Abstract
srd2 is a temperature-sensitive mutant of Arabidopsis thaliana that exhibits peculiar defects in tissue culture responses including hypocotyl dedifferentiation and shoot regeneration. Its responsible gene, SRD2, was revealed to encode snRNA transcription activator. Our previous studies have shown involvement of SRD2-mediated increase of snRNAs in elevation of cell proliferation competence during dedifferentiation.
Here we report SRD2 expression analyzed using SRD2p::GUS transgenic lines. When hypocotyl segments were incubated on callus-inducing medium containing 2,4-D and kinetin, GUS was expressed strongly in the stele throughout the whole explant and also in non-stele tissues around the cut ends. A similar pattern was observed in explants incubated with 2,4-D alone. In culture with kinetin alone or no phytohormones, active GUS expression was limited to the near-cut-end region. In view of localization and phytohormone dependency of cell proliferation, the GUS expression in the stele induced by 2,4-D should reflect SRD2 expression required for dedifferentiation.
