In the recycling of zinc from electric arc furnace dust using microwave-based furnaces, the use of graphite powder as a reductant results in significant greenhouse gas emissions. In this study, ...graphite was replaced by a non-carbonaceous reductant in the form of silicon powder. The sample is heated in a microwave-based furnace under 7.5 kW maximum power irradiation at 2.45 GHz. The results clearly indicate that the reaction proceeded between zinc ferrite and silicon powder. The maximum removal rate of zinc obtained was 80% in cases where more than 10 times the stoichiometric amount of silicon powder was used for a heating time of more than 20 min. The apparent activation energy of microwave-based heating was 115.39 kJ/mol lower than that when heating with a conventional furnace.
Buckwheat (Fagopyrum esculentum Moench.) is an annual crop that originated in southern China. The nutritious seeds are used in cooking much like cereal grains. Buckwheat is an outcrossing species ...with heteromorphic self-incompatibility due to its dimorphic (i.e., short- and long-styled) flowers and intra-morph infertility. The floral morphology and intra-morph incompatibility are both determined by a single S locus. Plants with short-styled flowers are heterozygous (S/s) and plants with long-styled flowers are homozygous recessive (s/s) at this locus, and the S/S genotype is not found. Recently, we built a draft genome assembly of buckwheat and identified the 5.4-Mb-long S-allele region harbored by short-styled plants. In this study, the first report on the genome-wide diversity of buckwheat, we used a genotyping-by-sequencing (GBS) dataset to evaluate the genome-wide nucleotide diversity within cultivated buckwheat landraces worldwide. We also investigated the utility of the S-allele region for phylogenetic analysis of buckwheat.
Buckwheat showed high nucleotide diversity (0.0065), comparable to that of other outcrossing plants, based on a genome-wide simple nucleotide polymorphism (SNP) analysis. Phylogenetic analyses based on genome-wide SNPs showed that cultivated buckwheat comprises two groups, Asian and European, and revealed lower nucleotide diversity in the European group (0.0055) and low differentiation between the Asian and European groups. The nucleotide diversity (0.0039) estimated from SNPs in the S-allele region is lower than that in genome-wide SNPs. Phylogenetic analysis based on this region detected three diverged groups, S-1, S-2, and S-3.
The SNPs detected using the GBS dataset were effective for elucidating the evolutionary history of buckwheat, and led to the following conclusions: (1) the low nucleotide diversity of the entire genome in the European group and low differentiation between the Asian and European groups suggested genetic bottlenecks associated with dispersion from Asia to Europe, and/or recent intensified cultivation and selection in Europe; and (2) the high diversification in the S-allele region was indicative of gene flows from wild to cultivated buckwheat, suggesting that cultivated buckwheat may have multiple origins.
Combining high-throughput genotyping data with the latest wheat genomic information provided more detailed information on the genetic diversity of the Japanese wheat core collection (JWC). Analysis ...of genomic population structure divided the JWC accessions into three populations: northeast Japan accessions, native and southwest Japan accessions, and modern accessions showing mixed breeding patterns. This indicates that Japanese wheat varieties have a background of native genomes from southwest Japan incorporating valuable genes from various exotic lines, which is supported by the history of Japanese wheat breeding. Association analyses of several agronomic traits have revealed how genes or alleles have been selected in Japanese wheat breeding and how they differ from those in other regions of the world. This analysis of the JWC collection is expected to contribute not only to the elucidation of genetic diversity in Japanese wheat accessions but also to future wheat breeding by providing a new genetic resource.
The number of wheat grains is one of the major determinants of yield. Many quantitative trait loci (QTLs) and some causal genes such as
GNI-A1
and
WAPO-A1
that are associated with grain number per ...spike (GNS) have been identified, but the underlying mechanisms remain largely unknown. We analyzed QTLs for grain number and other related traits using 188 doubled haploid lines derived from the Japanese high-yield variety, Kitahonami, as a parent to elucidate the genetic mechanism determining grain number. The major QTLs for grain number at the apical, central, and basal parts of the spike were identified in different chromosomal regions. We considered
GNI-A1
and
WAPO-A1
as candidate genes controlling grain number at the central and basal parts of the spike, respectively. Kitahonami had the favorable 105Y allele of
GNI-A1
and
WAPO-A1b
allele and unfavorable alleles of QTLs for grain number at the apical part of spikes. Pyramiding the favorable alleles of these QTLs significantly increased GNS without significantly reducing thousand-grain weight (TGW). In contrast, the accumulation of favorable alleles of QTLs for TGW significantly decreased GNS, whereas days to heading positively correlated with GNS. Late heading increased the spikelet number per spike, resulting in a higher GNS. Pyramiding of the QTLs for TGW and days to heading also altered the GNS. In conclusion, GNS is a complex trait controlled by many QTLs, and it is essential for breeding to design.
Aegilops tauschii Coss. is the D‐genome progenitor of hexaploid wheat. Aegilops tauschii, a wild diploid species, has a wide natural species range in central Eurasia, spreading from Turkey to western ...China. Amplified fragment length polymorphism (AFLP) analysis using a total of 122 accessions of Ae. tauschii was conducted to clarify the population structure of this widespread wild wheat species. Phylogenetic and principal component analyses revealed two major lineages in Ae. tauschii. Bayesian population structure analyses based on the AFLP data showed that lineages one (L1) and two (L2) were respectively significantly divided into six and three sublineages. Only four out of the six L1 sublineages were diverged from those of western habitats in the Transcaucasia and northern Iran region to eastern habitats such as Pakistan and Afghanistan. Other sublineages including L2 were distributed to a limited extent in the western region. Subspecies strangulata seemed to be differentiated in one sublineage of L2. Among three major haplogroups (HG7, HG9 and HG16) previously identified in the Ae. tauschii population based on chloroplast variation, HG7 accessions were widely distributed to both L1 and L2, HG9 accessions were restricted to L2, and HG16 accessions belonged to L1, suggesting that HG9 and HG16 were formed from HG7 after divergence of the first two lineages of the nuclear genome. These results on the population structure of Ae. tauschii and the genealogical relationship among Ae. tauschii accessions should provide important agricultural and evolutionary knowledge on genetic resources and conservation of natural genetic diversity.
Although metals are fundamental to the economy and human well-being, natural ore depletion is inevitable with the continuation of mining. Awareness of the importance of new developments in ...technologies to process natural ores and to recycle waste materials to obtain pure metals with high efficiency has been growing over time. The microwave-based furnace, which heats samples rapidly, uniformly and selectively, has recently been given more attention as an alternative to the conventional heating systems. However, the current progress of microwave technology for obtaining pure metals has not been fully monitored. This study reviews the extractive metallurgical approaches for obtaining pure metals by subjecting virgin materials and waste materials to the microwave heating method. In this paper, the principles of the microwave-based furnace to heat the samples are first summarized. Then, the studies of microwave-based pyrometallurgical and hydrometallurgical approaches to produce the virgin metals and to recycle metals are abridged. Finally, the limitations of current progress and the future prospects of microwave-based metallurgical technology are identified. A number of clear advantages of microwave irradiation emerged through the review process. The two most noteworthy advantages are that some materials difficult to reduce using conventional technology can be treated effectively using microwave irradiation, and microwave technology has the potential for a number of materials to facilitate a more rapid chemical reaction with fewer impurities considering the more than 50% of reduction in the apparent activation energy under microwave irradiation.
The wheat florigen gene Wheat FLOWERING LOCUS T (WFT, which is identical to VRN3) is an integrator of the vernalization, photoperiod and autonomous pathways in wheat flowering. Many studies have ...indicated that VERNALIZATION 1 (VRN1) directly or indirectly up-regulates WFT expression in leaves. VRN1 encodes an APETALA1/FRUITFULL-like MADS box transcription factor that is up-regulated by vernalization and aging, leading to promotion of flowering. In this study, the VRN1 protein was expressed as a His-Tag fusion protein in Escherichia coli and used in an electrophoretic mobility shift assay (EMSA). The results from the EMSA indicated that the VRN1 protein directly binds to the CArG-box in the promoter region of WFT, suggesting the direct up-regulation of WFT by VRN1 in the leaves of wheat plants.
Background: Hybrid speciation is classified into homoploid and polyploid based on ploidy level. Common wheat is an allohexaploid species that originated from a naturally occurring interploidy cross ...between tetraploid wheat and diploid wild wheat Aegilops tauschii Coss. Aegilops tauschii provides wide naturally occurring genetic variation. Sometimes its triploid hybrids with tetraploid wheat show the following four types of hybrid growth abnormalities: types II and III hybrid necrosis, hybrid chlorosis, and severe growth abortion. The growth abnormalities in the triploid hybrids could act as postzygotic hybridization barriers to prevent formation of hexaploid wheat. Methodology/Principal Findings: Here, we report on the geographical and phylogenetic distribution of Ae. tauschii accessions inducing the hybrid growth abnormalities and showed that they are widely distributed across growth habitats in Ae. tauschii. Molecular and cytological characterization of the type III necrosis phenotype was performed. The hybrid abnormality causing accessions were widely distributed across growth habitats in Ae. tauschii. Transcriptome analysis showed that a number of defense-related genes such as pathogenesis-related genes were highly up-regulated in the type III necrosis lines. Transmission electron microscope observation revealed that cell death occurred accompanied by generation of reactive oxygen species in leaves undergoing type III necrosis. The reduction of photosynthetic activity occurred prior to the appearance of necrotic symptoms on the leaves exhibiting hybrid necrosis. Conclusions/Significance: Taking these results together strongly suggests that an autoimmune response might be triggered by intergenomic incompatibility between the tetraploid wheat and Ae. tauschii genomes in type III necrosis, and that genetically programmed cell death could be regarded as a hypersensitive response-like cell death similar to that observed in Arabidopsis intraspecific and Nicotiana interspecific hybrids. Only Ae. tauschii accessions without such inhibiting factors could be candidates for the D-genome donor for the present hexaploid wheat.
The timing of heading is largely affected by environmental conditions. In wheat, Vrn-1 and Ppd-1 have been identified as the major genes involved in vernalization requirement and photoperiod ...sensitivity, respectively. To compare the effects of Vrn-1 and Ppd-1 alleles on heading time under different environments, we genotyped Vrn-1 and Ppd-1 homoeologues and measured the heading time at Morioka, Tsukuba and Chikugo in Japan for two growing seasons. A total of 128 Japanese and six foreign varieties, classified into four populations based on the 519 genome-wide SNPs, were used for analysis. Varieties with the spring alleles (Vrn-D1a or Vrn-D1b) at the Vrn-D1 locus and insensitive allele (Hapl-I) at the Ppd-D1 locus were found in earlier heading varieties. The effects of Vrn-D1 and Ppd-D1 on heading time were stronger than those of the other Vrn-1 and Ppd-1 homoeologues. Analysis of variance revealed that heading time was significantly affected by the genotype-environment interactions. Some Vrn-1 and Ppd-1 alleles conferred earlier or later heading in specific environments, indicating that the effect of both alleles on the timing of heading depends on the environment. Information on Vrn-1 and Ppd-1 alleles, together with heading time in various environments, provide useful information for wheat breeding.
Wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) are widely cultivated temperate crops. In breeding programs with these crops in Japan, effective genomic-assisted selection was performed ...by selecting core marker sets from thousands of genome-wide amplicon sequencing markers. The core sets consist of 768 and 960 markers for barley and wheat, respectively. These markers are distributed evenly across the genomes and effectively detect widely distributed polymorphisms in the chromosomes. The core set utility was assessed using 1,032 barley and 1,798 wheat accessions across the country. Minor allele frequency and chromosomal distributions showed that the core sets could effectively capture polymorphisms across the entire genome, indicating that the core sets are applicable to highly-related advanced breeding materials. Using the core sets, we also assessed the trait value predictability. As observed via fivefold cross-validation, the prediction accuracies of six barley traits ranged from 0.56–0.74 and 0.62 on average, and the corresponding values for eight wheat traits ranged from 0.44–0.83 and 0.65 on average. These data indicate that the established core marker sets enable breeding processes to be accelerated in a cost-effective manner and provide a strong foundation for further research on genomic selection in crops.
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