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
Seed protein content, nutritional balance and processing property of flour are the three major aspects of wheat protein quality. Most Chinese wheat cultivars are comparable to their Western counterparts in terms of se...Seed protein content, nutritional balance and processing property of flour are the three major aspects of wheat protein quality. Most Chinese wheat cultivars are comparable to their Western counterparts in terms of seed protein content and nutritional balance. However, relatively few of them possess good processing property. The main reason underlying the poor processing property of hexaploid Chinese wheat varieties is the weakness in gluten strength. Considering that wheat gluten is mainly composed of a mixture of a finite number of storage protein species and that the storage protein species may determine gluten strength through combinatorial controls, we formed the following strategies in our studies on understanding and manipulating the genetic basis of protein quality in Chinese wheat. 1. Genetic analysis. By performing well structured genetic analysis, we hope to identify two types of storage protein genes, those genes whose presence is associated with good processing property (the desirable genes, or the D type genes) and those whose presence is always associated with undesirable processing property (the undesirable genes, or the U type genes). Two sets of genetic analysis are being conducted currently. The aim of the first set of analysis is to obtain nonfunctional mutants for the majority of the genes whose products are present in the gluten. This analysis is expected to yield information on the function of individual members of storage proteins, some of which may be encoded by the D type genes, in gluten strength control. The aim of the second set of analysis is to identify potential genetic factors that may be responsible for causing weakness in gluten strength in Chinese wheat through the use of recombinant inbreed lines. This analysis may produce information on the function of the storage proteins specified by the U type genes. 2. Molecular analysis. On the basis of above genetic analysis, a molecular approach will be undertaken to clone the D and U type genes. The cloned genes will be characterized in terms of genetic diversity in cultivated wheat and wild species related to wheat and potential application in molecular breeding for processing property improvement. Because of the known association between the HMW glutenin subunit 1D×5 and good processing quality, we are now searching wheat related wild species for better versions of the 1D×5 subunit and testing their potential in wheat processing quality improvement. 3. Molecular breeding. The above genetic and molecular analysis should result in sufficient gene and marker resources suitable for wheat processing quality improvement through molecular breeding. The D type genes will be transferred into high yielding, hexaploid wheat varieties using the transgenic technology. The molecular markers linked to the U type of genes will be used to screen breeding materials for an early avoidance of this type of genes in breeding programs. In summary, the combination of theoretical and applied investigations described above should contribute to wheat protein quality improvement in both China and abroad. In the future, wheat quality breeding will be a more productive and efficient enterprise worldwide.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Seed protein content, nutritional balance and processing property of flour are the three major aspects of wheat protein quality. Most Chinese wheat cultivars are comparable to their Western counterparts in terms of seed protein content and nutritional balance. However, relatively few of them possess good processing property. The main reason underlying the poor processing property of hexaploid Chinese wheat varieties is the weakness in gluten strength. Considering that wheat gluten is mainly composed of a mixture of a finite number of storage protein species and that the storage protein species may determine gluten strength through combinatorial controls, we formed the following strategies in our studies on understanding and manipulating the genetic basis of protein quality in Chinese wheat. 1. Genetic analysis. By performing well structured genetic analysis, we hope to identify two types of storage protein genes, those genes whose presence is associated with good processing property (the desirable genes, or the D type genes) and those whose presence is always associated with undesirable processing property (the undesirable genes, or the U type genes). Two sets of genetic analysis are being conducted currently. The aim of the first set of analysis is to obtain nonfunctional mutants for the majority of the genes whose products are present in the gluten. This analysis is expected to yield information on the function of individual members of storage proteins, some of which may be encoded by the D type genes, in gluten strength control. The aim of the second set of analysis is to identify potential genetic factors that may be responsible for causing weakness in gluten strength in Chinese wheat through the use of recombinant inbreed lines. This analysis may produce information on the function of the storage proteins specified by the U type genes. 2. Molecular analysis. On the basis of above genetic analysis, a molecular approach will be undertaken to clone the D and U type genes. The cloned genes will be characterized in terms of genetic diversity in cultivated wheat and wild species related to wheat and potential application in molecular breeding for processing property improvement. Because of the known association between the HMW glutenin subunit 1D×5 and good processing quality, we are now searching wheat related wild species for better versions of the 1D×5 subunit and testing their potential in wheat processing quality improvement. 3. Molecular breeding. The above genetic and molecular analysis should result in sufficient gene and marker resources suitable for wheat processing quality improvement through molecular breeding. The D type genes will be transferred into high yielding, hexaploid wheat varieties using the transgenic technology. The molecular markers linked to the U type of genes will be used to screen breeding materials for an early avoidance of this type of genes in breeding programs. In summary, the combination of theoretical and applied investigations described above should contribute to wheat protein quality improvement in both China and abroad. In the future, wheat quality breeding will be a more productive and efficient enterprise worldwide.
