Mapping Apomixis in the Plicatula Group of Paspalum through Genotyping by Sequencing

WAGNER AW; ORTIZ JPA; ESPINOZA F

Workshop; Proceedings of the 7th Series of Seminars on Advances in Apomixis Research; 2021

In the Paspalum, apomixis (asexual reproduction via seeds) is controlled by a singledominant complex locus (ACL). The Plicatula group includes species either with diploid sexual(2n=2x=20)andapomictictetraploid(2n=4x=40)cytotypes,andwithexclusively polyploid(mostlytetraploid)races. WhilegeneticlinkagemapsinP.notatumandP.simplex revealednon-recombinantACLs,initialAFLPmappinginP.guenoarum(Plicatula)revealed a recombinant ACL. This work aims at building a dense genetic linkage map of tetraploid Plicatula spp. through genotyping by sequencing (GBS), localizing the ACL and facilitating both identification and positional cloning of the genes governing apomixis. The mapping population (n = 82; 52 sexual and 32 apomict F1 plants) derives from a cross between P.plicatulum4-PT(a4×colchicine-inducedsexualplant)×P.guenoarumGR19(a4×natural apomict individual). Genomic DNA was digested with ApeKI and used for preparing Illumina NextSeq 550 libraries. A total of 366 million reads (75 bp single-end; 4.35 million reads/sample on average) were obtained. Initially, the STACKS and TASSEL_UNEAK softwares were used for de novo SNP discovery, but failed to identify relevant markers. Then, the TASSEL5GBSV2 pipeline was used with Setaria viridis, Zea mays, and P. notatum (draft) genomes as references and produced, respectively, 9,264; 2,365, and; 10,711 singledose markers. Genotypes related with the ACL (Aaaa and aaaa for apomictic and sexual plants, assuming a dominant simplex control) were assigned to each F1 in the GBS data matrix. Linkage analyses are ongoing using JoinMap 4.0 and a pseudo-test cross model.