Mapping genetic factors controlling pollen viability in an interspecific cross in Helianthus sect. Helianthus

Abstract

Segregation of 48 genetic markers, including one CMS restorer gene, one morphological character gene, six isozymes and 40 RAPD loci, was scored in a backcross progeny of an interspecific hybrid H. argophyllusxH. annuus cv RHA274. A linkage map was generated taking into account segregation distortions for 11 of the 48 loci in the frame of two different models considering locus-pair segregation in the context of either independent selection pressures or non-equilibrated parental classes. The map consists of nine linkage groups and nine isolated markers covering 390 cM. Approximately half of the plants of the BC1 were male fertile as expected for the segregation of one dominant male-fertility restorer gene; however, these displayed a large range of variation for pollen viability. About 80% of this variation was explained by three genomic regions located on linkage groups 1, 2 and 3. The observation of meiotic chromosomes revealed a significant rate of mispairing (rod bivalents and tetravalents) in tight correlation with pollen viability, indicating that chromosome rearrangements (translocations) are the preponderant factors reducing pollen viability in this progeny. Cytogenetic and mapping data suggest that the three genomic regions involved in pollen-viability variation are located close to translocation points which differentiate the parental-species karyotypes. Segregation distortion was observed for loci correlated with pollen-viability variation. These were most likely the result of two possible suggested mechanisms.

Linkage Maps of thedwarfand Normal Lake Whitefish (Coregonus clupeaformis) Species Complex and Their Hybrids Reveal the Genetic Architecture of Population Divergence

“…Both Whitkus (1998) and observed up to 50% distortion in interspecific hybrid crosses of plants where segregation distortion was presumed to be a consequence of hybridization between divergent genomes. Such postzygotic barriers typically manifest themselves in linkage maps of reciprocal hybrid crosses resulting from selection on the F 1 gametes or by selection on recombinant backcross (BC) zygotes (Li et al 1997;Kim and Rieseberg 1999), where the degree of segregation distortion appears to be correlated with increasing genetic divergence between parental lines (Zamir and Tadmor 1986;Quillet et al 1995;Grandillo and Tanksley 1996).…”

Chromosomal Evolution and Patterns of Introgression inHelianthus

“…ARG has also been identified as a possible source of favorable alleles for salt and drought tolerance (Richards 1992) and insect resistance (Rogers and Thompson 1980;Rogers et al 1982Rogers et al , 1987Sujatha and Lakshminarayana 2007). Crosses between ANN and ARG produce vigorous offspring with reduced pollen viability (F 1 = 5-50% viable, BC 1 = 24-97% viable) and chromosomal abnormalities (Heiser 1951;Chandler et al 1986;Quillet et al 1995), resulting in restricted introgression in experimental crossing programs. Cytological studies identified meiotic abnormalities (e.g., univalents, rod bivalents, and tetravalents) in the interspecific hybrids, indicating that ANN and ARG differ by at least two reciprocal translocations (Heiser 1951;Chandler et al 1986;Quillet et al 1995).…”

“…Crosses between ANN and ARG produce vigorous offspring with reduced pollen viability (F 1 = 5-50% viable, BC 1 = 24-97% viable) and chromosomal abnormalities (Heiser 1951;Chandler et al 1986;Quillet et al 1995), resulting in restricted introgression in experimental crossing programs. Cytological studies identified meiotic abnormalities (e.g., univalents, rod bivalents, and tetravalents) in the interspecific hybrids, indicating that ANN and ARG differ by at least two reciprocal translocations (Heiser 1951;Chandler et al 1986;Quillet et al 1995). A recent comparative mapping study identified five nonreciprocal translocations and two inversions between ANN and ARG (Heesacker et al 2009); however, this analysis was based on an ARG map with just 299 markers (i.e., SSRs, indels, and SSCPs), of which only 131 were orthologous to loci that had been mapped in ANN.…”

Variability among inbred lines and RFLP mapping of sunflower isozymes

“…There have been several reports on the inheritance of isozyme loci in populations of both wild and cultivated sunflower (Kahler and Lay, 1985;Torres, 1983;Rieseberg et al, 1993 and1995;Quillet et al, 1995), and several pairs of loci have been found to be linked (Table IV ). Mestries et al (1998) were the first authors who reported the mapping of a number of isozyme loci onto a proprietary RFLP linkage map.…”