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Proline is an important osmoprotectant in plant in response to osmotic stresses. Delta 1-pyrroline-5-carboxylate synthetase ( P5CS) is a key enzyme in proline biosynthesis. In this study, two P5CS genes ( PrP5CS1 and PrP5CS2) were isolated for the first time from perennial ryegrass. Expression analysis revealed that the transcript of PrP5CS1 in leaves was significantly up-regulated in two ryegrass cultivars exposed to 255 m m NaCl. The up-regulated level of PrP5CS1 was higher in salt-tolerant 'Overdrive' than in sensitive 'Pizzazz'. PrP5CS2 was significantly induced in 'Overdrive' but suppressed in 'Pizzazz' by NaCl treatment. In stems, however, there was no significant transcript change for both genes under salt treatment. The proline accumulation was significantly induced in both cultivars after salt treatment, and it was higher in 'Overdrive' than in 'Pizzazz' after 2 days of salt treatment. The results suggested that both genes are salt inducible and may be associated with salt-stress tolerance in perennial ryegrass. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (Lolium perenneL.) is the most important temperate forage grass species. Unfortunately, the nutritional value of perennial ryegrass declines as maturity progresses, mainly because of a high concentration of poorly digestible compounds in inflorescences. Therefore, the development of forage-type ryegrass varieties with extended vegetative growth is of interest for agriculture. To delay floral transition in perennial ryegrass theArabidopsis ATH1gene driven by the maize ubiquitin promoter, the rice actin promoter or the rice OSH1 promoter, respectively was introduced. InATH1-expressing plants heading was delayed, and in a number of cases the plants never flowered at all. Such non- or late-heading was accompanied by the outgrowth of normally quiescent lateral meristems into extra leaves, resulting in a leafy growth habit. When eventually heading, these plants generally produced a reduced number of inflorescences. These observations suggest thatATH1-mediated delay of heading may be useful to improve fodder quality of perennial ryegrass. [ABSTRACT FROM AUTHOR]

Genetic control of the capacity to respond to anther culture in perennial ryegrass was studied in F1 offspring from crosses between 11 clones selected for anther-culture response ('inducers') and 10 clones selected from breeding material on the basis of good agronomic performance. Large differences in anther-culture response were observed between the two types of parent, with inducer clones producing an average of 10.7 green plants per 100 anthers, compared with only 0.3 for breeding clones. Hybrid populations produced an average of 2.2 green plants per 100 plated anthers, which is 7.3 times the response of the breeding material. This improvement was mainly due to a 9.4-fold increase in the percentage of green plants regenerated from hybrid populations to 4.7% compared to an average of 0.5% from breeding clones. Most of the GCA (general combining ability) in the experiment was contributed by the breeding material, constituting 55.8, 100.0 and 36.7% of genetic variation among hybrids for embryo formation, regeneration and green plant percentage, respectively. Any remaining genetic variation among hybrids was predominantly due to SCA (specific combining ability) effects, with percentages of 44.2 and 63.3%, respectively, for embryo and green plant formation. These results are discussed with respect to the possible exploitation of genes controlling anther-culture response for haploid production in breeding programmes of perennial ryegrass. [ABSTRACT FROM AUTHOR]

A defined method for the rapid establishment of cell suspensions releasing small-cell colonies and their regeneration to fertile plants is described Cell suspensions were obtained from 10 mature, lengthwise-divided embryos Five of the 10 suspensions regenerated green plants. Filtration of suspensions through a 150 μm mesh followed by generation was carried out 28 days after initiation of the suspensions, to demonstrate a rapid release of regeneration small cell colonies from cell suspensions using the protocol described. Two of the 10 filtered suspensions regenerated green plants from small cell colonies. [ABSTRACT FROM AUTHOR]

Anther-culture response in Lolium perenne was studied in the hybrid populations horn three responsive diploid parent clones to obtain genotypes with superior another-culture response through hybridization. Genetic variation for another-culture response was significant both within and between the four hybrid families and their parents. A reciprocal effect was indicated for embryo formation and regeneration non percentages for one of the cross combinations. Among 55 hybrid clones tested in two environments, 6 clones were identified with an anther- culture response level superior to their parents. While the parents produced one green plant or less per 100 anthers, these superior clones produced from 11 to 59 green plants/100 anthers, mainly as the result of improved embryo formation and improved percentages of regenerated plants being green. A significant correlation (r = 0.397**) was observed between embryo formation and percentage of green plants. The results are discussed with regard to the possible transfer of anther-culture response to non-responsive breeding material through hybridization. [ABSTRACT FROM AUTHOR]

Components of seed yield were estimated for each set of 100 plants derived from six varieties of Lolium perenne. Significant differences between the varieties were found for all components of seed yield, but the range was broader within each variety. An indirect selection of seed yield using the character seeds per spike produced a selection response similar to that obtained by direct selection on high seed yield per plant. A direct and indirect selection of characters estimated in small, drilled plots of topcross off- springs (F1) was less successful than the selection based on the single plants. Spearman rank correlation coefficients between the single plants and their offsprings did not show significant agreement for seed yield. But altogether the results indicated that the increase of seed yield/area was about 6 % when 10 % of the best plants were selected. [ABSTRACT FROM AUTHOR]

New opportunities for plant breeding using androgenesis in Lolium × Festuca hybrids have been identified. Plants derived by anther culture from a Lolium multiflorum × Festuca arundinacea (5x) hybrid were screened for freezing-tolerance, and their post-freezing recovery compared. The androgenic population showed extreme diversity in freezing-tolerance. While the majority of androgenic plants had inferior freezing-tolerance compared with the freezing-sensitive L. multiflorum parent, 6% of the population were more freezing resistant than the freezing-tolerant Festuca parent. Novel Lolium and Festuca gene combinations resulting from rare meiotic events were recovered within the androgenic population. The two most freezing-tolerant androgenic plants carried virtually the entire F. pratensis subgenome of F. arundinacea. F. pratensis is known to carry genes for freezing-tolerance and would be expected to be the primary source of genes governing this trait within the F. arundinacea genome. The most freezing-tolerant androgenic plants were more freezing-tolerant than the hybrid plant from which they were derived. Consequently, androgenesis was also effective in removing factor(s) reducing the expression of freezing-tolerance within the L. multiflorum × F. arundinacea (5x) hybrid. [ABSTRACT FROM AUTHOR]