Gene SGL, encoding a kinesin-like protein with transactivation activity, is involved in grain length and plant height in rice.

Grain shape, a complex agronomic trait, plays an important role in determining yield and quality in rice. In the present study, a mutant named short grain length (sgl) was identified among explants of tissue cultured japonica variety Kita-ake. It exhibited reduced plant height (about 72 % of WT) and short grain length (about 80 % of WT). The reduced length was due to decreased cell elongation. The Short Grain Length (SGL) gene was isolated via map-based cloning and identified to encode a kinesin-like protein. SGL was expressed in the whole plant, especially in the stem and panicles. SGL was shown to have transcriptional activity. In onion epidermal cells, SGL protein was found mainly in the nucleus. Real-time PCR analyses showed that expression levels of genes involved in gibberellin metabolic pathways were affected in the sgl mutant. These data suggested that SGL protein may be involved in regulating GA synthesis and response genes, that in turn, regulates grain length and plant height.