Fine Mapping of qFIS1‐2, a Major QTL for Kernel Fissure Resistance in Rice

要旨

Rice ( Oryza sativa L.) kernel fissuring causes breakage during milling and thereby decreases the value of rice. This study employed molecular gene‐tagging methods to fine map a fissure resistance (FR) locus in ‘Cybonnet’, a semidwarf tropical japonica cultivar, as well as to transfer this trait to rice genotypes of non‐semidwarf stature that are better adapted to some rice production systems. Three quantitative trait loci (QTLs) for FR were previously reported, with the FR locus linked with the semidwarf sd‐1 locus on chromosome 1 having the strongest effect. For fine mapping, F 2 progeny were produced from a cross between US breeding line RU1201108, having non‐semidwarf height ( Sd‐1/Sd‐1 ) and poor milling quality, and Cybonnet ( sd‐1/sd‐1 ), having semidwarf height and containing multiple FR loci. Simple sequence repeat (SSR) markers were used to select F 2 plants that both retained at least one copy of the Sd‐1 allele and showed evidence of genetic recombination in the region of chromosome 1 known to contain Sd‐1 and qFIS1 ‐ 2, a QTL for FR. Progeny from three F 2 individuals with desirable recombination at the qFIS1 ‐ 2 were phenotyped for kernel FR. Marker‐trait linkages observed in the three populations indicated that the qFIS1‐2 locus resides on chromosome 1 distal to RM1068 at 38.44 Mb, but anterior to RM3482 at 39.72 Mb, placing it ∼6 to 10 cM distal to sd‐1 on chromosome 1. The recombination documented in this study verifies that the previously identified qFIS1‐2 is not pleiotropic with nor reliant on sd‐1 and can be recombined with Sd‐1 to increase the FR of non‐semidwarf rice cultivars.

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