GmDim1 Gene Encodes Nucleolar Localized U5-Small Nuclear Ribonucleoprotein in Glycine max

Abstract

The dim1⁺ gene family is essential for G2/M transition during mitosis and encodes a small nuclear ribonucleoprotein that functions in the mRNA splicing machinery of eukaryotes. However, the plant homolog of DIM1 gene has not been defined yet. Here, we identified a gene named GmDim1 positioned on chromosome 9 of soybean (Glycine max (L.) Merr.) with 80% homology to other eukaryotic dim1⁺ family genes. A domain of soybean DIM1 protein was primarily conserved with U5 snRNP protein family and secondarily aligned with mitotic DIM1 protein family. The GmDim1 gene was expressed constitutively in all soybean organs. The transgenic Arabidopsis thaliana (L.) plants overexpressing GmDim1 showed early flowering and stem elongation, produced multiple shoots and continued flowering after the post-flowering stage. DIM1 proteins transiently expressed in onion cells were localized in the nucleus with dense deposition in the nucleolus. Therefore, we propose that the soybean GmDim1 gene is a component of plant U5 snRNP involved in mRNA splicing and normal progress of plant growth.