The Experts below are selected from a list of 627 Experts worldwide ranked by ideXlab platform

Ian Dundas - One of the best experts on this subject based on the ideXlab platform.

  • transfer to wheat of potentially new stem rust resistance genes from Aegilops speltoides
    2015
    Co-Authors: Ian Dundas, Yue Jin, Dawn Verlin, Peng Zhang, J Manisterski, Rafiqul Islam
    Abstract:

    Stem rust resistance genes have been found in four different sources of Aegilops speltoides. These include diploid accessions AEG357-4 and AEG874-60 and the amphiploids Chinese Spring/Ae. speltoides TA8026 and TS01. Stem rust resistance was mapped to the 2S chromosomes derived from each of these lines. The previously reported 2B-2S#3 translocation derived from AEG357-4 was found to carry two stem rust resistance genes, here temporarily named SrAes2t and SrAes3t. The resistance genes found on the 2S chromosomes each derived from TA8026, TS01 and AEG874-60 are named SrAes4t, SrAes5t and SrAes6t, respectively. Lines carrying genes SrAes2t and SrAes3t are being distributed to wheat breeding programs around the world.

  • development of wheat Aegilops speltoides recombinants and simple pcr based markers for sr32 and a new stem rust resistance gene on the 2s 1 chromosome
    Theoretical and Applied Genetics, 2013
    Co-Authors: Rohit Mago, Yue Jin, Dawn Verlin, Peng Zhang, Urmil Bansal, H S Bariana, Jeffrey G Ellis, Sami Hoxha, Ian Dundas
    Abstract:

    Key message Wheat– Aegilops speltoides recombinants carrying stem rust resistance genes Sr32 and SrAes1t effective against Ug99 and PCR markers for marker-assisted selection.

  • development of wheat Aegilops speltoides recombinants and simple pcr based markers for sr32 and a new stem rust resistance gene on the 2s 1 chromosome
    Theoretical and Applied Genetics, 2013
    Co-Authors: Rohit Mago, Yue Jin, Dawn Verlin, Peng Zhang, Urmil Bansal, H S Bariana, Jeffrey G Ellis, Sami Hoxha, Ian Dundas
    Abstract:

    Wheat– Aegilops speltoides recombinants carrying stem rust resistance genes Sr32 and SrAes1t effective against Ug99 and PCR markers for marker-assisted selection. Wild relatives of wheat are important resources for new rust resistance genes but underutilized because the valuable resistances are often linked to negative traits that prevent deployment of these genes in commercial wheats. Here, we report ph1b-induced recombinants with reduced alien chromatin derived from E.R. Sears’ wheat–Aegilops speltoides 2D-2S#1 translocation line C82.2, which carries the widely effective stem rust resistance gene Sr32. Infection type assessments of the recombinants showed that the original translocation in fact carries two stem rust resistance genes, Sr32 on the short arm and a previously undescribed gene SrAes1t on the long arm of chromosome 2S#1. Recombinants with substantially shortened alien chromatin were produced for both genes, which confer resistance to stem rust races in the TTKSK (Ug99) lineage and representative races of all Australian stem rust lineages. Selected recombinants were back crossed into adapted Australian cultivars and PCR markers were developed to facilitate the incorporation of these genes into future wheat varieties. Our recombinants and those from several other labs now show that Sr32, Sr39, and SrAes7t on the short arm and Sr47 and SrAes1t on the long arm of 2S#1 form two linkage groups and at present no rust races are described that can distinguish these resistance specificities.

  • development of wheat lines carrying stem rust resistance gene sr39 with reduced Aegilops speltoides chromatin and simple pcr markers for marker assisted selection
    Theoretical and Applied Genetics, 2009
    Co-Authors: Rohit Mago, Dawn Verlin, Peng Zhang, Urmil Bansal, H S Bariana, Jeffrey G Ellis, Ian Dundas
    Abstract:

    The use of major resistance genes is a cost-effective strategy for preventing stem rust epidemics in wheat crops. The stem rust resistance gene Sr39 provides resistance to all currently known pathotypes of Puccinia graminis f. sp. tritici (Pgt) including Ug99 (TTKSK) and was introgressed together with leaf rust resistance gene Lr35 conferring adult plant resistance to P. triticina (Pt), into wheat from Aegilops speltoides. It has not been used extensively in wheat breeding because of the presumed but as yet undocumented negative agronomic effects associated with Ae. speltoides chromatin. This investigation reports the production of a set of recombinants with shortened Ae. speltoides segments through induction of homoeologous recombination between the wheat and the Ae. speltoides chromosome. Simple PCR-based DNA markers were developed for resistant and susceptible genotypes (Sr39#22r and Sr39#50s) and validated across a set of recombinant lines and wheat cultivars. These markers will facilitate the pyramiding of ameliorated sources of Sr39 with other stem rust resistance genes that are effective against the Pgt pathotype TTKSK and its variants.

Yue Jin - One of the best experts on this subject based on the ideXlab platform.

  • physical mapping of dna markers linked to stem rust resistance gene sr47 in durum wheat
    Theoretical and Applied Genetics, 2017
    Co-Authors: Daryl L Klindworth, Justin D. Faris, Jyoti Saini, Yunming Long, Matthew N Rouse, Yue Jin
    Abstract:

    Key message Markers linked to stem rust resistance gene Sr47 were physically mapped in three small Aegilops speltoides chromosomal bins. Five markers, including two PCR-based SNP markers, were validated for marker-assisted selection.

  • transfer to wheat of potentially new stem rust resistance genes from Aegilops speltoides
    2015
    Co-Authors: Ian Dundas, Yue Jin, Dawn Verlin, Peng Zhang, J Manisterski, Rafiqul Islam
    Abstract:

    Stem rust resistance genes have been found in four different sources of Aegilops speltoides. These include diploid accessions AEG357-4 and AEG874-60 and the amphiploids Chinese Spring/Ae. speltoides TA8026 and TS01. Stem rust resistance was mapped to the 2S chromosomes derived from each of these lines. The previously reported 2B-2S#3 translocation derived from AEG357-4 was found to carry two stem rust resistance genes, here temporarily named SrAes2t and SrAes3t. The resistance genes found on the 2S chromosomes each derived from TA8026, TS01 and AEG874-60 are named SrAes4t, SrAes5t and SrAes6t, respectively. Lines carrying genes SrAes2t and SrAes3t are being distributed to wheat breeding programs around the world.

  • development of wheat Aegilops speltoides recombinants and simple pcr based markers for sr32 and a new stem rust resistance gene on the 2s 1 chromosome
    Theoretical and Applied Genetics, 2013
    Co-Authors: Rohit Mago, Yue Jin, Dawn Verlin, Peng Zhang, Urmil Bansal, H S Bariana, Jeffrey G Ellis, Sami Hoxha, Ian Dundas
    Abstract:

    Key message Wheat– Aegilops speltoides recombinants carrying stem rust resistance genes Sr32 and SrAes1t effective against Ug99 and PCR markers for marker-assisted selection.

  • development of wheat Aegilops speltoides recombinants and simple pcr based markers for sr32 and a new stem rust resistance gene on the 2s 1 chromosome
    Theoretical and Applied Genetics, 2013
    Co-Authors: Rohit Mago, Yue Jin, Dawn Verlin, Peng Zhang, Urmil Bansal, H S Bariana, Jeffrey G Ellis, Sami Hoxha, Ian Dundas
    Abstract:

    Wheat– Aegilops speltoides recombinants carrying stem rust resistance genes Sr32 and SrAes1t effective against Ug99 and PCR markers for marker-assisted selection. Wild relatives of wheat are important resources for new rust resistance genes but underutilized because the valuable resistances are often linked to negative traits that prevent deployment of these genes in commercial wheats. Here, we report ph1b-induced recombinants with reduced alien chromatin derived from E.R. Sears’ wheat–Aegilops speltoides 2D-2S#1 translocation line C82.2, which carries the widely effective stem rust resistance gene Sr32. Infection type assessments of the recombinants showed that the original translocation in fact carries two stem rust resistance genes, Sr32 on the short arm and a previously undescribed gene SrAes1t on the long arm of chromosome 2S#1. Recombinants with substantially shortened alien chromatin were produced for both genes, which confer resistance to stem rust races in the TTKSK (Ug99) lineage and representative races of all Australian stem rust lineages. Selected recombinants were back crossed into adapted Australian cultivars and PCR markers were developed to facilitate the incorporation of these genes into future wheat varieties. Our recombinants and those from several other labs now show that Sr32, Sr39, and SrAes7t on the short arm and Sr47 and SrAes1t on the long arm of 2S#1 form two linkage groups and at present no rust races are described that can distinguish these resistance specificities.

  • molecular and cytogenetic characterization of a durum wheat Aegilops speltoides chromosome translocation conferring resistance to stem rust
    Chromosome Research, 2008
    Co-Authors: Justin D. Faris, Xiwen Cai, Timothy L. Friesen, Yue Jin
    Abstract:

    Stem rust is a serious disease of wheat that has caused historical epidemics, but it has not been a threat in recent decades in North America owing to the eradication of the alternative host and deployment of resistant cultivars. However, the recent emergence of Ug99 (or race TTKS) poses a threat to global wheat production because most currently grown wheat varieties are susceptible. In this study, we evaluated a durum wheat–Aegilops speltoides chromosome translocation line (DAS15) for reaction to Ug99 and six other races of stem rust, and used molecular and cytogenetic tools to characterize the translocation. DAS15 was resistant to all seven races of stem rust. Two durum–Ae. speltoides translocated chromosomes were detected in DAS15. One translocation involved the short arm, centromere, and a major portion of the long arm of Ae. speltoides chromosome 2S and a small terminal segment from durum chromosome arm 2BL. Thus, this translocated chromosome is designated T2BL-2SL•2SS. Cytogenetic mapping assigned the resistance gene(s) in DAS15 to the Ae. speltoides segment in T2BL-2SL•2SS. The Ae. speltoides segment in the other translocated chromosome did not harbour stem rust resistance. A comparison of DAS15 and the wheat stocks carrying the Ae. speltoides-derived resistance genes Sr32 and Sr39 indicated that stem rust resistance gene present in DAS15 is likely novel and will be useful for developing germplasm with resistance to Ug99. Efforts to reduce Ae. speltoides chromatin in T2BL-2SL•2SS are currently in progress.

Parveen Chhuneja - One of the best experts on this subject based on the ideXlab platform.

  • cloning expression analysis and in silico characterization of hsp101 a potential player conferring heat stress in Aegilops speltoides tausch gren
    Physiology and Molecular Biology of Plants, 2021
    Co-Authors: Pratibha Jakhu, Priti Sharma, Inderjit Singh Yadav, Parampreet Kaur, Satinder Kaur, Parveen Chhuneja, Kuldeep Singh
    Abstract:

    Heat shock protein (HSP101) function as molecular chaperones and confer thermotolerance to plants. In the present investigation, identification, comprehensive expression analysis, phylogeny and protein modelling of HSP101 gene has been done in Aegilops speltoides accession Pau3583. In the present study, we cloned and in silico characterized a HSP101C gene designated as AsHSP101C-Pau3583. AsHSP101C-Pau3583 is 4180 bp long with seven exons and six introns and encoded a polypeptide of 910 amino acids predicted by FGENESH. We have identified 58 SNPs between the AsHSP101C-Pau3583 and reference gene sequence extracted from Ae. speltoides TGAC assembly. Real-time RT-PCR analysis of expression levels of HSP101 gene in two wheat genotypes under heat stress revealed that gene namely HSP101C was up-regulated in Aegilops speltoides acc. Pau3583 by > fourfold in comparison to Triticum aestivum cv. PBW343 under heat stress signifies that it plays a role in conferring heat tolerance. Sequence comparison and phylogenetic analysis of AsHSP101C-Pau3583 with seven wheat homologs Triticum aestivum, Aegilops speltoides (TGAC), Triticum durum cv Cappelli, Triticum durum cv Strongfield, Triticum monococcum, Aegilops tauschii and Triticum urartu showed significant similarities with highly conserved coding regions and functional domains (AAA, AAA + 2, ClpB domains), suggesting the conserved function of HSP101C in different species. The illustration of the protein models of HSP101C in homologs provided information for the ATP-binding motifs within the nucleotide binding domains (NBD), specific for the chaperone activity. These findings are important and identified SNPs could be used for designing markers for ensuring the transfer of AsHSP101C-Pau3583 gene into hexaploid wheat and its role in heat tolerance.

  • marker assisted mobilization of heat tolerance qtls from triticum durum Aegilops speltoides introgression lines to hexaploid wheat
    Indian Journal of Genetics and Plant Breeding, 2021
    Co-Authors: Guriqbal Singh Dhillon, Satinder Kaur, Niranjan Das, Puja Srivastava, N S Bains, Parveen Chhuneja
    Abstract:

    Most of the modern-day cultivars of spring wheat cultivated in the Indian sub-continent are susceptible to high-temperature stress during reproductive stages, and breeding for heat-tolerant genotypes is the plausible solution to mitigate effects of global warming on wheat productivity. Triticum durum - Aegilops speltoides backcross introgression lines were used for transferring seven heat tolerance QTLs to three different hexaploid backgrounds using marker assisted selection. A total of 164 BC2F3 progenies with different combinations of QTLs were generated and 40 progenies were evaluated in replicated trials across two years under normal (OE) and heat stress environments (HSE). Phenotypic evaluation and heat tolerance index (HTI) analysis over two environments showed that grain filling duration, spikelets/spike, tiller number, thousand grain weight, and yield showed were enhanced due to the introgression of heat stress tolerance QTLs. Progenies pauHTIL_10, 11, 12, 33, and 34 have shown higher yield than tested cultivars under OE with pauHTIL_10, 11, and 12 showed yields higher than 2.0 kgs/plot under OE and pauHTIL_14 showed yield of 1.6kg/plot under HSE. The progenies developed during this study can further be used for developing heat-tolerant wheat varieties.

  • characterization and mapping of spot blotch in triticum durum Aegilops speltoides introgression lines using snp markers
    Frontiers in Plant Science, 2021
    Co-Authors: Jashanpreet Kaur, Satinder Kaur, Guriqbal Singh Dhillon, Puja Srivastava, Jaspal Kaur, Harmandeep Kaur, Jasvir Singh, Ritu Bala, Achla Sharma, Parveen Chhuneja
    Abstract:

    Spot blotch of wheat is emerging as a major threat to successful wheat production in warm and humid areas of the world. Spot blotch (SB), also called leaf blight, is caused by Bipolaris sorokiniana, and is responsible for high yield losses in Eastern Gangetic Plains Zone in India. More recently, SB is extending gradually towards cooler, traditional wheat growing North-western part of the country which is a major contributor to national cereal basket. Deployment of resistant cultivars is considered as the most economical and ecologically sound measure to avoid losses due to this disease. In the present study, 89 backcross introgression lines (DSBILs) derived from Triticum durum (cv. PDW274-susceptible) X Aegilops speltoides (resistant) were evaluated against SB for four consecutive years, 2016-2020. Phenotypic evaluation of these lines showed a continuous variation in disease severity indicating that the resistance to SB is certainly quantitative in nature. Phenotypic data of DSBILs was further used for mapping QTLs using SNPs obtained by genotyping by sequencing. In order to identify QTLs stable across the environments, Best Linear Unbiased Estimates (BLUEs) and Predictions (BLUPs) were used for mapping QTLs based on stepwise regression-based Likelihood Ratio Test (RSTEP-LRT) for additive effect of markers and single marker analysis (SMA). Five QTLs, Q.Sb.pau-2A, Q.Sb.pau-2B, Q.Sb.pau-3B, Q.Sb.pau-5B, and Q.Sb.pau-6A linked to SB resistance were mapped across chromosomes 2A, 2B, 3B, 5B and 6A. Genes found adjacent to the SNP markers linked to these QTLs were literature mined to identify possible candidate genes by studying their role in plant pathogenesis. Further, highly resistant DSBIL (DSBIL-13) was selected to cross with a susceptible hexaploidy cultivar (HD3086) generating BC2F1 population. The QTL Q.Sb.pau-5B, linked to SNP S5B_703858864, was validated on this BC2F1 population and thus, may prove to be a potential diagnostic marker for spot blotch resistance.

  • qtl mapping for stripe rust and powdery mildew resistance in triticum durum Aegilops speltoides backcross introgression lines
    Plant Genetic Resources, 2020
    Co-Authors: Guriqbal Singh Dhillon, Satinder Kaur, Niranjan Das, Rohtas Singh, Jesse Poland, Jaspal Kaur, Parveen Chhuneja
    Abstract:

    Wheat, a major food crop, faces significant yield constraints due to losses caused by various diseases, especially rusts and powdery mildew. Since the causal organisms are always evolving, there is a never-ending hunt for new genes/quantitative trait loci (QTLs) for resistance to control the damage. For this purpose, Triticum durum–Aegilops speltoides backcross introgression lines (DS-BILs) developed in our wide hybridization programme were screened against stripe rust and powdery mildew at both seedling and adult plant stages. DS-BILs showed complete to moderate resistance at the adult plant stage while varying resistance and susceptibility at the seedling stage. A total of 1095 single-nucleotide polymorphisms (SNPs) identified on 14 chromosomes of T. durum, using genotyping by sequencing, were used for QTL mapping. Eleven unique QTLs, across six chromosomes (chr1B, chr2A, chr2B, chr3B, chr6B and chr7B) were identified for resistance, four QTLs for field mixture of stripe rust pathotypes, two QTLs for stripe rust pathotype 78S84 and five QTLs for field mixture of powdery mildew pathotypes using stepwise regression-based likelihood ratio test for additive effect of markers and single-marker analysis. Eleven DS-BILs carrying multiple QTLs were identified which will serve as a useful resource to transfer the respective resistance to susceptible cultivars to develop all stage resistant elite cultivars where QTL for stripe rust resistance QYrAs.pau-2A.1 (LOD 3.8, PVE 24.51 linked to SNP S2A_16016633) and QTL for powdery mildew resistance QPmAs.pau-6B (logarithm of the odds (LOD) 3.2, phenotypic variation explained (PVE) 17.75 linked to SNP S6B_26793381) are major targets of the transfer.

  • transfer and mapping of the heat tolerance component traits of Aegilops speltoides in tetraploid wheat triticum durum
    Molecular Breeding, 2016
    Co-Authors: Satinder Kaur, N S Bains, Rohtas Singh, Zewdu Teshome Awlachew, Parveen Chhuneja
    Abstract:

    Aegilops speltoides is an important genetic resource for wheat improvement and has high levels of heat tolerance. A heat-tolerant accession of Ae. speltoides pau3809 was crossed with Triticum durum cv. PDW274, and BC2F4-6 backcross introgression lines (BILs) were developed, phenotyped for important physiological traits, genotyped using SSR markers and used for mapping the QTL governing heat tolerance component traits. A set of 90 BILs was selected from preliminary evaluation of a broader set of 262 BILs under heat stress. Phenotyping was conducted for physiological traits such as cell membrane thermostability, chlorophyll content, acquired thermotolerance, canopy temperature and stay green. Much variation for these traits was observed in random as well as selected sets of BILs, and comparison of the BILs with the recurrent parent showed improvement for these traits under normal as well as heat stress conditions, indicating that introgressions from Ae. speltoides might have led to the improvement in the heat tolerance potential of the BILs. Introgression profiling of the 90 BILs using SSR markers identified Ae. speltoides introgression on all the 14 chromosomes with introgressions observed on A as well as B genome chromosomes. QTL mapping identified loci for various heat tolerance component traits on chromosomes 2B, 3A, 3B, 5A, 5B and 7A at significant LOD scores and with phenotypic contributions varying from 11.1 to 28.7 % for different traits. The heat-tolerant BILs and QTL reported in the present study form a potential resource that can be used for wheat germplasm enhancement for heat stress tolerance.

Jan Dvorak - One of the best experts on this subject based on the ideXlab platform.

  • recombination between homoeologous chromosomes induced in durum wheat by the Aegilops speltoides su1 ph1 suppressor
    Theoretical and Applied Genetics, 2019
    Co-Authors: Le Wang, Mingcheng Luo, Fang Nie, Yun Zhou, Patrick E Mcguire, Assaf Distelfeld, Xiongtao Dai, Chunpeng Song, Jan Dvorak
    Abstract:

    Su1-Ph1, which we previously introgressed into wheat from Aegilops speltoides, is a potent suppressor of Ph1 and a valuable tool for gene introgression in tetraploid wheat. We previously introgressed Su1-Ph1, a suppressor of the wheat Ph1 gene, from Aegilops speltoides into durum wheat cv Langdon (LDN). Here, we evaluated the utility of the introgressed suppressor for inducing introgression of alien germplasm into durum wheat. We built LDN plants heterozygous for Su1-Ph1 that simultaneously contained a single LDN chromosome 5B and a single Ae. searsii chromosome 5Sse, which targeted them for recombination. We genotyped 28 BC1F1 and 84 F2 progeny with the wheat 90-K Illumina single-nucleotide polymorphism assay and detected extensive recombination between the two chromosomes, which we confirmed by non-denaturing fluorescence in situ hybridization (ND-FISH). We constructed BC1F1 and F2 genetic maps that were 65.31 and 63.71 cM long, respectively. Recombination rates between the 5B and 5Sse chromosomes were double the expected rate computed from their meiotic pairing, which we attributed to selection against aneuploid gametes. Recombination rate between 5B and 5Sse was depressed compared to that between 5B chromosomes in the proximal region of the long arm. We integrated ND-FISH signals into the genetic map and constructed a physical map, which we used to map a 172,188,453-bp Ph1 region. Despite the location of the region in a low-recombination region of the 5B chromosome, we detected three crossovers in it. Our data show that Su1-Ph1 is a valuable tool for gene introgression and gene mapping based on recombination between homoeologous chromosomes in wheat.

  • introgression of the Aegilops speltoides su1 ph1 suppressor into wheat
    Frontiers in Plant Science, 2017
    Co-Authors: Karin R Deal, Assaf Distelfeld, Mingcheng Luo, Jan Dvorak
    Abstract:

    Meiotic pairing between homoeologous chromosomes in polyploid wheat is inhibited by the Ph1 locus on the long arm of chromosome 5 in the B genome. Aegilops speltoides (genomes SS), the closest relative of the progenitor of the wheat B genome, is polymorphic for genetic suppression of Ph1. Using this polymorphism, two major suppressor loci, Su1-Ph1 and Su2-Ph1, have been mapped in Ae. speltoides. Su1-Ph1 is located in the distal, high-recombination region of the long arm of the Ae. speltoides chromosome 3S. Its location and tight linkage to marker Xpsr1205-3S makes Su1-Ph1 a suitable target for introgression into wheat. Here, Xpsr1205-3S was introgressed into hexaploid bread wheat cv. Chinese Spring (CS) and from there into tetraploid durum wheat cv. Langdon (LDN). Sequential fluorescence in situ hybridization and genomic in situ hybridization showed that an Ae. speltoides segment with Xpsr1205-3S replaced the distal end of the long arm of chromosome 3A. In the CS genetic background, the chromosome induced homoeologous chromosome pairing in interspecific hybrids with Ae. peregrina but not in progenies from crosses involving alien disomic substitution lines. In the LDN genetic background, the chromosome induced homoeologous chromosome pairing in both interspecific hybrids and progenies from crosses involving alien disomic substitution lines. We conclude that the recombined chromosome harbors Su1-Ph1 but its expression requires expression of complementary gene that is present in LDN but absent in CS. We suggest that it is unlikely that Su1-Ph1 and ZIP4-1, a paralog of Ph1 located on wheat chromosomes 3A and 3B and Ae. tauschii chromosome 3D, are equivalent. The utility of Su1-Ph1 for induction of recombination between homoeologous chromosomes in wheat is illustrated.

  • BAC libraries of Triticum urartu, Aegilops speltoides and Ae. tauschii, the diploid ancestors of polyploid wheat
    TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik, 2005
    Co-Authors: Eduard Akhunov, Alina Akhunova, Jan Dvorak
    Abstract:

    Triticum urartu, Aegilops speltoides and Ae. tauschii are respectively the immediate diploid sources, or their closest relatives, of the A, B and D genomes of polyploid wheats. Here we report the construction and characterization of arrayed large-insert libraries in a bacterial artificial chromosome (BAC) vector, one for each of these diploid species. The libraries are equivalent to 3.7, 5.4 and 4.1 of the T. urartu, Ae. speltoides, Ae. tauschii genomes, respectively. The predicted levels of genome coverage were confirmed by library hybridization with single-copy genes. The libraries were used to estimate the proportion of known repeated nucleotide sequences and gene content in each genome by BAC-end sequencing. Repeated sequence families previously detected in Triticeae accounted for 57, 61 and 57% of the T. urartu, Ae. speltoides and Ae. tauschii genomes, and coding regions accounted for 5.8, 4.5 and 4.8%, respectively.

  • comparative genetic maps reveal extreme crossover localization in the Aegilops speltoides chromosomes
    Theoretical and Applied Genetics, 2005
    Co-Authors: Mingcheng Luo, Karin R Deal, Z L Yang, Jan Dvorak
    Abstract:

    A total of 137 loci were mapped in Aegilops speltoides, the closest extant relative of the wheat B genome, using two F2 mapping populations and a set of wheat-Ae. speltoides disomic addition (DA) lines. Comparisons of Ae. speltoides genetic maps with those of Triticum monococcum indicated that Ae. speltoides conserved the gross chromosome structure observed across the tribe Triticeae. A putative inversion involving the short arm of chromosome 2 was detected in Ae. speltoides. A translocation between chromosomes 2 and 6, present in the wheat B genome, was absent. The ligustica/aucheri spike dimorphism behaved as allelic variation at a single locus, which was mapped in the centromeric region of chromosome 3. The genetic length of each chromosome arm was about 50 cM, irrespective of its physical length. Compared to T. monococcum genetic maps, recombination was virtually eliminated from the proximal 50–100 cM and was localized in short distal regions, which were often expanded compared to the T. monococcum maps. The wheat B genome and the genome of Ae. longissima, a close relative of Ae. speltoides, do not show the extreme localization of crossovers observed in Ae. speltoides.

Peng Zhang - One of the best experts on this subject based on the ideXlab platform.

  • transfer to wheat of potentially new stem rust resistance genes from Aegilops speltoides
    2015
    Co-Authors: Ian Dundas, Yue Jin, Dawn Verlin, Peng Zhang, J Manisterski, Rafiqul Islam
    Abstract:

    Stem rust resistance genes have been found in four different sources of Aegilops speltoides. These include diploid accessions AEG357-4 and AEG874-60 and the amphiploids Chinese Spring/Ae. speltoides TA8026 and TS01. Stem rust resistance was mapped to the 2S chromosomes derived from each of these lines. The previously reported 2B-2S#3 translocation derived from AEG357-4 was found to carry two stem rust resistance genes, here temporarily named SrAes2t and SrAes3t. The resistance genes found on the 2S chromosomes each derived from TA8026, TS01 and AEG874-60 are named SrAes4t, SrAes5t and SrAes6t, respectively. Lines carrying genes SrAes2t and SrAes3t are being distributed to wheat breeding programs around the world.

  • development of wheat Aegilops speltoides recombinants and simple pcr based markers for sr32 and a new stem rust resistance gene on the 2s 1 chromosome
    Theoretical and Applied Genetics, 2013
    Co-Authors: Rohit Mago, Yue Jin, Dawn Verlin, Peng Zhang, Urmil Bansal, H S Bariana, Jeffrey G Ellis, Sami Hoxha, Ian Dundas
    Abstract:

    Key message Wheat– Aegilops speltoides recombinants carrying stem rust resistance genes Sr32 and SrAes1t effective against Ug99 and PCR markers for marker-assisted selection.

  • development of wheat Aegilops speltoides recombinants and simple pcr based markers for sr32 and a new stem rust resistance gene on the 2s 1 chromosome
    Theoretical and Applied Genetics, 2013
    Co-Authors: Rohit Mago, Yue Jin, Dawn Verlin, Peng Zhang, Urmil Bansal, H S Bariana, Jeffrey G Ellis, Sami Hoxha, Ian Dundas
    Abstract:

    Wheat– Aegilops speltoides recombinants carrying stem rust resistance genes Sr32 and SrAes1t effective against Ug99 and PCR markers for marker-assisted selection. Wild relatives of wheat are important resources for new rust resistance genes but underutilized because the valuable resistances are often linked to negative traits that prevent deployment of these genes in commercial wheats. Here, we report ph1b-induced recombinants with reduced alien chromatin derived from E.R. Sears’ wheat–Aegilops speltoides 2D-2S#1 translocation line C82.2, which carries the widely effective stem rust resistance gene Sr32. Infection type assessments of the recombinants showed that the original translocation in fact carries two stem rust resistance genes, Sr32 on the short arm and a previously undescribed gene SrAes1t on the long arm of chromosome 2S#1. Recombinants with substantially shortened alien chromatin were produced for both genes, which confer resistance to stem rust races in the TTKSK (Ug99) lineage and representative races of all Australian stem rust lineages. Selected recombinants were back crossed into adapted Australian cultivars and PCR markers were developed to facilitate the incorporation of these genes into future wheat varieties. Our recombinants and those from several other labs now show that Sr32, Sr39, and SrAes7t on the short arm and Sr47 and SrAes1t on the long arm of 2S#1 form two linkage groups and at present no rust races are described that can distinguish these resistance specificities.

  • development of wheat lines carrying stem rust resistance gene sr39 with reduced Aegilops speltoides chromatin and simple pcr markers for marker assisted selection
    Theoretical and Applied Genetics, 2009
    Co-Authors: Rohit Mago, Dawn Verlin, Peng Zhang, Urmil Bansal, H S Bariana, Jeffrey G Ellis, Ian Dundas
    Abstract:

    The use of major resistance genes is a cost-effective strategy for preventing stem rust epidemics in wheat crops. The stem rust resistance gene Sr39 provides resistance to all currently known pathotypes of Puccinia graminis f. sp. tritici (Pgt) including Ug99 (TTKSK) and was introgressed together with leaf rust resistance gene Lr35 conferring adult plant resistance to P. triticina (Pt), into wheat from Aegilops speltoides. It has not been used extensively in wheat breeding because of the presumed but as yet undocumented negative agronomic effects associated with Ae. speltoides chromatin. This investigation reports the production of a set of recombinants with shortened Ae. speltoides segments through induction of homoeologous recombination between the wheat and the Ae. speltoides chromosome. Simple PCR-based DNA markers were developed for resistant and susceptible genotypes (Sr39#22r and Sr39#50s) and validated across a set of recombinant lines and wheat cultivars. These markers will facilitate the pyramiding of ameliorated sources of Sr39 with other stem rust resistance genes that are effective against the Pgt pathotype TTKSK and its variants.

  • development of a complete set of triticum aestivum Aegilops speltoides chromosome addition lines
    Theoretical and Applied Genetics, 2000
    Co-Authors: Bernd Friebe, Shuhei Nasuda, Peng Zhang, N A Tuleen, B. S. Gill
    Abstract:

    Aegilops speltoides Tausch (2n = 2x = 14, SS) is considered as the closest living relative of the B and G genomes of polyploid wheats. A complete set of Triticumaestivum L. cv Chinese Spring-Ae. speltoides whole chromosomes and seven telosomic addition lines was established. A low pairing accession was selected for the isolation of the chromosome addition lines. Except for chromosomes 3S and 6S, which are presently only available as monosomic additions, all other lines were recovered as disomic or ditelosomic additions. The individual Ae. speltoides chromosomes isolated in the wheat background were assayed for their genetic effects on plant phenotype and cytologically characterized in terms of chromosome length, arm ratio, distribution of marker C-bands, and FISH sites using a Ae. speltoides-specific repetitive element, Gc1R-1, as a probe. The homoeology of the added Ae. speltoides chromosomes was established by using a standard set of RFLP probes. No chromosomal rearrangements relative to wheat were detected.