Previous studies on the inheritance of aposporous apomixis in bahiagrass showed a wide range of segregation ratios in crosses involving sexual and aposporous apomictic plants. The F1 progenies were classified through a visual progeny test carried out on few F2 plants. The number of sexual F1s highly exceeded the apomictics leading to the conclusion that apomixis was controlled by a few recessive genes. The present study examines the inheritance of apospory in bahiagrass. A sexual plant was self-pollinated and crossed with an aposporous apomictic plant as pollen donor. Backcross and F2 progenies were obtained in several combinations. All self-pollinated sexual plants or sexual x sexual crosses produced progenies free of apospory. All crosses involving a sexual and an apomictic plant produced approximately three times more apospory-free plants than plants with apospory. Bahiagrass is of autotetraploid origin and hence is expected to display tetrasomic inheritance. The most widely accepted genetic model for inheritance of apospory in tropical grasses is a single dominant gene with tetrasomic inheritance. In the present experiments none of the apospory-free F1s segregated for the apospory trait indicating that it is most likely a dominant character. However, the observed results fit better a modified model: tetrasomic inheritance of a single dominant gene with pleiotropic effect and incomplete penetrance. The excess of apospory-free plants in the F1 progeny could be ascribed to some distortion in the segregation pattern due to a pleiotropic lethal effect of the dominant A allele with incomplete penetrance. Alternatively, partial lethality of factors linked to aposporous gene may account for segregation distortion against apospory.

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The objective of this review is to analyze and describe the impact that mode of reproduction in Paspalum has on germplasm conservation, genetic improvement, and commercialization of cultivars. Germplasm collection and conservation can now be rethought considering the newly available information related to how diversity is allocated in nature and how it can be transferred between the sexual and apomictic germplasm using novel breeding approaches. An inventory of species and accessions conserved around the world is analyzed in relation to the main germplasm banks. Because of the importance of apomixis in Paspalum species different breeding approaches have been used and tested. Knowledge related to the inheritance of apomixis, variable expressivity of the trait and techniques for early identification of apomicts has helped to improve the efficiency of the breeding methods. Novel breeding techniques are also being developed and are described regarding its advantages and limitations. Finally, the impact of reproductive mode on the adoption of the released cultivars is discussed.

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Paspalum is considered a genetic model for studying the sources of genotypic variability and breeding techniques in apomictic plants. Paspalum simplex is a warm‐season forage grass that well represents the genus since it contains different ploidy levels and apomixis is linked to polyploidy. The objective was to evaluate the diversity present within and among apomictic polyploid populations of P. simplex. Germplasm was collected from 17 sites covering the species’ region of natural distribution. The diversity present at the molecular level within and among populations was evaluated using ISSR markers. Variability for agronomic traits was also evaluated by cultivating all populations into the field. The 17 analyzed populations were all polyploid, including 13 pure tetraploid, and 4 mixed tetraploid‐hexaploid with predominance of the tetraploid cytotype. Most of the diversity was present among polyploid populations (85% of the total variation), and there was not a correlation between genetic and geographical distances. The within‐population diversity was low for most populations with the exception of one of them. Each genotype was restricted to a single location. Variability for initial growth, spring and fall growth, and the extent of the vegetative phase was observed within and among polyploid populations. The within‐population variation for these phenotypic traits was mainly due to the presence of one or a few off‐type plants. A highly genotype‐specific colonization of new sites appears to occur in P. simplex, and then apomixis mediates the formation of uniform populations.

The tetraploid cytotype of Paspalum simplex Morong has a wide geographical distribution and reproduces by apomixis while the diploid grows in a restricted area in northern Argentina and behaves as cross‐pollinated. The objective was to evaluate the genetic diversity among and within natural diploid and tetraploid populations of P. simplex growing in sympatry and allopatry by studying the phenotypic variability and DNA polymorphisms. Twenty‐three phenotypic traits and 10 inter‐simple sequence repeat (ISSR) molecular markers were used for evaluating the variability present in six populations of P. simplex. Two populations were diploid and four were tetraploid. One of the tetraploid populations was sympatric to a diploid population while the rest of the populations were allopatric. A rich diversity was observed for specific traits, especially for seasonal biomass yield, presence of a terminal raceme in the inflorescence, and leaf pubescence. The 2x and 4x populations growing in proximity were closely related. Diversity was higher within diploid populations when compared with the evaluated tetraploid populations. Among the tetraploid populations, the one sympatric with a diploid population exhibited the greatest diversity. Gene flow occurs between 2x sexual and 4x apomictic populations of P. simplex. Diploid populations seem to be the main source of the diversity observed among tetraploid populations.