GISH investigation of crossover events during meiosis of interspecific hybrids of lily

Crossover not only establishes proper segregation of omologous/homoeologous
chromosomes during meiosis I, but also promotes genetic diversity though
creating new recombination of maternal and paternal alleles, which is essential for introgression breeding. In this paper, crossovers between non-sister chromatids were observed during meiosis of interspecific hybrids of Lilium longiflorum × Asiatic (LA) using genomic in situ hybridization (GISH). Results showed that different types of crossing over events, viz. single, two strand double, three strand double, four strand double crossovers, occurred between non-sister chromatids during meiosis of selected interspecific lily hybrids. From an analysis of a total of 637 pairs of half-bivalents it was evident that a large majority (65%) was two strand single crossovers, 5.5% were two strands double, 3.0% three strand double, 9.3% four strand double and 17.3% were multiple crossing over events. In one specific genotype which showed the existence of a reciprocal translocation, the frequency of multiple crossovers was relatively high, which might alter the map distances of markers on the translocated
chromosomes.