There is limited genetic mapping data useful for breeding programs of watermelon. Introgression lines should be a use-ful tool for genetic studies and genetic enhancement of watermelon cultivars. In this study, we use...There is limited genetic mapping data useful for breeding programs of watermelon. Introgression lines should be a use-ful tool for genetic studies and genetic enhancement of watermelon cultivars. In this study, we used an advanced re-combinant population (BC2F2) to identify and map chromosomal segments of the wild watermelon Citrullus lanatus var. citroides that were incorporated in the genome of the watermelon cultivar Crimson Sweet (Citrullus lanatus var. lana-tus). An advanced recombinant population (BC2F2) was constructed using a United States Plant Introduction (PI) 494817 (C. lanatus var. citroides) (known to have moderate resistance to bacterial fruit blotch) as a donor parent, and the elite watermelon cultivar Crimson Sweet (C. lanatus var. lanatus) as the recurrent parent. The genetic linkage map consists of 272 markers, including 89 sequence-related amplified polymorphism (SRAP), 72 targeted region amplifica-tion polymorphism (TRAP), and 111 high frequency oligonucleotide-targeting active gene (HFO-TAG) markers. The 272 markers were assembled into 51 linkage groups, covering a total genetic distance of 2162 cM, with an average genetic distance of 7.9 cM between markers. Also, we expended the genetic linkage map for watermelon derived from a testcross population {Griffin 14113 [C. lanatus var. citroide (L.H. Bailey) Mansf.] x watermelon cultivar New Hamp-shire Midget (C. lanatus var. lanatus)} x PI 386015 [C. colocynthis (L.) Schrad.]. The genetic linkage map based on the test cross population consists of 558 markers that cover a genetic distance of 2760.8 cM. This linkage map consists of 41 linkage group, including 10 large linkage groups (ranging from102-240 cM), nine intermediate size linkage groups (ranging from 62-93 cM), and 22 small linkage groups (ranging from 2-56 cM). Comparative mapping between these two linkage maps identified high consensus in 25 HFO-TAG markers and one TRAP marker that represent 8 linkage groups in the BC2F2 population and 9 linkage groups in the testcross population. These results indicate that HFO-TAG markers should be useful in comparative mapping. The extended genetic maps and the genetic population in this study should be useful in breeding programs using marker assisted selection and should serve as a platform for further de-velopment of introgression lines for watermelon.展开更多
With a ＂two-way pseudo-testcross＂ mapping strategy, we applied the amplified fragment length polymorphism （AFLP） markers to construct two moderate density genetic linkage maps for Laminaria. The linkage maps were ...With a ＂two-way pseudo-testcross＂ mapping strategy, we applied the amplified fragment length polymorphism （AFLP） markers to construct two moderate density genetic linkage maps for Laminaria. The linkage maps were generated from the 60 progenies of the F1 cross family （Laminaria iongissima Aresch. × L. Japonica Miyabe） with twenty pairs of primer combinations. Of the 333 polymorphic loci scored in 60 progenies, 173 segregated in a 1：1 ratio, corresponding to DNA polymorphisms heterozygous in a single parent, and the other 58 loci existing in both parents followed a 3：1 Mendelian segregation ratio. Among the loci with 1：1 segregating ratios, 79 loci were ordered in 14 linkage groups （648.6 cM） of the paternal map, and 72 loci were ordered in 14 linkage groups （601.9 cM） of the maternal map. The average density of loci was approximately 1 per 8 cM. To Investigate the homologies between two parental maps, we used 58 loci segregated 3：1 for further analysis, and deduced one homologous linkage group. The linkage data developed in these maps will be useful for detecting loci-controlling commercially important traits for Laminaria.展开更多
Based on the genetic inheritance and segregation of random amplified polymorphism DNA(RAPDs) markers,the analysis of linkage groups for birch was performed by using a pseudo-testcross strategy.A segregating population...Based on the genetic inheritance and segregation of random amplified polymorphism DNA(RAPDs) markers,the analysis of linkage groups for birch was performed by using a pseudo-testcross strategy.A segregating population comprising of 79 progenies from the cross between Betula pendula and B.platyphylla was obtained.A set of 1 000 random oligonucleotide primers were screened,and 178 primers were selected to generate RAPD markers within a sample of 79 F\-1 progenies.A total of 296 segregating sites was identified.Among them,273 sites belonged to 1∶1 segregating site,and 36 sites were found distorted from the 1∶1 ratio.The 273 sites segregating 1∶1(testcross configuration) were used to construct parent-specific linkage group,among which 137 sites were found for B.pendula and 136 sites for B.platyphylla.The resulting linkage maps consisted of 117 marker sites in 12 groups(four or more sites per group),2 triples and 3 pairs for B.pendula,which covered the map distance about 1 533.3 cM(Kosambi units),and the average map distance between adjacent markers was 16.4 cM.In the B.platyphylla,162 linked marker sites were integrated into 12 groups(four or more sites per group),2 triples and 4 pairs,which covered the map distance about 1 847.8 cM,and the average map distance between adjacent markers was 19.2 cM.The calculated genome coverage rate of B.pendula and B.platyphylla were respectively 68.5% and 68.9%.Further study is required to integrate the two maps to one density map and to locate important genes on the maps.展开更多
Estimating genetic parameters of parental lines through progeny testing and choosing good hybrid parents are important for genetically improving seed orchard trees.In this study, 24 tetraploid progeny seedlings were u...Estimating genetic parameters of parental lines through progeny testing and choosing good hybrid parents are important for genetically improving seed orchard trees.In this study, 24 tetraploid progeny seedlings were used as experimental materials, which came from test cross design：six tetraploid Betula platyphylla lines（Q33, Q13, Q103,Q19, Q83 and Q14） as female parents and four individual B. platyphylla diploid lines（F3, F4, F9 and F11） as male parents were crossed. Variance analysis of height, diameter, height-to-diameter ratio, and internodal distance showed that the differences between hybrid combinations reached highly significant levels. Using multi-objective decisionmaking, we performed a comprehensive assessment of the various hybrid combinations. Using a selection rate of 20 % of the standard, five hybrids were selected;their genetic gains in average height, diameter, height-todiameter ratio, and internodal distance were 20.95, 6.07,13.07 and 8.96 %, respectively. We also analyzed the combining ability and genetic parameter effect values of parents and hybrid combinations. The combined analysis revealed that Q13, Q103, Q33 and Q83 were superior females; F3, F4, and F9 were superior males; and F3 × Q13, F4 × Q83 and F9 × Q33 were superior hybrid combinations. The heights and diameters of these progenies were 22.49 and 11.48 % greater than average,respectively.展开更多
Since the combining ability was proposed in 1942, efforts to uncover the genetic basis underlying this phenomenon have been ongoing for nearly 70 yr, with little success. Some breeding strategies based on evaluation o...Since the combining ability was proposed in 1942, efforts to uncover the genetic basis underlying this phenomenon have been ongoing for nearly 70 yr, with little success. Some breeding strategies based on evaluation of combining ability have been produced, and are still extensively used in hybrid breeding. In this review, the genetic basis underlying these breeding strategies is discussed, and a potential genetic control of general combining ability （GCA） is postulated. We suggested that GCA and the yields of inbred lines might be genetically controlled by different sets of loci on the maize genome that are transmitted into offspring. Different inbred lines might possess different favorable alleles for GCA. In hybrids, loci involved in multiple pathways, which are directly or indirectly associated with yield performance, might be regulated by GCA loci. In addition, a case of GCA mapping using a set of testcross progeny from introgression lines is provided.展开更多
文摘There is limited genetic mapping data useful for breeding programs of watermelon. Introgression lines should be a use-ful tool for genetic studies and genetic enhancement of watermelon cultivars. In this study, we used an advanced re-combinant population (BC2F2) to identify and map chromosomal segments of the wild watermelon Citrullus lanatus var. citroides that were incorporated in the genome of the watermelon cultivar Crimson Sweet (Citrullus lanatus var. lana-tus). An advanced recombinant population (BC2F2) was constructed using a United States Plant Introduction (PI) 494817 (C. lanatus var. citroides) (known to have moderate resistance to bacterial fruit blotch) as a donor parent, and the elite watermelon cultivar Crimson Sweet (C. lanatus var. lanatus) as the recurrent parent. The genetic linkage map consists of 272 markers, including 89 sequence-related amplified polymorphism (SRAP), 72 targeted region amplifica-tion polymorphism (TRAP), and 111 high frequency oligonucleotide-targeting active gene (HFO-TAG) markers. The 272 markers were assembled into 51 linkage groups, covering a total genetic distance of 2162 cM, with an average genetic distance of 7.9 cM between markers. Also, we expended the genetic linkage map for watermelon derived from a testcross population {Griffin 14113 [C. lanatus var. citroide (L.H. Bailey) Mansf.] x watermelon cultivar New Hamp-shire Midget (C. lanatus var. lanatus)} x PI 386015 [C. colocynthis (L.) Schrad.]. The genetic linkage map based on the test cross population consists of 558 markers that cover a genetic distance of 2760.8 cM. This linkage map consists of 41 linkage group, including 10 large linkage groups (ranging from102-240 cM), nine intermediate size linkage groups (ranging from 62-93 cM), and 22 small linkage groups (ranging from 2-56 cM). Comparative mapping between these two linkage maps identified high consensus in 25 HFO-TAG markers and one TRAP marker that represent 8 linkage groups in the BC2F2 population and 9 linkage groups in the testcross population. These results indicate that HFO-TAG markers should be useful in comparative mapping. The extended genetic maps and the genetic population in this study should be useful in breeding programs using marker assisted selection and should serve as a platform for further de-velopment of introgression lines for watermelon.
文摘With a ＂two-way pseudo-testcross＂ mapping strategy, we applied the amplified fragment length polymorphism （AFLP） markers to construct two moderate density genetic linkage maps for Laminaria. The linkage maps were generated from the 60 progenies of the F1 cross family （Laminaria iongissima Aresch. × L. Japonica Miyabe） with twenty pairs of primer combinations. Of the 333 polymorphic loci scored in 60 progenies, 173 segregated in a 1：1 ratio, corresponding to DNA polymorphisms heterozygous in a single parent, and the other 58 loci existing in both parents followed a 3：1 Mendelian segregation ratio. Among the loci with 1：1 segregating ratios, 79 loci were ordered in 14 linkage groups （648.6 cM） of the paternal map, and 72 loci were ordered in 14 linkage groups （601.9 cM） of the maternal map. The average density of loci was approximately 1 per 8 cM. To Investigate the homologies between two parental maps, we used 58 loci segregated 3：1 for further analysis, and deduced one homologous linkage group. The linkage data developed in these maps will be useful for detecting loci-controlling commercially important traits for Laminaria.
文摘Based on the genetic inheritance and segregation of random amplified polymorphism DNA(RAPDs) markers,the analysis of linkage groups for birch was performed by using a pseudo-testcross strategy.A segregating population comprising of 79 progenies from the cross between Betula pendula and B.platyphylla was obtained.A set of 1 000 random oligonucleotide primers were screened,and 178 primers were selected to generate RAPD markers within a sample of 79 F\-1 progenies.A total of 296 segregating sites was identified.Among them,273 sites belonged to 1∶1 segregating site,and 36 sites were found distorted from the 1∶1 ratio.The 273 sites segregating 1∶1(testcross configuration) were used to construct parent-specific linkage group,among which 137 sites were found for B.pendula and 136 sites for B.platyphylla.The resulting linkage maps consisted of 117 marker sites in 12 groups(four or more sites per group),2 triples and 3 pairs for B.pendula,which covered the map distance about 1 533.3 cM(Kosambi units),and the average map distance between adjacent markers was 16.4 cM.In the B.platyphylla,162 linked marker sites were integrated into 12 groups(four or more sites per group),2 triples and 4 pairs,which covered the map distance about 1 847.8 cM,and the average map distance between adjacent markers was 19.2 cM.The calculated genome coverage rate of B.pendula and B.platyphylla were respectively 68.5% and 68.9%.Further study is required to integrate the two maps to one density map and to locate important genes on the maps.
基金supported by National Science and Technology Supporting Topics of China(2012BAD01B05)
文摘Estimating genetic parameters of parental lines through progeny testing and choosing good hybrid parents are important for genetically improving seed orchard trees.In this study, 24 tetraploid progeny seedlings were used as experimental materials, which came from test cross design：six tetraploid Betula platyphylla lines（Q33, Q13, Q103,Q19, Q83 and Q14） as female parents and four individual B. platyphylla diploid lines（F3, F4, F9 and F11） as male parents were crossed. Variance analysis of height, diameter, height-to-diameter ratio, and internodal distance showed that the differences between hybrid combinations reached highly significant levels. Using multi-objective decisionmaking, we performed a comprehensive assessment of the various hybrid combinations. Using a selection rate of 20 % of the standard, five hybrids were selected;their genetic gains in average height, diameter, height-todiameter ratio, and internodal distance were 20.95, 6.07,13.07 and 8.96 %, respectively. We also analyzed the combining ability and genetic parameter effect values of parents and hybrid combinations. The combined analysis revealed that Q13, Q103, Q33 and Q83 were superior females; F3, F4, and F9 were superior males; and F3 × Q13, F4 × Q83 and F9 × Q33 were superior hybrid combinations. The heights and diameters of these progenies were 22.49 and 11.48 % greater than average,respectively.
基金supported by the National Basic Research Program of China (2011CB100100)the National Natural Science Foundation of China (30971791)
文摘Since the combining ability was proposed in 1942, efforts to uncover the genetic basis underlying this phenomenon have been ongoing for nearly 70 yr, with little success. Some breeding strategies based on evaluation of combining ability have been produced, and are still extensively used in hybrid breeding. In this review, the genetic basis underlying these breeding strategies is discussed, and a potential genetic control of general combining ability （GCA） is postulated. We suggested that GCA and the yields of inbred lines might be genetically controlled by different sets of loci on the maize genome that are transmitted into offspring. Different inbred lines might possess different favorable alleles for GCA. In hybrids, loci involved in multiple pathways, which are directly or indirectly associated with yield performance, might be regulated by GCA loci. In addition, a case of GCA mapping using a set of testcross progeny from introgression lines is provided.
