A set of recombinant inbred lines (RIL) derived from Yuyu22, an elite hybrid widespread in China, was used to construct an immortalized F2 (IF2) population comprising 441 different crosses. Genetic linkage maps were c...A set of recombinant inbred lines (RIL) derived from Yuyu22, an elite hybrid widespread in China, was used to construct an immortalized F2 (IF2) population comprising 441 different crosses. Genetic linkage maps were constructed containing 10 linkages groups with 263 simple sequence repeat (SSR) molecular markers. Twelve and ten quantitative trait loci (QTL) were detected for plant height in the IF2 and RIL populations respectively, using the composite interval mapping method, and six same QTL were identified in the two populations. In addition, ten unique heterotic loci (HL) located on seven different chromosomes were revealed for plant height using the mid-parent heterosis as the input data. These HL explained 1.26%―8.41% of the genotypic variance in plant height heterosis and most expressed overdominant effects. Only three QTL and HL were located in the same chromosomal region, it implied that plant height and its heterosis might be controlled by two types of genetic mechanisms.展开更多
By adding thirty-one markers in the pre- vious linkage map, a new genetic linkage map con- taining 205 markers was constructed, spanning a total of 2305.4 cM with an average interval of 11.2 cM. The genotypic errors i...By adding thirty-one markers in the pre- vious linkage map, a new genetic linkage map con- taining 205 markers was constructed, spanning a total of 2305.4 cM with an average interval of 11.2 cM. The genotypic errors in the whole genome were de- tected by the statistical method and removed manu- ally. The precision of the linkage map was improved significantly. Main and epistatic QTL were detected by R/qtl, and main QTL were confirmed and refined by multiple interval mapping (MIM). Finally, MIM de- tected seven QTL for rows number, and five QTL for each grain yield, kernels per row and 100-kernel weight. The contribution to genetic variations of QTL varied from 35.3% for grain yield to 61.5% for rows number. Only kernels per row exhibited significant epistatic interactions between QTL. Twenty-four epistatic QTL were detected which distributed on almost all the ten chromosomes. About two-third epistatic QTL were observed between main QTL and another locus, which had no significant effects. These results indicate rather clearly that there are a number of QTL affecting trait expressions, not directly but indirectly through interactions with other loci. Thus, epistatic QTL effects may play a crucial role, if not more important than main QTL effects, in the genetic variation for the measured traits in present study.展开更多
Transposable elements (TEs)-mediated gene sequence movement is thought to play an important role in genome expansion and origin of genes with novel functions. In this study, a gene, HGGT, involved in vitamin E synthes...Transposable elements (TEs)-mediated gene sequence movement is thought to play an important role in genome expansion and origin of genes with novel functions. In this study, a gene, HGGT, involved in vitamin E synthesis was used in a case study to discover and characterize transposons carrying gene fragments in maize. A total of 69 transposons that are distributed across the 10 chromosomes and have an average length of 3689 bp were identified from the maize sequence database by using the BLAST search algorithm. Three of these carry gene fragments from the progenitor HGGT gene, while the rest (66) contain gene fragments from other cellular genes. Nine of the 69 transposons contain fragments derived from two locations in the genome. By querying the maize Expressed Sequence Tag (EST) database, we found that at least thirteen out of the 69 TEs had corresponding transcripts. More interestingly, two transposons that carry gene fragments from two different chromosomal loci could be expressed as chimeric transcripts.展开更多
基金Supported by the State Key Basic Research and Development Plan of China (Grant No. 2001CB10801)the National High-Technology Project of China (Grant No. 2002AA207008)
文摘A set of recombinant inbred lines (RIL) derived from Yuyu22, an elite hybrid widespread in China, was used to construct an immortalized F2 (IF2) population comprising 441 different crosses. Genetic linkage maps were constructed containing 10 linkages groups with 263 simple sequence repeat (SSR) molecular markers. Twelve and ten quantitative trait loci (QTL) were detected for plant height in the IF2 and RIL populations respectively, using the composite interval mapping method, and six same QTL were identified in the two populations. In addition, ten unique heterotic loci (HL) located on seven different chromosomes were revealed for plant height using the mid-parent heterosis as the input data. These HL explained 1.26%―8.41% of the genotypic variance in plant height heterosis and most expressed overdominant effects. Only three QTL and HL were located in the same chromosomal region, it implied that plant height and its heterosis might be controlled by two types of genetic mechanisms.
基金The authors thank Dr.E.Coe for providing RFLP probes.This work was supported by the National Natural Science Foundation of China(Grant No.39893350)the State Key Basic Research and Development Plan of China(Grant No.2001CB 1088).
文摘By adding thirty-one markers in the pre- vious linkage map, a new genetic linkage map con- taining 205 markers was constructed, spanning a total of 2305.4 cM with an average interval of 11.2 cM. The genotypic errors in the whole genome were de- tected by the statistical method and removed manu- ally. The precision of the linkage map was improved significantly. Main and epistatic QTL were detected by R/qtl, and main QTL were confirmed and refined by multiple interval mapping (MIM). Finally, MIM de- tected seven QTL for rows number, and five QTL for each grain yield, kernels per row and 100-kernel weight. The contribution to genetic variations of QTL varied from 35.3% for grain yield to 61.5% for rows number. Only kernels per row exhibited significant epistatic interactions between QTL. Twenty-four epistatic QTL were detected which distributed on almost all the ten chromosomes. About two-third epistatic QTL were observed between main QTL and another locus, which had no significant effects. These results indicate rather clearly that there are a number of QTL affecting trait expressions, not directly but indirectly through interactions with other loci. Thus, epistatic QTL effects may play a crucial role, if not more important than main QTL effects, in the genetic variation for the measured traits in present study.
基金Supported by National Natural Science Foundation of China (Grant No. 30500322)National Hi-Tech Research and Development Program of China (Grant Nos. 2006AA10Z183, 2006AA10A107)
文摘Transposable elements (TEs)-mediated gene sequence movement is thought to play an important role in genome expansion and origin of genes with novel functions. In this study, a gene, HGGT, involved in vitamin E synthesis was used in a case study to discover and characterize transposons carrying gene fragments in maize. A total of 69 transposons that are distributed across the 10 chromosomes and have an average length of 3689 bp were identified from the maize sequence database by using the BLAST search algorithm. Three of these carry gene fragments from the progenitor HGGT gene, while the rest (66) contain gene fragments from other cellular genes. Nine of the 69 transposons contain fragments derived from two locations in the genome. By querying the maize Expressed Sequence Tag (EST) database, we found that at least thirteen out of the 69 TEs had corresponding transcripts. More interestingly, two transposons that carry gene fragments from two different chromosomal loci could be expressed as chimeric transcripts.
