a ACC, 1-Aminocyclopropane-1-carboxylic acid.