Repression of stress-responsive genes by FIERY2, a novel
transcriptional regulator in Arabidopsis.
Xiong L, Lee H, Ishitani M, Tanaka Y, Stevenson B, Koiwa H, Bressan RA,
Hasegawa PM, Zhu JK.
Department of Plant Sciences, University of Arizona, Tucson, AZ 85721; and
Center for Plant Environmental Stress Physiology, 1165 Horticulture Building,
Purdue University, West Lafayette, IN 47907-1165.
Low temperature, drought, and high salinity induce the expression of many plant
genes. To understand the mechanisms for the transcriptional activation of these
genes, we conducted a reporter gene-aided genetic screen in Arabidopsis. Seven
allelic mutations in the FIERY2 (FRY2) locus result in significant increases in
the expression of stress-responsive genes with the DRE/CRT
(drought-responsive/C-repeat) cis element but non-DRE/CRT type stress-responsive
genes were less affected. The specific regulation of DRE/CRT class of genes by
FRY2 appears to be caused by repression of stress induction of the upstream CBF/DREB
transcription factor genes. fry2 mutants show increased tolerance to salt stress
and to abscisic acid during seed germination but are more sensitive to freezing
damage at the seedling stage. FRY2/CPL1 encodes a novel transcriptional
repressor harboring two double-stranded RNA-binding domains and a region
homologous to the catalytic domain of RNA polymerase II C-terminal domain
phosphatases found in yeast and in animals that regulate gene transcription.
These data indicate that FRY2 is an important negative regulator of stress gene
transcription and suggest that structured RNA may regulate hormone and stress
responses in plants as it does in animals.