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Cadmium (Cd) is as an extremely toxic metal that can contaminate agricultural soils. To reduce the risk of Cd intake in food cereals, the development of cultivars with low grain Cd concentration (GCC) is an effective countermeasure. We analyzed quantitative trait loci (QTLs) for GCC in a doubled haploid (DH) common wheat (Triticum aestivum L.) population derived from ‘Chugoku 165’ (low GCC) × ‘Chukei 10-22’ (high GCC). We found novel loci for low GCC on the short arm of chromosome 4B and on the long arm of chromosome 6B. These QTLs accounted for 9.4%–25.4% (4B) and 9.0%–17.8% (6B) of the phenotypic variance in the DH population. An association analysis with 43 cultivars identified 3 loci at these QTLs: QCdc.4B-kita, QCdc.6B-kita1, and QCdc.6B-kita2. In contrast to durum wheat and barley, no QTL was detected on the chromosomes of homeologous group 5 for heavy metal P1B-type ATPase 3. These results will contribute to marker-assisted selection for low GCC in breeding of common wheat.

Preharvest sprouting (PHS) of durum wheat (Triticum turgidum ssp. durum (Desf.) Husn.) is an important problem in Japan, where the rainy season overlaps with the harvest season. Since there are few PHS-resistant genetic resources in durum wheat, we introduced an R-gene for red seeds, the MFT gene, and the QPhs-5AL QTL, all of which are associated with PHS resistance, into durum wheat from a PHS-resistant bread wheat (T. aestivum L.) cultivar, ‘Zenkoujikomugi’ (Zen), by backcross breeding. Developed near isogenic lines (NILs) with red seeds had a lower percentage germination (PG) and germination index (GI) than the recurrent parent, and seed color had the greatest effect. A NIL combining all three sequences had the lowest GI and PG, with a similar GI to that of ‘Shiroganekomugi’ bread wheat. Among NILs with white seeds, a NIL combining MFT and QPhs-5AL had the lowest GI and PG. As the combination of all three sequences from Zen conferred PHS resistance on durum wheat, PHS-resistant genetic resources in bread wheat can be used in breeding durum wheat.

To study the influence of genes from Thinopyrum intermedium on traits affecting the bread-making quality of wheat, two derivatives from a putative disomic addition line in cultivar ‘Vilmorin 27’ were used in cytological, biochemical and molecular characterization. Cytological analysis suggested that one of the derivatives (Line-1) had a terminal deletion involving the long arm of chromosome 1D (2n = 42, Del-1DL”), and the other (Line-2) was a conventional addition line, but also carried the same deletion on chromosome 1D (2n = 44, Thi”+Del-1DL”). Amplification and sequencing of high-molecular-weight glutenin subunit (HMW-GS) genes coded by the Th. intermedium chromosome in Line-2 indicated the presence of one x-type with an extra cysteine and four (rather than one) unique y-type genes. Rheological studies of Line-1 showed significantly lower dough strength compared to ‘Vilmorin 27’, confirming the recognized role of Glu-1D coded HMW-GSs. Line-2 showed significantly higher dough strength compared to the background cultivar, indicating a significant potential of Th. intermedium for improvement of bread-making quality in wheat.

Phytoextraction using indica rice plants (Indian Rice Oryza ssp.) is a promising technique for remediating cadmium (Cd)-polluted paddy fields. Because this technique has only been established for paddy fields, we decided to examine phytoextraction in upland fields that have been converted from paddy fields. Although “CHOKOUKOKU” shows a shattering habit and lodging, its Cd uptake was significantly higher than that of other indica rice varieties. On the other hand, “IR8”, which was able to accumulate only moderate levels of Cd in its shoots, has a lodging tolerance, making it an optimal variety for southwest Japan, which experiences several typhoons each year. Therefore, both “CHOKOUKOKU” and “IR8” were useful in estimating practical phytoextraction in upland fields. A practical phytoextraction examination showed that the total Cd uptake of “CHOKOUKOKU” and “IR8” was 822 and 545 g ha−1, respectively, after a 4-year period. After phytoextraction by planting high Cd-accumulating rice plants, the Cd c...

Jasmonates, including jasmonic acid and its derivatives such as methyl jasmonate (MeJA), are plant growth substances that control various responses. Jasmonates regulate leaf trichome density in dicotyledonous plants, but their effects on the trichome density of monocotyledonous plants, such as those in the Poaceae, remain unclear. In the present study we examined the effects of exogenous MeJA on the trichome density of Rhodes grass, which has three kinds of trichomes: macrohairs, salt glands, and prickles. Exogenous MeJA significantly increased the densities of macrohairs and salt glands on the adaxial and abaxial leaf surfaces and those of prickles on the adaxial leaf surface. Because exogenous MeJA significantly reduced the leaf area, we calculated the number of trichomes per 1000 epidermal cells to eliminate the effects of reduced leaf area. Exogenous MeJA significantly increased the number of macrohairs per 1000 epidermal cells on both adaxial and abaxial leaf surfaces, but it significantly decreased the number of salt glands per 1000 epidermal cells on both surfaces. Exogenous MeJA had no significant effects on the number of prickles per 1000 epidermal cells on either of the leaf surfaces. These results indicate that exogenous MeJA alters the trichome density by affecting leaf area and trichome initiation, and the effects of exogenous MeJA on trichome initiation differ among the various trichome types.

A “two-line system” using photoperiod-sensitive cytoplasmic male sterility (PCMS) caused by Aegilops crassa cytoplasm under long-day photoperiods (≧15 h) has been proposed as a means of producing hybrid varieties in common wheat (Triticum aestivum). The PCMS line is maintained by self-pollination under short-day conditions, and hybrid seeds can be produced through outcrossing of the PCMS line with a pollinator line under long-day conditions. Our previous studies revealed that PCMS lines showing complete male sterility under long-day conditions are necessary for practical hybrid wheat breeding, especially to obtain high hybrid purity in F1 seeds. Furthermore, practical PCMS lines should have high seed fertility under short-day conditions, which is associated with female fertility. Wheat cv. Norin 26 with Ae. crassa cytoplasm exhibits high seed fertility under short-day conditions, and cv. Fujimikomugi with Ae. crassa cytoplasm shows high male sterility under long-day conditions. Here we developed practical PCMS lines derived from the F1 generation of Norin 26 and Fujimikomugi (with Ae. crassa cytoplasm) that were then backcrossed to elite wheat lines.

Allelic variation of high molecular weight glutenin subunits (HMW-GS) encoded by Glu-A1, Glu-B1 and Glu-D1 in wheat landraces originating from the Xinjiang Uygur Autonomous District (Xinjiang District) of China was investigated by SDS-PAGE and the relationship between the variation and the winter habit was examined. The most frequent allele at the Glu-A1 locus was Glu-A1c (null allele: 75.5%), followed by Glu-A1b encoding subunit 2* (22.3%). These two alleles were distinctive at Glu-A1 in the landraces of both spring and winter cultivars. No difference in allele frequency was found between the spring and the winter wheat cultivars. At the Glu-B1 locus, the most frequent allele was Glu-B1b (90.8%) encoding subunits 7 + 8, the allele frequency of which was almost the same between the spring and the winter wheat cultivars. Glu-D1a (72.0%) encoding subunits 2 + 12 was a major allele at the Glu-D1 locus among the landraces. Although no cultivar with Glu-d1f encoding subunits 2.2 + 12 was found, the novel subunit pair 2.6 + 12 (24.5%) was observed only in the winter wheat cultivars. Subunit 2.6 was slightly less mobile than subunit 2.2. The major Glu-D1 allele was Glu-D1a (94.5%) among the spring wheat cultivars and this allele characterized the spring wheat cultivars in the Xinjiang District. Both the subunit pair 2.6 + 12 encoded by the Glu-D1bp(t) allele (58.5%) and the subunit pair 2 + 12 encoded by the Glu-D1a allele (40.7%) predominated among the winter wheat cultivars. The large difference in allelic variation at the Glu-D1 locus suggested that the origin of the spring wheat cultivars was different from that of the winter wheat cultivars. The absence of landrace with Glu-D1f suggested that Xinjiang wheat was not related to Japanese wheat.