Intermediate fertile Triticum aestivum (+) Agropyron elongatum somatic hybrids are generated by low doses of UV irradiation.
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We report the production and characterization of somatic hybrids between Triticum aestivum L. and Agropyron elongatum (Host) Nevishi (the synonym is Thinopyrum ponticum). Asymmetric protoplast fusion was performed between Agropyron elongatum protoplasts irradiated with a low UV dose and protoplasts of wheat taken from nonregenerable suspension cultures. More than 40 green plantlets were obtained from 15 regenerated clones and one of them produced seeds. The phenotypes of the hybrid plants and seeds were intermediate between wheat and Agropyron elongatum. All of the regenerated calli and plants were verified as intergeneric hybrids on the basis of morphological observation and analysis of isozyme, cytological, 5SrDNA spacer sequences and random amplified polymorphic DNA (RAPD). RFLP analysis of the mitochondrial genome revealed evidence of random segregation and recombination of mtDNA. (+info)
Two quality-associated HMW glutenin subunits in a somatic hybrid line between Triticum aestivum and Agropyron elongatum.
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High-molecular-weight glutenin subunits (HMW-GSs) from hybrid line II-12 between wheat (Triticum aestivum L.) and Agropyron elongatum (Host) Nivski were characterized with SDS-PAGE. Out of these HMW-GSs, two subunits, h1Bx and h1By, had mobilities similar to the subunits 1Bx13 and 1By16 from common wheat 4072, which was used as control. Polyclonal antibodies (pAbs) of h1Bx and h1By were prepared, and Western blotting showed that the pAbs had strong affinities for h1Bx and h1By, separately. The specificity of h1Bx-pAb was further checked; it preferentially recognized subunits h1Bx and 1Bx13. HMW-GS gene coding sequences were amplified by genomic polymerase chain reaction from hybrid II-12. Two of the five amplicons, marked II2a and II31b, were sequenced. Their coding sequences are clustered to Glu-1Bx7 and Glu-1By9 of common wheat. Three discrepant regions in deduced amino acid sequences of II2a and 31b repeated one time more than Glu-1Bx7 and Glu-1By9. N-terminal sequences of h1Bx and h1By were determined, which were identical to the published sequences of 1Bx13 and 1By16 and in agreement with that deduced from II2a and II31b, respectively. These results indicated that the two novel genes separated from the hybrid wheat derived from the allelic variation of 1Bx7 and 1By9 of the parent wheat. There is an additional cysteine residue positioned at 271st amino acid of the mature peptide of II2a, which may be related to the high quality of the flour. (+info)
New choke diseases and their molecular phylogenetic analysis in Agropyron ciliare var. minus and Agropyron tsukushiense var. transiens.
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Choke diseases were surveyed in two closely related grass species, Agropyron ciliare var. minus and Agropyron tsukushiense var. transiens, in Shiga Prefecture, Japan. Perithecia and ascospores were not observed in either case. Stromata on A. ciliare var. minus enclosed and sterilized young inflorescences, as in the typical choke symptoms by Epichloe typhina. On the other hand stromata on A. tsukusiense var. transiens thinly covered mature spikes with white epiphyllous hyphae, as in stromata of Ephelis spp. The fungal isolates produced typical Neotyphodium-type conidia. Molecular phylogenetic analyses using the beta-tubulin gene (tubB) indicated that the two Agropyron species are infected with the species grouping into a novel single clade among Epichloe species and they are closely related to a haploid of hybrid Neotyphodium species. The host plant features may be the cause of the differences between stromata of A. ciliare var. minus and A. tsukushiense var. (+info)
A new species of Epichloe symbiotic with Chinese grasses.
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Epichloe species are fungal symbionts (endophytes) of grasses, six European and four North American biological species in genus Epichloe have been described in previous researches. In this study we describe a new Epichloe species, Epichloe yangzii Li et Wang, found in natural symbioses with Roegneria kamoji native to China. We investigated the host specificity, morphology, interfertility tests and molecular phylogenetic evidences of this new species. The results indicated that E. yangzii is host specific and seedborne. Most morphological characteristics of this new species are typical in the genus. However differences are evident in several features including size of perithecia, asci and ascospores. In mating tests E. yangzii was not interfertile with E. elymi isolates from related hosts in genera Elymus. Phylogenetic relationships based on sequences of beta-tubulin gene (tub2) introns and translation elongation factor 1-alpha gene (tef1) introns showed that members of the new species grouped into exclusive clades with high bootstrap value. (+info)
Generation of novel high quality HMW-GS genes in two introgression lines of Triticum aestivum/Agropyron elongatum.
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BACKGROUND: High molecular weight glutenin subunits (HMW-GS) have been proved to be mostly correlated with the processing quality of common wheat (Triticum aestivum). But wheat cultivars have limited number of high quality HMW-GS. However, novel HMW-GS were found to be present in many wheat asymmetric somatic hybrid introgression lines of common wheat/Agropyron elongatum. RESULTS: To exploit how these new subunits were generated, we isolated HMW-GS genes from two sib hybrid lines (II-12 and 11-4-6) and compared them with those from their parents. The result shows that two genes of hybrid (H11-3-3 and H11-4-3) are directly introgressed from the donor parent Agropyron elongatum; one hybrid gene (H1Dx5) comes from point mutation of a parental wheat gene (1Dx2.1); two other hybrid genes (H1By8 and H1By16) are likely resulting from unequal crossover or slippage of a parental wheat gene (1By9.1); and the sixth novel hybrid gene (H1Dy12) may come from recombination between two parental genes. CONCLUSION: Therefore, we demonstrate that novel HMW-GS genes can be rapidly created through asymmetric somatic hybridization in a manner similar with the evolution mechanism of these genes supposed before. We also described gene shuffling as a new mechanism of novel HMW-GS gene formation in hybrids. The results suggest that asymmetric somatic hybridization is an important approach for widening HMW-GS genebank of wheat quality improvement. (+info)
Preferential elimination of chromosome 1D from homoeologous group-1 alien addition lines in hexaploid wheat.
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Alien chromosome addition lines are useful genetic material for studying the effect of an individual chromosome in the same genetic background. However, addition lines are sometimes unstable and tend to lose the alien chromosome in subsequent generations. In this study, we report preferential removal of chromosome 1D rather than the alien chromosome from homoeologous group-1 addition lines. The Agropyron intermedium chromosome 1Agi (1E) addition line, created in the background of 'Vilmorin 27', showed loss of a part of chromosome 1D, thereby losing its HMW glutenin locus. Even in the case of Aegilops longissima and Ae. peregrina, the genomes of which are closer to the B genome than D genome, chromosome 1D was lost from chromosome 1Sl and 1Sv addition lines in cv. 'Chinese Spring' rather than chromosome 1B during transfer from one generation to another. A similar observation was also observed in the case of a chromosome 1E disomic addition line of Ag. elongatum and alloplasmic common wheat line with Ag. intermedium ssp. trichophorum cytoplasm. The reason for this strange observation is thought to lie in the history of wheat evolution, the size of chromosome 1D compared to 1A and 1B, or differing pollen competition abilities. (+info)
Characterizing HMW-GS alleles of decaploid Agropyron elongatum in relation to evolution and wheat breeding.
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Bread wheat quality is mainly correlated with high molecular weight glutenin subunits (HMW-GS) of endosperm. The number of HMW-GS alleles with good processing quality is limited in bread wheat cultivars, while there are plenty of HMW-GS alleles in wheat-related grasses to exploit. We report here on the cloning and characterization of HMW-GS alleles from the decaploid Agropyron elongatum. Eleven novel HMW-GS alleles were cloned from the grass. Of them, five are x-type and six y-type glutenin subunit genes. Three alleles Aex4, Aey7, and Aey9 showed high similarity with another three alleles from the diploid Lophopyrum elongatum, which provided direct evidence for the Ee genome origination of A. elongatum. It was noted that C-terminal regions of three alleles of the y-type genes Aey8, Aey9, and Aey10 showed more similarity with x-type genes than with other y-type genes. This demonstrates that there is a kind of intermediate state that appeared in the divergence between x- and y-type genes in the HMW-GS evolution. One x-type subunit, Aex4, with an additional cysteine residue, was speculated to be correlated with the good processing quality of wheat introgression lines. Aey4 was deduced to be a chimeric gene from the recombination between another two genes. How the HMW-GS genes of A. elongatum may contribute to the improvement of wheat processing quality are discussed. (+info)
Nitrogen and water addition reduce leaf longevity of steppe species.
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