Genomic affinities in the subseries Turnera (Turnera, Turneraceae) inferred by In Situ Hybridization techniques

LOPEZ, ALICIA; FERNANDEZ, AVELIANO; POGGIO, LIDIA

GENOME

NATL RESEARCH COUNCIL CANADA-N R C RESEARCH PRESS

Año: 2010 vol. 53 p. 585 - 593

0831-2796

Subseries Turnera constitutes a polyploid complex with ploidy levels ranging from diploid (2n=2x=10) to octoploid (2n=8x=40). The use of FISH greatly improved the knowledge of the karyotypes of Turnera by detecting and mapping rDNA sites. Interspecific variability in the number of sites was detected, but not in correlation with the ploidy level. A chromosome pair with a high hybridization signal was always visible and corresponded to the secondary constriction evident by conventional techniques. GISH experiments combined with meiotic pairing in species and interspecific hybrids revealed that homologies detected by molecular analysis are greater than those detected by chromosome pairing. These suggest that the formation of the allopolyploids could involve species more closely related than previously assumed. Despite of the molecular affinity among the genomes the meiotic pairing is probably controlled by specific genes that restrict homeologous pairing in polyploids.