Abstract
We report the identification of the causal gene of a new small and round mutant, srs3 in rice. By the map-based cloning method, we found a candidate for the causal gene of srs3-1 in the 5th chromosome, in which a putative gene, Os05g06280.2 were encoded. We introduced the SRS3 cDNA into srs3-1 by Agrobacterium-mediated transformation method. The transformants showed wild type phenotypes. SRS3 consists from 12 exons. The SRS3 protein was consisted with 819 amino acids and grouped into the kinesin 13 family. The kinesin-motor domain containing ATPase activity locates in the region from 3rd exon to 10th exon. The srs3-1 caused one base substitution in the 9th exon, which resulting in the 1 amino acid substitution from leucine492 to phenylalanine492. It was suggested that this mutation might lead to the decrease in motor activity and consequently the development of seeds may be impaired in srs3-1.
