High-resolution mapping revealed a 1.3-Mbp genomic inversion in Ssi1, a dominant semidwarf gene in rice (Oryza sativa)

Abstract

Dwarf or semidwarf characters are an important trait for crop breeding as they provide lodging resistance. The rice mutant line DMF-1 has a dm-type semidwarf phenotype and high-lodging resistance controlled by the dominant gene, Short second internode 1 (Ssi1). To elucidate the mechanism of reducing culm length in DMF-1, we sought to identify the Ssi1 gene by positional cloning using the chromosome segment substitution line as a crossing parent. As a result of high-resolution mapping, we found a 1.3-Mbp genomic inversion and a newly arranged gene in the Ssi1 locus. In this study, we report the high-resolution mapping and physical mapping of Ssi1. We also discuss the possible function of a novel rearranged Ssi1 gene for the dominant dm-type semidwarf phenotype. © 2008 The Authors.