title: A Parthenogenesis Gene Candidate and Evidence for Segmental Allopolyploidy in Apomictic Brachiaria decumbens.
abstract: Apomixis, asexual reproduction through seed, enables breeders to identify and faithfully propagate superior heterozygous genotypes by seed without the disadvantages of vegetative propagation or the expense and complexity of hybrid seed production. The availability of new tools such as genotyping by sequencing and bioinformatics pipelines for species lacking reference genomes now makes the construction of dense maps possible in apomictic species, despite complications including polyploidy, multisomic inheritance, self-incompatibility, and high levels of heterozygosity. In this study, we developed saturated linkage maps for the maternal and paternal genomes of an interspecific Brachiaria ruziziensis (R. Germ. and C. M. Evrard) × B. decumbens Stapf. F1 mapping population in order to identify markers linked to apomixis. High-resolution molecular karyotyping and comparative genomics with Setaria italica (L.) P. Beauv provided conclusive evidence for segmental allopolyploidy in B. decumbens, with strong preferential pairing of homologs across the genome and multisomic segregation relatively more common in chromosome 8. The apospory-specific genomic region (ASGR) was mapped to a region of reduced recombination on B. decumbens chromosome 5. The Pennisetum squamulatum (L.) R.Br. PsASGR-BABY BOOM-like (psASGR-BBML)-specific primer pair p779/p780 was in perfect linkage with the ASGR in the F1 mapping population and diagnostic for reproductive mode in a diversity panel of known sexual and apomict Brachiaria (Trin.) Griseb. and P. maximum Jacq. germplasm accessions and cultivars. These findings indicate that ASGR-BBML gene sequences are highly conserved across the Paniceae and add further support for the postulation of the ASGR-BBML as candidate genes for the apomictic function of parthenogenesis.
authors.affiliation: International Center for Tropical Agriculture (CIAT), Cali 763537, Colombia m.worthington@cgiar.org.
authors.forename: Margaret
authors.identifier: 0000-0001-8019-165X
authors.initials: M
authors.lastname: Worthington
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520.
authors.forename: Christopher
authors.initials: C
authors.lastname: Heffelfinger
authors.affiliation: International Center for Tropical Agriculture (CIAT), Cali 763537, Colombia.
authors.forename: Diana
authors.initials: D
authors.lastname: Bernal
authors.affiliation: International Center for Tropical Agriculture (CIAT), Cali 763537, Colombia.
authors.forename: Constanza
authors.initials: C
authors.lastname: Quintero
authors.affiliation: International Center for Tropical Agriculture (CIAT), Cali 763537, Colombia.
authors.forename: Yeny Patricia
authors.initials: YP
authors.lastname: Zapata
authors.affiliation: International Center for Tropical Agriculture (CIAT), Cali 763537, Colombia.
authors.forename: Juan Guillermo
authors.initials: JG
authors.lastname: Perez
authors.affiliation: The Genome Analysis Centre, Norwich Research Park, Colney, Norwich NR4 7UH, United Kingdom.
authors.forename: Jose
authors.identifier: 0000-0003-2847-5158
authors.initials: J
authors.lastname: De Vega
authors.affiliation: International Center for Tropical Agriculture (CIAT), Cali 763537, Colombia.
authors.forename: John
authors.initials: J
authors.lastname: Miles
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520.
authors.forename: Stephen
authors.initials: S
authors.lastname: Dellaporta
authors.affiliation: International Center for Tropical Agriculture (CIAT), Cali 763537, Colombia.
authors.forename: Joe
authors.initials: J
authors.lastname: Tohme
mesh_terms: D060832:Apomixis / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics; D035201:Brachiaria / Q000235:genetics* / Q000254:growth & development; D002874:Chromosome Mapping; D032461:Chromosomes, Plant / Q000235:genetics*; D008040:Genetic Linkage; D005838:Genotype; D010312:Parthenogenesis / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D011123:Polyploidy; D012100:Reproduction, Asexual / Q000235:genetics*; D012639:Seeds / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; C518629:BABY BOOM protein, Arabidopsis; D014157:Transcription Factors
keywords: apospory; genetic linkage map; genotyping by sequencing; molecular karyotyping; polyploidy