Development of a new experimental line carrying a mutable slender glume gene, slg, in rice

摘要

A mutable slender glume mutant (mutant line IM294) was induced by gamma-ray irradiation of japonica variety Gimbozu seeds. This mutant slender glume character is controlled by a recessive mutant gene slg (slender glume), but has never been fixed inspite of repeated self-propagation. Successive generations showed not only wild-type glume plants (revertants) but also chimeric plants which appear in low frequency. The mutability of slg resulted from a precise excision of an active MITE (miniature inverted-repeat transposable element) 'mPing' inserted in exon 4 of the Rurml~m gene (locus: Rice iibiqiiitin-related modifier- l), the same gene as slg (Teraishi et al. 1999, Nakazaki el al. 2002). The revertants (wild-type glume plants: slg~+slg) are useful materials for functional genomics in rice because they have a mPing insertional mutation at a new site in the genome. However, IM294 exhibits very low seed fertility due to mPing-insertion at Rurml locus, which brings about frequent outcrosses with other variety/lines. Therefore, recessive marker genes tightly linked to slg and quite visible in the field are required for efficient screening of true revertants. The objectives of the present study are to develop a new line carrying slg and a recessivemarker gene, and to develop isogenic lines for these two loci.