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The gene pool of Aegilops tauschii, the D-genome donor of common wheat ( Triticum aestivum L.), can be easily accessed in wheat breeding, but remains largely unexplored. In our previous studies, many synthetic hexaploid wheat lines were produced through interspecific crosses between the tetraploid wheat cultivar Langdon and various A. tauschii accessions. The synthetic hexaploid wheat lines showed wide variation in many characteristics. To elucidate the genetic basis of variation in flowering-related traits, we analyzed quantitative trait loci (QTL) affecting time to heading, flowering and maturity, and the grain-filling period using four different F populations of synthetic hexaploid wheat lines. In total, 10 QTLs located on six D-genome chromosomes (all except 4D) were detected for the analyzed traits. The QTL on 1DL controlling heading time appeared to correspond to a flowering time QTL, previously considered to be an ortholog of Eps- A 1 which is related to the narrow-sense earliness in einkorn wheat. The 5D QTL for heading time might be a novel locus associated with wheat flowering, while the 2DS QTL appears to be an allelic variant of the photoperiod response locus Ppd- D1. Some of the identified QTLs seemed to be novel loci regulating wheat flowering and maturation, including a QTL controlling the grain filling period on chromosome 3D. The exercise demonstrates that synthetic wheat lines can be useful for the identification of new, agriculturally important loci that can be transferred to, and used for the modification of flowering and grain maturation in hexaploid wheat. [ABSTRACT FROM AUTHOR]

Japanese rice (Oryza sativaL.) cultivars that are strictly used for the brewing of sake (Japanese rice wine) represent a unique and traditional group. These cultivars are characterized by common traits such as large grain size with low protein content and a large, central white-core structure. To understand the genetic diversity and phylogenetic characteristics of sake-brewing rice, we performed amplified fragment length polymorphism and simple sequence repeat analyses, using 95 cultivars of local and modern sake-brewing rice together with 76 cultivars of local and modern cooking rice. Our analysis of both nuclear and chloroplast genome polymorphisms showed that the genetic diversity in sake-brewing rice cultivars was much smaller than the diversity found in cooking rice cultivars. Interestingly, the genetic diversity within the modern sake-brewing cultivars was about twofold higher than the diversity within the local sake-brewing cultivars, which was in contrast to the cooking cultivars. This is most likely due to introgression of the modern cooking cultivars into the modern sake-brewing cultivars through breeding practices. Cluster analysis and chloroplast haplotype analysis suggested that the local sake-brewing cultivars originated monophyletically in the western regions of Japan. Analysis of variance tests showed that several markers were significantly associated with sake-brewing traits, particularly with the large white-core structure. [ABSTRACT FROM AUTHOR]

We have constructed a linkage map of the rice brown planthopper (BPH) resistance gene, Bph1. RFLP and AFLP markers were selected by the bulked segregant analysis and used in the mapping study of 262 F2s that were derived from a cross of `Tsukushibare', a susceptible japonica cultivar, and `Norin-PL3', an authentic japonica Bph1-introgression line. Twenty markers were mapped within a 28.9-cM region containing the Bph1 locus on the long arm of rice chromosome 12. Combining the result of segregation analysis of BPH resistance by the mass seedling test and that of the markers, the Bph1 locus was mapped within a 5.8-cM region between two flanking markers. The closest AFLP markers, em5814N and em2802N, was at 2.7 cM proximal to the Bph1 locus. Together with the previously constructed high-resolution map of bph2 locating the locus at ca. 10 cM proximal to the Bph1 locus, this improved version of the linkage map would facilitate pyramiding these two important BPH resistance genes. [ABSTRACT FROM AUTHOR]