Abstract
We previously isolated a combination of high-light and heat-shock stress (HL+HS)-inducible genes, including a suppressor of the G2 allele of skp1 (Sgt1a) from Arabidopsis. Arabidopsis contains two Sgt1 genes (Sgt1a and Sgt1b). Here we explored the physiological function of Arabidopsis Sgt1a or Sgt1b under stressful conditions. The transcript and protein levels of Sgt1a markedly increased under not only HL+HS stress, but also HS stress or H2O2 treatment. There was no significant difference in acquired thermotolerance between the wild-type, Sgt1a-overexpressing or Sgt1b-overexpressing plants or Sgt1b-disrupted mutants (edm1). However, the acquired thermotolerance was lower in the knock-out Sgt1a mutants (KO-Sgt1a) than the wild-type plants. Furthermore, the transcript levels of some heat shock proteins (Hsp) were significantly lower in the KO-Sgt1a mutants than the wild-type plants and edm1 mutants. The present findings indicated Sgt1a to be important for the acquired thermotolerance.
