DNA methylation is one of the epigenetic phenomena which can be transferred to the offspring by cell division in the evolution of organisms. The epigenetic regulation accompanied by gene expression can be found direct...DNA methylation is one of the epigenetic phenomena which can be transferred to the offspring by cell division in the evolution of organisms. The epigenetic regulation accompanied by gene expression can be found directly in the phenotype of haploidy plants. DNA cytosine methylation at the 5＇-CpCpGpG sites of haploid, Shuhui 527, Shuhui 363 and their hybrids was analyzed by methylation sensitive amplification polymorphism （MSAP） method. There were 765 DNA methylated sites detected and the methylation level was lower in hybrids than parents. Meanwhile, the different bands between hybrids and parents were analyzed and two types of methylated sites were detected, of which one inherited from haploid, and the other did not. The biological functions of genes related to methylated sites involved in cell structure, metabolize and response factor. Therefore, DNA methylated modifications can activate and silence the genes and play an important role in plant growth, development and evolution.展开更多
Eighteen pairs of diploid-haploid twin-seedlings were identified and screened out fromspecial rice SARII-628 population. Five pairs of themwere selected and randomly designated as A, B, C, Dand E. Simple sequence repe...Eighteen pairs of diploid-haploid twin-seedlings were identified and screened out fromspecial rice SARII-628 population. Five pairs of themwere selected and randomly designated as A, B, C, Dand E. Simple sequence repeats (SSR) analysisshowed that there was no difference among 310 siteswhich indicated that there was no base mutation onDNA primary structure. DNA methylation plays animportant role in gene expression regulation duringgrowth and development stages in eukaryotes. Amodified AFLP technique (methylation-sensitiveAFLP, MSAP) was employed to detect the DNA me-thylation patterns in the 5′-CCGG sites of the fivepairs of twin-seedlings. Although no methylationmutation was detected among the five diploids,forty-three methylation mutation sites were foundfrom the corresponding haploids. The MSAP ratios,which were the ratios of MSAP sites to the total am-plified sites, in five haploids were 18.79%, 19.35%,18.49%, 18.45% and 18.75%, respectively. And cor-responding full methylation levels (5′-CmCGG indouble strands) of those haploids were 10.58%,11.3%, 10.11%, 10.09% and 10.34%, respectively.Both MSAP and full methylation levels in the fivehaploids were higher than that of their correspondingdiploids, which suggested that hypermethylation oc-curred in some 5′-CCGG sites. Five types of MASPpatterns among the five pairs of twin-seedlings weredetected as follows: (1) no changes, methylation lev-els were the same in both haploids and diploids; (2) demethylation, diploid was methylated but no me-thylation in the same site in haploid; (3) hypermethy-lation, the methylation level in haploid was higher than those in diploid; (4) hypomethylation, methyla-tion in haploid was lower than those in diploid; (5) undecided pattern, change trend of methylation lev-els in haploids was not decided. The bands of 18 sites were reclaimed, then sequenced and searched on website to determine the sites of those sequences on rice chromosomes. The result showed that the methylation mutation involved the whole rice genome and 12 pairs of chromosomes. The mutation was site-related and there were different mutation sites for different haploids. Compared to diploids, the higher methylation level in haploids might be a readjusting reaction to the decrease in ploidy for the sake of sur-vival.展开更多
Nearly 100 maize specific repeated DNA clones were screened from a maize random genomic library, and used for RFLP analysis of two wheat DH populations from wheat and maize crosses. The result showed that a maize frag...Nearly 100 maize specific repeated DNA clones were screened from a maize random genomic library, and used for RFLP analysis of two wheat DH populations from wheat and maize crosses. The result showed that a maize fragment in clone MR64 was transferred into two wheat DH lines, i.e. No.18 in common wheat DHs and No.15 in persicum wheat DHs, in which strong hybridization signals were detected. It is first proved at DNA level that some maize specific DNA can be transferred into wheat DH progenies through fertilization at low frequency. Sequencing revealed that the size of the cloned insert DNA is 695 bp, containing 58% A+T. Southern hybridization to maize genome with several restriction enzymes indicated that MR64 is a dispersed repeat with 2-3 dominant tandem units. Its sequence structure, methylation pattern, copy number and chromosomal distribution were also determined. The possible mechanism of alien DNA transfer was discussed.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 30771157and 30971618)Science and Technology in Sichuan Province,China (Grant No. 2008JY0094)
文摘DNA methylation is one of the epigenetic phenomena which can be transferred to the offspring by cell division in the evolution of organisms. The epigenetic regulation accompanied by gene expression can be found directly in the phenotype of haploidy plants. DNA cytosine methylation at the 5＇-CpCpGpG sites of haploid, Shuhui 527, Shuhui 363 and their hybrids was analyzed by methylation sensitive amplification polymorphism （MSAP） method. There were 765 DNA methylated sites detected and the methylation level was lower in hybrids than parents. Meanwhile, the different bands between hybrids and parents were analyzed and two types of methylated sites were detected, of which one inherited from haploid, and the other did not. The biological functions of genes related to methylated sites involved in cell structure, metabolize and response factor. Therefore, DNA methylated modifications can activate and silence the genes and play an important role in plant growth, development and evolution.
文摘Eighteen pairs of diploid-haploid twin-seedlings were identified and screened out fromspecial rice SARII-628 population. Five pairs of themwere selected and randomly designated as A, B, C, Dand E. Simple sequence repeats (SSR) analysisshowed that there was no difference among 310 siteswhich indicated that there was no base mutation onDNA primary structure. DNA methylation plays animportant role in gene expression regulation duringgrowth and development stages in eukaryotes. Amodified AFLP technique (methylation-sensitiveAFLP, MSAP) was employed to detect the DNA me-thylation patterns in the 5′-CCGG sites of the fivepairs of twin-seedlings. Although no methylationmutation was detected among the five diploids,forty-three methylation mutation sites were foundfrom the corresponding haploids. The MSAP ratios,which were the ratios of MSAP sites to the total am-plified sites, in five haploids were 18.79%, 19.35%,18.49%, 18.45% and 18.75%, respectively. And cor-responding full methylation levels (5′-CmCGG indouble strands) of those haploids were 10.58%,11.3%, 10.11%, 10.09% and 10.34%, respectively.Both MSAP and full methylation levels in the fivehaploids were higher than that of their correspondingdiploids, which suggested that hypermethylation oc-curred in some 5′-CCGG sites. Five types of MASPpatterns among the five pairs of twin-seedlings weredetected as follows: (1) no changes, methylation lev-els were the same in both haploids and diploids; (2) demethylation, diploid was methylated but no me-thylation in the same site in haploid; (3) hypermethy-lation, the methylation level in haploid was higher than those in diploid; (4) hypomethylation, methyla-tion in haploid was lower than those in diploid; (5) undecided pattern, change trend of methylation lev-els in haploids was not decided. The bands of 18 sites were reclaimed, then sequenced and searched on website to determine the sites of those sequences on rice chromosomes. The result showed that the methylation mutation involved the whole rice genome and 12 pairs of chromosomes. The mutation was site-related and there were different mutation sites for different haploids. Compared to diploids, the higher methylation level in haploids might be a readjusting reaction to the decrease in ploidy for the sake of sur-vival.
文摘Nearly 100 maize specific repeated DNA clones were screened from a maize random genomic library, and used for RFLP analysis of two wheat DH populations from wheat and maize crosses. The result showed that a maize fragment in clone MR64 was transferred into two wheat DH lines, i.e. No.18 in common wheat DHs and No.15 in persicum wheat DHs, in which strong hybridization signals were detected. It is first proved at DNA level that some maize specific DNA can be transferred into wheat DH progenies through fertilization at low frequency. Sequencing revealed that the size of the cloned insert DNA is 695 bp, containing 58% A+T. Southern hybridization to maize genome with several restriction enzymes indicated that MR64 is a dispersed repeat with 2-3 dominant tandem units. Its sequence structure, methylation pattern, copy number and chromosomal distribution were also determined. The possible mechanism of alien DNA transfer was discussed.
