Meiosis in barley: Mixing it up

ongoing

Progress in plant breeding towards superior varieties relies on selecting favourable traits after creating genetically diverse material. This is primarily achieved by homologous recombination (HR) during meiosis, when programmed DNA double strand breaks (DSBs) are alternatively repaired as crossover (CO, resulting in new parental chromosome combinations) or as non-crossover (NCO, restoring the previous situation). In cereal crops such as barley, recombination by CO occurs mainly near chromosome ends leaving the main body of genetic material untouched. NCO repair can also result in NCO gene conversion (NCO-GC), non-reciprocal exchange of short DNA stretches between alleles. More than 90% of meiotic DSB repair results in NCO, and NCO-GCs are typically not considered in breeding practices as little is known about their tract length, frequency or formation mechanism. MEIOBARMIX aims at uncovering new strategies and developing novel tools to increase and redirect meiotic HR outcome to improve and accelerate plant breeding. Based on novel and high throughput single pollen nuclei genotyping tools, NCO-GC frequency, length, and sequence context and their potential as natural source of genetic variation will be determined. Using the power of a forward genetic approach in Arabidopsis, components regulating the formation of a NCO-GC and/or CO will be identified and genome editing tools will be used to explore novel strategies for site-specific DSB induction as trigger for targeted meiotic recombination. Moreover, novel virus-based tools and ‘stresses’ will be employed to modify the barley recombination landscape. This study will provide ground-breaking results regarding the role of NCO-GCs for genome diversity, explore the feasibility of novel targeted meiotic recombination approaches and uncover novel tools to develop new strategies to harness and influence the outcome, frequency and/or distribution of meiotic recombination in barley ultimately boosting plant breeding.