In this article, the available literature characterizing apomixis in Paspalum spp. and its use in breeding is critically reviewed. In particular, a comparison is made across species of the structure and function of the genomic region controlling apomixis in order to identify a common core region shared by all apomictic Paspalum species and where apomixis genes are likely to be localized. Candidate genes are discussed, either as possible genetic determinants (including homologs to signal transduction and RNA methylation genes) or as downstream factors (such as cell-to-cell signalling and auxin response genes) depending, respectively, on their co-segregation with apomixis or less. Strategies to validate the role of candidate genes in apomictic process are also discussed, with special emphasis on plant transformation in natural apomictic species.

The common races of bahiagrass, Paspalum notatum, are tetraploid (2n=4x=40) and reproduce by aposporous apomixis. Paspalum notatum var. saurae is the corresponding diploid (2n=2x=20) sexual race that outbreeds due to self-incompatibility. Chromosome doubling was induced by colchicine treatments in three individual plants from a natural diploid population. Embryological studies demonstrated that one of the induced autotetraploid plants reproduced sexually. The other two autotetraploids were facultative apomicts. These results indicate that an unexpressed gene(s) for apomixis exists at the diploid level. The expression of the trait is ploidydependent. The ploidy dependency may act either on the locus controlling apomixis through some transcription factors or via a secondary locus which requires a higher allele dosage to affect the expression of the main locus.

Paspalum plicatulum Michx. is a wild forage grass species. The common races are tetraploid and apomictic, while sexual diploid representatives have been reported sporadically. Objectives of this study were to induce sexual 4x individuals from sexual diploids, determine the capacity for hybridization with other apomictic 4x species closely related with P. plicatulum, and thus create a tetraploid sexual material cross compatible with apomictic 4x species of the Plicatula group of Paspalum. Two induced tetraploid plants were recovered from germinating 2x seeds treated for 24 h with colchicine. Bivalent and quadrivalent chromosomes were the most common association at meiosis in these autotetraploids. Embryological analysis and progeny tests using molecular markers revealed that both induced tetraploids reproduced sexually. Single‐seed screening by flow cytometry confirmed full sexual reproduction. These plants retained the high self‐incompatibility system of the diploids, but set seed after reciprocal crosses and when crossed with pollen of apomictic 4x P. guenoarum Arechav. of the Plicatula group. Both sexual 4x plants constitute the foundational material for plant improvement through gene exchange and selection in apomictic 4x P. plicatulum and possibly in several apomictic species of the Plicatula group.

Paspalum notatum is a subtropical grass widely distributed in the temperate areas of America. Diploids are sexual while polyploids give rise to clonal seeds through aposporous apomixis. RAPD markers were used to analyze the genetic structure of three natural populations: i) diploids reproducing sexually (R2X); ii) sympatric apomictic tetraploids collected in the vicinity of the diploids (R4X); iii) allopatric apomictic tetraploids growing in isolation (C4X). The apomictic reproduction rate was evaluated by the use of molecular markers in progeny tests, while chromosome-counting allowed the verification of ploidy levels. Data revealed that the R4X group presented a variation considerably higher than that observed for C4X. Jaccard ´s coefficients were used to produce a cluster diagram using the UPGMA method. All but one tetraploid genotypes grouped together and were associated to diploid genotype A21. The possibility of occasional generation of novel tetraploid clones from the interaction between tetraploid and diploid individuals is discussed.