Attempts to induce homoeologous pairing between wheat and Agropyron cristatum genomes
Mélanie JubaultAnne-Marie A.-M. TanguyPaulette AbelardOlivier O. CoritonJean-Claude J.-C. DusautoirJoseph J. Jahier
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Abstract:
Agropyron cristatum (2n = 4x = 28, PPPP) possesses potentially valuable traits that could be used in wheat (Triticum aestivum) improvement through interspecific hybridization. Homoeologous pairing between wheat chromosomes and P chromosomes added to wheat in a set of wheat - A. cristatum addition lines was assessed. First, the Ph-suppressing effect of P chromosomes (except 7P) was analyzed. It was concluded that this system is polygenic with no major gene, and consequently, has no prospect in the transfer of alien genes from wild relatives. In a second step, the potential of the deletion ph1b of the Ph1 gene for inducing P-ABD pairing was evaluated. Allosyndetic associations between P and ABD genomes are very rare. This very low level of pairing is likely due to divergence in the repeated sequences between Agropyron and wheat genomes. Development of translocation lines using ionizing radiation seems to be a more suitable technique than homoeologous recombination to exploit the A. cristatum genome in wheat improvement.Keywords:
Agropyron cristatum
Agropyron
Chromosome pairing
Common wheat
Triticeae
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Agropyron
Chromosome pairing
Common wheat
Embryo rescue
Triticeae
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Dewey, Douglas R. (Utah State U., Logan.) Morphology and (cytology of synthetic hybrids of Agropyron trichophorum X Agropyron cristatum. Amer. Jour. Bot. 50(10): 1028–1034. Illus 1963.—Three hybrids were obtained from controlled crosses of pubescent wheatgrass, A. trichophorum (2 n = 42), and hexaploid crested wheatgrass, A. cristatum (211 = 42). The hybrids were intermediate between the parent plants for all vegetative and spike characteristics observed. Under open pollination, 2 of the hybrids set 2 seeds each, and the other hybrid produced 60 seeds. Meiosis in the parent plants was basically regular. Average motaphase‐I chromosome associations were 0.09 I, 20.56 II, 0.05 III, and 0.16 IV per cell in the A. trichophorum parent, which was described as a segmental autoallohexaploid. The hexaploid A. cristatum parent averaged 0.18 I, 7.44 II, 0.81 III, 2.86 IV, 0.08 V, and 2.11 VI per cell at diakinesis and was described as an autohexaploid. Chromosome pairing in the hexaploid hybrid averaged 5.08 I, 8.94 II, 4.33 III, 1.11 IV, 0.27 V, and 0.05 VI per cell. On the basis of chromosome pairing in the parent species and their hybrids, it was concluded that 1 of the A. trichophorum genomes was partially homologous with the 3 genomes of hexaploid A. cristatum . Genome formulae for hexaploid A. cristatum , A. trichophorum , and their hybrids were represented as AAAAAA, A 1 A 1 B 1 B 1 B 2 B 2 , and AAAA 1 B 1 B 2 respectively.
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Agropyron
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Perennial Triticeae species comprise some of the most valuable grasses in the temperate regions of the world, in addition, they have been a source of genes for pest resistance and other traits in wide hybridization programs to improve cultivated cereal crops. Intense breeding efforts have been restricted primarily to species of Agropyron (Gaertn.), Psathyrostachys Nevski, Thinopyrum Löve, Leymus Hochst., Elymus L., and Pseudoroegneria (Nevski) Löve. Crested wheatgrass (Agropyron ssp.) has received the most attention in breeding programs as evidenced by the release of several improved cultivars. Stand establishment vigor of Russian wildrye, Psathyrostachys juncea (Fisch.) Nevski, has been substantially increased through breeding, and selection for improved forage quality and disease resistance has been effective in intermediate wheatgrass, Thinopyrum intermedium (Host) Barkw. & Dewey. Interspecific hybridization is a promising breeding procedure in the perennial Triticeae. The recently released cultivars 'Hycrest' and 'NewHy' are notable examples of progress through interspecific hybridization. 'Hycrest' was derived from hybrids between induced tetraploid Agropyron cristatum (L.) Gaertn. and natural tetraploid Agropyron desertorum (Fisch. ex Link) Schultes. The parentage of 'NewHy' traces to hybrids between quackgrass, Elytrigia repens (L.) Nevski, and bluebunch wheatgrass, Pseudoroegneria spicata (Pursh) Löve. Genetic progress through induced amphiploidy has also been reported. Continued success in breeding programs will be accelerated by expanded plant exploration efforts along with improved technology and breeding methods.
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Triticeae
Elymus
Repens
Agropyron cristatum
Introgression
Leymus
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The taxonomy of the perennial grasses of the Triticeae tribe ( Agropyron, Elymus , et al.) has been in an unsettled state for many years, with Eurasian and North American authorities often using different systems of classification and applying different names to the same species. North Americans have generally relied on the treatment given in A.S. Hitchcock's 1951 Manual of the Grasses of the United States , while realizing that it was seriously outdated. Publication of treatments of the Triticeae in Poaceae URSS by N.N. Tzvelev in 1976 and in Flora Europaea by A. Melderis et al. in 1980 has made it advisable for North Americans to reevaluate their taxonomic traditions with respect to these grasses. Tzvelev's treatment is compatible with biological relationships as determined by chromosome pairing in interspecific and intergeneric hybrids. The perennial genera of the Triticeae recognized by Tzvelev include: 1) Agropyron (restricted to A. cristatum and other crested wheatgrasses), 2) Elymus (self‐fertilizing and caespitose species previously in Elymus and Agropyron ) 3) Leymus (usually cross‐pollinating and often rhizomatous species previously in Elymus ), 4) Elytrigia (usually cross‐pollinating and rhizomatous or caespitose species previously included in Agropyron , with the exception of the crested wheatgrasses), 5) Psathyrostachys (crosspollinating species with brittle rachises and multiple spikelets, including Russian wildrye), and 6) Hordeum (treated in its traditional sense). With a few exceptions, I endorse Tzvelev's treatment because it closely reflects biological and phylogenetic relationships.
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Elymus
Agropyron
Leymus
Agropyron cristatum
Polyploid
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The basic genome of Agropyron spp.distributed in the cold and temperate plateau and sands of the Eurasia is the P genome.These species are not only adapted to abiotic stresses,such as drought,low temperature,and barren soils, but also resistant to powdery mildew,Barley dwarf virus,and the rusts in wheat.Moreover,Agropyron species produce multiple tillers,spikelets,and florets. The P genome of Agropyron can be a source of desirable genes for wheat improvement.In the 1990s,cross between wheat and Agropyron species was made,resulting in the development of a number of wheat-Agropyron chromosome addition lines,which made possible to transfer genes from the P genome into wheat by producing chromosome translocations between wheat and Agropyron.The gametocidal chromosome of Aegilops speicies,which is added to wheat genome, is able to induce various structural variations of chromosomes.Compared to the methods for inducing chromosome variations,such as irradiation,tissue culture and Ph mutant,gametocidal method is highly effective in inducing chromosome variations between wheat and relative species.This method has been used to produce chromosome translocations between wheat and Haynaldia villosa,Leymus racemosus,Elytrigia elongate,and Secale cereale,with a frequency of over 10%.However,no study has been reported on producing wheat-Agropyron chromosome translocation using gametocidal method.In the present study,eight wheat-Agropyron cristatum addition lines were crossed with Chinese Spring-Aegilops cylindrica(2C) addition lines and their morphological and cytological performances were investigated.The objective of this study was to lay a foundation on developing wheat-Agropyron chromosome translocations by inducing chromosome variations between wheat ABD genomes and Agropyron P genomes with gametocidal chromosome.The results showed that the chromosome addition lines Ⅱ-4-2,Ⅱ-21-6,Ⅱ-21-2,and Ⅱ-11-1 had transmission rate of 100%.The transmission rate was high in lines Ⅱ-5-1 and Ⅱ-9-3,but low in lines Ⅱ-292 and Ⅱ-5038.Chromosome abnormality was observed in F1 plants during meiosis.The frequency of pollen mother cells with over 3 univalents was 35.3%.Micronuclei were observed in 74% of tetrads,and chromosome fragments and bridges appeared in 20.3% and 23.8% of cells.In certain crosses multivalents,multifid quadrants,and retrogression were observed.These aberrations of chromosome behaviors indicated that the gametocidal chromosome was effective during the formation of gametes.The percentage of seed setting in F1 plants varied from 51.67% to 71.37%,indicating that the gametocidal chromosome 2C had a different effect on various wheat-Agropyron chromosome addition lines.
Agropyron
Secale
Common wheat
Agropyron cristatum
Triticeae
Leymus
Aegilops
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Intergeneric hybridizations for the transfer of disease resistance and cold and drought tolerance were performed between 34 Triticum aestivum L. cultivars or strains and 10 wild Triticeae species (Agropyron J. Gaertn., Elymus L., Elytrigia Desv., Lophopyrum A. Löve). The crosses of wheat and A. cristatum, A. pectiniforme, E. gmelinii ssp. ugamicum, E. scabriglumis, E. trachycaulus, Elytrigia intermedia ssp. barbulala, Elytrigia repens, and Lophopyrum elongalum succeeded. The plantlets derived were cloned in vitro. In the combinations T. aestivum x Elytrigia intermedia ssp. barbulata and T. aestivum x Elytrigia repens, a segregating F2 and a BC1 generation were obtained. All other combinations have so far been perennial and sterile. By crossing Triticale 'Lasko' x Lophopyrum elongalum (2x) a good yielding Agrotriticale was produced.
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Elymus
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Agropyron cristatum
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A total of 520 decamer oligonucleotides were used to perform random amplified polymorphic DNA(RAPD) analysis on Z804,Z559,Z1750,Chinese Spring,Fukuho,T.monococcum and T.durum.Two P genome specific markers,OPC04 and OPP12 were screened.These two specific primers were then used to amplify on other genome of Triticeae,and 8 wheat-Agropyron cristatum disomic addition lines.The results showed that there is no PCR amplification on ABD,C,E,AG,I,M,R,S,V,Y genome by primer OPC04 and OPP12.However,there are PCR products in all 8 wheat-Agropyron cristatum disomic addition lines.The results further indicated that OPC04 and OPP12 were the specific amplifications for the P genomes.Therefore,OPC04 and OPP12 could be the specific markers on detecting the chromatin of P genome in the wheat-Agropyron progeny.
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Agropyron
Triticeae
Common wheat
Primer (cosmetics)
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Agropyron cristatum L. Gaertner (2n = 14) and Agropyron desertorum (Fisch. ex Link) Schultes (2n = 28) cultivars were crossed with common wheat (Triticum aestivum L. em. Thell. 2n = 42, ABD genomes) in an attempt to bring the P genome of Agropyron into a wheat background for future genetic exploitation and to evaluate possible homoeology with the wheat genomes. Interspecific hybrid plants were obtained from crosses using both Agropyron species. Chromosome doubled amphiploids (2n = 56, AABBDDPP) were successfully produced by colchicine treatment of hybrid plants from the T. aestivum – A. cristatum cross. Meiotic cells of the amphiploid contained the expected 28 chromosome pairs but also exhibited a considerable amount of chromosome pairing disturbance, resulting in an average of 3.55 univalents per cell. Consequently, fertility was reduced in the amphiploid and the progeny were frequently aneuploid. Homoeologous pairing in the T. aestivum – A. cristatum hybrid was low, but the pairing disruption exhibited in the amphiploid suggested that homoeologous relationships may have been masked in the hybrid.Key words: Triticum aestivum, Agropyron cristatum, chiasma frequency, intergeneric hybrid, amphiploid.
Agropyron cristatum
Agropyron
Chromosome pairing
Common wheat
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Citations (51)
Agropyron cristatum (2n = 4x = 28, PPPP) possesses potentially valuable traits that could be used in wheat (Triticum aestivum) improvement through interspecific hybridization. Homoeologous pairing between wheat chromosomes and P chromosomes added to wheat in a set of wheat - A. cristatum addition lines was assessed. First, the Ph-suppressing effect of P chromosomes (except 7P) was analyzed. It was concluded that this system is polygenic with no major gene, and consequently, has no prospect in the transfer of alien genes from wild relatives. In a second step, the potential of the deletion ph1b of the Ph1 gene for inducing P-ABD pairing was evaluated. Allosyndetic associations between P and ABD genomes are very rare. This very low level of pairing is likely due to divergence in the repeated sequences between Agropyron and wheat genomes. Development of translocation lines using ionizing radiation seems to be a more suitable technique than homoeologous recombination to exploit the A. cristatum genome in wheat improvement.
Agropyron cristatum
Agropyron
Chromosome pairing
Common wheat
Triticeae
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Elymus
Repens
Agropyron
Agropyron cristatum
Triticale
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