A genetic map of tetraploid Paspalum notatum Flügge (bahiagrass) based on single-dose molecular markers

Abstract

Abstract Paspalum notatum Flugge is a warm-season forage grass with mainly diploid (2n =20) and autotetraploid (2n = 40) representa-tives.Diploid races reproduce sexually andrequire crosspollination due to a self-incom-patible mating system, while autotetraploids reproduce by aposporous apomixis. The objec-tives of this work were to develop a genetic linkage map of Paspalum notatum Flugge at the tetraploid level, identify the linkage/s group/s associated with apomixis and carry out a general characterization of its mode of inheritance. A pseudo test-cross F1 family of 113 individuals segregating for the mode of reproduction was obtained by crossinga syn-thetic completely sexual tetraploid plant (Q4188) as female parent with a natural<br />aposporous individual (Q4117) as pollen donor.Map construction was based on single-dose markers (SDAFs) segregating from both par-ents. Two linkage maps (female and male) were constructed. Within each map, homolo-gous groups were assembled by detectingrepulsion-phase linked SDAFs. Putative Q4188 and Q4117 homolog groups were identified by mapping shared single dose mark-ers (BSDF). The Q4188 map consisted of 263 markers distributed on 26 co-segregation groups over a total genetic distance of 1.590.6 cM, while the Q4117 map contained 216 loci dispersed on 39 co-segregation groups along 2.265.7 cM, giving an estimated genome cov-erage of 88% and 83%, respectively. Seven and 12 putative homologous chromosomes were detected within Q4188 and Q4117 maps,respectively. Afterward, ten female and male homologous chromosomes were identified by mapping BSDFs. In the Q4117 map, a single linkage group was associated with apospory. It was characterized by restriction in recombina-tion and preferential chromosome pairing. A BPSD marker mapping within this group allowed the detection of the female homolog and the putative four male groups of the set carrying apospory.