The adenomatous polyposis coli gene (APC) is mutated in familial adenomatous polyposis and in sporadic colorectal tumors, and its product binds to the adherens junction protein beta-catenin. Overexpression of APC blocks cell cycle progression. The APC-beta-catenin complex was shown to bind to DLG, the human homolog of the Drosophila discs large tumor suppressor protein. This interaction required the carboxyl-terminal region of APC and the DLG homology repeat region of DLG. APC colocalized with DLG at the lateral cytoplasm in rat colon epithelial cells and at the synapse in cultured hippocampal neurons. These results suggest that the APC-DLG complex may participate in regulation of both cell cycle progression and neuronal function.

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The domestication of emmer wheat (Triticum turgidum spp. dicoccoides, genomes BBAA) was one of the key events during the emergence of agriculture in southwestern Asia, and was a prerequisite for the evolution of durum and common wheat. Single- and multilocus genotypes based on restriction fragment length polymorphism at 131 loci were analyzed to describe the structure of populations of wild and domesticated emmer and to generate a picture of emmer domestication and its subsequent diffusion across Asia, Europe and Africa. Wild emmer consists of two populations, southern and northern, each further subdivided. Domesticated emmer mirrors the geographic subdivision of wild emmer into the northern and southern populations and also shows an additional structure in both regions. Gene flow between wild and domesticated emmer occurred across the entire area of wild emmer distribution. Emmer was likely domesticated in the Diyarbakir region in southeastern Turkey, which was followed by subsequent hybridization and introgression from wild to domesticated emmer in southern Levant. A less likely scenario is that emmer was domesticated independently in the Diyarbakir region and southern Levant, and the Levantine genepool was absorbed into the genepool of domesticated emmer diffusing from southeastern Turkey. Durum wheat is closely related to domesticated emmer in the eastern Mediterranean and likely originated there.

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Aegilops tauschii Coss. is the D-genome progenitor of hexaploid wheat. Aegilops tauschii, a wild diploid species, has a wide natural species range in central Eurasia, spreading from Turkey to western China. Amplified fragment length polymorphism (AFLP) analysis using a total of 122 accessions of Ae. tauschii was conducted to clarify the population structure of this widespread wild wheat species. Phylogenetic and principal component analyses revealed two major lineages in Ae. tauschii. Bayesian population structure analyses based on the AFLP data showed that lineages one (L1) and two (L2) were respectively significantly divided into six and three sublineages. Only four out of the six L1 sublineages were diverged from those of western habitats in the Transcaucasia and northern Iran region to eastern habitats such as Pakistan and Afghanistan. Other sublineages including L2 were distributed to a limited extent in the western region. Subspecies strangulata seemed to be differentiated in one sublineage of L2. Among three major haplogroups (HG7, HG9 and HG16) previously identified in the Ae. tauschii population based on chloroplast variation, HG7 accessions were widely distributed to both L1 and L2, HG9 accessions were restricted to L2, and HG16 accessions belonged to L1, suggesting that HG9 and HG16 were formed from HG7 after divergence of the first two lineages of the nuclear genome. These results on the population structure of Ae. tauschii and the genealogical relationship among Ae. tauschii accessions should provide important agricultural and evolutionary knowledge on genetic resources and conservation of natural genetic diversity.

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Microstructural changes such as insertions and deletions (=indels) are a major driving force in the evolution of non-coding DNA sequences. To better understand the mechanisms by which indel mutations arise, as well as the molecular evolution of non-coding regions, the number and pattern of indels and nucleotide substitutions were compared in the whole chloroplast genomes. Comparisons were made for a total of over 38 kb non-coding DNA sequences from 126 intergenic regions in two data sets representing species with different divergence times: sugarcane and maize and Oryza sativa var. indica and japonica. The main findings of this study are: (i) Approximately half of all indels are single nucleotide indels. This observation agrees with previous studies in various organisms. (ii) The distribution and number of indels was different between two data sets, and different patterns were observed for tandem repeat and non-repeat indels. (iii) Distribution pattern of tandem repeat indels showed statistically significant bias towards A/T-rich. (iv) The rate of indel mutation was estimated to be approximately 0.8 +/- 0.04 x 10(-9) per site per year, which was similar to previous estimates in other organisms. (v) The frequencies of nucleotide substitutions and indels were significantly lower in inverted repeat (IR).

Timing of flowering is a reproductive trait that has significant impact on fitness in plants. In contrast to recent advances in understanding the molecular basis of floral transition, few empirical studies have addressed questions concerning population processes of flowering time diversification within species. We analyzed chloroplast DNA genealogical structure of flowering time variation in central Eurasian wild wheat Aegilops tauschii Coss. using 200 accessions that represent the entire species range. Flowering time measured as days from germination to flowering varied from 144.0 to 190.0 days (average 161.3 days) among accessions in a common garden/greenhouse experiment. Subsequent genealogical and statistical analyses showed that (1) there exist significant longitudinal and latitudinal clines in flowering time at the species level, (2) the early-flowering phenotype evolved in two intraspecific lineages, (3) in Asia, winter temperature was an environmental factor that affected the longitudinal clinal pattern of flowering time variation, and (4) in Transcaucasus-Middle East, some latitudinal factors affected the geographic pattern of flowering time variation. On the basis of palaeoclimatic, biogeographic, and genetic evidence, the northern part of current species' range [which was within the temperate desert vegetation (TDV) zone at the Last Glacial Maximum] is hypothesized to have harbored species refugia. Postglacial southward dispersal from the TDV zone seems to have been driven by lineages that evolved short-flowering-time phenotypes through different genetic mechanisms in Transcaucasus-Middle East and Asia.