Abstract
To study low-temperature signaling in plants, we previously screened for cold stress response mutants using bioluminescent Arabidopsis plants that express the firefly luciferase reporter gene driven by the stress-responsive
RD29A
promoter. Here, we report on the characterization and cloning of one mutant,
frostbite1
(
fro1
), which shows reduced luminescence induction by cold.
fro1
plants display reduced cold induction of stress-responsive genes such as
RD29A
,
KIN1
,
COR15A
, and
COR47
.
fro1
leaves have a reduced capacity for cold acclimation, appear water-soaked, leak electrolytes, and accumulate reactive oxygen species constitutively.
FRO1
was isolated through positional cloning and found to encode a protein with high similarity to the 18-kD Fe-S subunit of complex I (NADH dehydrogenase, EC 1.6.5.3) in the mitochondrial electron transfer chain. Confocal imaging shows that the FRO1:green fluorescent protein fusion protein is localized in mitochondria. These results suggest that cold induction of nuclear gene expression is modulated by mitochondrial function.