Recent work revealed that, in the genomes of polyploid wheat, there exists a class of low_copy and chromosome_specific sequences that are labile upon polyploid formation. This class of sequences was proposed to play ...Recent work revealed that, in the genomes of polyploid wheat, there exists a class of low_copy and chromosome_specific sequences that are labile upon polyploid formation. This class of sequences was proposed to play a critical role in the stabilization and establishment of nascent plant polyploids as new species. To further study this issue, five wheat chromosome 7B_specific sequences, isolated from common wheat (Triticum aestivum L.) by chromosome microdissection, were characterized. The sequences were studied by genomic Southern hybridizations on a collection of polyploid wheats and their diploid progenitors. Four sequences hybridized to all polyploid species, but at the diploid level to only species closely related to the B_genome of polyploid wheat. This indicates that these sequences originated with the divergence of the diploid species, and was then vertically transmitted to polyploids. One sequence hybridized to all species at both the diploid and polyploid levels, suggesting its elimination after the polyploid wheat formation. The hybridization of this sequence to two synthetic polyploid wheats indicated that sequence elimination is a rapid event and probably related to methylation status of the sequence. Based on the above results, we suggest that selective changes of low_copy sequences occur rapidly after polyploid formation, which may contribute to the differentiation of chromosomes in newly formed allopolyploid wheats.展开更多
In order to marker dominant nuclear gene Ms2 with a blue grain, a 4E disomic addition line ＇xiaoyanlanli＇（2n=44, AABBDD＋4EII） as the male parent to pollinate with male-sterile plants of durum wheat, controlled by...In order to marker dominant nuclear gene Ms2 with a blue grain, a 4E disomic addition line ＇xiaoyanlanli＇（2n=44, AABBDD＋4EII） as the male parent to pollinate with male-sterile plants of durum wheat, controlled by a dominant nuclear gene Ms2, and a durum wheat line 89-2343 with Ms2 and blue seed marker on the same addition chromosome was developed. The genotype 89-2343 was crossed and backcrossed with a common wheat genotype 7739-3 to produce male fertile plants with blue seeds （MFP-BS）. To combine the blue seed marker, dwarf male-sterile plants carrying RhtlO and Ms2 were fertilized by pollen from selected MFP-BS. At last, the combination of blue seed marker, Ms2 and RhtlO was successfully produced. The segregation ratio of male sterility, seed color as well as chromosome configurations of the combinations suggested that the blue seed marker, Ms2 and RhtlO were located on the same chromosome. Cytological analysis indicated that the male sterile wheat line with a blue seed marker was 43 in chromosome number, with an additional chromosome. The transmission rate for blue seed male-sterile plants was 22.1% in common. In addition, the potential value for blue marker sterile lines in wheat breeding and hybrid production is discussed.展开更多
文摘Recent work revealed that, in the genomes of polyploid wheat, there exists a class of low_copy and chromosome_specific sequences that are labile upon polyploid formation. This class of sequences was proposed to play a critical role in the stabilization and establishment of nascent plant polyploids as new species. To further study this issue, five wheat chromosome 7B_specific sequences, isolated from common wheat (Triticum aestivum L.) by chromosome microdissection, were characterized. The sequences were studied by genomic Southern hybridizations on a collection of polyploid wheats and their diploid progenitors. Four sequences hybridized to all polyploid species, but at the diploid level to only species closely related to the B_genome of polyploid wheat. This indicates that these sequences originated with the divergence of the diploid species, and was then vertically transmitted to polyploids. One sequence hybridized to all species at both the diploid and polyploid levels, suggesting its elimination after the polyploid wheat formation. The hybridization of this sequence to two synthetic polyploid wheats indicated that sequence elimination is a rapid event and probably related to methylation status of the sequence. Based on the above results, we suggest that selective changes of low_copy sequences occur rapidly after polyploid formation, which may contribute to the differentiation of chromosomes in newly formed allopolyploid wheats.
文摘In order to marker dominant nuclear gene Ms2 with a blue grain, a 4E disomic addition line ＇xiaoyanlanli＇（2n=44, AABBDD＋4EII） as the male parent to pollinate with male-sterile plants of durum wheat, controlled by a dominant nuclear gene Ms2, and a durum wheat line 89-2343 with Ms2 and blue seed marker on the same addition chromosome was developed. The genotype 89-2343 was crossed and backcrossed with a common wheat genotype 7739-3 to produce male fertile plants with blue seeds （MFP-BS）. To combine the blue seed marker, dwarf male-sterile plants carrying RhtlO and Ms2 were fertilized by pollen from selected MFP-BS. At last, the combination of blue seed marker, Ms2 and RhtlO was successfully produced. The segregation ratio of male sterility, seed color as well as chromosome configurations of the combinations suggested that the blue seed marker, Ms2 and RhtlO were located on the same chromosome. Cytological analysis indicated that the male sterile wheat line with a blue seed marker was 43 in chromosome number, with an additional chromosome. The transmission rate for blue seed male-sterile plants was 22.1% in common. In addition, the potential value for blue marker sterile lines in wheat breeding and hybrid production is discussed.
