Using probes obtained by PCR amplification, we have isolated two cognate rice cDNAs (cdc2Os-1 and cdc2Os-2) encoding structural homologues of the cdc2+/CDC28 (cdc2) protein kinase from a cDNA library prepared from cultured rice cells. Comparison of the deduced amino acid sequences of cdc2Os-1 and cdc2Os-2 showed that they are 83% identical. They are 62% identical to CDC28 of Saccharomyces cerevisiae and much more similar to the yeast and mammalian p34cdc2 kinases than to rice R2, a cdc2-related kinase isolated previously by screening the same rice cDNA library with a different oligonucleotide probe. Southern blot analysis indicated that the three rice clones (cdc2Os-1, cdc2Os-2 and R2) are derived from distinct genes and are each found in a single copy per rice haploid genome. RNA blot analysis revealed that these genes are expressed in proliferating rice cells and in young rice seedlings. cdc2Os-1 could complement a temperature-sensitive yeast mutant of cdc28. However, despite the similarity in structure, both cdc2Os-2 and R2 were unable to complement the same mutant. Thus, the present results demonstrate the presence of structurally related, but functionally distinct cognates of the cdc2 cell cycle kinase in rice.

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Fertile transgenic barley (Hordeum vulgare L.) plants were obtained by high velocity particle bombardment. The plasmid pBCl was used to deliver the selectable hph gene and reporter Gus gene into immature embryo. After the selection culture 18 hygromycin resistant plants were obtained. Samples for Southern hybridization and enzymatic Gus assay were obtained from 11 plants. Southern hybridization confirmed the presence of the hph gene in the 11 hygromycin resistant plants(T0). Enzymatic assay indicated that all the t0 plants that showed hph positive in Southern analysis possessed detectable amount of Gus activity. To date all the 11 t0 plants reached maturity and mature seeds were obtained Transmission of the hph gene to progeny(T1) of two independent t0 plants was confirmed by Southern hybridization.

A genetic linkage map of the Japanese pear (Pyrus pyrifolia Nakai) 'Housui' was constructed based on simple sequence repeat (SSR) and amplified fragment length polymorphism (AFLP) markers. A mapping population derived from a cross between 'Bartlett' and 'Housui' was used to create the linkage map of 'Housui'. Segregation data on 63 progeny were scored using a pseudo-testcross strategy. The linkage map of 'Housui' consisted of 17 linkage groups (LGs) spanned 1,174 cM with an average distance of 3.5 cM between markers. A total of 335 loci (105 SSRs, 224 AFLPs, and 6 others) were used to construct the genetic linkage map. We successfully aligned allLGs to European pear and apple reference maps with common SSR markers. Compared to the reference map of 'Bartlett', constructed using same mapping population, LG 4 and LG 5 of 'Housui' were small and covered 9.7 cM and 23.2 cM, respectively. Furthermore, LG 12 of 'Housui' was established with only one SSR marker. These results indicated that three particular genomic regions (LG 4, LG 5, and LG 12) of 'Housui' were homozygous because a pseudo-testcross strategy was applied to construct the linkage maps. Genotyping of parental and ancestral cultivars of 'Housui' demonstrated that homozygous regions were increased on particularLGs of Japanese pear, maybe due to biased crossing and selection of seedlings during the Japanese pear breeding program.