Recurrent phenotypic selection and recurrent selection based on combining ability in tetraploid bahiagrass

Abstract

Paspalum notatum Flüggé is an apomictic grass used for forage and turf. The recent generation of a sexual synthetic tetraploid population of the species provides the unique advantage to exploit heterosis by accumulating favorable alleles through recurrent selection cycles. The objective was to evaluate recurrent phenotypic selection (RPS) and recurrent selection based on combining ability (RSCA) as breeding methods. The best sexual genotypes in terms of warm-season growth from a sexual synthetic tetraploid population were selected by RPS and RSCA. The selected genotypes were polycrossed and two new sexual populations were created, which were crossed with superior apomictic genotypes. Both methods allowed obtaining families that were evaluated for summer, fall, and spring growth. Breeding values and heterosis were also calculated. Summer growth for RPS families was greater than for RSCA families (33.1 and 29.08 g plant −1 , respectively); however, fall, spring, and accumulated growth were similar. The breeding value for RPS sexual parents was greater than for RSCA sexual parents for summer growth, whereas those for fall and spring growth were similar. A greater level of families with heterosis (80%) was observed for RPS than for RSCA (30%) for summer growth, whereas the levels for fall and spring growth were similar. These results indicate that both breeding methods were successful in improving tetraploid P. notatum. They increased the mean value of the progenies and produced families superior for forage yield by accumulating favorable alleles.Abbreviations: ISSR, inter-simple sequence repeat; PCR, polymerase chain reaction; RPS, recurrent phenotypic selection; RSCA, recurrent selection based on combining ability; SSTP, sexual synthetic tetraploid population.

How to Become an Apomixis Model: The Multifaceted Case of Paspalum

“…[ 140 ]. Marcón et al [ 141 ] evaluated the use of recurrent phenotypic selection (RPS) and recurrent selection based on combining ability (RSCA) in tetraploid P. notatum . Both methods proved to be efficient for improving forage yield in P. notatum .…”

“…Both methods proved to be efficient for improving forage yield in P. notatum . Although RSCA was expected to be more appropriate for exploiting heterosis since it was developed to accumulate heterotic effects over cycles, no difference was observed between the RPS and RSCA procedures for increasing forage yield [ 141 ]. A modified version of RSCA was used to identify superior tetraploid hybrids within the sexual population of Plicatula [ 138 ].…”

Evaluating General Combining Ability for Multiple Traits in Tetraploid Bahiagrass

“…And then obtain superior apomictic hybrids by crossing the improved sexual genotypes with apomictic ones. Based on the scheme proposed by Miles (2007), Marcón et al (2020) carried out recurrent selection based on general combining ability to improve the SSTP of bahiagrass. This breeding approach consisted in a four-step process where (1) plants of the SSTP where crossed by a group of elite apomictic genotypes used as testers, (2) superior sexual parents were selected on the basis of the performance of their testcross progeny, (3) the selected sexual parents were polycrossed to form a recombinant superior population, and (4) sexual plants of the recombined population were crossed by superior apomictic plants.…”

“…The testcross progeny test was successful in improving tetraploid bahiagrass for forage yield since it allowed to obtain superior hybrid families by the accumulation of dominant favorable alleles (Marcón et al 2020). However, the success of this method depends on the accuracy of selection of the best parents to form a new recombinant population (Miles 2007;Hallauer et al 2010).…”

“…However, the success of this method depends on the accuracy of selection of the best parents to form a new recombinant population (Miles 2007;Hallauer et al 2010). Marcón et al (2020) selected the best parents based on their general combining ability which was estimated by using analysis of variance. Nonetheless, this type of analysis considers the genotypes as fixed, so lot of information might be missed by unbalanced data (Little et al 1996).…”