Activation tagging screening of Arabidopsis dosage-dependent crossover rate modulators

Abstract

During meiosis, homologous chromosomes (homologs) pair and undergo reciprocal exchange of non-sister chromosomes, called crossover. Crossover is essential for segregation of homologs and provides genetic diversity. Number of crossovers tends to one per homolog pair in plants, indicating that anti-crossover factors restrict crossovers. Here, we performed genetic screening to identify novel crossover rate mutants using 420 fluorescent crossover reporter and activation tagging. Approximately 1,000 T1 individuals were measured for crossover frequency, which isolated 8 high crossover rate dominant (hcr-D) mutants and 1 low crossover rate dominant (lcr-D) mutant. T-DNA insertion sites were mapped via long read sequencing and adapter-ligation PCR, and overexpression of casual genes were examined by RT-qPCR. Using a genomic set of fluorescent seed reporter lines we revealed that hcr10-D showed increased crossover frequency in chromosomal arm but decreased crossover frequency around centromeres. Future studies will investigate the role of HCR10-D in meiotic recombination.