The American geneticist, E. R. Sears, was the founder of wheat chromosome engineering.He established the monosomic series of common wheat, which greatly facilitated cytogenetic analysis of wheat. However, problems of ...The American geneticist, E. R. Sears, was the founder of wheat chromosome engineering.He established the monosomic series of common wheat, which greatly facilitated cytogenetic analysis of wheat. However, problems of univalent shift and labor involved in chromosome counting have limited the common usage of these materials. To circumvent these problems, I developed an alternative set of monosomic lines, in which the presence of the univalent chromosome was indicated by the production of blue pigmentation in the aleurone tissue of seeds. The gene(s) responsible for the blue pigmentation were carried on a short chromosomal fragment of Agropyron elongatum. This chromosomal fragment has been transferred to the different chromosomes of common wheat using radiation induced translocation. On the spike derived from a blue grained monosomic wheat (2 n =41, the univalent chromosome carries the gene for the blue pigmentation), four types of seeds are produced. The deep blue seed has 42 chromosomes, the medium blue and light blue seed has 41 chromosomes, and the white seed has 40 chromosomes. The monosomic genotype is easily identified based on the color of the seed, without the use of microscope. So far, blue grained monosomic lines have peoduced 11 of the 21 different wheat chromosomes. In the course of propagating the blue grained monosomics, I found that the fertility of the nullisomic lines (2 n =40, represented by white seeds) could be improved by continued selfing and reselection. Using the resulted self fertile nullisomic lines, I established an efficient procedure for producing alien substitution lines of wheat. The utilization of the blue grained monosomic lines and the self fertile nullisomic lines may facilitate chromosome engineering studies in wheat.展开更多
Fluorescence in situ hybridization was applied with total genomic DNA extracted from D.villosum as a probe to characterize chromosome translocations arising from tissue culture in crosses of Triticum aestivum × T...Fluorescence in situ hybridization was applied with total genomic DNA extracted from D.villosum as a probe to characterize chromosome translocations arising from tissue culture in crosses of Triticum aestivum × T. durum D. villosum amphiploids. Chromosome translocations between wheat and D.villosum occurred indeed in callus cells at an average frequency of 1.9 %. Translocations existed not only in callus cells but also in regenerate plants. Three plants with translocation chromosomes were characterized among 66 regenerated plants. One of them was proved to be a reciprocal translocation with break point of wheat chromosome at about one third of a chromosome arm, and that of D. villosum at about one half of a chromosome arm. The break point of the other two translocations was located at, or near centromeres. These similar results from both callus cells and regenerated plants provided evidence that chromosomal translocations could take place in tissue culture. Additional chromosome structure changes (fragments, telocentrics, dicentromeres, and deletions) as well as numerical alterations (including aneuploid and polyploid) were also observed in tissue cultured cells.For 175 regenerated plants arising from immature embryos of crosses between wheat ( Triticum aestivum L.) and 6D/6V substitution stocks, electrophoresis of glutamate oxaloacetate transaminase (GOT) isoenzymes was performed. The GOT V2 enzyme band was absent in two plants (designated as 98R149 and 98R159, respectively). Fluorescence in situ hybridization with total genomic DNA extracted from D.villosum as a probe confirmed the occurrence of translocation between 6V chromosome and an unknown wheat one in the two regenerants mentioned above. 98R149 and 98R159 were immune to powdery mildew ( Erysiphe graminis DC.f.sp. tritici ) inoculation with mix races collected from Hebei Province.These results demonstrated that useful translocations might be produced via tissue culture.展开更多
文摘The American geneticist, E. R. Sears, was the founder of wheat chromosome engineering.He established the monosomic series of common wheat, which greatly facilitated cytogenetic analysis of wheat. However, problems of univalent shift and labor involved in chromosome counting have limited the common usage of these materials. To circumvent these problems, I developed an alternative set of monosomic lines, in which the presence of the univalent chromosome was indicated by the production of blue pigmentation in the aleurone tissue of seeds. The gene(s) responsible for the blue pigmentation were carried on a short chromosomal fragment of Agropyron elongatum. This chromosomal fragment has been transferred to the different chromosomes of common wheat using radiation induced translocation. On the spike derived from a blue grained monosomic wheat (2 n =41, the univalent chromosome carries the gene for the blue pigmentation), four types of seeds are produced. The deep blue seed has 42 chromosomes, the medium blue and light blue seed has 41 chromosomes, and the white seed has 40 chromosomes. The monosomic genotype is easily identified based on the color of the seed, without the use of microscope. So far, blue grained monosomic lines have peoduced 11 of the 21 different wheat chromosomes. In the course of propagating the blue grained monosomics, I found that the fertility of the nullisomic lines (2 n =40, represented by white seeds) could be improved by continued selfing and reselection. Using the resulted self fertile nullisomic lines, I established an efficient procedure for producing alien substitution lines of wheat. The utilization of the blue grained monosomic lines and the self fertile nullisomic lines may facilitate chromosome engineering studies in wheat.
文摘Fluorescence in situ hybridization was applied with total genomic DNA extracted from D.villosum as a probe to characterize chromosome translocations arising from tissue culture in crosses of Triticum aestivum × T. durum D. villosum amphiploids. Chromosome translocations between wheat and D.villosum occurred indeed in callus cells at an average frequency of 1.9 %. Translocations existed not only in callus cells but also in regenerate plants. Three plants with translocation chromosomes were characterized among 66 regenerated plants. One of them was proved to be a reciprocal translocation with break point of wheat chromosome at about one third of a chromosome arm, and that of D. villosum at about one half of a chromosome arm. The break point of the other two translocations was located at, or near centromeres. These similar results from both callus cells and regenerated plants provided evidence that chromosomal translocations could take place in tissue culture. Additional chromosome structure changes (fragments, telocentrics, dicentromeres, and deletions) as well as numerical alterations (including aneuploid and polyploid) were also observed in tissue cultured cells.For 175 regenerated plants arising from immature embryos of crosses between wheat ( Triticum aestivum L.) and 6D/6V substitution stocks, electrophoresis of glutamate oxaloacetate transaminase (GOT) isoenzymes was performed. The GOT V2 enzyme band was absent in two plants (designated as 98R149 and 98R159, respectively). Fluorescence in situ hybridization with total genomic DNA extracted from D.villosum as a probe confirmed the occurrence of translocation between 6V chromosome and an unknown wheat one in the two regenerants mentioned above. 98R149 and 98R159 were immune to powdery mildew ( Erysiphe graminis DC.f.sp. tritici ) inoculation with mix races collected from Hebei Province.These results demonstrated that useful translocations might be produced via tissue culture.
