Chromosome segregation in plant meiosis

Abstract

Faithful chromosome segregation in meiosis is essential for ploidy stability over sexual life cycles. In plants, defective chromosome segregation caused by gene mutations or other factors leads to the formation of unbalanced or unreduced gametes creating aneuploid or polyploid progeny, respectively. Accurate segregation requires the coordinated execution of conserved processes occurring throughout the two meiotic cell divisions. Synapsis and recombination ensure the establishment of chiasmata that hold homologous chromosomes together allowing their correct segregation in the first meiotic division, which is also tightly regulated by cell-cycle dependent release of cohesin and monopolar attachment of sister kinetochores to microtubules. In meiosis II, bi-orientation of sister kinetochores and proper spindle orientation correctly segregate chromosomes in four haploid cells. Checkpoint mechanisms acting at kinetochores control the accuracy of kinetochore-microtubule attachment, thus ensuring the completion of segregation. Here we review the current knowledge on the processes taking place during chromosome segregation in plant meiosis, focusing on the characterization of the molecular factors involved.

Anaphase asymmetry and dynamic repositioning of the division plane during maize meiosis

“…Meiosis in plants such as maize have been heavily studied at the level of fixed specimens (Dawe, 1998;Zamariola et al, 2014) but far less studied at the level of live cells (Yu et al, 1997(Yu et al, , 1999, leaving gaps in our understanding of spindle and chromosome movements.…”

Research Article Contributions of classical and molecular cytogenetic in meiotic analysis and pollen viability for plant breeding.

“…In the first meiotic division occurs segregation of homologous chromosomes (reduction division) and in the second division is the segregation of sister chromatids (equational division) and each daughter cell carries half the parents' genetic material (Zamariola et al, 2014). The formation of a synaptonemal complex, allowing the pairing between homologous chromosomes and meiotic recombination, is characteristic of prophase I of meiosis and is a prerequisite for the reduction division (Bass et al, 2003).…”

“…However, high recombination rates in polyploid plants can lead to a rapid process of diversification and optimize the domestication of wild species in different environments (Pecinka et al, 2011). Polyploid plants can be generated through polyploidy events by somatic duplication or unreduced gametes and are considered an evolution in the plant genome (Zamariola et al, 2014).…”

Chromatid Abnormalities in Meiosis: A Brief Review and a Case Study in the Genus Agave (Asparagales, Asparagaceae)

“…There is the formation of bivalents in chiasmata, and this generates an adequate chromosome segregation in meiosis [21]. The chromatids that are conforming the unit called chromosome are called "sister chromatids".…”

“…The cohesin complex is highly conserved in eukaryotes and is mainly composed of four conserved proteins found in yeast, animals and plants (reviewed in [21][22][23][24][25]). In mitosis as in meiosis, cohesins have a ring-like structure formed by SMC1, SMC2, α-kleisin (RAD21 / SCC1 in mitosis or Rec8 in meiosis) and SCC3, each element of the cohesin complex is of a key importance for proper segregation of chromosomes.…”