Meiosis in crops: from genes to genomes

Abstract

Meiosis is a key feature of sexual reproduction. During meiosis homologous chromosomes replicate, recombine and randomly segregate, followed by the segregation of sister chromatids to produce haploid cells. The unique genotypes of recombinant gametes are an essential substrate for the selection of superior genotypes in natural populations and plant breeding. In this review we summarize knowledge on meiosis in diverse monocot and dicot crop species and provide a thorough resource of cloned meiotic mutants in six crop species (rice, maize, wheat, barley, tomato and brassicas). Generally, the functional roles of meiotic proteins are conserved between plant species, but we highlight notable differences in mutant phenotypes. The physical lengths of plant chromosomes vary greatly, for instance wheat chromosomes are roughly one order of magnitude longer than those of rice. We explore how chromosomal distributions of crossover recombination can vary between species. We conclude that research on meiosis in crops will continue to complement that in Arabidopsis, and alongside possible applications in plant breeding will facilitate a better understanding of how the different stages of meiosis are controlled in plant species.

A chromosome scale tomato genome built from complementary PacBio and Nanopore sequences alone reveals extensive linkage drag during breeding

“…DSBs inside the introgression are likely repaired as non‐crossovers. It is possible that the modulation of factors that can change chromosomal distributions of meiotic crossover (e.g., non‐CG DNA methylation) could open up this region to meiotic recombination (Underwood et al., 2018; Wang et al., 2021; Zhao et al., 2021).…”

Frequent spontaneous structural rearrangements promote rapid genome diversification in a Brassica napus F1 generation

“…Meiosis also generates other forms of genomic diversity, not only by recombination through crossovers (CO), but also via meiotic mutations in gametes due to errors in the repair of DNA double-strand breaks (DSB). In particular, non-homologous end-joining (NHEJ) (Kuo et al, 2021;Wang et al, 2021) can lead to a variety of de novo genomic rearrangements (Cai and Xu, 2007). According to the theoretical framework of Mendel's laws of inheritance (Mendel, 1866), meiotic mutations should be inherited in heterozygous form by all F1 offspring whose parents are highly homozygous.…”

Technology-driven approaches for meiosis research in tomato and wild relatives

“…Genome editing approaches have democratized reverse genetic studies in genetically transformable plant species, and this has facilitated an increase in the availability of meiotic mutants in a wide array of plant species (Wang et al 2021 ). Tomato is no exception—a number of studies have employed genome editing to generate DNA repair and meiotic mutants in tomato (Mieulet et al 2018 ; de Maagd et al 2020 ; Whitbread et al 2021 ).…”

“…After the resolution of COs, and the loss of molecular links between the recombining chromosomes, segregation of homologous chromosomes occurs. In diploid sexual organisms, sister chromatids segregate during the second meiotic division to generate haploid spores (Wang et al 2021 ). After meiosis the spores enter gametogenesis and eventually the fusion of male and female gametes, by fertilization, leads to the establishment of genetically unique, diploid, offspring (Dresselhaus et al 2016 ).…”