The Formation of Bivalents and the Control of Plant Meiotic Recombination

Abstract

During the first meiotic division, the segregation of homologous chromosomes depends on the physical association of the recombined homologous DNA molecules. The physical tension due to the sites of crossing-overs (COs) is essential for the meiotic spindle to segregate the connected homologous chromosomes to the opposite poles of the cell. This equilibrated partition of homologous chromosomes allows the first meiotic reductional division. Thus, the segregation of homologous chromosomes is dependent on their recombination. In this review, we will detail the recent advances in the knowledge of the mechanisms of recombination and bivalent formation in plants. In plants, the absence of meiotic checkpoints allows observation of subsequent meiotic events in absence of meiotic recombination or defective meiotic chromosomal axis formation such as univalent formation instead of bivalents. Recent discoveries, mainly made in Arabidopsis, rice, and maize, have highlighted the link between the machinery of double-strand break (DSB) formation and elements of the chromosomal axis. We will also discuss the implications of what we know about the mechanisms regulating the number and spacing of COs (obligate CO, CO homeostasis, and interference) in model and crop plants.

The meiotic cohesin subunit REC8 contributes to multigenic adaptive evolution of autopolyploid meiosis in Arabidopsis arenosa

“…During diploid meiosis, the formation of crossovers (COs) between pairs of homologous chromosomes is essential for promoting the stable segregation of homologs during anaphase I, as well as for introducing genetic diversity within offspring [ 23 ]. In most organisms, CO maturation is facilitated by formation of the meiotic axis and synaptonemal complex, proteinaceous structures that organise chromosomes into threadlike arrays of chromatin loops and synapse homologous axes together along their length, respectively [ 24 , 25 ]. In autopolyploids, due to the presence of more than two copies of each homolog, synapsis and subsequent CO formation can occur between multiple homologs simultaneously, creating linkages called multivalents.…”

Synthetically induced Arabidopsis thaliana autotetraploids provide insights into the analysis of meiotic mutants with altered crossover frequency

“…Cytogenetic studies in A . thaliana meiotic mutants have significantly contributed to providing essential knowledge on the functionality of key meiotic proteins (Gutiérrez Pinzón et al ., 2021). Arabidopsis thaliana is a powerful model, but it should be considered that it is a diploid species and that most crops are polyploid species.…”

“…Factors controlling meiotic recombination in plants have been extensively studied over the last decades, particularly in the model species Arabidopsis thaliana (see the reviews Osman et al ., 2011; Mercier et al ., 2015; Wang & Copenhaver, 2018; Gutiérrez Pinzón et al ., 2021). Proteins involved in either double‐strand break (DSB) formation or processing and elements of the chromosomal axes are essential to ensure the formation of COs, which may be generated from at least two coexisting pathways (class I and class II) controlled by different genes.…”

Epidemiology of Δ8THC-Related Carcinogenesis in USA: A Panel Regression and Causal Inferential Study

“…Both single-and double-stranded breaks (SSB and DSB) are a common feature of cell karyotype studies after cannabis exposure [7][8][9][10]12,13,99]. It therefore becomes important in the present context to note that the epigenome plays an often determinative role in influencing or selecting the site of DNA breakage generally [118][119][120][121][122][123][124][125][126][127][128][129][130][131], during meiotic crossing over [132][133][134][135][136][137][138][139], in the immune gene hypervariable region [140][141][142][143][144][145][146], and in oncogenic pathways [120,123,124,[147][148][149][150][151][152][153]…”