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Premise: Parthenogenesis is the capacity of organisms to develop embryos from unfertilized eggs. When parthenogenesis is coupled with unreduced gamete formation (apomeiosis), genetically maternal progeny result. Genetic elucidation of this form of reproduction in plants, apomixis, has important agronomic implications. However, genetic characterization of apomeiosis and parthenogenesis has been problematic in part because the traits usually co-occur and are restricted to polyploids. In this work, the inheritance of parthenogenetic embryo development, by itself, was studied at the diploid level., Methods: Progeny resulting from a cross between a diploid (2n = 18), heterozygous, parthenogenetic pollen donor, and a diploid, wildtype, sexual seed parent were evaluated. Paternity was tested with conserved orthologous sequence (COS) markers, reproductive development of F1s was evaluated with microscopy of cleared ovules, and an amplified fragment length polymorphism (AFLP) marker (Eagc × Macg.615) co-segregating with parthenogenesis was characterized at the sequence level., Results: Of 102 diploid biparental progeny, 47 exhibited parthenogenetic embryo and endosperm development, and 55 lacked development of the egg and central cell. This result is consistent with Mendelian inheritance for a single locus (P = 0.43). Isolation and sequencing of the AFLP marker indicates that it is likely a portion of a Ty-Gypsy retrotransposon. Attempts to develop a sequence-characterized amplified region marker from the AFLP were unsuccessful., Conclusions: This work shows that parthenogenesis can be transmitted simply at the diploid level. This advance is key in the development of a tractable system in Erigeron aimed at the identification of the parthenogenesis locus using genetic mapping strategies., (© 2022 Botanical Society of America.)

Unlabelled: •, Premise of the Study: Dihaploids result when tetraploids produce reduced eggs that develop without fertilization into diploid progeny. This process is useful for reducing genome complexity and studying trait expression at different ploidal levels. In this study we evaluated genetic inheritance and expression of diplospory (D) and parthenogenesis (P) in a population of dihaploids produced by tetraploid apomictic Erigeron•, Methods: From 400 mostly maternal (tetraploid) progeny, we identified 64 (16%) dihaploids with 2n = 18 (53 plants) or 2n = 19 (11 plants). Differential interference contrast (DIC) imaging of ovules was used to evaluate megasporogenesis (meiosis vs. diplospory) and capacity for parthenogenetic embryo development. Seed production was estimated as the proportion of filled seeds.•, Key Results: For 60 analyzed dihaploids, diplospory vs. meiosis segregated approximately 1: 1 (P = 0.44) while all exhibited parthenogenetic embryo development. Parthenogenesis for meiotic progeny (n = 27) was observed in approximately 50% of ovules. Apomictic dihaploids (combining D and P; n = 33) produced seeds with mean 24.8% (range 1.3-74.4%) of total flowers.•, Conclusions: The dihaploid population consisted of half apomicts (D + P) and half parthenogens (P only). We infer that formation of dihaploid seeds requires the parthenogenesis locus. The highest seed values obtained for diploid apomicts are comparable to those recorded for wild type polyploid apomicts. This is one of the first reports of diploid apomixis in the Asteraceae and it demonstrates that both diplospory and parthenogenesis can be transmitted and expressed at a high level in the diploid condition., (© 2014 Botanical Society of America, Inc.)

Erigeron geiseri Shinners is a tap-rooted herbaceous daisy occurring from south-eastern Texas to southern Oklahoma. Our study of pollen quality from 67 herbarium specimens supports the hypothesis that the species comprises sexual diploid populations, restricted to southern locations, and polyploid, putatively apomictic, populations that are widespread. We successfully amplified and sequenced ITS and ETS spacer regions of nrDNA for five specimens (two putative sexual diploids, three putative apomictic polyploids). Phylogenetic analysis conducted using maximum likelihood and Bayesian methods support a topology showing that 1) sexual and apomictic populations of E. geiseri form a well-supported monophyletic group, and, 2) E. geiseri is sister to E. strigosus of eastern North America. The results support the classification of E. geiseri with E. strigosus in E. sect. Phalacroloma. [ABSTRACT FROM AUTHOR]

Studies the segregation for asexual seed production of hybrids resulting from a cross between diploid sexual Erigeron strigosus and triploid agamospermous Erigeron annuus. Distribution of chromosome numbers; Diplosporous versus meiotic megagametohyte development; Inheritance of diplospory in Erigeron.

Complex geographical distribution patterns and agamospermy have united to obscure systematic relationships in the genus Erigeron (400+ species). Sequence data were analyzed from the internal transcribed spacer region of nrDNA (ITS) and 5.8S cistron for 77 taxa including 63 Erigeron species. Results support the North American origin of Erigeron and document that Aphanostephus, Conyza, and three small genera restricted to South America ( Apopyros, Hysterionica, Neja) are all derived from within Erigeron. Phylogenetic data indicate that agamospermy has arisen at least three times in Erigeron and that autogamy has evolved independently in Conyza and in E. sect. Trimorpha. [ABSTRACT FROM AUTHOR]

Assesses the variation and population structure in Erigeron compositus. Characterization of individual multilocus genotypes within putative agamospermously producing plant populations; Determination of the cytotype and pollen-producing capacity of specimens of each genotype; Evaluation of genetic variability within and among agamospermos populations.