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M. W. Humphreys - One of the best experts on this subject based on the ideXlab platform.
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introgression mapping of genes for winter hardiness and frost tolerance transferred from festuca arundinacea into Lolium multiflorum
Journal of Heredity, 2007Co-Authors: Arkadiusz Kosmala, Elŝbieta Zwierzykowska, Z Zwierzykowski, Dagmara Gasior, Marcin Rapacz, Michal W Luczak, M. W. HumphreysAbstract:Genes for winter hardiness and frost tolerance were introgressed from Festuca arundinacea into winter-sensitive Lolium multiflorum. Two partly fertile, pentaploid (2n 5 5x 5 35) F1 hybrids F. arundinacea (2n 5 6x 5 42) � L. multiflorum (2n 5 4x 5 28) were generated and backcrossed twice onto L. multiflorum (2x). The backcross 1 (BC1) and backcross 2 (BC2) plants were preselected for high vigor and good fertility, and subsequently, a total of 83 BC2 plants were selected for winter hardiness after 2 Polish winters and by simulated freezing tests. Genomic in situ hybridization (GISH) was performed on 6 winter-hardy plants selected after the first winter and shown to be significantly (P , 0.05) more frost tolerant than theL. multiflorum control. Among the analyzed BC2 winter survivors, only diploid (2n 5 2x 5 14) plants were found. Five plants carried 13 intact L. multiflorum chromosomes and 1 L. multiflorum chromosome with a single introgressed F. arundinacea terminal chromosome segment. The sixth BC2 winter survivor appeared to be Lolium without any Festuca introgression capable of detection by GISH. A combined GISH and fluorescence in situ hybridization analysis with rDNA probes of the most winter-hardy (after 2 winters) and frost-tolerant BC2 plant revealed the location of an F. arundinacea introgression on the nonsatellite arm of L. multiflorum chromosome 2, the same chromosome location reported previously as a site for frost tolerance genes in the diploid and winter-hardy species Festuca pratensis.
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gish fish mapping of genes for freezing tolerance transferred from festuca pratensis to Lolium multiflorum
Heredity, 2006Co-Authors: Arkadiusz Kosmala, Elŝbieta Zwierzykowska, Z Zwierzykowski, Dagmara Gasior, Marcin Rapacz, M. W. HumphreysAbstract:GISH/FISH mapping of genes for freezing tolerance transferred from Festuca pratensis to Lolium multiflorum
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gish fish mapping of genes for freezing tolerance transferred from festuca pratensis to Lolium multiflorum
Heredity, 2006Co-Authors: Arkadiusz Kosmala, Elŝbieta Zwierzykowska, Z Zwierzykowski, Dagmara Gasior, Marcin Rapacz, M. W. HumphreysAbstract:The first backcross breeding programme for the transfer of freezing-tolerance genes from winter hardy Festuca pratensis to winter-sensitive Lolium multiflorum is described. A partly fertile, triploid F(1) hybrid F. pratensis (2n=2x=14) x L. multiflorum (2n=4x=28) was employed initially, and after two backcrosses to L. multiflorum (2x) a total of 242 backcross two (BC(2)) plants were generated. Genomic in situ hybridisation (GISH) was performed on 61 BC(2) plants selected for their good growth and winter survival characters in the spring following one Polish winter (2000-2001). Among the winter survivors, diploid chromosome numbers were present in 80% of plants. An appropriate single Festuca introgression in an otherwise undisturbed Lolium genome could provide increased freezing tolerance without compromise to the good growth and plant vigour found in Lolium. Among all the diploids, a total of 20 individuals were identified, each with a single F. pratensis chromosome segment. Another diploid plant contained 13 Lolium chromosomes and a large metacentric F. pratensis chromosome, identified as chromosome 4, with two large distal Lolium introgressions on each chromosome arm. Three of the diploid BC(2), including the genotype with Festuca chromosome 4 DNA sequences, were found to have freezing tolerance in excess of that of L. multiflorum, and in one case in excess of the F. pratensis used as control. A detailed cytological analysis combining GISH and fluorescence in situ hybridisation analyses with rDNA probes revealed that the other two freezing-tolerant genotypes carried a Festuca chromosome segment at the same terminal location on the non-satellite arm of Lolium chromosome 2.
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introgression mapping of genes for drought resistance transferred from festuca arundinacea var glaucescens into Lolium multiflorum
Theoretical and Applied Genetics, 2005Co-Authors: Janet Humphreys, John Harper, M. W. HumphreysAbstract:Procedures for the transfer of genes for drought resistance from Festuca glaucescens (2n=4x=28) into Lolium multiflorum (2n=2x=14) are described. Following the initial hybridisation of a synthetic autotetraploid of L. multiflorum (2n=4x=28) with F. glaucescens, the F1 hybrid was backcrossed twice onto diploid L. multiflorum (2n=2x=14) to produce a diploid Lolium genotype with a single F. glaucescens introgression located distally on the nucleolar organiser region arm of chromosome 3. The transmission of F. glaucescens-derived amplified fragment length polymorphisms and a sequence-tagged-site (STS) marker was monitored throughout the breeding programme. Those genotypes of a mapping population of backcross 3 that survived combined severe drought and heat stress all contained the F. glaucescens-derived markers. The STS marker provided a prototype for a PCR-based system for high-throughput screening during cultivar development for the presence of the F. glaucescens-derived genes for drought resistance. The frequency of intergeneric recombination between L. multiflorum and F. glaucescens is described. During the initial stages of the breeding programme, preferential intraspecific chromosome pairing between Lolium homologues and Festuca homoeologues dominated with low frequencies of intergeneric chromosome associations. However, these increased in the backcross 1 due to the absence of opportunities for intraspecific chromosome pairing between homoeologous Festuca chromosomes following the loss of half of the Festuca chromosomes. Once transferred to Lolium, F. glaucescens sequences recombined with Lolium at high frequencies, thereby enabling the loss of potentially deleterious gene combinations that might reduce the forage quality of Lolium.
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variation for winter hardiness generated by androgenesis from festuca pratensis Lolium multiflorum amphidiploid cultivars with different winter susceptibility
Euphytica, 2005Co-Authors: Marcin Rapacz, Z Zwierzykowski, Dagmara Gasior, M. W. Humphreys, A Plazek, A LeśniewskabocianowskaAbstract:Androgenic populations produced from three Festuca pratensis × Lolium multiflorum amphidiploid (2n = 4x = 28) cultivars show wide within population variation for winter hardiness. Populations comprising a total of 423 androgenic plants derived from 23 donor plants from 3 Polish F. pratensis × L. multiflorum cultivars Felopa, Sulino, and Rakopan were studied over 3 years (1999–2002) in a field experiment at Lopuszna, Poland (20∘08′E, 49∘28′N, altitude 568 m). The results indicate that despite differences in winter hardiness between the three amphidiploid cultivars, the mean winter hardiness of androgenic progeny from each cultivar was the same. Thus an androgenesis component in a plant breeding programme may provide an opportunity to recover winter hardy genotypes from high yielding cultivars that are themselves adapted poorly to stress conditions. Androgenesis also evoked variation in snow mould resistance. In this case, androgenic plants with the greatest snow mould resistance were recovered from the least winter hardy donor cultivars and plants. The results indicated the low importance of snow mould resistance as a component of winter hardiness under the field conditions used for these experiments.
Howard Thomas - One of the best experts on this subject based on the ideXlab platform.
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introgression of crown rust puccinia coronata resistance from meadow fescue festuca pratensis into italian ryegrass Lolium multiflorum genetic mapping and identification of associated molecular markers
Plant Pathology, 2006Co-Authors: J. A. Harper, Ian P. King, Leif Skot, Lesley B Turner, Mervyn O Humphreys, W G Morgan, Howard Thomas, H W RoderickAbstract:Crown rust (Puccinia coronata) resistance (CRres), which had been introgressed from meadow fescue (Festuca pratensis) into the Italian ryegrass (Lolium multiflorum) background, was genetically mapped with amplified fragment length polymorphism (AFLP) and sequence tagged site (STS) markers to a terminal segment of chromosome 5. Comparative mapping had previously shown that this region of the Lolium/Festuca genome has a degree of conserved genetic synteny with chromosomes 11 and 12 of rice. Sequences from rice chromosome 12 were used as templates for identifying further STS markers that cosegregated with CRres. The relative genomic positions of molecular markers associated with CRres in L. multiflorum, L. perenne, F. pratensis and oats is discussed, along with their relationships to physical positions on rice chromosomes C11 and C12.
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introgression of crown rust puccinia coronata resistance from meadow fescue festuca pratensis into italian ryegrass Lolium multiflorum and physical mapping of the locus
Heredity, 2003Co-Authors: H W Roderick, J. A. Harper, W G Morgan, Howard ThomasAbstract:Resistance was found in the meadow fescue (Festuca pratensis) to crown rust (Puccinia coronata), originating from ryegrasses (Lolium spp). A backcrossing programme successfully transferred this resistance into diploid Italian ryegrass (Lolium multiflorum) and genomic in situ hybridisation (GISH) was used to identify the introgressed fescue chromosome segment. The resistant (R) plants in two BC3 lines all carried an introgressed segment on a single chromosome, which in one of the lines was confined to the short arm of the chromosome. Susceptible (S) plants either contained no introgressed chromosome segment or a segment which was physically smaller than the segments in resistant plants. Using GISH the resistance locus could be physically mapped to the midpoint of a short arm. Segregation ratios of the progeny of BC3 plants, when crossed as R × S and R × R, were in agreement with the hypothesis that the resistance was controlled by a single gene or very closely linked genes. No R plants were produced by crossing S × S plants.
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androgenesis from festuca pratensis Lolium multiflorum amphidiploid cultivars in order to select and stabilize rare gene combinations for grass breeding
Heredity, 2001Co-Authors: Alicja Wiśniewska, Elŝbieta Zwierzykowska, A Ponitka, Z Zwierzykowski, Aurelia ślusarkiewiczjarzina, A R James, Howard Thomas, M. W. HumphreysAbstract:Lesniewska, A., Ponitka, A., Slusarkiewicz-Jarzina, A., Zwierzykowska, E., Zwierzykowski, Z., James, A. R., Thomas, Henry, Humphreys, M. W. (2001). Androgenesis from Festuca pratensis x Lolium multiflorum amphidiploid cultivars in order to select and stabilise rare gene combinations for grass breeding. Heredity, 86, (2), 167-176. Sponsorship: This work was supported in part by the Agriculture Agency of the State Treasury in Warsaw, Poland. Agnieszka Leniewska acknowledges the support of the European Science Foundation during her six months stay at IGER, Aberystwyth, U.K.
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androgenesis from festuca pratensis Lolium multiflorum amphidiploid cultivars in order to select and stabilize rare gene combinations for grass breeding
Heredity, 2001Co-Authors: Alicja Wiśniewska, Elŝbieta Zwierzykowska, A Ponitka, Z Zwierzykowski, Aurelia ślusarkiewiczjarzina, A R James, Howard Thomas, M. W. HumphreysAbstract:Lesniewska, A., Ponitka, A., Slusarkiewicz-Jarzina, A., Zwierzykowska, E., Zwierzykowski, Z., James, A. R., Thomas, Henry, Humphreys, M. W. (2001). Androgenesis from Festuca pratensis x Lolium multiflorum amphidiploid cultivars in order to select and stabilise rare gene combinations for grass breeding. Heredity, 86, (2), 167-176. Sponsorship: This work was supported in part by the Agriculture Agency of the State Treasury in Warsaw, Poland. Agnieszka Leniewska acknowledges the support of the European Science Foundation during her six months stay at IGER, Aberystwyth, U.K.
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identification of parental and recombined chromosomes in hybrid derivatives of Lolium multiflorum festuca pratensis by genomic in situ hybridization
Theoretical and Applied Genetics, 1994Co-Authors: Howard Thomas, M. R. Meredith, M. W. Humphreys, W G Morgan, J. M. LeggettAbstract:Genomic in situ hybridization (GISH) was used to identify Festuca chromatin in mitotic chromosomes of Lolium multiflorum (Lm) × Festuca pratensis (Fp) hybrids and hybrid derivatives. In two inverse autoallotriploids LmLmFp and LmFpFp, in situ hybridization was able to discriminate between the Lolium and Festuca chromosomes. In a third triploid hybrid produced by crossing an amphiploid of L. multiflorum × F. pratensis (2n=4x=28) with L. multiflorum (2n=2x=14), the technique identified chromosomes with interspecific recombination. Also, in an introgressed line of L. multiflorum which was homozygous for the recessive sid (senescence induced degradation) allele from F. pratensis, a pair of chromosome segments carrying the sid gene could be identified, indicating the suitability of GISH in showing the presence and location of introgressed genes. By screening backcross progeny for the presence of critical alien segments and the absence of other segments the reconstitution of the genome of the recipient species can be accelerated.
H W Roderick - One of the best experts on this subject based on the ideXlab platform.
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introgression of crown rust puccinia coronata resistance from meadow fescue festuca pratensis into italian ryegrass Lolium multiflorum genetic mapping and identification of associated molecular markers
Plant Pathology, 2006Co-Authors: J. A. Harper, Ian P. King, Leif Skot, Lesley B Turner, Mervyn O Humphreys, W G Morgan, Howard Thomas, H W RoderickAbstract:Crown rust (Puccinia coronata) resistance (CRres), which had been introgressed from meadow fescue (Festuca pratensis) into the Italian ryegrass (Lolium multiflorum) background, was genetically mapped with amplified fragment length polymorphism (AFLP) and sequence tagged site (STS) markers to a terminal segment of chromosome 5. Comparative mapping had previously shown that this region of the Lolium/Festuca genome has a degree of conserved genetic synteny with chromosomes 11 and 12 of rice. Sequences from rice chromosome 12 were used as templates for identifying further STS markers that cosegregated with CRres. The relative genomic positions of molecular markers associated with CRres in L. multiflorum, L. perenne, F. pratensis and oats is discussed, along with their relationships to physical positions on rice chromosomes C11 and C12.
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introgression of crown rust puccinia coronata resistance from meadow fescue festuca pratensis into italian ryegrass Lolium multiflorum and physical mapping of the locus
Heredity, 2003Co-Authors: H W Roderick, J. A. Harper, W G Morgan, Howard ThomasAbstract:Resistance was found in the meadow fescue (Festuca pratensis) to crown rust (Puccinia coronata), originating from ryegrasses (Lolium spp). A backcrossing programme successfully transferred this resistance into diploid Italian ryegrass (Lolium multiflorum) and genomic in situ hybridisation (GISH) was used to identify the introgressed fescue chromosome segment. The resistant (R) plants in two BC3 lines all carried an introgressed segment on a single chromosome, which in one of the lines was confined to the short arm of the chromosome. Susceptible (S) plants either contained no introgressed chromosome segment or a segment which was physically smaller than the segments in resistant plants. Using GISH the resistance locus could be physically mapped to the midpoint of a short arm. Segregation ratios of the progeny of BC3 plants, when crossed as R × S and R × R, were in agreement with the hypothesis that the resistance was controlled by a single gene or very closely linked genes. No R plants were produced by crossing S × S plants.
Phillip Morris - One of the best experts on this subject based on the ideXlab platform.
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agrobacterium tumefaciens mediated transformation of festuca arundinacea schreb and Lolium multiflorum lam
Plant Cell Reports, 2003Co-Authors: Andy J E Bettany, Susan Dalton, E Timms, B Manderyck, M S Dhanoa, Phillip MorrisAbstract:Agrobacterium tumefaciens strain LBA4404 carrying plasmid pTOK233 encoding the hygromycin resistance (hph) and β-glucuronidase (uidA) genes has been used to transform two agronomic grass species: tall fescue (Festuca arundinacea) and Italian ryegrass (Lolium multiflorum). Embryogenic cell suspension colonies or young embryogenic calli were co-cultured with Agrobacterium in the presence of acetosyringone. Colonies were grown under hygromycin selection with cefotaxime and surviving colonies plated on embryogenesis media. Eight Lolium (six independent lines) and two Festuca plants (independent lines) were regenerated and established in soil. All plants were hygromycin-resistant, but histochemical determination of GUS activity showed that only one Festuca plant and one Lolium plant expressed GUS. Three GUS-negative transgenic L. multiflorum and the two F. arundinacea plants were vernalised and allowed to flower. All three Lolium plants were male- and female-fertile, but the Festuca plants failed to produce seed. Progeny analysis of L. multiflorum showed a 24–68% inheritance of the hph and uidA genes in the three lines with no significant difference between paternal and maternal gene transmission. However, significant differences were noted between the paternal and maternal expression of hygromycin resistance.
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co transformed diploid Lolium perenne perennial ryegrass Lolium multiflorum italian ryegrass and Lolium temulentum darnel plants produced by microprojectile bombardment
Plant Cell Reports, 1999Co-Authors: Susan Dalton, Andy J E Bettany, E Timms, Phillip MorrisAbstract:A total of 37 plants (30 Lolium multiflorum Lam., 6 L. perenne L., 1 L. temulentum L.) were regenerated from cell suspension colonies bombarded with plasmid DNAs encoding a hygromycin resistance gene (HYG) expressed under a CaMV35S promoter and a β-glucuronidase (GUS) gene expressed under a truncated rice actin1 promoter and first intron, or a maize ubiquitin promoter and first intron. Resistant plants were regenerated under hygromycin selection and transferred to soil. PCR analysis showed that the co-transformation frequency of the GUS gene varied from 33% to 78% of transformants, while histochemical staining of leaf tissue from soil-grown plants showed that the co-expression frequency varied from 37% to 50%. The transgenic nature of the plants was demonstrated by Southern hybridisation analysis, which also showed that the non-selected (GUS) gene was generally present at a higher copy number than the selected (HYG) gene.
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transgenic plants of Lolium multiflorum Lolium perenne festuca arundinacea and agrostis stolonifera by silicon carbide fibre mediated transformation of cell suspension cultures
Plant Science, 1998Co-Authors: Susan Dalton, Andy J E Bettany, E Timms, Phillip MorrisAbstract:Seven Lolium multiflorum, one Lolium perenne, 12 Festuca arundinacea and six Agrostis stolonifera plants were regenerated following transformation with a hygromycin resistance gene and hygromycin selection, from cell suspension colonies treated with silicon–carbide whiskers. Transformation was confirmed by PCR and Southern blotting; the latter also showed that six of the L. multiflorum plants were independent transformants (insufficient molecular evidence was obtained for the seventh), nine of the 12 F. arundinacea plants were independent transformants, but that all the A. stolonifera plants were derived from a single transformation event. Most plants tested contained fewer than five integrated transgene copies. Transgene expression was confirmed by reverse transcriptase-PCR (RT-PCR). Of the one A. stolonifera and three L. multiflorum transformants regenerated after co-transformation with both the hygromycin resistance gene and the β-glucuronidase (gusA) gene, none were found to express GUS activity. L. multiflorum regenerants from older (14–16 week old) cell suspensions showed loss of female fertility, but analysis of the progeny from three plants showed that the transgenes were being inherited as a single dominant allele with a high frequency of transmission of hygromycin resistance.
Z Zwierzykowski - One of the best experts on this subject based on the ideXlab platform.
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physiological basis for differences in resistance to microdochium nivale fr samuels and hallett in two androgenic genotypes of festuLolium derived from tetraploid f1 hybrids of festuca pratensis Lolium multiflorum festuLolium
Journal of Phytopathology, 2008Co-Authors: Ewa Pociecha, A Plazek, Franciszek Janowiak, A Janeczko, Z ZwierzykowskiAbstract:The aim of this study was to investigate the physiological basis for differences in resistance to pink snow mould (Microdochium nivale) in two androgenic genotypes of FestuLolium (Festuca pratensis x Lolium multiflorum) which differed in terms of their resistance to M. nivale. Genotype 716 was more resistant than genotype 729. The study consisted of two experiments. The aim of the first experiment was to estimate the ability of the plants to survive winter conditions. The aim of the second experiment was to find physiological markers of resistance to snow mould. FestuLolium plants were infected with M. nivale mycelium after pre-hardening and hardening. After 2 weeks in the dark at 2°C, there was a sharp increase in the phenolic content in both genotypes. The increase was greater in the more resistant genotype 716 than in genotype 729. Phenolics therefore may play a very important role in overwintering in grasses, similar to carbohydrates. Based on the differences between the two genotypes, potential indicators of resistance to M. nivale in FestuLolium include increased soluble carbohydrate content, increased phenolic content, increased hydrogen peroxide accumulation, decreased catalase activity, increased abscisic acid content and reduced heat emission.
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introgression mapping of genes for winter hardiness and frost tolerance transferred from festuca arundinacea into Lolium multiflorum
Journal of Heredity, 2007Co-Authors: Arkadiusz Kosmala, Elŝbieta Zwierzykowska, Z Zwierzykowski, Dagmara Gasior, Marcin Rapacz, Michal W Luczak, M. W. HumphreysAbstract:Genes for winter hardiness and frost tolerance were introgressed from Festuca arundinacea into winter-sensitive Lolium multiflorum. Two partly fertile, pentaploid (2n 5 5x 5 35) F1 hybrids F. arundinacea (2n 5 6x 5 42) � L. multiflorum (2n 5 4x 5 28) were generated and backcrossed twice onto L. multiflorum (2x). The backcross 1 (BC1) and backcross 2 (BC2) plants were preselected for high vigor and good fertility, and subsequently, a total of 83 BC2 plants were selected for winter hardiness after 2 Polish winters and by simulated freezing tests. Genomic in situ hybridization (GISH) was performed on 6 winter-hardy plants selected after the first winter and shown to be significantly (P , 0.05) more frost tolerant than theL. multiflorum control. Among the analyzed BC2 winter survivors, only diploid (2n 5 2x 5 14) plants were found. Five plants carried 13 intact L. multiflorum chromosomes and 1 L. multiflorum chromosome with a single introgressed F. arundinacea terminal chromosome segment. The sixth BC2 winter survivor appeared to be Lolium without any Festuca introgression capable of detection by GISH. A combined GISH and fluorescence in situ hybridization analysis with rDNA probes of the most winter-hardy (after 2 winters) and frost-tolerant BC2 plant revealed the location of an F. arundinacea introgression on the nonsatellite arm of L. multiflorum chromosome 2, the same chromosome location reported previously as a site for frost tolerance genes in the diploid and winter-hardy species Festuca pratensis.
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gish fish mapping of genes for freezing tolerance transferred from festuca pratensis to Lolium multiflorum
Heredity, 2006Co-Authors: Arkadiusz Kosmala, Elŝbieta Zwierzykowska, Z Zwierzykowski, Dagmara Gasior, Marcin Rapacz, M. W. HumphreysAbstract:GISH/FISH mapping of genes for freezing tolerance transferred from Festuca pratensis to Lolium multiflorum
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gish fish mapping of genes for freezing tolerance transferred from festuca pratensis to Lolium multiflorum
Heredity, 2006Co-Authors: Arkadiusz Kosmala, Elŝbieta Zwierzykowska, Z Zwierzykowski, Dagmara Gasior, Marcin Rapacz, M. W. HumphreysAbstract:The first backcross breeding programme for the transfer of freezing-tolerance genes from winter hardy Festuca pratensis to winter-sensitive Lolium multiflorum is described. A partly fertile, triploid F(1) hybrid F. pratensis (2n=2x=14) x L. multiflorum (2n=4x=28) was employed initially, and after two backcrosses to L. multiflorum (2x) a total of 242 backcross two (BC(2)) plants were generated. Genomic in situ hybridisation (GISH) was performed on 61 BC(2) plants selected for their good growth and winter survival characters in the spring following one Polish winter (2000-2001). Among the winter survivors, diploid chromosome numbers were present in 80% of plants. An appropriate single Festuca introgression in an otherwise undisturbed Lolium genome could provide increased freezing tolerance without compromise to the good growth and plant vigour found in Lolium. Among all the diploids, a total of 20 individuals were identified, each with a single F. pratensis chromosome segment. Another diploid plant contained 13 Lolium chromosomes and a large metacentric F. pratensis chromosome, identified as chromosome 4, with two large distal Lolium introgressions on each chromosome arm. Three of the diploid BC(2), including the genotype with Festuca chromosome 4 DNA sequences, were found to have freezing tolerance in excess of that of L. multiflorum, and in one case in excess of the F. pratensis used as control. A detailed cytological analysis combining GISH and fluorescence in situ hybridisation analyses with rDNA probes revealed that the other two freezing-tolerant genotypes carried a Festuca chromosome segment at the same terminal location on the non-satellite arm of Lolium chromosome 2.
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chromosome pairing in triploid intergeneric hybrids of festuca pratensis with Lolium multiflorum revealed by gish
Journal of Applied Genetics, 2006Co-Authors: Arkadiusz Kosmala, Elŝbieta Zwierzykowska, Z ZwierzykowskiAbstract:Genomicin situ hybridisation (GISH) was used to reveal chromosome pairing in two partly fertile, triploid (2n = 3x = 21) hybrids obtained by crossing the diploid (2n = 2x = 14)Festuca pratensis Huds. (designated FpFp), used as a female parent, with the autotetraploid (2n = 4x = 28)Lolium multiflorum Lam. (designated LmLmLmLm), used as a male parent. The pattern of chromosome pairing calculated on the basis of the mean values of chromosome configurations identified in all 100 PMCs analysed, was: 0.71I Lm + 2.24I Fp + 2.18II Lm/Lm + 0.54II Lm/Fp + 4.18III Lm/Lm/Fp. A relatively high number of Lm/Lm bivalents and Fp univalents, and a low number of Lm/Fp bivalents and Lm univalents indicated that the pairing was preferential betweenL. multiflorum chromosomes. Other observations regarding chromosome pairing within the Lm/Lm/Fp trivalents also confirmed this preferential pairing in the analysed triploids, as the Fp chromosome was not randomly located in the chain- and frying-pan-shaped trivalents. The similarities and differences in chromosome pairing at metaphase I and the level of preferential pairing betweenLolium chromosomes in the different triploidLolium-Festuca hybrids are discussed.
