title: Molecular mapping of genes for  opposite leafing in maize using simple-sequence repeat markers.
abstract: Maize with opposite  phyllotaxy (OP) and also initiating ears in opposite pairs is an aberrant  mutant and also precious material for maize breeding and plant evolution  studies. Mapping and identifying the markers closely linked to genes for the OP  trait are essential for cloning the gene and marker-assisted selection in  breeding. We established H14D, a near-isogenic line of the OP trait with H53  genetic background. We found that the OP trait is regulated by two independent  dominant genes with mutually complementary relations, named Opp-1 and Opp-2.  Screening of seven simple-sequence repeat (SSR) markers among the 105 pairs of  SSR primers showed polymorphism between the inbred lines H14D and H53. The  polymorphic SSR markers were then used to determine linkage with the trait in  an F(2) population with 441  progeny, suggesting that SSR marker umc2094 in the Bin2.01 region is linked  with Opp-1 at 6.7 cM, and bnlg1831 in Bin2.06 is linked with Opp-2 at  6.1 cM. Further investigation showed that bnlg1092 and umc1028 are linked to Opp-1 and Opp-2 genes, with genetic distances of 12.2 and 1.9 cM. It was  also found that the four SSR markers flank the two OP genes, respectively.  These results will be useful for marker-assisted selection breeding of OP maize  and will also strengthen the basis for cloning of the opposite leafing gene.
authors.affiliation: Institute of Life Science, Anhui Agricultural University, Hefei, China.
authors.forename: Y Q
authors.initials: YQ
authors.lastname: Tan
authors.forename: C X
authors.initials: CX
authors.lastname: Xie
authors.forename: H Y
authors.initials: HY
authors.lastname: Jiang
authors.forename: H
authors.initials: H
authors.lastname: Ye
authors.forename: Y
authors.initials: Y
authors.lastname: Xiang
authors.forename: S W
authors.initials: SW
authors.lastname: Zhu
authors.forename: B J
authors.initials: BJ
authors.lastname: Cheng
mesh_terms: D002874:Chromosome Mapping / Q000379:methods*; D020090:Chromosome Segregation / Q000235:genetics; D003433:Crosses, Genetic; D018744:DNA, Plant / Q000235:genetics; D017343:Genes, Plant / Q000235:genetics*; D008040:Genetic Linkage; D005819:Genetic Markers; D018895:Microsatellite Repeats / Q000235:genetics*; D010641:Phenotype; D018515:Plant Leaves / Q000033:anatomy & histology* / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D003313:Zea mays / Q000235:genetics*
chemical_list: D018744:DNA, Plant; D005819:Genetic Markers