Heat shock factors HsfB1 and HsfB2b are involved in the regulation of Pdf1.2 expression and pathogen resistance in Arabidopsis.
In order to assess the functional roles of heat stress-induced class B-heat shock factors in Arabidopsis, we investigated T-DNA knockout mutants of AtHsfB1 and AtHsfB2b. Micorarray analysis of double knockout hsfB1/hsfB2b plants revealed as strong an up-regulation of the basal mRNA-levels of the defensin genes Pdf1.2a/b in mutant plants. The Pdf expression was further enhanced by jasmonic acid treatment or infection with the necrotrophic fungus Alternaria brassicicola. The single mutant hsfB2b and the double mutant hsfB1/B2b were significantly improved in disease resistance after A. brassicicola infection. There was no indication for a direct interaction of Hsf with the promoter of Pdf1.2, which is devoid of perfect HSE consensus Hsf-binding sequences. However, changes in the formation of late HsfA2-dependent HSE binding were detected in hsfB1/B2b plants. This suggests that HsfB1/B2b may interact with class A-Hsf in regulating the shut-off of the heat shock response. The identification of Pdf genes as targets of Hsf-dependent negative regulation is the first evidence for an interconnection of Hsf in the regulation of biotic and abiotic responses.
Kumar
Mukesh
M
Heinrich-Pette-Institut, Martinistrabe 52, D-20251 Hamburg, Germany.
Busch
Wolfgang
W
Birke
Hannah
H
Kemmerling
Birgit
B
Nürnberger
Thorsten
T
Schöffl
Friedrich
F
D017360:Arabidopsis / Q000235:genetics / Q000382:microbiology / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics*; D001483:Base Sequence; D017931:DNA Primers; D023082:Defensins / Q000235:genetics*; D024202:Electrophoretic Mobility Shift Assay; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D055786:Gene Knockout Techniques; D017343:Genes, Plant; D006360:Heat-Shock Proteins / Q000502:physiology*; D016133:Polymerase Chain Reaction
D029681:Arabidopsis Proteins; D017931:DNA Primers; D023082:Defensins; D006360:Heat-Shock Proteins; C487542:At5g44420 protein, Arabidopsis