Improvement of preharvest sprouting resistance with MOTHER OF FT AND TFL 1 + mutated ABA 8'-hydroxylase in white-seeded durum wheat.

Improvement of preharvest sprouting (PHS) resistance is an important objective in the breeding of durum wheat (Triticum turgidum ssp. durum (Desf.) Husn.) in Japan, where the harvest timing overlaps with the rainy season. In a previous study, we showed that an R-gene associated with red seed color was the most effective at promoting PHS resistance in durum wheat. However, red-seeded durum wheat is not popular because it discolors pasta. Here, to improve PHS resistance without the R-gene, we introduced a PHS resistance allele of MOTHER OF FT AND TFL 1 (MFT) and a mutated ABA 8'-hydroxylase (ABA8'OH1-A), which is involved in abscisic acid (ABA) catabolism, singly or together into white-seeded durum wheat. The introduction of both genes reliably and stably improved PHS resistance under all tested conditions. Modification of ABA catabolism might be an effective way to improve PHS resistance in durum wheat. Our findings will contribute to improved PHS resistance in breeding for white-seeded durum wheat.

Exploitation of Tolerance of Wheat Kernel Weight and Shape-Related Traits from Aegilops tauschii under Heat and Combined Heat-Drought Stresses.

Kernel weight and shape-related traits are inherited stably and increase wheat yield. Narrow genetic diversity limits the progress of wheat breeding. Here, we evaluated kernel weight and shape-related traits and applied genome-wide association analysis to a panel of wheat multiple synthetic derivative (MSD) lines. The MSD lines harbored genomic fragments from Aegilops tauschii. These materials were grown under optimum conditions in Japan, as well as under heat and combined heat-drought conditions in Sudan. We aimed to explore useful QTLs for kernel weight and shape-related traits under stress conditions. These can be useful for enhancing yield under stress conditions. MSD lines possessed remarkable genetic variation for all traits under all conditions, and some lines showed better performance than the background parent Norin 61. We identified 82 marker trait associations (MTAs) under the three conditions; most of them originated from the D genome. All of the favorable alleles originated from Ae. tauschii. For the first time, we identified markers on chromosome 5D associated with a candidate gene encoding a RING-type E3 ubiquitin-protein ligase and expected to have a role in regulating wheat seed size. Our study provides important knowledge for the improvement of wheat yield under optimum and stress conditions. The results emphasize the importance of Ae. tauschii as a gene reservoir for wheat breeding.

Novel quantitative trait loci for low grain cadmium concentration in common wheat (Triticum aestivum L.).

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.

Effect of combining additional bakery enzymes and high pressure treatment on bread making qualities.

Various enzymes are added to dough to improve the quality. Two enzymes are α-amylase and hemicellulase (bakery enzymes), whose substrates are damaged starch and insoluble dietary fiber, respectively. They improve the formation of gluten networks in the dough, resulting in a higher specific loaf volume (SLV). The use of high-pressure treatment has also increased as a substitute for heat treatment and various products are being processed utilizing high-pressure treatment. This study investigated the effect of combing bakery enzyme and high-pressure treatment on dough qualities. The optimal concentration of bakery enzymes and high-pressure level were determined using response surface methodology and optimization technique. Bread dough was prepared by the optimal condition, 0.20% of bakery enzyme and 43 MPa of high-pressure treatment, and the bread dough was then baked. Optimal combining bakery enzyme and high-pressure treatment drastically improved bread making qualities such as increased SLV, higher concentrations of reducing sugar, and lower concentrations of damaged starch and insoluble dietary fiber compared to the control and to those that were only treated with bakery enzymes or high-pressure treatment, respectively. In addition, the bread with both bakery enzymes and high-pressure treatment showed improved micro structure in the crumb and maintained freshness longer.

Analysis of the relationship between bread-making quality and dough stress during the proofing process using near-isogenic lines of 'Harunoakebono'.

The physical properties of various white bread doughs made from the flours of 'Harunoakebono' and 10 genotypes of its near-isogenic lines with different compositions of high molecular weight glutenin subunit (HMWGs) were measured with the Creep method based on a Maxwell-2-element model. The expansion stress in the proofing process of various doughs was obtained by a numerical calculation method. The results indicated that doughs with high elastic characteristics, namely large relaxation time (τ0) and regularity coefficient of viscosity (ηN), have high dough stress throughout the proofing process and high stress at the proofing end (σend) and conversely, the low elastic dough with the small τ0 and ηN has the completely opposite tendency. This study also showed that there are significantly high correlations between the calculated σend and bread-making quality (BMQ) such as gas retention of dough and specific loaf volume (SLV). These results showed that BMQ, represented by SLV, of various white bread doughs were greatly influenced by the dough's physical properties, especially τ0 and ηN, which change with differences in the compositions of the HMWGs.

Improving preharvest sprouting resistance in durum wheat with bread wheat genes.

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.

Identification and distribution of Puroindoline b-2 variant gene homologs in Hordeum.

The barley hordoindoline genes (Hina and Hinb) are homologous to the wheat puroindoline genes (Pina and Pinb). These genes are involved in grain hardness, which is an important quality for barley processing. We identified novel variants of Hina and Hinb in 10 wild Hordeum species (H. bogdanii, H. brachyantherum, H. bulbosum, H. chilense, H. comosum, H. marinum, H. murinum, H. patagonicum, H. pusillum, and H. roshevitzii) covering all Hordeum genomes and preliminarily named them Hinc. These nucleotide sequences were highly similar to those of Puroindoline b-2 variant genes (Pinb-2v) and were located on chromosome 7I in H. chilense. The Hinc genes in H. bogdanii, H. bulbosum, H. patagonicum, and H. roshevitzii were pseudogenes possessing in-frame stop codons. We also found a partial Hinc sequence in H. murinum. This gene was not found in cultivated barley and H. vulgare subsp. spontaneum. The phylogenetic tree of Gsp-1, Hin, and Pin genes demonstrates that Hinc and Pinb-2v genes formed one cluster. Therefore, we considered that Hinc and Pinb-2v genes shared a common ancestral gene and were homologous to each other. We also studied the evolutional process of Gsp-1, Hin, and Pin genes. Our results suggested that Gsp-1 might be the most closely related to a putative ancestral gene on Ha locus.

Distribution of Hordoindoline genes in the genus Hordeum.

Hordoindoline (Hin) genes, which are known to comprise Hina, Hinb-1, and Hinb-2, are associated with grain hardness in barley. However, the interspecific variation in the Hin genes in the genus Hordeum has not been studied in detail. We examined the variation in Hin genes and used it to infer the phylogenetic relationships between the genes found in two H. vulgare subspecies (cultivated barley and H. vulgare subsp. spontaneum) and 10 wild relatives (H. bogdanii, H. brachyantherum, H. bulbosum, H. chilense, H. comosum, H. marinum, H. murinum, H. patagonicum, H. pusillum, and H. roshevitzii). The Hina and Hinb genes of these species were amplified by PCR. We found two Hinb genes in three wild species (H. bogdanii, H. brachyantherum, and H. roshevitzii) and preliminarily named them Hinb-A and Hinb-B. Cluster analysis showed that the 17 Hinb genes present in Hordeum formed two distinct clusters (named A and B). Seven Hinb genes were included in Cluster-A, and 10 Hinb genes were included in Cluster-B. All Hinb-A genes were included in Cluster-A, while all of the Hinb-B genes were included in Cluster-B. In contrast, the Hinb-1 and Hinb-2 genes in H. vulgare were included in Cluster-B. These results suggest that the Hinb genes duplicated during the early stages of diversification in the genus Hordeum. On the other hand, the Hinb-1 and Hinb-2 genes in H. vulgare seem to have been generated by a duplication of the Hinb gene after the split of the lineages leading to H. vulgare and H. bulbosum.

Chromosome 5H of Hordeum species involved in reduction in grain hardness in wheat genetic background.

Grain hardness is an important factor affecting end-use quality in wheat. Mutations of the puroindoline genes, which are located on chromosome 5DS, control a majority of grain texture variations. Hordoindoline genes, which are the puroindoline gene homologs in barley, are located on chromosome 5HS and are also responsible for grain texture variation. In this study, we used three types of wheat-barley species (Hordeum vulgare, H. vulgare ssp. spontaneum, and H. chilense) chromosome addition lines and studied the effect of chromosome 5H of these species on wheat grain characteristics. The 5H chromosome addition lines showed significantly lower grain hardness and higher grain weight than the corresponding wheat parents. The effect of enhancing grain softness was largest in the wheat-H. chilense line regardless of having an increase in grain weight similar to those in the wheat-H. vulgare and wheat-H. spontaneum lines. Our results indicated that chromosome 5H of the Hordeum species plays a role in enhancing grain softness and increasing grain weight in the wheat genetic background, and the extent of effect on grain hardness depends on the type of Hordeum species. Protein analysis of hordoindolines indicated that profiles of 2D-electrophoresis of hordoindolines were different among Hordeum species and hordoindolines in the addition lines appeared to be most abundant in wheat-H. chilense line. The differences in enhancing grain softness among the Hordeum species might be attributed to the quantity of hordoindolines expressed in the 5H chromosome addition lines. These results suggested that the barley hordoindolines located on chromosome 5HS play a role in reducing grain hardness in the wheat genetic background.

Longer Bread Shelf-Life and Improved Noodle-Making Properties Imparted by a Novel Wheat Genotype Are Stable in Different Genetic Backgrounds.

A recently developed wheat variety, known as 5-5 wheat, which has inactive GBSSI-B1, GBSSI-D1, SSIIa-B1, and SSIIa-D1 isozymes, accumulates a novel type of starch, affecting bread texture and leading to reduction in bread staling. These properties are potentially useful for commercial bakery products; thus, the 5-5 genotype represents a new resource for wheat breeding. In this study, the 5-5 alleles were backcrossed into the hard wheat variety "Minaminokaori" and the soft wheat variety "Shirogane-Komugi", which are both leading Japanese wheat varieties. In comparison to their parental varieties, the two 5-5 near-isogenic lines (NILs) showed a decrease in amylose levels, an increase in the proportion of short chains of amylopectin, a lower gelatinization temperature and enthalpy change, a higher peak viscosity and breakdown viscosity as measured by a Rapid Visco Analyzer, a reduced retrogradation rate, and an increase in grain hardness. Importantly, the 5-5 NILs also showed lower bread crumb firmness and reduced hardening after storage for 2 days at either 20 °C or 7 °C. Considering the results obtained here along with those from the original line, it is clear that the 5-5 genotype can generate specific changes in starch characteristics and staling regardless of its genetic background. Thus, we renamed the 5-5 wheat lines "Slow Staling" (SS) wheat. As expected, our results indicated that the hard wheat SS NIL was more suitable for bread-making. On the other hand, we found that white salted noodle made with the SS NIL of the soft wheat variety had a relatively shorter cooking time, a softer texture, and a reduction in textural changes during storage, all of which are potentially useful for noodle manufacturers.

Deoxynivalenol Distribution in Flour and Bran of Spring Wheat Lines with Different Levels of Fusarium Head Blight Resistance.

The level of the fungal toxin deoxynivalenol (DON) in milled flour and its partitioning between flour and bran of 15 spring wheat (Triticum aestivum) lines with different levels of Fusarium head blight (FHB; mainly caused by Fusarium graminearum) resistance was investigated in Hokkaido, Japan between 2004 and 2007. The DON levels in flour (DONf) and bran (DONb) showed positive linear relationships with DON levels in whole kernels (DONk) (R2 = 0.94, n = 60, P ≤ 0.01 and R2 = 0.93, n = 60, P ≤ 0.01, respectively). Results indicated that the DON partitioning ratio between flour and bran is primarily related to the level of DONk, and the DON level was approximately doubled in DONb and halved in DONf for any level of DONk. Only one pattern of DON partitioning supported the conventional strategy to select FHB-resistant lines.

Influence of Cold-Hardening and Soil Matric Potential on Resistance to Speckled Snow Mold in Wheat.

The influence of soil matric potential, cold-hardening temperature, and duration on resistance to speckled snow mold caused by Typhula ishikariensis in wheat was investigated. Six winter wheat lines were subjected to cold-hardening temperatures of 2 or 4°C for 1, 2, 3, or 4 weeks with soil matric potential of -0.1 or -0.01 MPa. Plants were inoculated with T. ishikariensis after cold-hardening, incubated at 10°C for 25 days in the dark, and then evaluated for regrowth. Overall recovery from snow mold was least when plants were hardened at 2°C for 1 week at -0.01 MPa and greatest when hardened at 4°C for 4 weeks at -0.1 MPa. Survival of plants following snow mold was greater when plants were cold-hardened at 4 than at 2°C and at -0.1 than -0.01 MPa soil matric potential. The greatest difference in survival among lines and correlation with field observations occurred when plants were hardened at 4°C at -0.1 MPa matric potential for 3 weeks. Understanding the influence of temperature and soil matric potential during cold-hardening on speckled snow mold resistance will be useful to breeding programs developing snow-mold-resistant cultivars under controlled environment conditions.

Wheat cultivar-specific proteins in grain revealed by 2-DE and their application to cultivar identification of flour.

Wheat flour proteins were studied to identify the cultivar-specific proteins and use them to identify cultivars in flours. Proteins extracted from flours of Japanese wheat (cultivars Hokushin, Horoshirikomugi, Kitanokaori and Kachikei 33) and Canadian wheat (Canada Western Red Spring Wheat No. 1; 1CW) were analyzed by 2-DE with IEF gels over three pH ranges: pH 4-7, pH 5-8, and pH 6-11. This system enabled detection of more than 1600 protein spots. We recognized that among 50 protein spots showing cultivar-dependent qualitative changes, 25 proteins were wheat cultivar specific. These 50 protein spots were analyzed by N-terminal Edman degradation microsequencing and MALDI-TOF-MS; 21 protein spots were storage proteins, such as gliadin and low-molecular mass glutenin subunit. Five protein spots were identified as dehydroascorbate reductase (Triticum aestivum), triticin precursor (T. aestivum), alpha-amylase inhibitor (Oryza sativa), DNA-binding with one finger (Dof) zinc family protein (O. sativa), and nonphototropic hypocotyl 1 (NPH1) protein (Avena sativa). The other protein spots appeared to be hypothetical proteins (O. sativa or Arabidopsis thaliana) or functional unknown proteins. These specific proteins can be used as markers to identify wheat cultivars in blended flour composed of two or three flours.