High Genomic Affinity between Torenia baillonii and Torenia fournieri Revealed by Genome Analysis Using a Triploid Hybrid

Abstract

To analyze the genetic relationship between Torenia baillonii (2n=2x=16) and Torenia fournieri (2n=2x=18), an interspecific diploid hybrid (2n=2x=17) and a triploid hybrid (2n=3x=26) were produced. The behavior of meiotic chromosomes in the hybrids was examined by fluorescence in situ hybridization (FISH) with species-specific repeats. The mean pairing configuration of the diploid hybrid was 1.95 I+6.75 II+0.48 III and that of the triploid hybrid was 5.6 I+6.74 II+2.44 III. Genome analysis in the triploid hybrid using FISH revealed that the affinity between the genomes was x=0.79. The relatively low value indicates considerable conservation between homoeologous chromosomes of T. baillonii and T. fournieri, even though the two species have different chromosome numbers.