GRUSP, an Universal Stress Protein, Is Involved in Gibberellin-dependent Induction of Flowering in Arabidopsis thaliana.

The effect of T-DNA insertion in the 3'-UTR region of Arabidopsis thaliana At3g58450 gene encoding the Germination-Related Universal Stress Protein (GRUSP) was studied. It was found that under a long-day condition this mutation delays transition to flowering of grusp-115 transgenic line that due to a reduced content of endogenous bioactive gibberellins GA1 and GA3 in comparison to the wild-type plants (Col-0). Exogenous GA accelerated flowering of both lines but did not change the time of difference in the onset of flowering between Col-0 and grusp-115. In addition to changes in GA metabolism, grusp-115 evidently has disturbances in realization of the signal that induces flowering. This is confirmed by the results of gene expression of the floral integrator FLOWERING LOCUS T (FT) and the floral repressor FLOWERING LOCUS C (FLC), which are key flowering regulators and acting opposite. We hypothesize that the formation of grusp-115 phenotype can also be affected by a low expression level of FT due to up-regulated FLC expression.

The Gene Encoding the Universal Stress Protein AtUSP is Regulated by Phytohormones and Involved in Seed Germination of Arabidopsis thaliana.

For the first time, the organ-specific expression pattern of the AtUSP (At3g58450) gene, which also undergoes hormonal regulation, was shown. The USP protein encoded by this gene is involved in seed germination of Arabidopsis thaliana and, unlike abscisic acid, stimulates this process.