GISH Analysis of the Introgression of the B Subgenome Genetic Material of Wild Allotetraploid Species Solanum stoloniferum into Backcrossing Progenies with Potato

Abstract

Wild relatives of cultivated potato are used in breeding to increase the genetic diversity of Solanum tuberosum (AAAA genome) varieties. Wild Mexican allotetraploid species Solanum stoloniferum (AABB genome) was used in breeding for extreme resistance to viruses and late blight. In this study, genomic in situ hybridization (GISH) was used for visualization of introgression of genetic material of the B subgenome of S. stoloniferum into the genome of backcross hybrids. The fertile hexaploid hybrid had 48 chromosomes of the A genome and 24 chromosomes of the B subgenome. Plants of the BC1 generation were pentaploid having the AAAAB genome constitution and three selected BC2 hybrids were aneuploid, containing one to six chromosomes of the B subgenome and 48 chromosomes of the A genome. The B subgenome of S. stoloniferum was inherited in the backcross generations as single chromosomes and in rare cases as recombinant chromosomes. GISH showed that chromosome pairing in the backcross hybrids was predominantly intragenomic. Most chromosomes of the B subgenome remained as univalents in backcross hybrids. Rare homeologous A/B chromosome pairing was detected in all analyzed hybrids. The obtained data indicate that the B subgenome of S. stoloniferum was able to recombine with the A genome.