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We constructed a genetic linkage map of red clover ( Trifolium pratense L., 2n=2 x=14) using RFLP markers from cDNA probes of a backcrossed mapping population, and investigated the transferability of the markers to other red clover germplasm. The map contains 157 RFLP markers and one morphological marker on seven linkage groups. The total map distance was 535.7 cM and the average distance between two markers was 3.4 cM. All of the cDNA probes of the map were hybridized to the fragments of genomic DNA from 12 plants derived from three varieties, and 87% of the cDNA probes detected polymorphic bands that corresponded to those of mapping parents. This result indicated that RFLP markers on the present map were transferable to the genome analysis of other red clover germplasm. This is the first report to construct a linkage map of Trifolium species; it should provide fundamental and useful genetic information relevant to the breeding of red clover and genus Trifolium.

Red clover (Trifolium pratense L.) is a diploid (2n = 14), self-incompatible legume that is widely cultivated as a forage legume in cold geographical regions. Because it is a short-lived perennial species, improvement of plant persistency is the most important objective for red clover breeding. To develop a marker-assisted selection (MAS) approach for red clover, we identified candidate QTLs related to plant persistency. Two full-sib mapping populations, 272 × WF1680 and HR × R130, were used for QTL identification. Resistance to Sclerotinia trifoliorum and Fusarium species, as well as to winter hardiness, was investigated in the laboratory and in field experiments in Moscow region (Russia), and Sapporo (Japan). With the genotype data derived from microsatellite and other DNA markers, candidate QTLs were identified by simple interval mapping (SIM), Kruskal–Wallis analysis (KW analysis) and genotype matrix mapping (GMM). A total of 10 and 23 candidate QTL regions for plant persistency were identified in the 272 × WF1680 and the HR × R130 mapping populations, respectively. The QTLs identified by multiple mapping approaches were mapped on linkage group (LG) 3 and LG6. The significant QTL interactions identified by GMM explained the higher phenotypic variation than single effect QTLs. Identification of haplotypes having positive effect QTLs in each parent were first demonstrated in this study for pseudo-testcross mapping populations in plant species using experimental data.Electronic supplementary materialThe online version of this article (doi:10.1007/s00122-009-1253-5) contains supplementary material, which is available to authorized users.

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SummaryIn a search for cold-regulated genes that are differentially expressed in alfalfa genotypes of contrasting freezing tolerance, we screened 1036 arrayed cDNA clones. The screening resulted in isolation of cDNA clones, which demonstrated dramatic differences in expression between hardy and un-hardy alfalfa varieties. Detailed analysis revealed that these cDNAs represent parts of novel non-coding repetitive elements carrying long-terminal repeats (LTR) and other retroelement-like features. Despite strong expression under low temperatures, DNA templates remained highly methylated, and a drug-induced decrease in methylation did not activate transcription under normal temperatures. We identi®ed that these repetitive elements represent a large family and could insert into, or be adjacent to, the unrelated polyprotein sequences of putative retrotransposons. These retrotransposons also showed low temperature-induced transcriptional activation; however, this activation was not genotype-dependent. The retroelements described in this study are the ®rst retroelement characterized in the Medicago genus. Furthermore, they represent the only known example of genotype-speci®c cold-induced transcriptional activation of multiple copies of a repetitive element whose expression is associated with a genotype difference in cold acclimation.

Breeding potential of the backcross progenies of a hybrid between Trifolium medium × × T. pratense to T. pratense. Can. J. Plant Sci. 82: [395][396][397][398][399]. In this study, T. medium (zigzag clover, 2n = 80 and T. pratense (red clover, 2n = 28) were hybridized and backcrossed four times to T. pratense (BC 1 , BC 2 , BC 3 and BC 4 ), and the seed production and vigor of the backcross progenies were assessed under field conditions. Both female and pollen fertility of the backcross progenies increased as the backcross generations advanced. Female and pollen fertility of BC 4 were 21.3 and 65.3%, respectively. When honeybees were used as pollinators, almost all BC 4 plants produced mature seeds in the field. Most of the BC 1 , BC 2 , and BC 3 plants died by the end of the fourth year in the field, whereas 61% of the BC 4 plants survived for 4 yr. The number of chromosomes in 79% of the BC 4 plants was more than 28, which is greater than that of T. pratense. Mots clés: Rétrocroisement, matériel génétique, hybridation interspécifique, Trifolium medium, Trifolium pratenseTrifolium pratense L. (red clover) is an important forage legume in the northern part of Japan because it is easy to cultivate due to high adaptability to acidic and humid conditions. However, its usefulness is limited due to its lack of perenniality, which is a common deficiency of T. Pratense throughout the world. Introgression of genes for longevity from perennial Trifolium species to T. pratense is a potential means for improving the persistence of T. pratense. Various hybridizations with T. pratense have been carried out with several species: T. pallidum [Palestine clover (Armstrong and Cleveland 1970)], T. diffusum (Taylor et al. 1963;Schwer and Cleveland 1972), T. hirtum [Rose clover (Schwer and Cleveland 1972)], T. sarosiense Collins et al. 1983), T. alpestre [Purple glove clover (Merker 1988;Phillips et al. 1992)], and T medium [Zigzag clover (Merker 1982);Nedbalkova et al. 1995;Sawai et al. 1990Sawai et al. , 1995. Although many hybrids have been successfully produced, there have been no reports of hybrid plants being used as germplasm in conventional breeding programs. The reason for this lack of use is that the plants have not shown sufficient levels of fertility and vigor to justify employing them as practical breeding materials. Anderson et al. (1991) produced third backcross progenies of hybrids between T. ambiguum (Kura clover) × T. repens (White clover) to T. repens, and succeeded in increasing their fertility to a sufficient level for direct use in forage production. Their study showed that backcrossing is an effective means for increasing fertility and vigor.To introduce the rhizomatous growth habit and perenniality from T. medium to T. pratense, Sawai et al. (1995) obtained first and second backcross progenies of the hybrid between T. medium × T. pratense to T. pratense. The fertility of the backcross progenies increased as their generations advanced. However, neither the fertility nor the vigor were adequate for use in a ...

Lignin is a major component of the secondary cell walls of vascular plants, and an obstacle in the conversion of plant cell wall polysaccharides into biofuels. Erianthus spp. are large gramineous plants of interest as potential energy sources. However, lignocelluloses of Erianthus spp. have not been chemically characterized. In this study, we analysed lignins, related compounds, enzymatic saccharification efficiencies, and minerals in the ash of the inner and outer parts of the internode, leaf blade and leaf sheath of Erianthus arundinaceus. Lignins in four organs consisted of guaiacyl, syringyl, and p-hydroxyphenyl units. The ratios of syringyl to guaiacyl lignins and lignin contents ranged from 0.43 to 0.79 and 20 to 28%, respectively, with values highest in the outer part of the internode. The amounts of ferulic acid were similar (7.3-11.8 mg g −1 dry weight of cell-wall material) in all four organs, while there was more p-coumaric acid in the inner part of the internode (44.7 mg g −1 dry weight of cell-wall material) than in other organs (25.7-28.8 mg g −1 dry weight of cell-wall material). The enzymatic saccharification efficiency (24 h reaction time) of the leaf blade was 21.6%, while those of the other organs ranged from 10.0 to 15.2%. The leaf blade had the highest ash content (17.1%); the main inorganic element was silicon. This paper provides the first fundamental knowledge of E. arundinaceus lignins.

We evaluated genetic variations in the non-structural carbohydrate (NSC) and the cell-wall components of stem in rice, sorghum, and sugar cane to assess the potential suitability of these gramineous crops for bioethanol production. For NSC, the maximum soluble sugar concentration was highest in sugar cane, followed by sorghum with sucrose. The major NSC in rice was starch, but there were wide variations in the starch to soluble sugar ratios among the cultivars. The total concentration of cell-wall components was negatively correlated with the NSC concentration, indicating competition for carbon sources. Among the cell-wall components, lignin was relatively stable within each group. The major sugar species composing hemicellulose was xylose in all crop groups, but there were differences in composition, with a higher fraction of arabinose and glucose in rice as compared to the other crops. In rice, there was less lignin than in sorghum or sugar cane; this might be advantageous for the efficient saccharification of cellulose.