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
MicroRNAs （miRNAs） are endogenous small RNAs that play important regulatory roles in the growth and development processes of plants and animals. In this study, we examined the expression profiles of pollen miRNAs fr...MicroRNAs （miRNAs） are endogenous small RNAs that play important regulatory roles in the growth and development processes of plants and animals. In this study, we examined the expression profiles of pollen miRNAs from a maize S type cytoplasmic male sterile line and its fertility restored line. In total, 100 known miRNAs belonging to 20 families and 81 novel miRNAs belonging to 44 families were identified. Two and seven known miRNAs had significant expression difference between the two lines at the level of P-value〈0.01 and 0.01〈P-value〈0.05, respectively. Four miRNAs showing 〉1.5 fold expression difference were verified by stem-loop RT-qPCR. Gene Ontology analysis of miRNA target genes revealed that these genes mainly participated in the transcriptional regulation processes.展开更多
Mutants on stalk strength are essential materials for the studies on the formation of plant cell wall.In this study,a brittle stalk mutant of maize,designated as Bk-x,was screened from a Mutator inserted mutant librar...Mutants on stalk strength are essential materials for the studies on the formation of plant cell wall.In this study,a brittle stalk mutant of maize,designated as Bk-x,was screened from a Mutator inserted mutant library.At the germination and early seedling stage,the mutant plants were indistinguishable from the normal ones.However,all of the plant organs were brittle after the 5th-leaf stage and remained brittle throughout the rest of the growing period.Microstructure observation showed that the cell wall in vascular bundle sheath of Bk-x was thinner than that in normal plants.The leaf mechanical strength in Bk-x was 77.9% of that in normal plants growing at Xishuangbanna（BN）,Yunnan province and that was 61.7% in Wuhan（WH）,Hubei Province,China.The proportion of cellulose was 12.3% in Bk-x,which was significantly lower than that in normal plants（26.7%）,while the soluble sugar content was 36.1% in Bk-x,which is significantly higher than that in normal plants（12.4%）.Genetic analysis using two F 2 populations and one F 2：3 families demonstrated that the trait of brittle stalk is controlled by a single recessive gene.展开更多
Mutator transposable element （Mu） has been used as an effective tool to clone maize （Zea mays L.） genes. One opaque endosperm mutant （miol6） was identified in a pool of Mu inserted mutants. A modified method, te...Mutator transposable element （Mu） has been used as an effective tool to clone maize （Zea mays L.） genes. One opaque endosperm mutant （miol6） was identified in a pool of Mu inserted mutants. A modified method, termed the double selected amplification of insertion flanking fragments （DSAIFF）, was employed to isolate the Mu flanking fragments （MFFs） of miol6. The target site duplications （TSDs） isolated from the Msp I and Mse I digested MFFs had a same 9-bp sequence and were confirmed to be the flanking sequence of one identically inserted gene. Co-segregation analysis suggested that the MFFs were associated with the mutant opaque endosperm, and miol6 was mapped in silico onto the physical position ranged from 229 965 021 to 229 965 409 bp of the maize chromosome 4.09 bin. The full-length cDNA of the wild-type gene was obtained by an RT-PCR primer-scanning technique, and Mio16 was found to putatively encode a homolog of the Arabidopsis MAP3K delta-1 protein kinase. RT-PCR result the mRNA expression of miol6 region anchored by primers Mu20 and af276 was not interrupted by Mu insertion. Further researches will be done to elucidate how the expression of miol6 is alternated by Mu insertion.展开更多
Mitochondrial orf355-orf77 and the nuclear fertility restorer locus Rf3/rf3 mutually control the fertility of male gametes in CMS-S in maize （Zea mays L.）. A fragment of gene Zm26Sub5 was identified through cDNA-AFL...Mitochondrial orf355-orf77 and the nuclear fertility restorer locus Rf3/rf3 mutually control the fertility of male gametes in CMS-S in maize （Zea mays L.）. A fragment of gene Zm26Sub5 was identified through cDNA-AFLP from a set of Rf3/rf3 near-isogenic lines in a previous study. In the present study, real-time PCR analysis revealed that Zm26Sub5 expression levels were much higher in pollen of S-Mo17Rf3Rf3 than in pollen of S-Mo17rf3rf3, and also higher than in fresh leaves, mature leaves, and roots of both S-Mo17Rf3Rf3 and S-Mo17rf3rf3. In silico cloning of full-length cDNA was successfully implemented. Gene Zm26Sub5 was 1 451 bp in size, of which 1 329 bp encoded a protein with 443 amino acids. The structure of this gene was analyzed by comparing its full length cDNA to homologous genomic DNA sequence （GenBank accession： Ac209463.3）. Subsequent sequence analysis led to sub cellular localization of protein ZM26SUB5, and construction of a phylogenetic tree. In silico mapping indicated that Zm26Sub5 was located on chromosome 5 and closed to a reported starch-filled pollen ratio QTL. ZM26SUB5, therefore might have potential roles in repressing mitochondrial PCD which is associated with sterile activity in pollen in S-type cytoplasm.展开更多
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.
基金financially supported by the National Natural Science Foundation of China(31171565)
文摘MicroRNAs （miRNAs） are endogenous small RNAs that play important regulatory roles in the growth and development processes of plants and animals. In this study, we examined the expression profiles of pollen miRNAs from a maize S type cytoplasmic male sterile line and its fertility restored line. In total, 100 known miRNAs belonging to 20 families and 81 novel miRNAs belonging to 44 families were identified. Two and seven known miRNAs had significant expression difference between the two lines at the level of P-value〈0.01 and 0.01〈P-value〈0.05, respectively. Four miRNAs showing 〉1.5 fold expression difference were verified by stem-loop RT-qPCR. Gene Ontology analysis of miRNA target genes revealed that these genes mainly participated in the transcriptional regulation processes.
基金supported by the National High-Tech R&D Program of China(2006AA10A106)
文摘Mutants on stalk strength are essential materials for the studies on the formation of plant cell wall.In this study,a brittle stalk mutant of maize,designated as Bk-x,was screened from a Mutator inserted mutant library.At the germination and early seedling stage,the mutant plants were indistinguishable from the normal ones.However,all of the plant organs were brittle after the 5th-leaf stage and remained brittle throughout the rest of the growing period.Microstructure observation showed that the cell wall in vascular bundle sheath of Bk-x was thinner than that in normal plants.The leaf mechanical strength in Bk-x was 77.9% of that in normal plants growing at Xishuangbanna（BN）,Yunnan province and that was 61.7% in Wuhan（WH）,Hubei Province,China.The proportion of cellulose was 12.3% in Bk-x,which was significantly lower than that in normal plants（26.7%）,while the soluble sugar content was 36.1% in Bk-x,which is significantly higher than that in normal plants（12.4%）.Genetic analysis using two F 2 populations and one F 2：3 families demonstrated that the trait of brittle stalk is controlled by a single recessive gene.
基金supported by the High-Tech R&D Program of China(2006AA10A106)the open funds of the National Key Laboratory of Crop Genetic Improvement and China National Fundamental Fund of Personnel Training (J0730649)
文摘Mutator transposable element （Mu） has been used as an effective tool to clone maize （Zea mays L.） genes. One opaque endosperm mutant （miol6） was identified in a pool of Mu inserted mutants. A modified method, termed the double selected amplification of insertion flanking fragments （DSAIFF）, was employed to isolate the Mu flanking fragments （MFFs） of miol6. The target site duplications （TSDs） isolated from the Msp I and Mse I digested MFFs had a same 9-bp sequence and were confirmed to be the flanking sequence of one identically inserted gene. Co-segregation analysis suggested that the MFFs were associated with the mutant opaque endosperm, and miol6 was mapped in silico onto the physical position ranged from 229 965 021 to 229 965 409 bp of the maize chromosome 4.09 bin. The full-length cDNA of the wild-type gene was obtained by an RT-PCR primer-scanning technique, and Mio16 was found to putatively encode a homolog of the Arabidopsis MAP3K delta-1 protein kinase. RT-PCR result the mRNA expression of miol6 region anchored by primers Mu20 and af276 was not interrupted by Mu insertion. Further researches will be done to elucidate how the expression of miol6 is alternated by Mu insertion.
基金supported by the National Natural Science Foundation of China (31000116)the National Ba-sic Research Program of China (973 Program,2007CB109005)
文摘Mitochondrial orf355-orf77 and the nuclear fertility restorer locus Rf3/rf3 mutually control the fertility of male gametes in CMS-S in maize （Zea mays L.）. A fragment of gene Zm26Sub5 was identified through cDNA-AFLP from a set of Rf3/rf3 near-isogenic lines in a previous study. In the present study, real-time PCR analysis revealed that Zm26Sub5 expression levels were much higher in pollen of S-Mo17Rf3Rf3 than in pollen of S-Mo17rf3rf3, and also higher than in fresh leaves, mature leaves, and roots of both S-Mo17Rf3Rf3 and S-Mo17rf3rf3. In silico cloning of full-length cDNA was successfully implemented. Gene Zm26Sub5 was 1 451 bp in size, of which 1 329 bp encoded a protein with 443 amino acids. The structure of this gene was analyzed by comparing its full length cDNA to homologous genomic DNA sequence （GenBank accession： Ac209463.3）. Subsequent sequence analysis led to sub cellular localization of protein ZM26SUB5, and construction of a phylogenetic tree. In silico mapping indicated that Zm26Sub5 was located on chromosome 5 and closed to a reported starch-filled pollen ratio QTL. ZM26SUB5, therefore might have potential roles in repressing mitochondrial PCD which is associated with sterile activity in pollen in S-type cytoplasm.
