title: MER3 is required for normal meiotic crossover formation, but not for presynaptic alignment in rice.
abstract: MER3, a ZMM protein, is required for the formation of crossovers in Saccharomyces cerevisiae and Arabidopsis. Here, MER3, the first identified ZMM gene in a monocot, is characterized by map-based cloning in rice (Oryza sativa). The null mutation of MER3 results in complete sterility without any vegetative defects. Cytological analyses show that chiasma frequency is reduced dramatically in mer3 mutants and the remaining chiasmata distribute randomly among different pollen mother cells, implying possible coexistence of two kinds of crossover in rice. Immunocytological analyses reveal that MER3 only exists as foci in prophase I meiocytes. In addition, MER3 does not colocalize with PAIR2 at the beginning of prophase I, but locates on one end of PAIR2 fragments at later stages, whereas MER3 foci merely locate on one end of REC8 fragments when signals start to be seen in early prophase I. The normal loading of PAIR2 and REC8 in mer3 implies that their loading is independent of MER3. On the contrary, the absence of MER3 signal in pair2 mutants indicates that PAIR2 is essential for the loading and further function of MER3.
authors.affiliation: State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Kejian
authors.initials: K
authors.lastname: Wang
authors.forename: Ding
authors.initials: D
authors.lastname: Tang
authors.forename: Mo
authors.initials: M
authors.lastname: Wang
authors.forename: Jufei
authors.initials: J
authors.lastname: Lu
authors.forename: Hengxiu
authors.initials: H
authors.lastname: Yu
authors.forename: Jiafan
authors.initials: J
authors.lastname: Liu
authors.forename: Baoxiang
authors.initials: B
authors.lastname: Qian
authors.forename: Zhiyun
authors.initials: Z
authors.lastname: Gong
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.forename: Jianmin
authors.initials: J
authors.lastname: Chen
authors.forename: Minghong
authors.initials: M
authors.lastname: Gu
authors.forename: Zhukuan
authors.initials: Z
authors.lastname: Cheng
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D023902:Chromosome Pairing / Q000235:genetics*; D003001:Cloning, Molecular; D003434:Crossing Over, Genetic / Q000235:genetics* / Q000502:physiology; D017343:Genes, Plant / Q000502:physiology*; D050505:Mutant Proteins / Q000502:physiology; D012275:Oryza / Q000235:genetics*; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D011485:Protein Binding; D014018:Tissue Distribution
chemical_list: D018797:Cell Cycle Proteins; D050505:Mutant Proteins; D010940:Plant Proteins