RESUMEN
In spring-type oat ( Avena sativa L.), quantitative trait loci (QTLs) detected in adapted populations may have the greatest potential for improving germplasm via marker-assisted selection. An F(6) recombinant inbred (RI) population was developed from a cross between two Canadian spring oat varieties: 'Terra', a hulless line, and 'Marion', an elite covered-seeded line. A molecular linkage map was generated using 430 AFLP, RFLP, RAPD, SCAR, and phenotypic markers scored on 101 RI lines. This map was refined by selecting a robust set of 124 framework markers that mapped to 35 linkage groups and contained 35 unlinked loci. One hundred one lines grown in up to 13 field environments in Canada and the United States between 1992 and 1997 were evaluated for 16 agronomic, kernel, and chemical composition traits. QTLs were localized using three detection methods with an experiment-wide error rate of approximately 0.05 for each trait. In total, 34 main-effect QTLs affecting the following traits were identified: heading date, plant height, lodging, visual score, grain yield, kernel weight, milling yield, test weight, thin and plump kernels, groat beta-glucan concentration, oil concentration, and protein. Several of these correspond to QTLs in homologous or homoeologous regions reported in other oat QTL studies. Twenty-four QTL-by-environment interactions and three epistatic interactions were also detected. The locus controlling the covered/hulless character ( N1) affected most of the traits measured in this study. Additive QTL models with N1 as a covariate were superior to models based on separate covered and hulless sub-populations. This approach is recommended for other populations segregating for major genes. Marker-trait associations identified in this study have considerable potential for use in marker-assisted selection strategies to improve traits within spring oat breeding programs.
Asunto(s)
Avena/genética , Mapeo Cromosómico , Ambiente , Fenotipo , Sitios de Carácter Cuantitativo/genética , Agricultura/métodos , Canadá , Cruzamientos Genéticos , Modelos Lineales , Polimorfismo de Longitud del Fragmento de Restricción , Técnica del ADN Polimorfo Amplificado Aleatorio , Estados UnidosRESUMEN
Daylength insensitive accessions of Avena sativa L. are being used to develop cultivars that will flower normally when grown under short or long photoperiods. Field data indicate that the insensitivity trait is under the control of a single dominant gene, designated Di1. The random amplified polymorphic DNA (RAPD) technique and bulk segregant analysis of daylength sensitive and insensitive plants were used to find markers for this gene. Five of 200 random decamer primers tested produced polymorphic bands, which were shown to be linked to the trait using 30 homozygous insensitive and 30 homozygous sensitive F3 individuals. Three of the markers produced a band in the presence of the dominant allele, and two in its absence. Segregation analysis showed that markers 221 and 136 could be mapped to within 9.8 +/- 4.6 and 13.9 +/- 5.4 cM of the trait, respectively; that is, close enough to be useful in a breeding program. A study of different cultivars suggested that the band produced by primer 136 is actually the more closely linked marker and the only one present in the original Di1 gene donor CAV2700. The possibility of using both markers in populations derived from different cultivars is discussed.