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PubMed2002

[Identification of blue grained wheat and its irradiation-mutated offsprings by genomic in situ hybridization (GISH)].

Transferring useful chromosome(s), chromosomal fragment(s) or genes from related species into common wheat (Triticum aestivum L.) is an effective method for improving wheat cultivars, and DNA:DNA in situ hybridization has been proven to be an effective method for directly demonstrating alien chromosome number and distribution in plant. In this study, genomic in situ hybridization (GISH) was used to identify the chromosomal constitutions of the blue-grained wheat Blue-58 originated from distant hybridization between Triticum aestivum L. and Agropyron elongatum (Host) Beauv (2n = 10x = 70) and its irradiation-mutated offsprings. The results showed that, as previously reported, Blue-58 (2n = 42) was a substitution line in which a pair of 4D chromosomes of common wheat was substituted by a pair of 4E chromosomes from Agropyron elongatum. Mutation line LW004 might be a homozygous reciprocal translocation line in which two pair of chromosomes might be involved in the translocation event and it showed high efficiency in utilizing soil phosphorus in our field screening experiments. Mutation line LW43-3-4 was a blue monosomic line with 40 wheat chromosomes plus one 4E chromosome from Agropyron elongatum in its genome and its seeds showed light-blue color. Some other chromosome rearrangements and structure changes were also detected among the mutated offsprings through GISH, such as telomonosomic line (40 W + 1't4E) and a line with a chromosomal constitution of 39 W + 1'4E + 1't4E. Our results indicated very clearly that it was the chromosome derived from Agropyron elongatum carried gene(s) responsible for the blue pigmentation in wheat grains and it was also illustrated from our results that the combination of effective methods for generating mutations at chromosomal level and convenient detection of these mutations played pivotal roles in creating materials for chromosome engineering and in breeding by means of chromosome engineering.

In Situ Hybridization↗

PubMed2004

[Comparative study on daily change of photosynthesis rate of the rhizomatous grasses in milky ripe stage].

Comparative study on daily change of photosynthesis rate of the rhizomatous grasses in their milky ripe stage was carried out, and the results showed that photosynthetic rate of five grasses appeared to be two-apex curve, except Elytrigia intermedia appeared to be one-apex curve. The general trend was that the higher the root/shoot ratio was, the later the first apex of the photosynthetic rate reached, and the shorter the noon break period was. Moreover, low relative humidity and high leaf temperature were the important factors for noon break. Leymus chinense, Pascopyrum smithii Rydb. cn. Rosana, Leymus secalinus, Leymus racemosus, Agropyron mongolicum and Elytrigia intermedia reached the first apex at 10:12, 10:00, 9:51, 9:39, 9:06 and 8:13, the noon break period was 471, 474, 464, 467 and 551 min, and the average leaf temperature during noon break was 37.8, 37.5, 36.9, 37.0 and 36.3 degrees C, respectively. Leymus chinense and Agropyron mongolicum, Leymus secalinus and Leymus racemosus had similar daily change in photosynthetic rate, respectively, and their r values were 0.88 and 0.96 respectively when R = 0.01.

Agropyron↗

PubMed1996

Molecular diversification of tandemly organized DNA sequences and heterochromatic chromosome regions in some Triticeae species.

The subtelomeric heterochromatin of rye (Secale cereale) chromosomes makes up 12-18% of the genome and consists largely of a small number of tandemly organized DNA sequence families. The genomic organization, chromosomal locations and the structural organization of monomer units of the major DNA sequences from these regions were investigated and compared in other Triticeae species from the genera Secale, Agropyron, Dasypyrum, Triticum and Hordeum. Southern hybridization and polymerase chain reaction analysis established that all studied species preserve the tandem type of sequence organization but the copy number is altered drastically between species. In the pSc200 family, a fraction of the tandem arrays is present with a head-to-head orientation of dimers in S. cereale and S. montanum. Members of the same family are more heterogeneous and present as head-to-head monomers in the Dasypyrum species and A. cristatum. In situ hybridization demonstrates different organization of the sequence families in the various species: pSc200 and pSc250 are concentrated in major blocks at the ends of most rye chromosome arms, whereas they are more dispersed and in smaller blocks in Dasypyrum and Agropyron, indicating that accumulation is not simply due to the sequence itself. In contrast to rye, D. villisum has large blocks of only pSc200 whereas D. breviaristatum shows greater amplification of pSc250. These data indicate that each repetitive family is an independent unit of evolution, and suggest that the two Dasypyrum species are not closely related. The data are discussed in terms of existing evolutionary models for repetitive DNA sequences. The contribution of random events, through molecular drive and selection, to the evolution of heterochromatic regions is considered.

Chromosomes↗

PubMed2002

Mitochondrial DNA sequence divergence among Schizaphis graminum (Hemiptera: Aphididae) clones from cultivated and non-cultivated hosts: haplotype and host associations.

A 1.0 kb region of the mitochondrial cytochrome oxidase subunit I gene from the greenbug aphid, Schizaphis graminum (Rondani), was sequenced for 24 field collected clones from non-cultivated and cultivated hosts. Maximum likelihood, maximum parsimony and neighbour-joining phylogenies were estimated for these clones, plus 12 previously sequenced clones. All three tests produced trees with identical topologies and confirmed the presence of three clades within S. graminum. Clones showed no relationship between biotype and mtDNA haplotype. At least one biotype was found in all three clades, suggesting exchange among clades of genetic material conditioning for crop virulence, or the sharing of a common ancestor. However, there was a relationship between host and haplotype. Clade 1 was the most homogeneous and contained 12 of 16 clones collected from cultivated hosts and five of the six collected from johnsongrass, Sorghum halepense, a congener of cultivated sorghum, S. bicolor. Four of the six clones collected from Agropyron spp. were found in clade 2. Clade 3 contained two clones from wheat, Triticum aestivum, and four from non-cultivated hosts other than Agropyron spp. A partitioning of populations by mtDNA haplotype and host suggests the occurrence of host adapted races in Schizaphis graminum.

Animals↗

PubMed2006

Phylogenetic relationships in Elymus (Poaceae: Triticeae) based on the nuclear ribosomal internal transcribed spacer and chloroplast trnL-F sequences.

To estimate the phylogenetic relationship of polyploid Elymus in Triticeae, nuclear ribosomal internal transcribed spacer (ITS) and chloroplast trnL-F sequences of 45 Elymus accessions containing various genomes were analysed with those of five Pseudoroegneria (St), two Hordeum (H), three Agropyron (P) and two Australopyrum (W) accessions. The ITS sequences revealed a close phylogenetic relationship between the polyploid Elymus and species from the other genera. The ITS and trnL-F trees indicated considerable differentiation of the StY genome species. The trnL-F sequences revealed an especially close relationship of Pseudoroegneria to all Elymus species included. Both the ITS and trnL-F trees suggested multiple origins and recurrent hybridization of Elymus species. The results suggested that: the St, H, P, and W genomes in polyploid Elymus were donated by Pseudoroegneria, Hordeum, Agropyron and Australopyrum, respectively, and the St and Y genomes may have originated from the same ancestor; Pseudoroegneria was the maternal donor of the polyploid Elymus; and some Elymus species showed multiple origin and experienced recurrent hybridization.

DNA, Chloroplast↗

PubMed2000

[Alien chromosomal identification in VE161 wheat].

VE161 wheat which has the function of promotting homoeologous pairing is a male sterile substitution line or a fertile addition line with one pair of alien chromosomes from Agropyron elongatum. The alien chromosome in VE161 wheat was detected by means of techniques of total genomic DNA in situ hybridization, RFLP and double-ditelo chromosomal analysis. The results from in situ hybridization confirmed that the alien chromosome was derived from Agropyron elongatum. The RFLP analysis showed that it belongs to fourth homoeologous group, and the results from double-ditelo chromosomal analysis gave evidence that 4B chromosome was replaced in the substitution line, so it can be concluded that, in VE161 wheat, the alien chromosome would be 4E and the replaced wheat chromosome would be 4B in the substitution line. The reason for the replaced chromosome identified as 7B in a earlier study might be due to the rearrangement occurred in the genome of wheat.

Chromosomes↗

PubMed1996

Physical and topographical mapping among Triticeae chromosomes.

Three principal approaches have been used in our laboratory to analyze Triticeae genomes. (i) Synteny analysis: synteny among different Gramineae genomes was studied employing the elegant system of the Agropyron chromosome-induced deletion lines of wheat. Deletion mapping, predominantly of the homoeologous group 7 chromosomes, has led to the construction of a high density physical consensus map of wheat. The integration of wheat, barley and oat RFLP markers proves the colinearity between the wheat A-, B- and D-genomes, the H-genome of barley, and the E-genome of Agropyron. (ii) Light microscopic in situ techniques: the recent improvement of a drop technique for plant protoplasts was crucial for the sensitivity enhancement of fluorescence in situ hybridization (FISH), the efficient preparation of plant chromosomes for high resolution scanning electron microscopy, mapping of low-copy sequences, and comparative in situ hybridization. A tandemly amplified repetitive sequence element from microdissected barley chromosomes has enabled the karyotyping of Gramineae genomes in a single step. We have isolated and characterized members of this element family from other Triticeae species using PCR. The significant interspecific sequence differences were useful to identify single plant genomes, chromosomes and chromosome segments via post-hybridization washes under different stringency conditions. These sequences are also useful for simultaneous double or triple hybridization experiments in an attempt to localize new sequences on specific chromosomes or chromosome segments. The physical mapping of the Sec-1 locus has been refined on the satellite of chromosome 1R of rye, and the syntenic locus on barley chromosome 1H was identified. (iii) Physical mapping of rDNA sequences by high resolution electron microscopy: a method was developed for in situ hybridization and signal detection using high resolution field emission scanning electron microscopy and a backscattered electron detector. Colloidal gold particles were localized on chromosome structures resembling the 30 nm fibre. An rDNA probe was located in the secondary constriction and the highly compact adjacent regions of barley chromosomes.

Chromosome Mapping↗

PubMed2006

Is the cereal rust mite, Abacarus hystrix really a generalist? - Testing colonization performance on novel hosts.

The majority of eriophyoid mites are highly host specific and restricted to a narrow range of acceptable host plant species. The cereal rust mite, Abacarus hystrix was considered to be one of a few exceptions among them and has been found to be using a relatively wide host range. Since this species is a vagrant, inhabiting short-lived plants and aerially dispersing, it has commonly been considered to be a host generalist. Here the opposite hypothesis is tested, that host populations of A. hystrix are specialized on their local host plants and may represent host races. For this purpose, females from two host populations (quack grass, Agropyron repens and ryegrass, Lolium perenne) were transferred, and subsequently reared, on their normal (grass species from which females came from) and novel (other grass species) hosts. The female's fitness was assessed by survival and fecundity on the normal and novel host. Females of both populations had no success in the colonization of the novel host. They survived significantly better and had significantly higher fecundity on their normal host than on the novel one. These findings correspond with observations on host-dependent phenotype variability and host acceptance. The presence of locally specialized host populations in A. hystrix may be evidence for high host specificity among eriophyoids and the viruses they transmit. The main conclusion is that A. hystrix, which so far has been considered as a host generalist, in fact may be a complex species consisting of highly specialized host races.

Agropyron↗

PubMed2005

Cesium desorption from illite as affected by exudates from rhizosphere bacteria.

Biogeochemical processes in the rhizosphere can significantly alter interactions between contaminants and soil minerals. In this study, several strains of bacteria that exude aluminum (Al)-chelating compounds were isolated from the rhizosphere of crested wheatgrass (Agropyron desertorum) collected from the Idaho National Laboratory (INL). We examined the effects of exudates from bacteria in the genera Bacillus, Ralstonia, and Enterobacter on cesium (Cs) desorption from illite. Exudates from these strains of bacteria significantly enhanced Cs desorption from illite. In addition, Cs desorption increased with increasing Bacillus exudate concentrations. Cesium desorption from illite as a function of both exudate type and concentration was positively correlated with Al dissolution, suggesting that the Al-complexing ability of the exudates played an important role in enhancing Cs desorption. The density of frayed edge sites (FES) on illite increased as a result of treatment with bacterial exudates, while the Cs/K selectivity of FES decreased. These results suggestthat exudates from bacteria isolated from the rhizosphere can enhance Cs desorption from frayed edges of illite and, therefore, can alter Cs availability in micaceous soils.

Agropyron↗

PubMed2003

The genome composition of hexaploid Psammopyrum athericum and octoploid Psammopyrum pungens (Poaceae: Triticeae).

The genomic constitution of two species in the genus Psammopyrum, i.e., Ps. athericum (2n = 6x = 42) and Ps. pungens (2n = 8x = 56), was studied by genomic in situ hybridization (GISH). In Ps. athericum, one diploid chromosome set hybridized to a genomic probe from Pseudoroegneria ferganensis (St genome), one diploid set to a probe from Agropyron cristatum (P genome), and one diploid set to a probe from Thinopyrum junceiforme (EbEe genomes) or Th. bessarabicum (Eb genome). Substituting the St-genome probe with an L-genome probe from Festucopsis serpentinii resulted in exactly the same hybridization pattern, suggesting a genomic constitution of EStP or ELP for Ps. athericum. The same probes used on Ps. pungens showed two diploid sets of chromosomes hybridizing to the St-genome probe, one diploid set hybridizing to the P-genome probe, and one diploid set hybridizing to the EbEe-genome probe. The L-genome probe hybridized to approximately 14 of the chromosomes that were labeled by the St-genome probe. Hence the genomic constitution for Ps. pungens is proposed to be EStStP or EStLP.

Agropyron↗

PubMed2005

Uptake of nonylphenol and nonylphenol ethoxylates by crested wheatgrass.

Nonylphenol (NP) and other hydrophobic biodegradation intermediates of nonylphenol ethoxylate (NPE) surfactants have been identified in wastewater treatment biosolids. These biosolids often are land applied, but little is known regarding the potential uptake of biosolid-derived contaminants by plants. Hydroponic experiments, 11 to 14 weeks in duration, were conducted to examine the uptake and translocation of 14C and unlabeled NP, nonylphenol tetraethoxylate (NPE4), and nonylphenol nonylethoxylate (NPE9) by crested wheatgrass (Agropyron cristatum). Phenol also was evaluated for comparison. Plant tissue was analyzed for 14C and for the parent compounds. Volatilization from the hydroponic system and rhizosphere mineralization also were quantified. At the conclusion of the study, most of the plant-associated 14C was found in the roots (NP = 98%, NPE4 = 92%, and NPE9 = 81%). Concentrations of 14C in the foliar tissue ranged from 0.002 to 0.045 mg-equivalent per kg (dry wt), but no parent compounds were detected, implying that the 14C was unextractable or in the form of metabolites. Transpiration stream concentration factors for NP, NPE4, and NPE9, calculated assuming the 14C was parent compound, were 0.012, 0.032, and 0.066, respectively. Little mineralization was observed for NP, NPE4, and NPE9 in the hydroponic system; however, for phenol, 16 to 30% of the added 14C was mineralized.

Agropyron↗

PubMed2006

An axenic plant culture system for optimal growth in long-term studies.

The symbiotic co-evolution of plants and microbes leads to difficulties in understanding which of the two components is responsible for a given environmental response. Plant-microbe studies greatly benefit from the ability to grow plants in axenic (sterile) culture. Several studies have used axenic plant culture systems, but experimental procedures are often poorly documented, the plant growth environment is not optimal, and axenic conditions are not rigorously verified. We developed a unique axenic system using inert components that promotes plant health and can be kept sterile for at least 70 d. Crested wheatgrass (Agropyron cristatum cv. CDII) plants were grown in sand within flow-through glass columns that were positively pressured with filtered air. Plant health was optimized by regulating temperature, light level, CO2 concentration, humidity, and nutrients. The design incorporates several novel aspects, such as pretreatment of the sand with Fe, graduated sand layers to optimize the air-water balance of the root zone, and modification of a laminar flow hood to serve as a plant growth chamber. Adaptations of several sterile techniques were necessary for maintenance of axenic conditions. Axenic conditions were verified by plating and staining leachates as well as a rhizoplane stain. This system was designed to study nutrient and water stress effects on root exudates, but is useful for assessing a broad range of plant-microbe-environment interactions. Based on total organic C analysis, 74% of exudates was recovered in the leachate, 6% was recovered in the bulk sand, and 17% was recovered in the rhizosphere sand. Carbon in the leachate after 70 d reached 255 microg d(-1). Fumaric, malic, malonic, oxalic, and succinic acids were measured as components of the root exudates.

Agropyron↗

PubMed2005

[Identification of an alien chromosome in the common wheat line multi 6R].

The chromosome of Agropyron intermedium (Host) Beauv. substituting chromosome 6D has been identified in the karyotype of the Triticum aestivum L. line Multi 6R with the use of C-banding. The alien chromosome, temporarily designated 6Ag1, contains gene(s) of the resistance to the Saratov population of Puccinia recondita Rob. ex. Desm. f. tritici. It has been demonstrated that the resistance gene(s) is(are) highly efficient and that chromosome 6Ag1 is preferably transferred through gametes.

Agropyron↗

PubMedDate not supplied

Structural proteins of three viruses in the Potyviridae adhere only to their homologous cylindrical inclusions in mixed infections.

Immunoelectron microscopy of serial sections of leaf cells of wheat doubly infected by wheat streak mosaic virus and Agropyron mosaic virus or wheat spindle streak mosaic virus showed that structural proteins or virions associated only with homologous cylindrical inclusions (CI) or with self in aggregates. CI protein of WSMV was seen firmly attached to, and extended through, a plasmodesma. Based on CI protein similarities with transport protein families, membrane-associated secretion proteins, other transport proteins in the GTPase superfamily, and the here reported findings, it is suggested that CI proteins could serve as cell-to-cell movement proteins in the Potyviridae.

Inclusion Bodies, Viral↗

PubMed1996

Phylogenetic justification for splitting the Rymovirus genus of the taxonomic family Potyviridae.

The Potyviridae family has been divided into four genera on the basis of vector transmission, as follows: Potyvirus genus (aphid), Rymovirus genus (mite), Bymovirus genus (fungus) and Ipomovirus genus (whitefly). However recent sequence comparisons of the coat protein and 3' NCR regions of the potyviruses have demonstrated that the rymoviruses appear to be a group of two unrelated clusters namely Ryegrass Mosaic Virus (RGMV), Agropyron Mosaic Virus (AgMV) and Hordeum Mosaic Virus (HoMV) in one group and Wheat Streak Mosaic Virus (WSMV) and Brome Streak Mosaic Virus (BrSMV) in the second group. We therefore propose that RGMV, AgMV and HoMV remain in the genus Rymovirus and WSMV and BrSMV form a separate genus, possibly the Whestrevirus genus.

Animals↗

PubMed2005

Development of PCR markers for the selection of wheat stem rust resistance genes Sr24 and Sr26 in diverse wheat germplasm.

The use of major resistance genes is the most cost-effective strategy for preventing stem rust epidemics in Australian wheat crops. The long-term success of this strategy is dependent on combining resistance genes that are effective against all predominant races of the pathogen, a task greatly assisted by the use of molecular markers linked to individual resistance genes. The wheat stem rust resistance genes Sr24 and Sr26 (derived from Agropyron elongatum) and SrR and Sr31 (derived from rye) are available in wheat as segments of alien chromosome translocated to wheat chromosomes. Each of these genes provides resistance to all races of wheat stem rust currently found in Australia . We have developed robust PCR markers for Sr24 and Sr26 (this study) and SrR and Sr31 (previously reported) that are applicable across a wide selection of Australian wheat germplasm. Wheat lines have recently become available in which the size of the alien segments containing Sr26, SrR and Sr31 has been reduced. Newly developed PCR-markers can be used to identify the presence of the shorter alien segment in all cases. Assuming that these genes have different gene-for-gene specificities and that the wheat industry will discourage the use of varieties carrying single genes only, the newly developed PCR markers will facilitate the incorporation of two or more of the genes Sr24, Sr26, SrR and Sr31 into wheat lines and have the potential to provide durable control to stem rust in Australia and elsewhere.

Alleles↗

PubMed2005

High transferability of bread wheat EST-derived SSRs to other cereals.

The increasing availability of expressed sequence tags (ESTs) in wheat (Triticum aestivum) and related cereals provides a valuable resource of non-anonymous DNA molecular markers. In this study, 300 primer pairs were designed from 265 wheat ESTs that contain microsatellites in order to develop new markers for wheat. Their level of transferability in eight related species [Triticum durum, T. monococcum, Aegilops speltoides, Ae. tauschii, rye (Secale cereale), barley (Hordeum vulgare), Agropyron elongatum and rice (Oryza sativa)] was assessed. In total, 240 primer pairs (80%) gave an amplification product on wheat, and 177 were assigned to wheat chromosomes using aneuploid lines. Transferability to closely related Triticeae species ranged from 76.7% for Ae. tauschii to 90.4% for T. durum and was lower for more distant relatives such as barley (50.4%) or rice (28.3%). No clear putative function could be assigned to the genes from which the simple sequence repeats (SSRs) were developed, even though most of them were located inside ORFs. BLAST: analysis of the EST sequences against the 12 rice pseudo-molecules showed that the EST-SSRs are mainly located in the telomeric regions and that the wheat ESTs have the highest similarity to genes on rice chromosomes 2, 3 and 5. Interestingly, most of the SSRs giving an amplification product on barley or rice had a repeated motif similar to the one found in wheat, suggesting a common ancestral origin. Our results indicate that wheat EST-SSRs show a high level of transferability across distantly related species, thereby providing additional markers for comparative mapping and for following gene introgressions from wild species and carrying out evolutionary studies.

Chromosome Mapping↗

PubMed2006

Identification and validation of molecular markers linked to the leaf rust resistance gene Lr19 in wheat.

A leaf rust resistance gene Lr19 on the chromosome 7DL of wheat derived from Agropyron elongatum was tagged with random amplified polymorphic DNA (RAPD) and microsatellite markers. The F(2) population of 340 plants derived from a cross between the leaf rust resistant near-isogenic line (NIL) of Thatcher (Tc + Lr19) and leaf rust susceptible line Agra Local that segregated for dominant monogenic leaf rust resistance was utilized for generating the mapping population. The molecular markers were mapped in the F(2) derived F(3) homozygous population of 140 seedlings. Sixteen RAPD markers were identified as linked to the alien gene Lr19 among which eight were in a coupling phase linkage. Twelve RAPD markers co-segregated with Lr19 locus. Nine microsatellite markers located on the long arm of chromosome 7D were also mapped as linked to the gene Lr19, including 7 markers which co-segregated with Lr19 locus, thus generating a saturated region carrying 25 molecular markers linked to the gene Lr19 within 10.2 +/- 0.062 cM on either side of the locus. Two RAPD markers S265(512) and S253(737) which flanked the locus Lr19 were converted to sequence characterized amplified region markers SCS265(512) and SCS253(736), respectively. The marker SCS265(512) was linked with Lr19 in a coupling phase and the marker SCS253(736) was linked in a repulsion phase, which when used together mimicked one co-dominant marker capable of distinguishing the heterozygous resistant seedlings from the homozygous resistant. The molecular markers were validated on NILs mostly in Thatcher background isogenic for 44 different Lr genes belonging to both native and alien origin. The validation for polymorphism in common leaf rust susceptible cultivars also confirmed the utility of these tightly linked markers to the gene Lr19 in marker-assisted selection.

Chromosome Mapping↗