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Public acceptance is important for the provision of potentially hazardous facilities and may be affected by many factors such as perceived risk/benefit/stress/fairness and public trust. In this study, the underlying mechanism behind the influence of perceived stress on public acceptance of waste-to-energy (WTE) incinerators was explored by structural equation modeling of a face-to-face questionnaire survey of 1066 urban residents in three regional central cities in China. The results indicate that, firstly, the perceived stress of the laypeople has an impact on their acceptance by influencing risk/fairness they perceived and public trust. Secondly, the paths of influence of individual perceptions on acceptance differ between cities with different economic, cultural, and social characteristics. Perceived stress mainly affects public acceptance through perceived risk in the eastern residents while perceived stress mainly affects public acceptance through public trust in the western residents. The findings clarify the theoretical role of perceived stress in shaping laypeople's acceptance of potentially hazardous facilities which are of value for both governments and owners in siting potentially hazardous facilities.

Spot blotch, caused by the pathogen Bipolaris sorokiniana, is an important foliar disease of wheat in warm and humid regions worldwide. The fungal virulence factor ToxA interacts with Tsn1 in wheat and leads to a susceptible reaction. ToxA has been found in B. sorokiniana populations of Australia, the USA, and India, and here we report its occurrence in Mexico, based on analysis of a collection of 196 Mexican isolates of B. sorokiniana. The isolates were collected from experimental stations and farmers’ fields in nine states of Mexico, during the period from 1992 to 2017. A PCR assay with the ToxA-specific marker was conducted, and the results revealed the presence of ToxA in 20 isolates (10.2%). Culture filtrate infiltration experiments confirmed that all the 20 isolates were able to induce necrosis reaction on Glenlea, a wheat genotype with Tsn1. This is the first report on the occurrence of ToxA in Mexican B. sorokiniana population, which is key information for breeding wheat for resistance against spot blotch.

Key message Wheat blast resistance in Caninde#1 is controlled by a major QTL on 2NS/2AS translocation and multiple minor QTL in an additive mode. Abstract Wheat blast (WB) is a devastating disease in South America, and it recently also emerged in Bangladesh. Host resistance to WB has relied heavily on the 2NS/2AS translocation, but the responsible QTL has not been mapped and its phenotypic effects in different environments have not been reported. In the current study, a recombinant inbred line population with 298 progenies was generated, with the female and male parents being Caninde#1 (with 2NS) and Alondra (without 2NS), respectively. Phenotyping was carried out in two locations in Bolivia, namely Quirusillas and Okinawa, and one location in Bangladesh, Jashore, with two sowing dates in each of the two cropping seasons in each location, during the years 2017–2019. Genotyping was performed with the DArTseq® technology along with five previously reported STS markers in the 2NS region. QTL mapping identified a major and consistent QTL on 2NS/2AS region, explaining between 22.4 and 50.1% of the phenotypic variation in different environments. Additional QTL were detected on chromosomes 1AS, 2BL, 3AL, 4BS, 4DL and 7BS, all additive to the 2NS QTL and showing phenotypic effects less than 10%. Two codominant STS markers, WGGB156 and WGGB159, were linked proximally to the 2NS/2AS QTL with a genetic distance of 0.9 cM, being potentially useful in marker-assisted selection.

Background Oral squamous cell carcinoma (OSCC), as one of the commonest malignancies showing poor prognosis, has been increasingly suggested to be modulated by circular RNAs (circRNAs). Through GEO (Gene Expression Omnibus) database, a circRNA derived from ZDBF2 (circZDBF2) was uncovered to be with high expression in OSCC tissues, while how it may function in OSCC remains unclear. Methods CircZDBF2 expression was firstly verified in OSCC cells via qRT-PCR. CCK-8, along with colony formation, wound healing, transwell and western blot assays was performed to assess the malignant cell behaviors in OSCC cells. Further, RNA pull down assay, RIP assay, as well as luciferase reporter assay was performed to testify the interaction between circZDBF2 and RNAs. Results CircZDBF2 expressed at a high level in OSCC cells and it accelerated OSCC cell proliferation, migration, invasion as well as EMT (epithelial-mesenchymal transition) process. Further, circZDBF2 sponged miR-362-5p and miR-500b-5p in OSCC cells to release their target ring finger protein 145 (RNF145). RNF145 expressed at a high level in OSCC cells and circZDBF2 facilitated RNF145 transcription by recruiting the transcription factor CCAAT enhancer binding protein beta (CEBPB). Moreover, RNF145 activated NFκB (nuclear factor kappa B) signaling pathway and regulated IL-8 (C-X-C motif chemokine ligand 8) transcription. Conclusion CircZDBF2 up-regulated RNF145 expression by sponging miR-362-5p and miR-500b-5p and recruiting CEBPB, thereby promoting OSCC progression via NFκB signaling pathway. The findings recommend circZDBF2 as a probable therapeutic target for OSCC. Graphical Abstract

Bread wheat improvement using genomic tools is essential for accelerating trait genetic gains. Here we report the genomic predictabilities of 35 key traits and demonstrate the potential of genomic selection for wheat end-use quality. We also performed a large genome-wide association study that identified several significant marker–trait associations for 50 traits evaluated in South Asia, Africa and the Americas. Furthermore, we built a reference wheat genotype–phenotype map, explored allele frequency dynamics over time and fingerprinted 44,624 wheat lines for trait-associated markers, generating over 7.6 million data points, which together will provide a valuable resource to the wheat community for enhancing productivity and stress resilience. Large-scale genomic analyses in wheat identify regions associated with 50 agronomic traits evaluated in South Asia, Africa and the Americas. This genotype–phenotype map can be used to enhance wheat productivity and stress resilience.

Fungal diseases pose a great challenge to Canadian barley production, among which are Fusarium head blight (FHB), yellow rust and scald. An integrated management approach is needed to mitigate these diseases, in which breeding for host resistance is the most effective component. Constant evaluation of advanced breeding lines for their resistance to the diseases is important for making steady progression. The main objective of this study was to screen 1,174 barley accessions, from a collaborative project between the Field Crop Development Center (FCDC), Alberta, Canada, and the International Maize and Wheat Improvement Center (CIMMYT), Mexico for their reactions to the three diseases. For FHB a 1–5 scale was employed to discard the very susceptible material in 2012 and 2013. In 2014, 514 most resistant lines having the score 1 in 2013 were re-evaluated in a replicated experiment. The most promising 166 genotypes were selected and advanced for their last evaluation in 2015 where FHB index was measured. Simultaneously, these 166 genotypes were subjected to two more experiments to test their reactions against stripe rust and scald. Eighteen two-rowed barley genotypes exhibiting broad-spectrum resistance to all of the three evaluated diseases were identified in addition to 40 lines combining FHB resistance with resistance to Mexican isolates and natural fungal population of either of the two foliar diseases and could be utilized in breeding programs aimed at improving resistance to multiple barley leaf and head blight diseases.

A nursery comprising 25 elite bread wheat genotypes were evaluated to identify the sources of resistance to wheat blast caused by Magnaporthe oryzae pathotype Triticum (MoT), under artificial and natural infection experiments in three consecutive years from 2018 to 2020 in two different locations of Bangladesh. Seedling evaluation results revealed the absence of resistant and most genotypes displayed moderately susceptible to susceptible reaction. In the adult-plant field testing, six genotypes namely Borlaug 100, BARI Gom 33, BAW 1272, BAW 1280, BAW 1286, and BAW 1297 consistently showed resistant response to wheat head blast (WHB) infection with low levels of disease severity ranging from 0.2 to 8.1%. Among the remaining genotypes, some were moderately resistant, and the others exhibited various levels of susceptibility. The resistant genotypes that were most promising showed good agronomic performance under inoculated field trials. A significant positive correlation was observed between seedling and adult plant resistance. The above mentioned six genotypes also showed resistant reaction to WHB infection under controlled conditions when tested with three selected MoT isolates. The presence of 2NS/2AS translocation conferring WHB resistance was confirmed in four of the tested genotypes. Three (BAW 1272, BAW 1286, and BAW 1297) lines having non-2NS background exhibited good blast resistance under both the field and controlled conditions. These results will be useful for breeders and pathologists in exploiting the 2NS and non-2NS based resistant sources to pyramid and develop broad genetic based resistant germplasm.

Background Fusarium crown rot (FCR) is a severe and chronic disease in common wheat and is able to cause serious yield loss and health problems to human and livestock. Results Here, 234 Chinese wheat cultivars were evaluated in four greenhouse experiments for FCR resistance and genome-wide association studies (GWAS) were performed using the wheat 660 K genotyping assay. The results indicated that most cultivars evaluated showed FCR disease index (DI) of 40–60, while some cultivars showed stably good FCR resistance (DI

Tan spot (TS), Stagonospora nodorum blotch (SNB), spot blotch (SB), and Septoria tritici blotch (STB) caused by Pyrenophora tritici-repentis, Parastagonospora nodorum, Cochliobolus sativus and Zymoseptoria tritici, respectively, are the four important fungal leaf spotting diseases of wheat with global importance. These diseases reduce the photosynthetic area of leaves resulting in poor grain filling and lower yields; particularly when the penultimate and flag leaves are severely infected. Fusarium head blight (FHB) is another important fungal disease that infects wheat heads causing significant yield and quality deterioration including mycotoxins contamination. Host plant resistance is one of the main strategies in the management of these diseases. To identify new resistant sources to TS, SNB, STB, SB and FHB, 110 wheat cultivars and advanced breeding lines from different geographic origins were evaluated in growth chambers and field nurseries at the International Maize and Wheat Improvement Center (CIMMYT), Mexico. These materials have been previously evaluated for their field FHB resistance (combination of type I and II resistance) and performed well, but in the current study they were tested in greenhouse with point inoculation to confirm exclusively their type II resistance. The frequency of resistant lines was similar for TS, SNB and STB with 45, 40 and 33 genotypes, respectively. However, only 11 lines showed resistance to SB while 51 genotypes showed FHB type II resistance. Two genotypes of Chinese origin, NANJING 8611 and NANJING 4840, exhibited broad-spectrum resistance to all of the studied diseases and were not significantly different (P ≤ 0.01) from the resistant check of the respective diseases. The multiple disease resistant accessions identified in this study could be utilized in breeding programs aimed at improving wheat resistance to either individual or multiple leaf and head blight diseases.

Fusarium head blight (FHB), also known as head scab, is a devastating fungal disease of bread and durum wheat worldwide. It reduces yield, lowers seed germination, reduces grain quality, and renders grain unsuitable for human or animal consumption due to mycotoxin contamination. Use of host resistance in commercially cultivated wheat varieties is an economical, effective and environmentally friendly method to manage FHB. In order to map loci underlying FHB resistance in synthetic-derived bread wheat line SYN1, a doubled haploid (DH) population of 169 lines was developed through hybridizing SYN1 with FHB-susceptible line Ocoroni. The DH population was evaluated in spray-inoculated field nurseries in the 2010 and 2011 cropping seasons at the El Batan Experiment Station of the International Maize and Wheat Improvement Center, Mexico. Ten marked spikes from each plot were scored for disease response and an FHB index was subsequently calculated. The population was genotyped with 1391 genotyping by sequencing and 106 simple-sequence repeat (SSR) loci and 28 linkage groups were constructed. These linkage groups were anchored by SSRs to all chromosomes, except 4D, 5D and 6D. Using the inclusive composite interval mapping algorithm, three genomic regions were associated with FHB resistance, including a major QTL on chromosome 2D accounting for 25 % of the phenotypic variation explained (PVE) and two minor QTLs on chromosomes 1B (4.7 % PVE) and 7A (4.2 % PVE), with all favorable alleles contributed by SYN1. The average FHB index of lines with all three SYN1 alleles was substantially lower (61.4 %) than that of those with Ocoroni alleles.

Spot blotch (SB) caused by Cochliobolus sativus is a serious biotic stress to wheat in warm and humid areas, particularly South Asia (SA). In order to support South Asian farmers to combat SB, International Maize and Wheat Improvement Center (CIMMYT) established an efficient SB screening system at Agua Fria, Mexico and developed a nursery under the project - Cereal Systems Initiative for South Asia (CSISA). The materials used to form CSISA-SB nursery were selected from advanced breeding lines from different wheat breeding programs at CIMMYT. Seed of CSISA-SB nursery was produced at disease-free plots at El Batan and Mexicali, and distributed to SA after rigorous seed health checks. The 4th CSISA-SB, made available in 2012, comprised 50 entries including two resistant and two susceptible checks. The nursery was evaluated in seven locations in Mexico, India, and Bangladesh in the 2012–13 cropping season. The results indicated that although few lines exhibited stable resistance across locations due to strong G × E interaction, promising lines with SB resistance and good agronomy can still be identified in each location. The two most promising lines showing consistent spot blotch resistance across the regions were CHUKUI#1 (CIMMYT germplasm bank identification number, GID 6178575) and VAYI#1 (GID 6279248). These lines could be promoted as sources of SB resistance or directly released as cultivars in SA.

As an important cereal disease in humid and semi-humid areas, Fusarium head blight (FHB) has caused severe epidemics on wheat (Triticum aestivum L.) in different countries worldwide. By causing both yield loss and quality degradation, FHB presents a two-fold threat to farmers and consumers. Since the beginning of FHB research at the International Maize and Wheat Improvement Centre (CIMMYT) in the early 1980s, a large-scale FHB screening has been conducted to identify and incorporate new resistance genes into elite CIMMYT germplasm. Candidates of the 15th Fusarium head blight screening nursery (FHBSN) were derived from different CIMMYT wheat breeding programs and were tested for 3 years successively in El Batan, Mexico, before being included in the 15th FHBSN set. From 2010 to 2012, a set of 44 out of 2794 lines were gradually selected depending on their FHB indices, pedigree information, and phenological traits like plant height and days to heading. The performance of these lines varied across years under different disease pressure, but they all showed high level of resistance compared to the susceptible checks. In 2013, the nursery was again evaluated in El Batan, as well as in artificially inoculated field trials in Norway, Uruguay, the Netherlands, and Japan (2014), and in naturally infected experiments in Toluca, Mexico, and Canada. Although not all lines demonstrated strong resistance across environments, promising lines with good FHB resistance can still be identified in each location. The genotypes were haplotyped with PCR-based markers for ten loci on seven chromosomes associated with known FHB resistance, and the results suggested that 24 of the genotypes (55 %) carried the 4BS QTL as in Wuhan 1, which was the most frequent QTL in this nursery, and the 7A QTL as in T. dicoccoides was noticed in five (11 %) of the genotypes. The resistance QTLs on chromosomes 3B, 5A and 6B as in Sumai 3 and 3A as in T. dicoccoides were not detected in any of the genotypes denoting the uniqueness of these lines. Fifteen (34 %) of the genotypes may not carry any of the ten QTLs examined. The results provide valuable information that could be successfully utilized by breeders to select resistant parents for crosses since novel resistance sources were detected for better targeted crosses toward diversifying and/or pyramiding FHB resistance.

A total of 3,671 sequence contigs and scaffolds were mapped to deletion bins on wheat chromosome 7B providing a foundation for developing high-resolution integrated physical map for this chromosome. Bread wheat (Triticum aestivum L.) has a large, complex and highly repetitive genome which is challenging to assemble into high quality pseudo-chromosomes. As part of the international effort to sequence the hexaploid bread wheat genome by the international wheat genome sequencing consortium (IWGSC) we are focused on assembling a reference sequence for chromosome 7B. The successful completion of the reference chromosome sequence is highly dependent on the integration of genetic and physical maps. To aid the integration of these two types of maps, we have constructed a high-density deletion bin map of chromosome 7B. Using the 270 K Nimblegen comparative genomic hybridization (CGH) array on a set of cv. Chinese spring deletion lines, a total of 3,671 sequence contigs and scaffolds (~7.8 % of chromosome 7B physical length) were mapped into nine deletion bins. Our method of genotyping deletions on chromosome 7B relied on a model-based clustering algorithm (Mclust) to accurately predict the presence or absence of a given genomic sequence in a deletion line. The bin mapping results were validated using three different approaches, viz. (a) PCR-based amplification of randomly selected bin mapped sequences (b) comparison with previously mapped ESTs and (c) comparison with a 7B genetic map developed in the present study. Validation of the bin mapping results suggested a high accuracy of the assignment of 7B sequence contigs and scaffolds to the 7B deletion bins.

Fusarium head blight (FHB) poses a challenge for wheat breeders worldwide; there are limited sources of resistance and the genetic basis for resistance is not well understood. In the mid-1980s, a shuttle breeding and germplasm exchange program launched between CIMMYT-Mexico and China, enabled the incorporation of FHB resistance from Chinese bread wheat germplasm into CIMMYT wheat. Most of the Chinese wheat materials conserved in the CIMMYT germplasm bank had not been fully characterized for FHB reaction under Mexican environments, until 2009, when 491 Chinese bread wheat lines were evaluated in a FHB screening nursery in Mexico, and 304 (61.9 %) showed FHB indices below 10 %. Subsequent testing occurred in 2010 for plant height (PH), days to heading (DH), and leaf rust response. In 2012, 140 elite lines with good agronomic types were further evaluated for field FHB reaction and deoxynivalenol (DON) accumulation. Most of the tested lines showed good resistance: 116 (82.9 %) entries displayed FHB indices lower than 10 %, while 89 (63.6 %) had DON contents lower than 1.0 ppm. Significant negative correlations were observed between FHB traits (FHB index, DON content, and Fusarium damaged kernels) and PH, DH, and anther extrusion. A subset of 102 elite entries was selected for haplotyping using markers linked to 10 well known FHB quantitative trait loci (QTL). 57 % of the lines possessed the same 2DL QTL marker alleles as Wuhan 1 or CJ 9306, and 26.5 % had the same 3BS QTL allele as Sumai 3. The remaining known QTL were of low frequency. These materials, especially those with none of the above tested resistance QTL (26.5 %), could be used in breeding programs as new resistance sources possessing novel genes for FHB resistance and DON tolerance.

During caries, dental pulp expresses a range of pro-inflammatory cytokines in response to the infectious challenge. Interferon gamma (IFN-γ) is a dimerized soluble cytokine, which is critical for immune responses. Previous study has demonstrated that IFN-γ at relative high concentration (100 ng/mL) treatment improved the impaired dentinogenic and immunosuppressive regulatory functions of disease-derived dental pulp stem cells (DPSCs). However, little is known about the regulatory effects of IFN-γ at relative low concentration on healthy DPSC behavior (including proliferation, migration, and multiple-potential differentiation). Here we demonstrate that IFN-γ at relatively low concentrations (0.5 ng/mL) promoted the proliferation and migration of DPSCs, but abrogated odonto/osteogenic differentiation. Additionally, we identified that NF-κB and MAPK signaling pathways are both involved in the process of IFN-γ-regulated odonto/osteogenic differentiation of DPSCs. DPSCs treated with IFN-γ and supplemented with pyrrolidine dithiocarbamate (PDTC, an NF-κB inhibitor) or SB203580 (a MAPK inhibitor) showed significantly improved potential for odonto/osteogenic differentiation of DPSCs both in vivo and in vitro. These data provide important insight into the regulatory effects of IFN-γ on the biological behavior of DPSCs and indicate a promising therapeutic strategy for dentin/pulp tissue engineering in future endodontic treatment.

Fusarium head blight (FHB) is a major threat to wheat production globally, causing not only yield losses but also food and feed contamination. FHB research began at the International Maize and Wheat Improvement Center (CIMMYT) in the early 1980’s, and since then, large-scale FHB screening has been conducted to identify and incorporate new resistance genes into elite CIMMYT germplasm. Promising lines with good FHB resistance were regularly compiled as a Fusarium Head Blight Screening Nursery (FHBSN) and distributed worldwide. The first FHBSN was assembled in 1985, and the most recent two were the 13th and 14th FHBSN that were released in 2011 and 2012, respectively. Candidate lines for a FHBSN came mainly from different CIMMYT wheat breeding programs and were tested for three consecutive years before being included in an FHBSN. FHBSN screening was conducted under strictly standardized field conditions at El Batan, where CIMMYT headquarters is located, using artificial inoculation of F. graminearum strains, whose aggressiveness and DON chemotypes had been previously identified. FHB index was scored at 31 days after inoculation for all lines and DON concentration was measured only for elite lines in their 2nd and 3rd year of evaluation. Haplotyping is a new tool for genetic characterization of FHBSN entries and helps to identify new resistance sources with novel resistance genes and to better target crosses toward diversifying and/or pyramiding resistance. The 13th FHBSN was taken as an example in this paper to show the procedure and strategy for the development of new FHB resistant lines.

Two hundred and seventy-three CIMMYT bread wheat cultivars and advanced lines grown under irrigated conditions in Mexico during the 2005-06 Yaqui crop cycle were characterized for quality-related genetic traits using gene-specific markers for some high- and low-molecular-weight glutenin subunit (HMW-GS and LMW-GS) genes, polyphenol oxidase (PPO), phytoene synthase (PSY), and waxy genes. Of them, 142 were analyzed for quality parameters including SDS sedimentation volume (SDS-SV), dough mixing time, and Alveograph parameters, and for HMW-GS and LMW-GS compositions using sodium-dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and reversed-phase high-performance liquid chromatography (RP-HPLC). For the Ppo-A1 locus tested with the marker PPO18, the frequencies of alleles Ppo-A1a and Ppo-A1b were 79.1 and 20.2%, respectively, and no PCR fragment was amplified in 2 lines (0.73%), whereas 227 lines (83.2%) contained the allele Ppo-D1a and 46 lines (16.8%) had Ppo-D1b detected by markers PPO16 and PPO29. For the marker YP7A, 142 lines (52.0%) were assumed to have the allele Psy-A1a and 131 lines (48.0%) contained the allele Psy-A1b. In the case of the marker YP7B for the gene Psy-B1, the alleles Psy-B1a and Psy-B1b were detected in 155 (56.8%) and 43 (15.8%) lines, respectively, and 75 (27.4%) lines possessed the allele Psy-B1d detected by the marker YP7B-3. All 273 lines contained the alleles Wx-A1a and Wx-D1a as determined by markers MAG264 and MAG269, respectively. Using the marker Wx-B1, 204 lines (74.7%) were presumed to have the Wx-B1a allele and 69 (25.3%) possessed Wx-B1b. The over-expressing allele of Bx7 OE and subunit By8*, not clearly seen with SDS-PAGE, were detected by RP-HPLC. The numbers of lines with subunits Ax2*, By8, By9, Bx17, Bx20, Dx5, and Glu-B3j were 90, 16, 57, 5, 46, 118, and 33, respectively, in the 142 lines analyzed with molecular markers, and were consistent with the results obtained by SDS-PAGE, except for one line with the 1A.1R translocation. Subunits Ax1 and Ax2* at the Glu-A1 locus showed significantly better effects on all quality parameters than subunit Null. Subunits 5 + 10 gave significantly better effects for all parameters. Subunit Glu-A3b showed more positive effects than its alternative alleles on SDS-SV and SDS-sedimentation volume/protein content index (SPI). The allele Glu-B3g showed the best effect on SDS-SV and Alveograph W, whereas Glu-B3j, associated with the 1B.1R translocation, exhibited a strongly negative effect on all quality parameters.

Cloning and phylogenetic analysis of Psy1 genes in common wheat and its relatives would help to understand the genetic diversity and evolution of Psy1 gene in common wheat and its related species. In the present study, common wheat (AABBDD) and eight relative species, including T. urartu (A(u)A(u)), T. boeoticum (A(m)A(m)), T. monococcum (A(m)A(m)), Ae. speltoides (SS), Ae. tauschii (DD), T. dicoccoides (AABB), T. dicoccum (AABB) and T. spelta (AABBDD), were sampled for the isolation of novel alleles at Psy1-A1, Psy1-B1/Psy1-S1 and Psy1-D1 loci corresponding to common wheat Psy1 genes, and 27 new alleles were identified at these loci, designated Psy1-A1f through Psy1-A1k, Psy1-A1m and Psy1-A1n, Psy1-B1h through Psy1-B1m, Psy1-S1a through Psy1-S1c, Psy1-D1a through Psy1-D1j, respectively. The genes contained six exons and five introns, and the sequences of exons were more conserved compared with those of introns. The Psy1-A1 genes encoded a polypeptide of 428 aminoacid residues, with one residue longer than those encoded by Psy1-D1 genes. The Psy1-B1/Psy1-S1 genes encoded four types of polypeptides, with 421 (Psy1-B1h through Psy1-B1j, Psy1-B1l), 427 (Psy1-B1k, Psy1-S1a and Psy1-S1c), 428 (Psy1-B1m), and 429 (Psy1-S1b) aminoacid residues, respectively. Neighbor joining tree was generated based on the gene sequences of the 27 novel alleles and those of the 13 alleles reported previously in common wheat and its relatives. The phylogenetic tree consisted of two subtrees. The subtree I comprised 11 of 14 alleles at Psy1-A1 locus, nine of 16 alleles at Psy1-B1/Psy1-S1 locus, and ten novel alleles at Psy1-D1 locus, while the subtree II included the other three alleles at Psy1-A1 locus, the remaining four Psy1-B1 alleles and three Psy1-S1 alleles. The alleles from different clusters showed high sequence divergences, indicated by various SNPs and InDels (insertion/deletion). The phylogenetic relationships of these allelic variants at the three loci in common wheat and its relatives also supported the hypothesis that common wheat was originated by recurrent hexaploidization events. In addition, 193 Chinese wheat cultivars with different yellow pigment contents were genotyped with two novel STS markers YP7D-1 and YP7D-2. The results indicated that 191 cultivars contained the allele Psy1-D1a, and two had Psy1-D1g.

Phytoene synthase genes influence yellow pigment (YP) content in wheat grain, and are associated with the quality of end-use products. In the present study, a suite of 217 Chinese winter wheat cultivars and 342 CIMMYT spring wheat cultivars were used to search for phytoene synthase 1 gene variations and to detect and compare their genetic effects in different genetic backgrounds. An initial focus on the Chinese winter wheat cultivars revealed four allelic variants of this gene on chromosome 7B (Psy-B1), designated as Psy-B1a, Psy-B1b, Psy-B1c and Psy-B1d. The frequencies of these four alleles were 39.6, 43.8, 15.7 and 0.9%, respectively. A co-dominant marker YP7B-1 based on a 5-bp InDel of poly C in the fifth intron of Psy-B1 amplified a 151-bp PCR fragment in accessions with the medium YP content allele Psy-B1a, and a 156-bp fragment in lower YP content accessions with Psy-B1b. Two dominant markers YP7B-2 (428 bp) and YP7B-3 (884 bp) were designed for accessions with Psy-B1c and Psy-B1d, respectively. Allele Psy-B1c was associated with high YP content, but the phenotypic effect of Psy-B1d was not determined due to the limited number of accessions. In CIMMYT spring wheat cultivars, Psy-B1a, Psy-B1b, Psy-B1d and a further allelic variant, Psy-B1e, were detected with frequencies of 50.6, 29.2, 19.6 and 0.6%, respectively. Psy-B1c was not found in the CIMMYT germplasm. However, no significant differences were detected for mean YP content among CIMMYT wheat lines with different Psy-B1 genotypes. A new allelic variant of Psy-A1, designated Psy-A1c, was identified in three CIMMYT wheat lines, and this allele was associated with higher YP content.

Cloning and phylogenetic analysis of polyphenol oxidase (PPO) genes in common wheat and its relatives would greatly advance the understanding of molecular mechanisms of grain PPO activity. In the present study, six wheat relative species, including T. urartu, T. boeoticum, T. monococcum, T. dicoccoides, T. durum and Ae. tauschii, were sampled to isolate new alleles at Ppo-A1 and Ppo-D1 loci corresponding to common wheat PPO genes, and seven new alleles were identified from these species, which were designated as Ppo-A1c (from T. urartu), Ppo-A1d (T. boeoticum), Ppo-A1e (T. monococcum and T. durum), Ppo-A1f (T. dicoccoides), Ppo-A1g (T. durum), Ppo-D1c (Ae. tauschii) and Ppo-D1d (Ae. tauschii), respectively. Five out of the seven alleles detected in the wheat relatives contained an open reading frame (ORF) of 1,731 bp, encoding a polypeptide of 577 residues, which is the same as those of Ppo-A1 and Ppo-D1 genes in common wheat, whereas, the full-length ORF of the allele Ppo-A1g from T. durum was not obtained, and a 73-bp deletion occurred in the third exon of Ppo-D1d, an allele from Ae. tauschii, resulting in a shorter polypeptide of 466 amino acids. The 191-bp insertion in the first intron reported previously in common wheat was also found in T. dicoccoides lines, implying that more than one tetraploid wheat lines may be involved in the origination of common wheat. Phylogenetic trees were constructed using the genomic DNA sequences of the seven alleles, together with four from common wheat and four partial PPO gene sequences deposited in GenBank. The genome tribe A was divided into two clusters, one of which contained Ppo-A1d and Ppo-A1e, and the other included the remaining five alleles at Ppo-A1 locus. The alleles from different clusters showed high sequence divergences, indicated by dozens of SNPs and five to six InDels. The genome tribe D comprised the alleles Ppo-D1a, Ppo-D1c, Ppo-D1d and Ppo-D1b, and the former three were clustered together, showing significant sequence divergence from Ppo-D1b. In addition, the relationships between these allelic variants and grain PPO activities were also discussed.

Polyphenol oxidase (PPO) activity is highly related to the undesirable browning of wheat-based end products, especially Asian noodles. Characterization of PPO genes and the development of their functional markers are of great importance for marker-assisted selection in wheat breeding. In the present study, complete genomic DNA sequences of two PPO genes, one each located on chromosomes 2A and 2D and their allelic variants were characterized by means of in silico cloning and experimental validation. Sequences were aligned at both DNA and protein levels. Two haplotypes on chromosome 2D showed 95.2% sequence identity at the DNA level, indicating much more sequence diversity than those on chromosome 2A with 99.6% sequence identity. Both of the PPO genes on chromosomes 2A and 2D contain an open reading frame (ORF) of 1,731 bp, encoding a PPO precursor peptide of 577 amino acids with a predicted molecular mass of approximately 64 kD. Two complementary dominant STS markers, PPO16 and PPO29, were developed based on the PPO gene haplotypes located on chromosome 2D; they amplify a 713-bp fragment in cultivars with low PPO activity and a 490-bp fragment in those with high PPO activity, respectively. The two markers were mapped on chromosome 2DL using a doubled haploid population derived from the cross Zhongyou 9507/CA9632, and a set of nullisomic-tetrasomic lines and ditelosomic line 2DS of Chinese Spring. QTL analysis indicated that the PPO gene co-segregated with the two STS markers and was closely linked to SSR marker Xwmc41 on chromosome 2DL, explaining from 9.6 to 24.4% of the phenotypic variance for PPO activity across three environments. In order to simultaneously detect PPO loci on chromosomes 2A and 2D, a multiplexed marker combination PPO33/PPO16 was developed and yielded distinguishable DNA patterns in a number of cultivars. The STS marker PPO33 for the PPO gene on chromosome 2A was developed from the same gene sequences as PPO18 that we reported previously, and can amplify a 481-bp and a 290-bp fragment from cultivars with low and high PPO activity, respectively. A total of 217 Chinese wheat cultivars and advanced lines were used to validate the association between the polymorphic fragments and grain PPO activity. The results showed that the marker combination PPO33/PPO16 is efficient and reliable for evaluating PPO activity and can be used in wheat breeding programs aimed for noodle and other end product quality improvement.