The old semidwarf, not very attractive, Japanese wheat variety Akakomugi was the source of the dwarfing gene Rht8 and photoperiodic insensitive gene PpD1 to many semidwarf wheat varieties in South and Central Europe in the 20th century. Integrating the Rht8 and PpD1 genes in wheat varieties offered the best opportunities for reducing plant height, accelerating time of flowering, improving grain fill before the onset of dry summer conditions, enhancing spikelet fertility, and consequently increasing yields. Many breeders from South and Central Europe and from the former Soviet Union were creating winter short high yielding wheat varieties without knowing at the time that Akakomugi was the donor of such important genes. At the end of the 20th century, it was discovered that dwarfing gene Rht8 and photoperiodic insensitive gene PpD1 are located on the short arm of chromosome 2D in wheat. Microsatellite analyses proved that Akakomugi is the source for the Rht8 and PpD1 genes in many short wheat varieties in South and Central Europe.
In an attempt to increase the efficiency of soybean transformation by particle bombardment, we examined the effects of bombardment parameters such as gold particle size, target distance, acceleration pressure, amount of DNA per bombardment, and number of bombardments. Transgene delivery to embryogenic tissue grown in suspension culture was evaluated by monitoring the transient expression of a gene for a modified form of jellyfish green fluorescent protein [sGFP(S65T)]. Optimal transient expression of sGFP(S65T) was obtained when the tissue was bombarded twice at an acceleration pressure of 7.6 MPa (1,100 psi) and a distance of 6 cm with gold particles that were 0.6 μm in diameter and coated with 0.8 μg of DNA. Application of these optimized conditions proved effective for the generation of stable transgenic soybean plants. Stable transgene integration in the transformants was confirmed by Southern blot analysis. The average transformation efficiency achieved with the optimized protocol was siginificantly higher than that with the conventional protocol.
The chromosomes of six Lycoris species and three interspecific hybrids were investigated using genomic in situ hybridization (GISH) to clarify the chromosome constitution in this genus. Total DNA from L. aurea (2n = 13, 9M + 4T) and L. sprengeri (2n = 22, 22A) was used as probe and blocking DNA, respectively. All the chromosomes of L. aurea (9M + 4T) and L. longituba (6M + 10T) were hybridized with probe DNA and were visualized as yellow labeled chromosomes, while those of L. sprengeri (22A), L. radiata var. pumila (22A) and L. sanguinea (22A) remained unlabeled and appeared as red chromosomes. Eight labeled (3M + 5T) and 22 unlabeled chromosomes (20A + 1M ′ + 1m) were observed in GISH of L. incarnata. Eight labeled (3M + 5T) and 33 unlabeled chromosomes (31A + 1M ′ + 1m) were detected in GISH of three interspecific hybrids between L. incarnata and 3 diploid species. The distinction between M + T and A type chromosomes at the DNA sequence level by GISH demonstrated that genome differentiation had occurred in the genus Lycoris.
The genetic diversity of wild chestnut populations naturally distributed in northern Japan was examined in the present study. Leaf samples from total of 245 individual chestnut trees were collected from 7 regions and genetic diversity was analyzed using 5 SSR (Simple Sequence Repeat) markers. Seventy-nine putative alleles were detected in all the populations with an average value of 15.8. The values of observed heterozygosity (HO) per locus in all the populations ranged from 0.638 to 0.835. Average value of the observed heterozygosity in each population was 0.677–0.793, showing extensive genetic diversity in wild chestnut populations. Six populations were divided into 3 clades (Otaru, Tsugaru-Aomori-Minamikayabe-Shimokita and Tsukuba) based on the phenogram obtained. A very small genetic differentiation was found in the clade of Tsugaru-Aomori-Minamikayabe-Shimokita, whereas there were rather large genetic differences from the other clades. When wild chestnut samples were compared with cultivated ones, no remarkable differences were observed in the heterozygosity value and the size range of alleles, suggesting that cultivated chestnuts were most likely selected from wild populations.
An incompletely dominant gene Ur1 (Undulate rachis -1) increases spikelet number per panicle, and can enhance grain yield by enlarging sink size. The yield-increasing effect of Ur1 was examined on five different genetic backgrounds. The Ur1 isogenic line of ‘Nishihikari’ (NU) has been developed by successive backcrossing. ‘Nishihikari’ (N) has the highest lodging-resistance in southern Japan. This isogenic line, N and their F1 possessing the Ur1/+ genotype (NH) were grown in 2000. The yield of the three genotypes was in the order NU > NH > N, though the difference between NU and NH was not significant. Ur1 increased spikelet number per panicle by 29 and 24%, respectively, in NU and NH, whereas Ur1 decreased panicle number per m2, ripened-grain percentage and 1000 grain weight by the ranges of 4 to 8% and 4 to 6%, respectively, in NU and NH. From the F1 of N × the isogenic line of ‘Taichung 65’ carrying both Ur1 and sd1-d, four isogenic-line pairs (e.g. 27U and 27+) were developed after maintaining the heterozygosity (Ur1/+) to F8 or F9 generation. These four number-named isogenic-line pairs, NU and N were planted under a field condition in 2001. Analysis of variance indicated that the effects of Ur1, genetic background and the interaction were significant in yield. The five Ur1-carrying isogenic lines had a varying yield from 752 (NU) to 542 (30U) g/m2. The yield increase by Ur1 ranged from 250 g/m2 (61%) to 75 g/m2 (16%). In spikelet number per panicle, the increase by Ur1 ranged from 62.1 to 39.2, while the percentage increase varied from 90 to 42%. The spikelet-increasing effect of Ur1 was greater on a small-panicled genetic background than on a large-panicled genetic background. Ur1 decreased ripened-grain percentage by 17% in 30U, relative to 30+, whereas no significant decreases were noticed in the other four Ur1-carrying isogenic lines. Ur1 increased culm length in 27U, 52U and 74U, whereas no increase was noticed in NU and 30U. It is concluded that NU could be a prospective material for developing high-yielding japonica varieties carrying Ur1, from the viewpoint of lodging tolerance as well as yield.
A genetic linkage map of the sweet pepper (Capsicum annuum L.) using an intraspecific doubled-haploid (DH) population was primarily constructed by amplified fragment-length polymorphism (AFLP) using the high efficiency genome scanning (HEGS) system and random amplified polymorphic DNA (RAPD). Linkage analysis was done using a total of 518 molecular markers that consisted of 382 AFLP, 122 RAPD, 3 RFLP, 7 SCAR and 4 CAPS markers. The linkage groups consisted of 11 large linkage groups (56.7 to 118.5 cM) and 5 small linkage groups (1.8 to 33.1 cM), covering a total distance of 1043.1 cM with an average distance between 224 framework markers of 4.6 cM. AFLP markers could be developed quickly using HEGS, even in an intraspecific DH population in which it is generally difficult to detect polymorphisms in comparison with interspecific crossing populations. The map was constructed essentially in two months. Linkage analysis also provided three AFLP markers and an RAPD marker linked to PMMoV resistance (L3), and an AFLP marker linked to C that was required for expression of pungency. A closer marker linked to C, Plastid-lipid-Associated Protein-simple sequence repeat (PAP-SSR), a microsatellite marker linked to C, was found at a distance of 0.6 cM. We examined the usefulness of PAP-SSR with three species in Capsicum using fragment analysis and nucleotide sequences, many alleles were found at this locus. The results suggested that these markers could be effective in marker-assisted selection (MAS) programs for sweet pepper breeding purposes.
Phragmites australis, common reed, could be useful in removing eutrophic substances from river and lake water. In this study, the genetic differences in nitrate uptake ability of the reed were investigated with a view to breeding a reed plant useful for phytoremediation. Two reed clones (W-6 and W-8) isolated from a reed community in the lakeside wetland along Lake Biwa, Japan, were used for a study on the physiological and molecular basis of nitrate uptake. Kms for nitrate uptake were 80.8 and 45.2 μM and Vmaxs for nitrate uptake were 10.62 and 2.37 μmol g−1 root f.w. h−1 in W-6 and W-8, respectively, suggesting that there were critical differences in kinetic parameters for nitrate uptake. To investigate these differences at the molecular level, we isolated a high-affinity nitrate transporter gene (NRT2) from the two reed clones and analyzed the reed NRT2 structure and expression. The deduced amino acid sequence of the reed NRT2 consisted of 523 residues and had a high similarity to NRT2 from other monocots. Reed NRT2 was strongly expressed in roots treated with 200 μM nitrate. There were three amino acid substitutions of the reed NRT2 between W-6 and W-8. Differences in NRT2 transcription were also observed between the two clones. It was not clear whether the difference in kinetic parameters for nitrate was due to the reed NRT2 structure or expression. These results indicate the possibility of selecting genotypes more useful for the removal of nitrate.
Important methods applied for the breeding of bread-quality wheat (Triticum æstivum L.) consist of small-scale bread-quality tests for the determination of the grain protein content, SDS-sedimentation volume and single-kernel characterization system (SKCS) grain hardness. The effect of the screening direction (upward vs. downward) and puroindoline alleles on the heritability of small-scale breadquality was investigated for the “Hokushin/KS 831957//Kitami 72/Satsukei 226” (Pinb-D1a/D1b//D1a/D1b), and “Tohoku 195/Satsukei 226//Kitami 72/KS 831957” (Pinb-D1b/D1b//D1a/D1b) lines and F3 and F4 populations derived from them. The SKCS hardness and SDS-sedimentation volume showed a relatively higher heritability (0.71–0.89), whereas the grain protein content showed a lower heritability (0.27–0.38). The SDS-sedimentation volume showed a higher heritability in downward screening (0.88–0.91) than in upward screening (0.66–0.67), while SKCS hardness showed a similar heritability in both directions. Although the SKCS hardness, and the grain protein content showed a higher heritability when Pinb-D1a/D1b//D1a/D1b was crossed, the heritability of the SDS-sedimentation volume was not affected. Overall, screening for the SDS-sedimentation volume was found to be useful for eliminating low-grade bread-quality lines, regardless of the puroindoline alleles. Efficient bread-quality wheat breeding could thus be achieved by concurrent screening for SDS-sedimentation volume and SKCS hardness, due to the higher heritability and relatively lower correlation coefficient of these parameters.
Tetraploid potato cv. Desiree was transformed using an Arabidopsis thaliana stress-inducible promoter rd29A and the DREB1A gene, which confers multiple tolerances to abiotic stresses (e.g., dehydration and elevated soil salinity). Transformed Desiree lines showed a direct correlation between the DREB1A expression levels and the tolerance to salinity. By producing a filial progeny from the transgenic lines which was considered to harbor a single copy of the DREB1A gene, crossed with a non-transgenic cultivar, the genotype at the transgenic locus of these tetrasomic tetraploids was estimated by chi-square test, suggesting the existence of a Simplex mode. The results showed that low-copy heterozygous loci with the DREB1A gene could sustain the expression, and consequently confer a significant tolerance to salinity in tetrasomic tetraploid potatoes.
The genetic basis of salinity tolerance of maize was examined using the triple test cross (TTC) method. The TTC progenies were evaluated for seedling root growth in saline solutions with NaCl concentrations of 0 (control) and 80 mM. Analysis of root length data of the progenies suggested that epistatic effects were important for salinity tolerance at the seedling stage. Additive × additive effects were more important for both absolute and relative root length under NaCl stress. Additive × treatment interaction was not significant, whereas epistasis × treatment interactions were significant. Non-additive effects predominantly controlled tolerance at the seedling stage, and dominance appeared to be ambidirectional for salinity tolerance.
Genetic analysis of vernalization and photoperiod responses was carried out using eight wheat cultivars, in order to investigate the relationship between their genotype and the earliness of heading in the southwestern part of Japan. Allelism test of the genes for the vernalization response showed that three wheat cultivars, ‘Fukuwasekomugi’, ‘Zenkoujikomugi’ and ‘Schomburgk’, harboured Vrn-D1, Vrn-D1 and Vrn-A1, respectively. Among the eight cultivars tested, ‘Haruhikari’ was sensitive to short photoperiod, while the others were insensitive. Segregation analysis of the photoperiod response in the F2 and B1F1 populations showed that the very late heading cultivar ‘Haruhikari’ did not harbour major genes for insensitivity to photoperiod. Six cultivars characterized by medium to late heading, ‘Norin 61’, ‘Zenkoujikomugi’, ‘Saitama 27’, ‘Schomburgk’, ‘Norin 59’ and ‘Norin 67’, carried a single gene for insensitivity, Ppd-S, in common. The extremely early heading cultivar ‘Fukuwasekomugi’ was found to carry two genes for insensitivity, Ppd-S and Ppd-F, the latter displaying a stronger effect for insensitivity to photoperiod. The present study revealed that the earliness of heading in the southwestern part of Japan was closely related to the Ppd genotype of wheat cultivars, whereas it was independent of the Vrn genotype.
The main objective of this study is to produce DNA markers of polymorphism between wheat and some important alien species. The applicability of 1,165 barley EST primer sets to amplify markers showing polymorphism between wheat and ten alien species, covering a wide range of variation in Triticeae, was investigated. These primers consisted of four series. Series 1 was randomly chosen from a pool of barley EST primer sets. The remaining three were pre-screened in a previous study and showed polymorphic and co-amplified patterns between barley and wheat. From 22% to 100% of the primer sets amplified single clear bands in the species; from 29% to 75% of which were polymorphic to wheat. The frequency of amplification corresponded with their phylogenetic distance from barley. Many DNA markers (78–859) showing polymorphism between each species and wheat were obtained. These markers are expected to be valuable in identifying the alien chromosomes added to a wheat genetic background. The usefulness of the markers in the basic and the applied studies of the wild species is discussed.
Quantitative trait loci (QTLs) controlling adventitious root formation (ARF) on the soil surface were evaluated under flooding conditions in 110 individuals of an F2 population derived from a cross between a dent inbred line ‘B64’ and a tropical Caribbean flint inbred line ‘Na4’. The ARF capacity of seedlings suggested the existence of continuous variation in the F2 population. The QTLs for ARF were located on chromosomes 3 (bin 3.07-8), 7 (bin 7.04-5) and 8 (bin 8.05). Alleles of line Na4, with a high capacity for ARF, increased ARF in the case of all the QTLs. By comparing chromosome positions of ARF loci in the B64 × Na4 population with those in a B64 × teosinte (Zea mays ssp. huehuetenangensis) population, the region conditioning ARF on chromosome 8 was consistent across the two populations. In the present study, overlap between the QTLs for ARF in the B64 × Na4 cross and QTLs for root traits measured in aerated hydroponic culture was also observed as reported in other mapping populations.
We analyzed the diversity of the low-molecular-weight glutenin subunit (LMW-GS) genes of Asian common wheat cultivars. Locus-specific primers for LMW-GSs revealed the presence of four alleles at the Glu-A3 locus, four at the Glu-B3 locus and one at the Glu-D3 locus. Frequency of Glu-A3 alleles in the Japanese cultivars was very different from that in other Asian cultivars. The combined alleles at the three Glu-3 loci were classified into 15 genotypes. The frequency of each genotype from the Asian collection or breeding areas varied. One Glu-3 genotype, BAA (consisting of the Glu-A3 allele B, Glu-B3 allele A and Glu-D3 allele A), occurred frequently in many Asian cultivars. Glu-3 genotypes BBA, CAA and DBA predominated in southern and northern Asia and in Japan, respectively. In addition, the Japanese cultivars with the BBA or CAA genotypes showed a specific composition of high-molecular-weight glutenin subunits and gliadins. DNA sequencing indicated that the Glu-A3 allele B carried an additional cysteine residue and that the allele C showed unusual amino-acid deletions. These mutations were likely to affect dough strength, which is a major characteristic of wheat flour quality.