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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]

The brown planthopper (BPH), Nilaparvata lugens Stål, is a significant insect pest of rice (Oryza sa-tiva L.). bph2 is one of the 12 major BPH resistance genes so far identified in several indica cultivars and two wild relatives. We have constructed a high-resolution linkage map as a foundation for map-based cloning of the bph2 locus. An advanced mapping population derived from a cross of ’Tsukushibare’ (a susceptible japonica cultivar) with ’Norin-PL4’ (an authentic bph2-introgression line) was used. Segregation analysis by the mass seedling test showed that bph2 behaved as a single dominant gene. Through bulked segregant analysis and linkage analysis, bph2 was located within a 3.2-cM region containing eight AFLP markers. One marker (KAM4) showed complete co-segregation with bph2, and bph2 was mapped within a 1.0-cM region delimited by KAM3 and KAM5, two flanking markers. KAM4 was converted into a PCR-based sequence-tagged-site (STS) marker and its co-segregation with bph2 was validated. [ABSTRACT FROM AUTHOR]

To develop a transposon tagging system in wheat ( Triticum aestivum L.), transgenic wheat lines containing a transposase gene of the maize Activator ( Ac) element were produced and characterized. The Ac transposase gene under the control of a cauliflower mosaic virus 35S promoter was introduced into cultured wheat embryos by particle bombardment. Several transgenic wheat plants expressing the transposase gene were independently recovered. Southern- and Northern-blot analyses of their progeny showed that the expression of the Ac transposase gene was stably inherited, and three fixed Ac lines were established. By RT-PCR analysis, products from fully spliced transcripts of the Ac element were confirmed. Cultured embryos isolated from the stable Ac lines were further bombarded with plasmids having a maize Dissociation ( Ds) element located between a rice Act1 promoter and a β-glucuronidase ( gus) gene, and transient gus expression was observed after the Ds excision. These findings suggest that the maize Ac transposase gene is precisely processed and an active transposase protein is synthesized in the transgenic Ac lines. The Ds element is trans-activated and excised in wheat cells by the action of the Ac transposase gene. [ABSTRACT FROM AUTHOR]