Abstract
SRD2 is an Arabidopsis gene encoding snRNA transcription activator. Phenotypic analysis of a temperature-sensitive mutant of this gene srd2-1 showed that SRD2-dependent snRNA accumulation is required for various aspects of development, including tissue culture responses such as hypocotyl dedifferentiation and shoot regeneration.
A reporter (SRD2::GUS), consisting of the -1,908 to +152 region (+1 = translation initiation site) of SRD2 and the GUS structural gene, was expressed strongly at the shoot apex, root apex, and root stele but not in the hypocotyl. When hypocotyl segments were cultured to form callus, dedifferentiation-associated expression of SRD2::GUS was induced in the stele and non-tissue-specific expression, possibly due to wounding, was observed near the cut ends. Deletion analysis of the regulatory region of SRD2::GUS suggested that cis elements important for spatial expression in planta and dedifferentiation-associated expression lie within the -1,241/+152 region while wound-responsive elements may be located in the region upstream from -1,214.
