To study cold signaling, we screened for Arabidopsis mutants with altered cold-induced transcription of a firefly luciferase reporter gene driven by the CBF3 promoter （CBF3-LUC）. One mutant, chy1-10, displayed reduc...To study cold signaling, we screened for Arabidopsis mutants with altered cold-induced transcription of a firefly luciferase reporter gene driven by the CBF3 promoter （CBF3-LUC）. One mutant, chy1-10, displayed reduced cold-induction of CBF3-LUC luminescence. RNA gel blot analysis revealed that expression of endogenous CBFs also was reduced in the chyl mutant, chy1-10 mutant plants are more sensitive to freezing treatment than wild-type after cold acclimation. Both the wild-type and chyl mutant plants are sensitive to darkness-induced starvation at warm temperatures, although chyl plants are slightly more sensitive. This dark-sensitivity is suppressed by cold temperature in the wildtype but not in chyl. Constitutive CBF3 expression partially rescues the sensitivity of chyl-10 plants to dark treatment in the cold. The chyl mutant accumulates higher levels of reactive oxygen species, and application of hydrogen peroxide can reduce cold-induction of CBF3-LUC in wild-type. Map-based cloning of the gene defective in the mutant revealed a nonsense mutation in CHY1, which encodes a peroxisomal β-hydroxyisobutyryl （HIBYL）-CoA hydrolase needed for valine catabolism and fatty acid β-oxidation. Our results suggest a role for peroxisomal metabolism in cold stress signaling, and plant tolerance to cold stress and darkness-induced starvation.展开更多
文摘To study cold signaling, we screened for Arabidopsis mutants with altered cold-induced transcription of a firefly luciferase reporter gene driven by the CBF3 promoter （CBF3-LUC）. One mutant, chy1-10, displayed reduced cold-induction of CBF3-LUC luminescence. RNA gel blot analysis revealed that expression of endogenous CBFs also was reduced in the chyl mutant, chy1-10 mutant plants are more sensitive to freezing treatment than wild-type after cold acclimation. Both the wild-type and chyl mutant plants are sensitive to darkness-induced starvation at warm temperatures, although chyl plants are slightly more sensitive. This dark-sensitivity is suppressed by cold temperature in the wildtype but not in chyl. Constitutive CBF3 expression partially rescues the sensitivity of chyl-10 plants to dark treatment in the cold. The chyl mutant accumulates higher levels of reactive oxygen species, and application of hydrogen peroxide can reduce cold-induction of CBF3-LUC in wild-type. Map-based cloning of the gene defective in the mutant revealed a nonsense mutation in CHY1, which encodes a peroxisomal β-hydroxyisobutyryl （HIBYL）-CoA hydrolase needed for valine catabolism and fatty acid β-oxidation. Our results suggest a role for peroxisomal metabolism in cold stress signaling, and plant tolerance to cold stress and darkness-induced starvation.
