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Descripción
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| Effi cient production of balanced gametes in diploid organisms depends on the regular bivalent formation at the prophase of the fi rst meiotic division. Homologous chromosomes fi nd each other and interact at early mei osis to become physically connected by chiasmata and form bivalents. Clustering of telomeres in the meiotic bouquet at the leptotene?zygotene transition facilitates the approximation of terminal regions of homologous chromosomes and their recognition (Naranjo and Corredor 2008 ). Homologous interactions are initiated after the production of a programmed set of double strand DNA breaks (DSBs) catalyzed by the topoisomerase II related enzyme SPO11 at the initiation of meiosis (Keeney et al. 1997 ). DSBs are immediately immersed in a repairing process, which is controlled to ensure that each homologous pair receives at least the obligate crossover necessary for accurate segregation. Concomitant with the bouquet organization, a linear protein axis is formed along each homolog. Some of the proteins that make up the axis, for example, ASY1 in Arabidopsis , play a key role by infl uencing DSB repair through interhomologous recombination (Sánchez-Morán et al. 2007 ). Then, homologous chromosomes become aligned, at least in their distal region, and undergo synapsis through the formation of a proteinaceous structure, the synaptonemal complexes (SC) that maintains the homologous chromosomes intimately juxtaposed along their length. | |
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Internacional
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DOI
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10.1007/978-3-319-23494-6 |
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Edición del Libro
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Editorial del Libro
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Springer |
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ISBN
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978-3-319-23493-9 |
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Serie
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Título del Libro
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Alien introgression in wheat. Cytogenetics, molecular biology and genomics |
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Desde página
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133 |
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Hasta página
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162 |