Partner und Internationale Organisationen
(Englisch)
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A, B, CZ, DK, FIN, F, D, GR, H, IRL, I, NL, N, PL, P, SK, SI, E, S, CH, GB
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Abstract
(Englisch)
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Wheat is a worldwide cereal crop and a staple food source for billions of people. Despite continuous breeding efforts, it is still subject to important yield losses due to diseases and pests as well as abiotic stresses such as poor climate and soil conditions. The introduction of genes that are not accessible by conventional breeding into the wheat genome through genetic engineering may provide an additional tool to control fungal wheat diseases, to provide virus resistance or to enhance drought or salt tolerance of wheat. Other interesting applications of genetic engineering in wheat breeding may be found in the fields of altered carbohydrate or nitrogen metabolism, enhanced photosynthesis, herbicide tolerance, increased yield and altered seed composition. Haploid techniques can play an important role in the production of homozygously transgenic wheat plants. Over the past years, we have developed an efficient protocol for the production of fully homozygous doubled haploid plants from immature pollen grains of several non-transgenic spring wheat genotypes. Optimised microspore culture media and procedures led to an average yield of 1350 androgenic embryos per 105 microspores in the model genotype DH83Z118.32 and 82 androgenic embryos per 105 microspores in the Bobwhite-derived genotype DHBW3. The influence of embryo age and size on the frequency of green plant regeneration was studied. On average, 80 or more haploid green plants were obtained from every 100 large (>4mm2) androgenic embryos transferred to regeneration medium 25 days after microspore isolation. Furthermore, we were able to show that isolated microspore culture procedures could also be applied to transgenic wheat lines. Lines of the spring wheat variety Bobwhite transformed by particle bombardment with the maize anthocyanin regulatory gene C1 as well as the selectable bar gene conferring resistance to the herbicide phosphinothricin were used. Microspore cultures were established from one line that showed segregation for the expression of the C1 anthocyanin regulatory gene. From 17 different microspore populations we obtained 24 fertile doubled haploid plants showing C1 expression (clearly distinguishable as red coleoptiles and red nodes), as well as 21 fertile doubled haploid plants that did not show anthocyanin over-expression. In order to demonstrate the homozygosity of these microspore-derived plants, the offspring of both anthocyanin over-expressing and anthocyanin negative plants were analysed visually. All of the 1037 offspring plants that were analysed showed the same anthocyanin expression pattern as their mother plants and none of the offspring populations segregated. We report thus on the production of homozygous transgenic plants from immature pollen of segregating transgenic lines in one single generation cycle. We conclude that haploid techniques have the potential to become a valuable tool for the rapid production of homozygous transgenic wheat plants and thus to assist established transformation techniques.
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