Search

Endophytes, which are widely found in host plants and have no harmful effects, are a vital biological resource. Plant endophytes promote plant growth and enhance plants' resistance to diseases, pests, and environmental stresses. In addition, they enhance the synthesis of important secondary metabolites in plants and improve the potential applicability of plants in agriculture, medicine, food, and horticulture. In this review, we summarize the recent progress in understanding the interaction between endophytes and plants and summarize the construction of synthetic microbial communities (SynComs) and metaomics analysis of the interaction between endophytes and plants. The application and development prospects of endophytes in agriculture, medicine, and other industries are also discussed to provide a reference for further study of the interaction between endophytes and plants and further development and utilization of endophytes. [ABSTRACT FROM AUTHOR]

To screen the genes regulating the biosynthesis of phenolic acid derivatives from the genome of Bletilla striata , we designed a suspension culture system to sample the cells for the following experiments. The contents of four phenolic acid derivatives were determined by high-performance liquid chromatography, and several full-length transcriptome sequencings of RNA samples at 10 time points were performed for bioinformatics analysis. The correlation analysis was used to identify and verify the key DEGs involved in the biosynthesis of the four phenolic acid derivatives. The results showed that the contents of p-hydroxybenzylalcohol (HBA), Dactylorhin A, Militarine, and Coelonin peaked at 33 days postinoculation (Dpi), 18 Dpi, 39 Dpi, and 39 Dpi of the culture system, respectively. Based on transcriptome data, 80 DEGs involved in the biosynthesis of phenolic acid derivatives were obtained. The KEGG pathway enrichment analysis classified them mostly into five metabolic pathways: phenylpropane biosynthesis, starch and sucrose metabolic, cyanoamino acid metabolism, gluconeogenesis and glycolysis, and phenylalanine metabolism. qPCR analysis revealed that the relative gene expression levels were consistent with the overall trend of transcriptome sequencing results. Among them, 14, 18, 23, and 41 unigenes were found to be involved in the synthesis of HBA, Dactylorhin A, Coelonin, and Militarine, respectively. These unigenes laid a solid foundation for elucidating the biosynthesis mechanism of phenolic acid derivatives in suspension cells of B. striata. [ABSTRACT FROM AUTHOR]

Wheat is one of the most important cereal crops worldwide. A consensus map combines genetic information from multiple populations, providing an effective alternative to improve the genome coverage and marker density. In this study, we constructed a consensus map from three populations of recombinant inbred lines (RILs) of wheat using a 90K single nucleotide polymorphism (SNP) array. Phenotypic data on plant height (PH), spike length (SL), and thousand-kernel weight (TKW) was collected in six, four, and four environments in the three populations, and then used for quantitative trait locus (QTL) mapping. The mapping results obtained using the constructed consensus map were compared with previous results obtained using individual maps and previous studies on other populations. A simulation experiment was also conducted to assess the performance of QTL mapping with the consensus map. The constructed consensus map from the three populations spanned 4558.55 cM in length, with 25,667 SNPs, having high collinearity with physical map and individual maps. Based on the consensus map, 21, 27, and 19 stable QTLs were identified for PH, SL, and TKW, much more than those detected with individual maps. Four PH QTLs and six SL QTLs were likely to be novel. A putative gene called TraesCS4D02G076400 encoding gibberellin-regulated protein was identified to be the candidate gene for one major PH QTL located on 4DS, which may enrich genetic resources in wheat semi-dwarfing breeding. The simulation results indicated that the length of the confidence interval and standard errors of the QTLs detected using the consensus map were much smaller than those detected using individual maps. The consensus map constructed in this study provides the underlying genetic information for systematic mapping, comparison, and clustering of QTL, and gene discovery in wheat genetic study. The QTLs detected in this study had stable effects across environments and can be used to improve the wide adaptation of wheat cultivars through marker-assisted breeding. [ABSTRACT FROM AUTHOR]

Among yield contributing traits, the contribution of canopy activity related traits has been less studied. In this study, quantitative trait loci (QTL) for the normalized difference vegetation index (NDVI) at the seedling (NDVI-S) and grain filling (NDVI-10) stages and the chlorophyll (Chl) content at the grain filling stage (Chl-10) were mapped using three recombinant inbred line (RIL) populations of wheat derived from the following crosses: Doumai × Shi 4185 (D × S), Gaocheng 8901 × Zhoumai 16 (G × Z) and Linmai 2 × Zhong 892 (L × Z). In the three RIL populations, 6, 16 and 14 QTL were identified for NDVI-S, NDVI-10 and Chl-10, respectively. Furthermore, 6, 10 and 10 of the QTL were newly detected. Three QTL QNDVI-10.caas-4BS, QNDVI-10.caas-4DS and QChl-10.caas-4BS, were commonly detected in two populations. Twelve QTL clusters for both canopy activity related traits in the present study and grain yield (GY) related traits in our previous study were identified. NDVI-S is phenotypically and genetically correlated with thousand-kernel weight (TKW), which can be used to select lines with a high TKW. The QTL clusters harbouring QTL for canopy activity related traits and GY related traits are valuable in marker-assisted selection (MAS) of loci with pleiotropic effects. In addition, the stable QTL QNDVI-S.caas-1AL and QNDVI-10.caas-3B can be used to identify high NDVI lines at the seedling and grain filling stages, respectively. Our study provided new insight into the genetic architecture of the GY based on canopy activity related traits. [ABSTRACT FROM AUTHOR]

Background: Bletilla striata has been widely used in the pharmacology industry. To effectively produce the secondary metabolites through suspension cultured cells of B. striata , it is important to exploring the full-length transcriptome data and the genes related to cell growth and chemical producing of all culture stages. We applied a combination of Real-Time Sequencing of Single Molecule (SMRT) and second-generation sequencing (SGS) to generate the complete and full-length transcriptome of B. striata suspension cultured cells. Methods: The B. striata transcriptome was formed in de novo way by using PacBio isoform sequencing (Iso-Seq) on a pooled RNA sample derived from 23 samples of 10 culture stages, to explore the potential for capturing full-length transcript isoforms. All unigenes were obtained after splicing, assembling, and clustering, and corrected by the SGS results. The obtained unigenes were compared with the databases, and the functions were annotated and classified. Results and conclusions: A total of 100,276 high-quality full-length transcripts were obtained, with an average length of 2530 bp and an N50 of 3302 bp. About 52% of total sequences were annotated against the Gene Ontology, 53,316 unigenes were hit by KOG annotations and divided into 26 functional categories, 80,020 unigenes were mapped by KEGG annotations and clustered into 363 pathways. Furthermore, 15,133 long-chain non-coding RNAs (lncRNAs) were detected. And 68,996 coding sequences were identified based on SSR analysis, among which 31 pairs of primers selected at random were amplified and obtained stable bands. In conclusion, our results provide new full-length transcriptome data and genetic resources for identifying growth and metabolism-related genes, which provide a solid foundation for further research on its growth regulation mechanisms and genetic engineering breeding mechanisms of B. striata. [ABSTRACT FROM AUTHOR]

Key message: We developed and validated 56 gene-specific semi-thermal asymmetric reverse PCR (STARP) markers for 46 genes of important wheat quality, biotic and abiotic stress resistance, grain yield, and adaptation-related traits for marker-assisted selection in wheat breeding. Development of high-throughput, low-cost, gene-specific molecular markers is important for marker-assisted selection in wheat breeding. In this study, we developed 56 gene-specific semi-thermal asymmetric reverse PCR (STARP) markers for wheat quality, tolerance to biotic and abiotic stresses, grain yield, and adaptation-related traits. The STARP assays were validated by (1) comparison of the assays with corresponding diagnostic STS/CAPS markers on 40 diverse wheat cultivars and (2) characterization of allelic effects based on the phenotypic and genotypic data of three segregating populations and 305 diverse wheat accessions from China and 13 other countries. The STARP assays showed the advantages of high-throughput, accuracy, flexibility, simple assay design, low operational costs, and platform compatibility. The state-of-the-art assays of this study provide a robust and reliable molecular marker toolkit for wheat breeding programs. [ABSTRACT FROM AUTHOR]

The primary cause of time‐dependent discoloration in wheat (Triticum aestivum L.)‐based products is polyphenol oxidase (PPO) activity. A comprehensive genetic characterization of PPO activity in wheat could expedite the development of wheat varieties with low PPO activity. To dissect the genetic architecture of PPO activity in wheat flour, a panel of 166 diverse bread wheat cultivars was phenotyped in four different environments and genotyped by high‐density wheat 90K and 660K arrays. A genome‐wide association study (GWAS) was performed by a mixed linear model that incorporated population structure and relative kinship. Four hundred and sixty‐five stable marker–trait associations representative of 43 quantitative trait loci (QTL) for PPO activity identified in at least two environments were located on all wheat chromosomes except 5A, with each explaining 6.6–32.4% of the phenotypic variance. Based on IWGSC RefSeq v1.0, we found that QPPO2A.3, QPPO2B.1, QPPO2B.2, and QPPO2D.2 were consistent with the previously reported QTL, and 12 QTL located on homoeologous group 1 chromosomes (6 QTL), chromosomes 4B, 4D, and 7A (2 QTL), and chromosome 7B (2 QTL) are likely to be new PPO loci. Based on physical positions of QTL and previous studies, Ppo‐A1, Ppo‐A2, Ppo‐B2, Ppo‐D2, Pinb‐D1, and genes encoding a Cu ion‐binding protein and a Cu‐transporting ATPase RAN1‐like protein were considered as candidates for QPPO2A.3, QPPO2B.1, QPPO2D.2, QPPO5D.1, QPPO4A.2, and QPPO7D.2, respectively. This study provided insights into the molecular basis of wheat PPO activity, and associated markers can be used for selection of low PPO breeding lines as a means of improving the marketing quality of wheat products. [ABSTRACT FROM AUTHOR]

Key message: Genetic dissection uncovered a major QTL QTKW.caas-4BS corresponding with a 483 kb deletion that included genes ZnF, EamA and Rht-B1. This deletion was associated with increased grain weight and semi-dwarf phenotype. Previous studies identified quantitative trait loci (QTL) for thousand kernel weight (TKW) in the region spanning the Rht-B1 locus in wheat (Triticum aestivum L.). We recently mapped a major QTL QTKW.caas-4BS for TKW spanning the Rht-B1 locus in a recombinant inbred line (RIL) population derived from Doumai/Shi 4185 using the wheat 90K array. The allele from Doumai at QTKW.caas-4BS significantly increased TKW and kernel number per spike, and conferred semi-dwarf trait, which was beneficial to improve grain yield without a penalty to lodging. To further dissect QTKW.caas-4BS, we firstly re-investigated the genotypes and phenotypes of the RILs and confirmed the QTL using cleaved amplified polymorphic sequence (CAPS) markers developed from flanking SNP markers IWA102 and IWB54814. The target sequences of the CAPS markers were used as queries to BLAST the wheat reference genome RefSeq v1.0 and hit an approximate 10.4 Mb genomic region. Based on genomic mining and SNP loci from the wheat 660K SNP array in the above genomic region, we developed eight new markers and narrowed QTKW.caas-4BS to a genetic interval of 1.5 cM. A 483 kb deletion in Doumai corresponded with QTKW.caas-4BS genetically, including three genes ZnF, EamA and Rht-B1. The other 15 genes with either differential expressions and/or sequence variations between parents were also potential candidate genes for QTKW.caas-4BS. The findings not only provide a toolkit for marker-assisted selection of QTKW.caas-4BS but also defined candidate genes for further functional analysis. [ABSTRACT FROM AUTHOR]

Key message: Genetic diversity, population structure, LD decay, and selective sweeps in 687 wheat accessions were analyzed, providing relevant guidelines to facilitate the use of the germplasm in wheat breeding. Common wheat (Triticum aestivum L.) is one of the most widely grown crops in the world. Landraces were subjected to strong human-mediated selection in developing high-yielding, good quality, and widely adapted cultivars. To investigate the genome-wide patterns of allelic variation, population structure and patterns of selective sweeps during modern wheat breeding, we tested 687 wheat accessions, including landraces (148) and cultivars (539) mainly from China and Pakistan in a wheat 90 K single nucleotide polymorphism array. Population structure analysis revealed that cultivars and landraces from China and Pakistan comprised three relatively independent genetic clusters. Cultivars displayed lower nucleotide diversity and a wider average LD decay across whole genome, indicating allelic erosion and a diversity bottleneck due to the modern breeding. Analysis of genetic differentiation between landraces and cultivars from China and Pakistan identified allelic variants subjected to selection during modern breeding. In total, 477 unique genome regions showed signatures of selection, where 109 were identified in both China and Pakistan germplasm. The majority of genomic regions were located in the B genome (225), followed by the A genome (175), and only 77 regions were located in the D genome. EigenGWAS was further used to identify key selection loci in modern wheat cultivars from China and Pakistan by comparing with global winter wheat and spring wheat diversity panels, respectively. A few known functional genes or loci found within these genome regions corresponded to known phenotypes for disease resistance, vernalization, quality, adaptability and yield-related traits. This study uncovered molecular footprints of modern wheat breeding and explained the genetic basis of polygenic adaptation in wheat. The results will be useful for understanding targets of modern wheat breeding, and in devising future breeding strategies to target beneficial alleles currently not pursued. [ABSTRACT FROM AUTHOR]

Key message: We identified 21 new and stable QTL, and 11 QTL clusters for yield-related traits in three bread wheat populations using the wheat 90 K SNP assay.Abstract: Identification of quantitative trait loci (QTL) for yield-related traits and closely linked molecular markers is important in order to identify gene/QTL for marker-assisted selection (MAS) in wheat breeding. The objectives of the present study were to identify QTL for yield-related traits and dissect the relationships among different traits in three wheat recombinant inbred line (RIL) populations derived from crosses Doumai × Shi 4185 (D × S), Gaocheng 8901 × Zhoumai 16 (G × Z) and Linmai 2 × Zhong 892 (L × Z). Using the available high-density linkage maps previously constructed with the wheat 90 K iSelect single nucleotide polymorphism (SNP) array, 65, 46 and 53 QTL for 12 traits were identified in the three RIL populations, respectively. Among them, 34, 23 and 27 were likely to be new QTL. Eighteen common QTL were detected across two or three populations. Eleven QTL clusters harboring multiple QTL were detected in different populations, and the interval 15.5-32.3 cM around the Rht-B1 locus on chromosome 4BS harboring 20 QTL is an important region determining grain yield (GY). Thousand-kernel weight (TKW) is significantly affected by kernel width and plant height (PH), whereas flag leaf width can be used to select lines with large kernel number per spike. Eleven candidate genes were identified, including eight cloned genes for kernel, heading date (HD) and PH-related traits as well as predicted genes for TKW, spike length and HD. The closest SNP markers of stable QTL or QTL clusters can be used for MAS in wheat breeding using kompetitive allele-specific PCR or semi-thermal asymmetric reverse PCR assays for improvement of GY. [ABSTRACT FROM AUTHOR]

Trehalose 6-phosphate phosphatase ( TPP) dephosphorylates trehalose 6-phosphate to trehalose, an important growth regulator, and is involved in starch accumulation and grain yield. In this study, wheat TPP homologs were isolated from chromosomes 6AL, 6BL, and 6DL, designated as TaTPP- 6AL1, TaTPP- 6BL1, and TaTPP-6DL1, respectively. Sequence alignment showed a single-nucleotide polymorphism (SNP) at TaTPP- 6AL1 locus between cultivars with contrasting thousand grain weight (TGW), forming alleles TaTPP- 6AL1a and TaTPP- 6AL1b, respectively. A cleaved amplified polymorphic sequence (CAPS) marker, TaTPP- 6AL1-CAPS, was developed to differentiate the two alleles. TaTPP- 6AL1 was mapped within the interval of IWB65749 and IWB60449 in a recombinant inbred line (RIL) population derived from Zhou8425B/Chinese Spring using the wheat 90K SNP assay. A QTL for TGW identified in the interval explained 12.1 -19.1% of the phenotypic variance across five environments. Association analysis on 141 Chinese wheat cultivars also indicated a significant correlation of TaTPP- 6AL1 with TGW. In conclusion, TaTPP- 6AL1 and its functional marker are valuable to improve grain yield in wheat breeding. [ABSTRACT FROM AUTHOR]

Early flowering 3 (ELF3) is a regulator to modulate photoperiod flowering in Arabidopsis. The homologs of ELF3 in rice and barley also have been identified essential for regulation of flowering time. In the current study, TaELF3 genes, homologs of ELF3 in bread wheat (Triticum aestivum L.), were cloned by a comparative genomics approach and located on homologous group 1 chromosomes, designated as TaELF3-1AL, TaELF3-1BL, and TaELF3-1DL, respectively. A sequence-tagged site (STS) marker was developed based on sequence polymorphism at the TaELF3-1DL locus. A quantitative trait locus (QTL) for heading date (HD) co-segregating with TaELF3-1DL explained 7.7–20.6% of the phenotypic variance in a RIL mapping population derived from the Gaocheng 8901/Zhoumai 16 cross genotyped using the wheat 90K iSelect assay. The late HD allele of TaELF3-1DL was prevalently selected in China’s specific wheat-growing regions and other countries. This study produces novel information in better understanding HD and provides a reliable functional marker for molecular marker-assisted selection in wheat breeding. [ABSTRACT FROM AUTHOR]

Key message : Nine QTL for black point resistance in wheat were identified using a RIL population derived from a Linmai 2/Zhong 892 cross and 90K SNP assay. Abstract: Black point, discoloration of the embryo end of the grain, downgrades wheat grain quality leading to significant economic losses to the wheat industry. The availability of molecular markers will accelerate improvement of black point resistance in wheat breeding. The aims of this study were to identify quantitative trait loci (QTL) for black point resistance and tightly linked molecular markers, and to search for candidate genes using a high-density genetic linkage map of wheat. A recombinant inbred line (RIL) population derived from the cross Linmai 2/Zhong 892 was evaluated for black point reaction during the 2011-2012, 2012-2013 and 2013-2014 cropping seasons, providing data for seven environments. A high-density linkage map was constructed by genotyping the RILs with the wheat 90K single nucleotide polymorphism (SNP) chip. Composite interval mapping detected nine QTL on chromosomes 2AL, 2BL, 3AL, 3BL, 5AS, 6A, 7AL (2) and 7BS, designated as QBp.caas- 2AL, QBp.caas- 2BL, QBp.caas- 3AL, QBp.caas- 3BL, QBp.caas- 5AS, QBp.caas- 6A, QBp.caas- 7AL.1, QBp.caas- 7AL.2 and QBp.caas- 7BS, respectively. All resistance alleles, except for QBp.caas- 7AL.1 from Linmai 2, were contributed by Zhong 892. QBp.caas- 3BL, QBp.caas- 5AS, QBp.caas- 7AL.1, QBp.caas- 7AL.2 and QBp.caas- 7BS probably represent new loci for black point resistance. Sequences of tightly linked SNPs were used to survey wheat and related cereal genomes identifying three candidate genes for black point resistance. The tightly linked SNP markers can be used in marker-assisted breeding in combination with the kompetitive allele specific PCR technique to improve black point resistance. [ABSTRACT FROM AUTHOR]

Water soluble carbohydrates (WSC) in stems play an important role in buffering grain yield in wheat against biotic and abiotic stresses; however, knowledge of genes controlling WSC is very limited. We conducted a genome-wide association study (GWAS) using a high-density 90K SNP array to better understand the genetic basis underlying WSC, and to explore marker-based breeding approaches. WSC was evaluated in an association panel comprising 166 Chinese bread wheat cultivars planted in four environments. Fifty two marker-trait associations (MTAs) distributed across 23 loci were identified for phenotypic best linear unbiased estimates (BLUEs), and 11 MTAs were identified in two or more environments. Liner regression showed a clear dependence of WSC BLUE scores on numbers of favorable (increasing WSC content) and unfavorable alleles (decreasing WSC), indicating that genotypes with higher numbers of favorable or lower numbers of unfavorable alleles had higher WSC content. In silico analysis of flanking sequences of trait-associated SNPs revealed eight candidate genes related to WSC content grouped into two categories based on the type of encoding proteins, namely, defense response proteins and proteins triggered by environmental stresses. The identified SNPs and candidate genes related to WSC provide opportunities for breeding higher WSC wheat cultivars. [ABSTRACT FROM AUTHOR]

Key message : We developed and validated a robust marker toolkit for high-throughput and cost-effective screening of a large number of functional genes in wheat. Abstract: Functional markers (FMs) are the most valuable markers for crop breeding programs, and high-throughput genotyping for FMs could provide an excellent opportunity to effectively practice marker-assisted selection while breeding cultivars. Here we developed and validated kompetitive allele-specific PCR (KASP) assays for genes that underpin economically important traits in bread wheat including adaptability, grain yield, quality, and biotic and abiotic stress resistances. In total, 70 KASP assays either developed in this study or obtained from public databases were validated for reliability in application. The validation of KASP assays were conducted by (a) comparing the assays with available gel-based PCR markers on 23 diverse wheat accessions, (b) validation of the derived allelic information using phenotypes of a panel comprised of 300 diverse cultivars from China and 13 other countries, and (c) additional testing, where possible, of the assays in four segregating populations. All KASP assays being reported were significantly associated with the relevant phenotypes in the cultivars panel and bi-parental populations, thus revealing potential application in wheat breeding programs. The results revealed 45 times superiority of the KASP assays in speed than gel-based PCR markers. KASP has recently emerged as single-plex high-throughput genotyping technology; this is the first report on high-throughput screening of a large number of functional genes in a major crop. Such assays could greatly accelerate the characterization of crossing parents and advanced lines for marker-assisted selection and can complement the inflexible, high-density SNP arrays. Our results offer a robust and reliable molecular marker toolkit that can contribute towards maximizing genetic gains in wheat breeding programs. [ABSTRACT FROM AUTHOR]

Key message: We cloned TaSST genes, developed a gene-specific marker for TaSST - D1 , and identified three QTL in the Doumai/Shi 4185 RIL population. TaSST - D1 is within one of the three QTL. Abstract: Sucrose:sucrose-1-fructosyltransferase (1-SST), a critical enzyme in the fructan biosynthetic pathway, is significantly and positively associated with water soluble carbohydrate (WSC) content in bread wheat stems. In the present study, wheat 1-SST genes ( TaSST) were isolated and located on chromosomes 4A, 7A and 7D. Sequence analysis of TaSST- D1 revealed 15 single nucleotide polymorphisms (SNP) in the third exon between cultivars with higher and lower WSC content. A cleaved amplified polymorphism sequence (CAPS) marker, WSC7D, based on the polymorphism at position 1216 (C-G) was developed to discriminate the two alleles. WSC7D was located on chromosome 7DS using a recombinant inbred line (RIL) population from a Doumai/Shi 4185 cross, and a set of Chinese Spring nullisomic-tetrasomic lines. TaSST- D1 co-segregated with the CAPS marker WSC7D and was linked to SNP marker BS00108793_51 on chromosome 7DS at a genetic distance of 6.1 cM. It explained 8.8, 10.9, and 11.3 % of the phenotypic variances in trials at Beijing and Shijiazhuang as well as the averaged data from those environments, respectively. Two additional QTL ( QWSC.caas- 4BS and QWSC.caas- 7AS) besides TaSST- D1 were mapped in the RIL population. One hundred and forty-nine Chinese wheat cultivars and advanced lines tested in four environments were used to validate a highly significant ( P < 0.01) association between WSC7D and WSC content in wheat stems. WSC7D can be used as a gene-specific marker for improvement of stem WSC content in wheat breeding programs. [ABSTRACT FROM AUTHOR]

Key message: Fifty-six QTL for flour color-related traits and polyphenol oxidase activity were identified using a genome-wide linkage mapping of data from a RIL population derived from a Gaocheng 8901/Zhoumai 16 cross. Abstract: Flour color-related traits, including L*, a*, b*, yellow pigment content (YPC), and polyphenol oxidase (PPO) activity are important parameters influencing the quality of wheat end-use products. Mapping quantitative trait loci (QTL) for these traits and characterization of candidate genes are important for improving wheat quality. The aims of this study were to identify QTL for flour color-related traits and PPO activity and to characterize candidate genes using a high-density genetic linkage map in a common wheat recombinant inbred line (RIL) population derived from a cross between Gaocheng 8901 and Zhoumai 16. A linkage map was constructed by genotyping the RILs with the wheat 90 K iSelect array. Fifty-six QTL were mapped on 35 chromosome regions on homoeologous groups 1, 2, 5 and 7 chromosomes, and chromosomes 3B, 4A, 4B and 6B. Four QTL were for PPO activity, and the others were for flour color-related traits. Compared with previous studies, five QTL for a*, two for b*, one for L*, one for YPC and one for PPO activity were new. The new QTL on chromosome 2DL was involved in both a* and YPC, and another on chromosome 7DS affected both a* and L*. The scan for SNP sequences tightly linked to QTL for flour color-related traits against the wheat and/or related cereals genomes identified six candidate genes significantly related to these traits, and five of them were associated with the terpenoid backbone biosynthesis pathway. The high-density genetic linkage map of Gaocheng 8901/Zhoumai 16 represents a useful tool to identify QTL for important quality traits and candidate genes. [ABSTRACT FROM AUTHOR]

The TGW6 gene encodes a novel indole-3-acetic acid-glucose hydrolase and plays a significant role in improving thousand grain weight (TGW) and yield in rice. In the current study, a TGW6 ortholog from bread wheat chromosome 3AL was isolated and designated as TaTGW6-A1. Sequencing and alignment analysis showed that the cloned TaTGW6-A1 consists of a 987-bp intronless open reading frame. Three single-nucleotide polymorphisms (SNPs) were identified between cultivars with higher and lower TGW, forming two haplotypes, TaTGW6-A1a and TaTGW6-A1b. A derived cleaved amplified polymorphic sequence marker, TaTGW6-A1-CAPS, was developed to differentiate the two haplotypes. Linkage analysis using the wheat 90K iSelect SNP array mapped TaTGW6-A1-CAPS at 18 cM from BobWhite_c47304_56 in a RIL population derived from Zhou 8425B/Chinese Spring. A QTL for yield at the TaTGW6-A1 locus explained 17.4 % of the phenotypic variance in average yield over four environments. Association analysis on 242 Chinese and foreign cultivars indicated that TaTGW6-A1 was significantly associated with TGW. The cumulative frequency of the TaTGW6-A1a allele associated with higher TGW was approximately 80 %, indicating that the TaTGW6-A1a allele was positively selected in wheat breeding. In conclusion, TaTGW6-A1 in conjunction with its molecular marker may contribute as a valuable gene in improving yield potential in wheat. [ABSTRACT FROM AUTHOR]

Stripe rust is one of the most devastating diseases of wheat (Triticum aestivum) worldwide. Adult-plant resistance (APR) is an efficient approach to provide long-term protection of wheat from the disease. The Chinese winter wheat cultivar Zhong 892 has a moderate level of APR to stripe rust in the field. To determine the inheritance of the APR resistance in this cultivar, 273 F6 recombinant inbred lines (RILs) were developed from a cross between Linmai 2 and Zhong 892. The RILs were evaluated for maximum disease severity (MDS) in two sites during the 2011–2012, 2012–2013 and 2013–2014 cropping seasons, providing data for five environments. Illumina 90k SNP (single nucleotide polymorphism) chips were used to genotype the RILs and their parents. Composite interval mapping (CIM) detected eight QTL, namely QYr.caas-2AL, QYr.caas-2BL.3, QYr.caas-3AS, QYr.caas-3BS, QYr.caas-5DL, QYr.caas-6AL, QYr.caas-7AL and QYr.caas-7DS.1, respectively. All except QYr.caas-2BL.3 resistance alleles were contributed by Zhong 892. QYr.caas-3AS and QYr.caas-3BS conferred stable resistance to stripe rust in all environments, explaining 6.2–17.4% and 5.0–11.5% of the phenotypic variances, respectively. The genome scan of SNP sequences tightly linked to QTL for APR against annotated proteins in wheat and related cereals genomes identified two candidate genes (autophagy-related gene and disease resistance gene RGA1), significantly associated with stripe rust resistance. These QTL and their closely linked SNP markers, in combination with kompetitive allele specific PCR (KASP) technology, are potentially useful for improving stripe rust resistances in wheat breeding. [ABSTRACT FROM AUTHOR]

Key message: Three novel QTL for peroxidase activity were mapped, and gene-specific markers for TaPod-A1 were developed and validated using RILs derived from the Doumai/Shi 4185 cross and 281 wheat cultivars. TaPod-A1 is within one of the three QTL. Abstract: Peroxidase (POD) activity in grain is an important factor determining the color of flour and end-use products of wheat, such as noodles and steamed bread. Mapping QTL for POD activity, characterization of POD genes and development of gene-specific markers are important for molecular marker-assisted selection in wheat breeding. Quantitative trait loci (QTL) for POD activity in common wheat were mapped using a recombinant inbred line (RIL) population derived from a Doumai/Shi 4185 cross grown in four environments and genotyped using the wheat 90 K iSelect assay. Three novel QTL for POD activity, QPod.caas- 3AL, QPod.caas- 4BS and QPod.caas- 5AS, were identified on chromosomes 3AL, 4BS and 5AS, explaining 5.3-21.2 % of phenotypic variance across environments. The full-length genomic DNA (gDNA) sequence of a POD gene, designated TaPod- A1, on chromosome 3A was characterized by homolog cloning and PCR verification. Two complementary dominant sequence-tagged site (STS) markers, POD-3A1 and POD-3A2, were developed based on single nucleotide polymorphisms (SNPs) between two alleles at the TaPod- A1 locus, amplifying 291- and 766-bp fragments in cultivars with lower and higher POD activities, respectively. The two gene-specific markers were mapped on chromosome 3AL using a set of Chinese Spring (CS) nulli-tetrasomic lines, and ditelosomic lines 3AL and 3AS. QTL analysis indicated that QPod.caas- 3AL co-segregated with the gene-specific markers POD-3A1 and POD-3A2. POD-3A1 and POD-3A2 were verified on 281 wheat cultivars and advanced lines, and showed significant ( P < 0.05) associations with POD activities. POD-3A1 and POD-3A2 may be useful as markers for improving color attributes in wheat breeding programs. [ABSTRACT FROM AUTHOR]

Background: Identification of loci for grain yield (GY) and related traits, and dissection of the genetic architecture are important for yield improvement through marker-assisted selection (MAS). Two genome-wide association study (GWAS) methods were used on a diverse panel of 166 elite wheat varieties from the Yellow and Huai River Valleys Wheat Zone (YHRVWD) of China to detect stable loci and analyze relationships among GY and related traits. Results: A total of 326,570 single nucleotide polymorphism (SNP) markers from the wheat 90 K and 660 K SNP arrays were chosen for GWAS of GY and related traits, generating a physical distance of 14,064.8 Mb. One hundred and twenty common loci were detected using SNP-GWAS and Haplotype-GWAS, among which two were potentially functional genes underpinning kernel weight and plant height (PH), eight were at similar locations to the quantitative trait loci (QTL) identified in recombinant inbred line (RIL) populations in a previous study, and 78 were potentially new. Twelve pleiotropic loci were detected on eight chromosomes; among these the interval 714.4–725.8 Mb on chromosome 3A was significantly associated with GY, kernel number per spike (KNS), kernel width (KW), spike dry weight (SDW), PH, uppermost internode length (UIL), and flag leaf length (FLL). GY shared five loci with thousand kernel weight (TKW) and PH, indicating significantly affected by two traits. Compared with the total number of loci for each trait in the diverse panel, the average number of alleles for increasing phenotypic values of GY, TKW, kernel length (KL), KW, and flag leaf width (FLW) were higher, whereas the numbers for PH, UIL and FLL were lower. There were significant additive effects for each trait when favorable alleles were combined. UIL and FLL can be directly used for selecting high-yielding varieties, whereas FLW can be used to select spike number per unit area (SN) and KNS. Conclusions: The loci and significant SNP markers identified in the present study can be used for pyramiding favorable alleles in developing high-yielding varieties. Our study proved that both GWAS methods and high-density genetic markers are reliable means of identifying loci for GY and related traits, and provided new insight to the genetic architecture of GY. [ABSTRACT FROM AUTHOR]