In Arabidopsis, FLOWERING LOCUS T (FT) and TERMINAL FLOWER 1 (TFL1) are known to control growth habit of determinate or indeterminate type. In cucumber (Cucumis sativus L.), any FT or TFL1 homolog is expected to be the candidate for the gene controlling the growth habit. Most cucumber cultivars show indeterminate type of growth habits. For more effective breeding, it is necessary to develop determinate type cultivars. In this study, we isolated one FT and five TFL1 homologs in cucumber. On these homologs, the genomic organizations, phylogenetic relationships, expression patterns, and linkage to growth habit are elucidated herein. Through genetic analysis of F₂ individuals, two homologs did not co-segregate with the determinate-indeterminate phenotypes. On the other hand, different expression patterns of several homologs were detected between determinate and indeterminate cultivars.

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Root hairs, projections from the epidermal cells of the roots, are contributing to water and nutrient uptake and anchorage to the soil. To better understand genetic control of root hair formation in rice, we analyzed root hairless 1 (rth1) mutant that was induced by NaN₃ treatment. SEM observation showed that in rth1 plants, root hair elongation was abolished after the formation of bulge. High-resolution mapping using 2,088 segregants revealed three predicted genes in a 38-kb candidate interval on chromosome 7. Sequences comparison of the three genes between wild-type Oochikara and rth1 detected a nucleotide substitution only in apyrase (OsAPY). This nucleotide substitution (G → A) lies in the junction between the third intron and the forth exon, and results in the splicing anomaly to the rth1 cDNA sequence. Transgenic plants with introduced OsAPY allele restored normal root hairs and plant growth, showing a complementation of rth1 phenotype. We concluded that the root hairless phenotype of rth1 is caused by a mutation of OsAPY. OsAPY appears to be an important gene for root hair elongation and plant growth in rice.

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Segregation analysis showed that eibi1, a drought hypersensitive cuticle wild barley mutant, was monogenic and recessive, and mapped in two F₂ populations, one made from a cross between the mutant and a cultivated barley (cv. Morex), and the other between the mutant and another wild barley. A microsatellite marker screen showed that the gene was located on barley chromosome 3H, and a set of markers already assigned to this chromosome, including both microsatellites and ESTs, was used to construct a genetic map. eibi1 co-segregated with barley EST AV918546, and was located to bin 6. The synteny between barley and rice in this region is incomplete, with a large discrepancy in map distances, and the presence of multiple inversions.

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NERICA (New Rice for Africa) cultivars were crossed with Oryza sativa L. and O. glaberrima Steud. All the F₁ hybrids between NERICA and two strains of O. glaberrima were highly sterile, while the F₁ hybrids of NERICA with two cultivars of O. sativa showed differing levels of fertility depending on the cross combinations. NERICA cultivars were classified into three groups: (1) those compatible with both ssp. indica and ssp. japonica of O. sativa (i.e. NERICA12, NERICA15, NERICA16, NERICA17 and NERICA18); (2) those compatible with japonica but incompatible with indica (NERICA3, NERICA4, NERICA7, NERICA8, NERICA9, NERICA11, NERICA13 and NERICA14); and (3) incompatible with both types (NERICA1). In the first group of NERICA cultivars, four cultivars from NERICA15 to NERICA18 are derived from the same cross of CG 14/3*WAB 181-18, and they have the cytoplasm of CG 14, from an O. glaberrima strain. No ‘bridging cultivar’ between both cultigens was found in NERICA cultivars, but some NERICA cultivars were compatible with both japonica and indica. This finding is very useful for improvement of NERICA cultivars through hybridization.

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Little is known about the physiological responses of higher plant cells during the early stages of embryogenesis and the genes that are involved in these responses. Carrot is an appropriate plant for the study of somatic embryogenesis as a model of zygotic embryogenesis. The system of stress induction of carrot somatic embryogenesis is useful for isolating genes expressed during embryogenesis, as embryogenic competence and the expression of certain embryo-specific genes increases with increased stress. Fluorescent differential display (FDD) was performed to isolate stress-induced genes in carrot somatic embryos, and five genes were isolated as embryonic tissue-specific genes. One of these genes was expressed until the early torpedo-shaped stage of zygotic embryogenesis. This result suggested that in the stress-induction system of carrot somatic embryos, embryo-specific genes expressed in the early stages of embryogenesis were induced during somatic embryo induction by stress treatment, concomitant with acquisition of embryonic competence. Unique genes expressed during early embryogenesis can be isolated from carrot by combining the appropriate experimental system and FDD. This strategy could be applied to many plant species for which genome information is not yet available.

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(1-3, 1-4)-β-D-glucan contained in barley (Hordeum vulgare L.) grains is a main component of endosperm cell walls and constitutes the cell wall matrix with arabinoxylan. A monofactorial recessive mutant gene for (1-3, 1-4)-β-D-glucanless grain was found and the new gene was designated as bgl (= (1-3, 1-4)-beta-D-glucanless grain). A linkage was found between the bgl gene and the naked caryopsis (nud) gene, and it was mapped to the centromeric region of chromosome 7H. Phenotypes in bgl cosegregated with the polymorphisms in HvCslF6, a member of cellulose synthase-like HvCslF gene family, indicating that bgl was caused by a mutation in the HvCslF6 locus. In order to clarify the characteristics of (1-3, 1-4)-β-D-glucanless barley grains, a near-isogenic line (NIL) was developed by backcrossing the Japanese two-rowed cultivar ‘Nishinohoshi’ as a recurrent parent. The NIL with bgl completely lacked (1-3, 1-4)-β-D-glucan in both the endosperm and aleurone layer cell walls. Microscopic analysis revealed that the NIL had thin endosperm cell walls. It also showed a softer grain texture and many more broken grains during the pearling process than the recurrent parent. The soft and friable grain texture of the NIL was probably caused by the thin endosperm cell walls.

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We analyzed 25 chloroplast simple sequence repeat (cpSSR) loci in 82 accessions, 59 of cultivated radish and 23 of three wild Raphanus species and identified 7 polymorphic loci and 20 haplotypes. The distribution of haplotypes in different species and different geographical areas was assessed. Minimum-spanning network (MSN) was used to identify phylogenetic relationships in cultivated and wild radish. The MSN provides evidence for at least three independent domestication events, including black Spanish radish and two distinct groups of cpSSR haplotypes. One of these two haplotype groups is restricted geographically to Asia. This led Asian cultivated radish haplotypes to higher cpSSR diversity than Mediterranean cultivated radish or wild radish. These data are consistent with the diversity and distribution of agronomic traits in cultivated radish. At the same time, this implies that Asian cultivated radish is not originated from the diffused descendants of European cultivated radish, probably originated from a wild species that is distinct from the wild ancestor of European cultivated radish. Unfortunately we do not know the wild ancestor of Asian cultivated radish.

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Variation in pathogenicity and microsatellite marker haplotype was investigated in 107 isolates of barley scald pathogen, Rhynchosporium secalis, collected from the Hokuriku and Tohoku districts in Japan during 2004 and 2005. By inoculation using 18 differential cultivars, 58 pathotypes were identified with complex variation in pathogenicity with no predominant pathotype. Among the 18 differential cultivars, Osiris exhibited highly stable resistance to all the isolates. As some differential cultivars with the same resistance gene(s) showed the different reaction pattern to the pathotypes, these differential cultivars may have unknown resistance gene(s) specific to Japanese isolates. DNA polymorphism was detected by 13 microsatellite markers to obtain 63 haplotypes that were classified into 6 clusters (I–VI). Two clusters (I and III) covered a broad region, and the remaining 4 covered a relatively limited region. Cluster VI was distributed only in Yamagata, and the isolates in this cluster showed higher pathogenicity than those in the other 5 clusters. Therefore, for resistance against the pathotypes in cluster VI, some differential cultivars including Osiris were recommended as genetic resources for scald resistance in barley breeding. Finally, the possibility of monitoring using microsatellite markers was discussed.

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This paper reports the development of new microsatellite markers for lentil (Lens culinaris subsp. culinaris) and their use for genetic diversity analysis of a lentil core collection developed at ICARDA (Aleppo-Syria). Fourteen new markers were developed from microsatellite flanking sequences of a genomic library from a cultivated lentil accession ILL5588. The core collection used comprises 109 accessions from 15 countries representing 57 cultigens (including 18 breeding lines) from 8 countries and 52 wild types of germplasm (L. culinaris subsp. orientalis, L. culinaris subsp. tomentosus and L. culinaris subsp. odemensis) from 11 countries. Total number of alleles detected across all microsatellite loci was 182, with a mean of 13 alleles per locus. The wild accessions were rich in alleles (151 alleles) compared to cultigens (114 alleles). The genetic diversity index for the microsatellite loci in the wild accessions ranged from 0.16 (for locus SSR28 in L. culinaris subsp. odemensis) to 0.93 (for locus SSR66 in L. culinaris subsp. orientalis) with a mean of 0.66, while in the cultigens genetic diversity varied between 0.03 (locus SSR28) and 0.87 (locus SSR207) with a mean of 0.65. The cluster analysis indicated two major clusters, mainly one with the cultigens and the other with the wild accessions.

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Asian cultivated rice (Oryza sativa L.) has genetic diversification of root characteristics, but this variation has not been elucidated fully with reference to the genetic background. To clarify the differences in root anatomical and morphological traits among different varietal groups of cultivated rice, we analyzed four anatomical traits (root thickness, stele transversal area, total transversal area and number of late metaxylem vessels) and two morphological traits (root length index and ratio of deep rooting) in 59 accessions. A previous principal-coordinate analysis study using data on 179 restriction fragment length polymorphisms classified these accessions into three varietal groups: 13 japonica, 21 indica-I, and 25 indica-II. Based on a principal-components analysis of the six traits, the japonica group had wide variation in root anatomy compared to the two indica groups. In particular, japonica upland rice was characterized by a larger stele and xylem structures. By contrast, the two indica groups had wide variation in root morphology compared to the japonica group. Of the two indica groups, on average, the indica-I accessions had deeper, thicker roots than the indica-II accessions. Our results demonstrate that the japonica and indica groups contain different genetic diversity with respect to their root characteristics.

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Ipomoea trifida (Convolvulaceae), a diploid relative of sweet potato, displays a sporophytic self-incompatibility (SSI) controlled by a single multi-allelic S locus. To prove an involvement of S gene candidates in the SSI system through analysis of transgenic plants, we developed an efficient method for Agrobacterium-mediated transformation in I. trifida by modifying the protocol used for the transformation of sweet potato. We used A. tumefaciens strain EHA101, which carries a binary vector, pIG121-Hm, containing GUS and HPT genes driven by the CaMV 35S promoter. Embryogenic calluses (ECs) were infected with it and then selected on medium supplemented with 10 mg/L hygromycin. The frequency of callus clusters producing hygromycin-resistant (Hyg^R) ECs reached a maximum of 84.5%, from which several transgenic plants could be regenerated. All the regenerated Hyg^R plants examined were confirmed to carry both transgenes. The ubiquitous expression of GUS and the stable inheritance of transgenes were also demonstrated. This transformation method is applicable to different genotypes in I. trifida and would thus be useful for the identification of S genes as well as functional analyses of genes involved in self-incompatibility in this species.

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Self/non-self discrimination between pollen and pistil in gametophytic self-incompatibility (GSI) system of Solanaceae is controlled by a single S locus with multiple haplotypes. However, genetic analyses have shown that factors outside the S locus are also required for GSI to take place. So far, a limited number of such non-S-specific factors have been cloned and characterized. HT-B is a pistil-expressed non-S-specific factor identified in Nicotiana, Solanum and Petunia. Here, we report that Petunia HT-B is genetically linked to HTL, an HT-like pistil-specific gene that is not involved in GSI. Further characterization of a BAC clone that contains HT-B showed that HTL is located ~5 kb downstream of HT-B. A 16,876 b genomic sequence that contains the two genes was completely determined. It was found that the transcriptional orientations of the two genes are the same, and they are separated by 4,552 b.

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We have developed a genetically engineered herbicide-tolerant Zoysia grass with potential commercial value. However, the possible flow of genes to wild-type or neighboring plant species raises ecological and commercial concerns, although herbicide-tolerant GM Zoysia grass does not appear to pose a significant risk. One efficient way to prevent transgene escape in GM plants is to control fertility. Thus, we attempted to generate GM Zoysia mutants with defects in the development of reproductive organs, but that can be vegetatively propagated. To induce mutation, a range of γ-rays from 10 to 50 Gy, initially determined to be the optimal dose for inducing mutation, was used to irradiate GM Zoysia during the pollination stage. Notably, nine (4%) lines displayed defects in the floral transition from the vegetative to reproductive phase, while all non-irradiated GM Zoysia grasses developed normally. Under greenhouse conditions (natural light and temperature), these GM Zoysia lines have been vegetatively propagated for four years without forming reproductive structures. This technology could also be applied in other GM plants being cultivated through vegetative propagation, such as creeping bent grass.

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