Progressive heterosis, i.e., the additional hybrid vigor in double-cross tetraploid hybrids not found in their single-cross tetraploid parents, has been documented in a number of species including alfalfa,potato, and ...Progressive heterosis, i.e., the additional hybrid vigor in double-cross tetraploid hybrids not found in their single-cross tetraploid parents, has been documented in a number of species including alfalfa,potato, and maize. In this study, four artificially induced maize tetraploids, directly derived from standard inbred lines, were crossed in pairs to create two single-cross hybrids. These hybrids were then crossed to create double-cross hybrids containing genetic material from all four original lines. Replicated fieldbased phenotyping of the materials over four years indicated a strong progressive heterosis phenotype in tetraploids but not in their diploid counterparts. In particular, the above ground dry weight phenotype of double-cross tetraploid hybrids was on average 34% and 56% heavier than that of the single-cross tetraploid hybrids and the double-cross diploid counterparts, respectively. Additionally,whole-genome resequencing of the original inbred lines and further analysis of these data did not show the expected spectrum of alleles to explain tetraploid progressive heterosis under the complementation of complete recessive model. These results underscore the reality of the progressive heterosis phenotype,its potential utility for increasing crop biomass production, and the need for exploring alternative hypothesis to explain it at a molecular level.展开更多
Tuber starch content and plant maturity are two important agronomic traits of potato.To investigate the complex genetic basis of these traits in the cultivated potato,as well as the relationship between them,we develo...Tuber starch content and plant maturity are two important agronomic traits of potato.To investigate the complex genetic basis of these traits in the cultivated potato,as well as the relationship between them,we developed a linkage map in a tetraploid population of 192 clones derived from the cross Longshu 8 × Zaodabai and mapped quantitative trait loci (QTL) for tuber starch content and plant maturity using data collected in three diverse environments over two years.We detected eleven QTL for tuber starch content distributed on seven chromosomes,of which four,on chromosomes I,II,and VIII,were expressed in at least three environments.For plant maturity,we identified six QTL on chromosomes II,IV,V,VII,and XI,one of which,on chromosome V,showed LOD peaks ranging from 45.2 to 62.5 cM and explained 21.6%–26.6% of phenotypic variation was expressed in five of the six environments.Because the reproducible QTL for plant maturity and tuber starch content mapped to different chromosomes and neither overlapping QTL,nor any genetic interaction between QTL were detected,we infer that tuber starch content and plant maturity are controlled by independent genetic loci.This inference supports the prospect of breeding potato for both early maturity and high starch content.展开更多
One major strategy to generate genetically modified mouse models is gene targeting in mouse embryonic stem(ES)cells,which is used to produce gene-targeted mice for wide applications in biomedicine.However,a major bott...One major strategy to generate genetically modified mouse models is gene targeting in mouse embryonic stem(ES)cells,which is used to produce gene-targeted mice for wide applications in biomedicine.However,a major bottleneck in this approach is that the robustness of germiine transmission of gene-targeted ES cells can be significantly reduced by their genetic and epigenetic instability after long-term culturing,which impairs the efficiency and robustness of mouse model generation.Recently,we have established a new type of pluripotent cells termed extended pluripotent stem(EPS)cells,which have superior developmental potency and robust germline competence compared to conventional mouse ES cells.In this study,we demonstrate that mouse EPS cells well maintain developmental potency and genetic stability after long-term passage.Based on gene targeting in mouse EPS cells,we established a new approach to directly and rapidly generate gene-targeted mouse models through tetraploid complementation,Haibo Li and Chaoran Zhao contributed equally to this work.Electronic supplementary material The online version of this article(https://doi.org/10.1007/s13238-018-0556-1)contains supplementary material,which is available to authorized users.which could be accomplished in approximately 2 months.Importantly,using this approach,we successfully constructed mouse models in which the human interleukin 3(IL3)or interleukin 6(IL6)gene was knocked into its corresponding locus in the mouse genome.Our study demonstrates the feasibility of using mouse EPS cells to rapidly generate mouse models by gene targeting,which have great application potential in biomedical research.展开更多
Betula platyphylla Sukaczev tetraploids have significantly larger leaf, fruit and stoma (gigantic phenotype) than diploids of the same species;however, the mechanism underlying this difference remains unclear. Tetrapl...Betula platyphylla Sukaczev tetraploids have significantly larger leaf, fruit and stoma (gigantic phenotype) than diploids of the same species;however, the mechanism underlying this difference remains unclear. Tetraploid B. platyphylla transcriptome data have indicated that the expression of genes related to indole-3-acetic acid (IAA) biosynthesis and signal transduction was altered after genome duplication. IAA exerts pleiotropic effects on growth and development by inducing the expression of Aux/IAA. We identified 20 Aux/IAA genes (BpIAA1– BpIAA20) in B. platyphylla distributed across 10 chromosomes. Multiple alignment and motif analyses revealed that nine BpIAA proteins shared all four conserved domains. Phylogenetic analysis indicated that Aux/IAA families were divided into four subfamilies and that there were two pairs of BpIAA sister genes. The BpIAAs were differentially expressed in diploids and tetraploids. Moreover, the expression levels of the nine BpIAA genes were specifically up-regulated in tetraploids from June to September compared with May (except August 5th) in tetraploids, while they were down-regulated in diploids. IAA levels were more than twofold higher in tetraploids than diploids during the vegetative season. These results indicate that genome duplication of B. platyphylla caused the up-regulated of genes involved in IAA synthesis, and the increased concentration of IAA may induce the constitutive expression of 20 BpIAA genes. Therefore, the significant changes in the expression patterns of the BpIAAs contributed to the gigantic phenotype of tetraploids to some extent. Our research sheds light on the phenotypic variations observed in B. platyphylla tetraploids.展开更多
为了从DNA分子水平探讨二倍体青檀(2n=2x=18)与经秋水仙素诱变获得的同源四倍体青檀(2n=4x=36)在遗传结构上的差异,本研究以2x及同源4x青檀为实验材料,利用AFLP(Amplified Fragment Length Polymorphism)分子标记技术,对供试材料...为了从DNA分子水平探讨二倍体青檀(2n=2x=18)与经秋水仙素诱变获得的同源四倍体青檀(2n=4x=36)在遗传结构上的差异,本研究以2x及同源4x青檀为实验材料,利用AFLP(Amplified Fragment Length Polymorphism)分子标记技术,对供试材料的DNA多态性及遗传距离进行分析。结果表明:经秋水仙素诱变获得的同源4x青檀与2x青檀在DNA分子遗传结构上具有显著差异,2x青檀单株间DNA多态性大于同源4x青檀,4x青檀单株间遗传距离在总体水平上大于2x青檀。本研究结果为进一步开展青檀多倍体育种、发挥青檀多倍体的优势提供理论依据。展开更多
基金supported by the National Science Foundation(USA)grant IOS-1545780.
文摘Progressive heterosis, i.e., the additional hybrid vigor in double-cross tetraploid hybrids not found in their single-cross tetraploid parents, has been documented in a number of species including alfalfa,potato, and maize. In this study, four artificially induced maize tetraploids, directly derived from standard inbred lines, were crossed in pairs to create two single-cross hybrids. These hybrids were then crossed to create double-cross hybrids containing genetic material from all four original lines. Replicated fieldbased phenotyping of the materials over four years indicated a strong progressive heterosis phenotype in tetraploids but not in their diploid counterparts. In particular, the above ground dry weight phenotype of double-cross tetraploid hybrids was on average 34% and 56% heavier than that of the single-cross tetraploid hybrids and the double-cross diploid counterparts, respectively. Additionally,whole-genome resequencing of the original inbred lines and further analysis of these data did not show the expected spectrum of alleles to explain tetraploid progressive heterosis under the complementation of complete recessive model. These results underscore the reality of the progressive heterosis phenotype,its potential utility for increasing crop biomass production, and the need for exploring alternative hypothesis to explain it at a molecular level.
基金by Earmarked Fund for China Agriculture Research System (CARS-09-P07)the National Natural Science Foundation of China (31160299,31760410).
文摘Tuber starch content and plant maturity are two important agronomic traits of potato.To investigate the complex genetic basis of these traits in the cultivated potato,as well as the relationship between them,we developed a linkage map in a tetraploid population of 192 clones derived from the cross Longshu 8 × Zaodabai and mapped quantitative trait loci (QTL) for tuber starch content and plant maturity using data collected in three diverse environments over two years.We detected eleven QTL for tuber starch content distributed on seven chromosomes,of which four,on chromosomes I,II,and VIII,were expressed in at least three environments.For plant maturity,we identified six QTL on chromosomes II,IV,V,VII,and XI,one of which,on chromosome V,showed LOD peaks ranging from 45.2 to 62.5 cM and explained 21.6%–26.6% of phenotypic variation was expressed in five of the six environments.Because the reproducible QTL for plant maturity and tuber starch content mapped to different chromosomes and neither overlapping QTL,nor any genetic interaction between QTL were detected,we infer that tuber starch content and plant maturity are controlled by independent genetic loci.This inference supports the prospect of breeding potato for both early maturity and high starch content.
基金the National Key Research and Development Program of China(2016YFA01001002017YFA0103000)+4 种基金the National Natural Science Foundation of China(Grant Nos.31730059 and 31521004)the Guangdong Innovative and En trepreneurial Research Team Program(2014ZT05S216)the Science and Technology Planning Project of Guangdong Province,China(2014B020226001 and 2016B030232001)the Science and Technology Program of Guangzhou,China(201508020001)National Natural Science Foundation of China(Grant No.31571052).
文摘One major strategy to generate genetically modified mouse models is gene targeting in mouse embryonic stem(ES)cells,which is used to produce gene-targeted mice for wide applications in biomedicine.However,a major bottleneck in this approach is that the robustness of germiine transmission of gene-targeted ES cells can be significantly reduced by their genetic and epigenetic instability after long-term culturing,which impairs the efficiency and robustness of mouse model generation.Recently,we have established a new type of pluripotent cells termed extended pluripotent stem(EPS)cells,which have superior developmental potency and robust germline competence compared to conventional mouse ES cells.In this study,we demonstrate that mouse EPS cells well maintain developmental potency and genetic stability after long-term passage.Based on gene targeting in mouse EPS cells,we established a new approach to directly and rapidly generate gene-targeted mouse models through tetraploid complementation,Haibo Li and Chaoran Zhao contributed equally to this work.Electronic supplementary material The online version of this article(https://doi.org/10.1007/s13238-018-0556-1)contains supplementary material,which is available to authorized users.which could be accomplished in approximately 2 months.Importantly,using this approach,we successfully constructed mouse models in which the human interleukin 3(IL3)or interleukin 6(IL6)gene was knocked into its corresponding locus in the mouse genome.Our study demonstrates the feasibility of using mouse EPS cells to rapidly generate mouse models by gene targeting,which have great application potential in biomedical research.
基金the National Natural Science Foundation of China (Grant Nos.31370660 and 31670673)the 111 Project (B16010).
文摘Betula platyphylla Sukaczev tetraploids have significantly larger leaf, fruit and stoma (gigantic phenotype) than diploids of the same species;however, the mechanism underlying this difference remains unclear. Tetraploid B. platyphylla transcriptome data have indicated that the expression of genes related to indole-3-acetic acid (IAA) biosynthesis and signal transduction was altered after genome duplication. IAA exerts pleiotropic effects on growth and development by inducing the expression of Aux/IAA. We identified 20 Aux/IAA genes (BpIAA1– BpIAA20) in B. platyphylla distributed across 10 chromosomes. Multiple alignment and motif analyses revealed that nine BpIAA proteins shared all four conserved domains. Phylogenetic analysis indicated that Aux/IAA families were divided into four subfamilies and that there were two pairs of BpIAA sister genes. The BpIAAs were differentially expressed in diploids and tetraploids. Moreover, the expression levels of the nine BpIAA genes were specifically up-regulated in tetraploids from June to September compared with May (except August 5th) in tetraploids, while they were down-regulated in diploids. IAA levels were more than twofold higher in tetraploids than diploids during the vegetative season. These results indicate that genome duplication of B. platyphylla caused the up-regulated of genes involved in IAA synthesis, and the increased concentration of IAA may induce the constitutive expression of 20 BpIAA genes. Therefore, the significant changes in the expression patterns of the BpIAAs contributed to the gigantic phenotype of tetraploids to some extent. Our research sheds light on the phenotypic variations observed in B. platyphylla tetraploids.
文摘为了从DNA分子水平探讨二倍体青檀(2n=2x=18)与经秋水仙素诱变获得的同源四倍体青檀(2n=4x=36)在遗传结构上的差异,本研究以2x及同源4x青檀为实验材料,利用AFLP(Amplified Fragment Length Polymorphism)分子标记技术,对供试材料的DNA多态性及遗传距离进行分析。结果表明:经秋水仙素诱变获得的同源4x青檀与2x青檀在DNA分子遗传结构上具有显著差异,2x青檀单株间DNA多态性大于同源4x青檀,4x青檀单株间遗传距离在总体水平上大于2x青檀。本研究结果为进一步开展青檀多倍体育种、发挥青檀多倍体的优势提供理论依据。