Unleashing meiotic crossovers in crops

Abstract

doi: bioRxiv preprint crossover pathways that rely on the activity of FANCM, RECQ4 and FIGL1, respectively. RECQ4 appears to be the most important anti-crossover factor, as the mutation of the corresponding genes (RECQ4A and RECQ4B) led to an almost fourfold increase in recombination in Arabidopsis hybrids 2,10 . RECQ4 is a DNA helicase homologue of mammalian BLOOM and yeast Sgs1 11,12 . FANCM, which encodes another conserved DNA helicase, is also an important anti-crossover factor in Arabidopsis. Mutation of this gene also leads to a large increase in recombination, but only in pure lines (~3-fold) with a very limited effect in hybrids 2,3,5,13 . FANCM was also shown to limit crossovers in a Brassica rapa pure line 14 . The third pathway depends on the AAA-ATPase FIGL1. Mutation in FIGL1 alone leads to a relatively modest increase in recombination (+25% in Arabidopsis hybrids), but when combined with recq4 2 it leads to an almost eight-fold increase. Mutation in FIGL1 leads to full sterility in rice 15 , raising doubts about the pertinence of manipulating this gene in crop species.Here we tested the effect of recq4, fancm and figl1 mutations on recombination in three crop species. We chose rice (Oryza sativa), the cultivated pea (Pisum sativum) and tomato (Solanum lycopersium) for their economic importance and because they represent distant clades. Indeed they are members of the three major clades of flowering plants, monocots, eudicots rosids and eudicots asterids, respectively 16 . Rice is the staple of more than half of mankind and as such is the number one cereal consumed. It belongs to the Poaceae family that also contains maize, wheat and barley 16 . Pea, in addition to be the genetic model used by Mendel, is the second most cultivated pulse crop in the world (http://faostat.fao.org/) and belongs to the Fabaceae family that contains many crop species such as chickpea, beans and lentil.Tomato, the second most cultivated fresh-market vegetable crop, is one of the most .

Chromosome Engineering in Tropical Cash Crops

“…Meiotic crossovers intermix homologous chromosomes to produce novel combinations of alleles that are transmitted to offspring [37]. The study of the formation of meiotic crossovers is important for activities related to plant breeding such as the detection and identification of quantitative trait loci and gene mapping [37]. Infertility results from defects in the formation of crossovers because the homologs segregate randomly during cell division [35].…”

“…The major one depends on the ZMM protein complex (MSH4, MSH5, MER3, HEI10, ZIP4, SHOC1, PTD) plus MLH1/3 and produces interfering crossovers, whereas the minor pathway relies on MUS81 and produces non-interfering crossovers [36]. Crossovers are relatively rare events because active mechanisms limit their formation [37]. In the model plant Arabidopsis, three anti-crossover pathways rely on the activity of the proteins RECQ4, FANCM, and FIGL1 [37].…”

“…Crossovers are relatively rare events because active mechanisms limit their formation [37]. In the model plant Arabidopsis, three anti-crossover pathways rely on the activity of the proteins RECQ4, FANCM, and FIGL1 [37]. RECQ4 is the homologue of yeast Sgsp and is a DNA helicase; FANCM is also a DNA helicase (which requires cofactors MHF1-2), whereas FIGL1 encodes an AAA-ATPase [37].…”

“…In the model plant Arabidopsis, three anti-crossover pathways rely on the activity of the proteins RECQ4, FANCM, and FIGL1 [37]. RECQ4 is the homologue of yeast Sgsp and is a DNA helicase; FANCM is also a DNA helicase (which requires cofactors MHF1-2), whereas FIGL1 encodes an AAA-ATPase [37]. In Arabidopsis, changes in their activity cause notable changes; for instance, recombination was increased four-fold in the recq4a/recq4b mutant but increased three-fold in the fancm−/− mutant [37].…”

“…RECQ4 is the homologue of yeast Sgsp and is a DNA helicase; FANCM is also a DNA helicase (which requires cofactors MHF1-2), whereas FIGL1 encodes an AAA-ATPase [37]. In Arabidopsis, changes in their activity cause notable changes; for instance, recombination was increased four-fold in the recq4a/recq4b mutant but increased three-fold in the fancm−/− mutant [37]. The recq4a/recq4b/figl mutant showed an impressive eight-fold increase in recombination [37].…”