The use of Anchored Hybrid Enrichment data to resolve higher-level phylogenetic relationships: A proof-of-concept applied to Asterales (Eudicotyledoneae; Angiosperms).

Anchored Hybrid Enrichment (AHE) is a tool for capturing orthologous regions of the nuclear genome shared in low or single copy across lineages. Despite the increasing number of studies using this method, its usefulness to estimate relationships at deeper taxonomic levels in plants has not been fully explored. Here we present a proof of concept about the performance of nuclear loci obtained with AHE to infer phylogenetic relationships and explore the use of gene sampling schemes to estimate divergence times in Asterales. We recovered low-copy nuclear loci using the AHE method from herbarium material and silica-preserved samples. Maximum likelihood, Bayesian inference, and coalescence approaches were used to reconstruct phylogenomic relationships. Dating analyses were conducted under a multispecies coalescent approach by jointly inferring species tree and divergence times with random gene sampling schemes and multiple calibrations. We recovered 403 low-copy nuclear loci for 63 species representing nine out of eleven families of Asterales. Phylogenetic hypotheses were congruent among the applied methods and previously published results. Analyses with concatenated datasets were strongly supported, but coalescence-based analyses showed low support for the phylogenetic position of families Argophyllaceae and Alseuosmiaceae. Estimated family ages were congruent among gene sampling schemes, with the mean age for Asterales around 130 Myr. Our study documents the usefulness of AHE for resolving phylogenetic relationships at deep phylogenetic levels in Asterales. Observed phylogenetic inconsistencies were possibly due to the non-inclusion of families Phellinceae and Pentaphragmataceae. Random gene sampling schemes produced consistent age estimates with coalescence and species tree relaxed clock approaches.

Why does pollen morphology vary? Evolutionary dynamics and morphospace occupation in the largest angiosperm order (Asterales).

Morphological diversity (disparity) is a key component of biodiversity and increasingly a focus of botanical research. Despite the wide range of morphologies represented by pollen grains, to date there are few studies focused on the controls on pollen disparity and morphospace occupation, and fewer still considering these parameters in a phylogenetic framework. Here, we analyse morphospace occupation, disparity and rates of morphological evolution in Asterales pollen, in a phylogenetic context. We use a dataset comprising 113 taxa from across the Asterales phylogeny, with pollen morphology described using 28 discrete characters. The Asterales pollen morphospace is phylogenetically structured around groups of related taxa, consistent with punctuated bursts of morphological evolution at key points in the Asterales phylogeny. There is no substantial difference in disparity among these groups of taxa, despite large differences in species richness and biogeographic range. There is also mixed evidence for whole-genome duplication as a driver of Asterales pollen morphological evolution. Our results highlight the importance of evolutionary history for structuring pollen morphospace. Our study is consistent with others that have shown a decoupling of biodiversity parameters, and reinforces the need to focus on disparity as a key botanical metric in its own right.

The genome sequence of common fleabane, Pulicaria dysenterica (L.) Bernh. (Asteraceae).

We present a genome assembly from an individual Pulicaria dysenterica (common fleabane; Tracheophyta; Magnoliopsida; Asterales; Asteraceae). The genome sequence is 833.2 megabases in span. Most of the assembly is scaffolded into 9 chromosomal pseudomolecules. The mitochondrial and plastid genomes were assembled and have lengths of 375.47 kilobases and 150.94 kilobases respectively.

Interstitial Arabidopsis-Type Telomeric Repeats in Asteraceae.

Tandem repeats of telomeric-like motifs at intra-chromosomal regions, known as interstitial telomeric repeats (ITR), have drawn attention as potential markers of structural changes, which might convey information about evolutionary relationships if preserved through time. Building on our previous work that reported outstanding ITR polymorphisms in the genus Anacyclus, we undertook a survey across 132 Asteraceae species, focusing on the six most speciose subfamilies and considering all the ITR data published to date. The goal was to assess whether the presence, site number, and chromosomal location of ITRs convey any phylogenetic signal. We conducted fluorescent in situ hybridization (FISH) using an Arabidopsis-type telomeric sequence as a probe on karyotypes obtained from mitotic chromosomes. FISH signals of ITR sites were detected in species of subfamilies Asteroideae, Carduoideae, Cichorioideae, Gymnarhenoideae, and Mutisioideae, but not in Barnadesioideae. Although six small subfamilies have not yet been sampled, altogether, our results suggest that the dynamics of ITR formation in Asteraceae cannot accurately trace the complex karyological evolution that occurred since the early diversification of this family. Thus, ITRs do not convey a reliable signal at deep or shallow phylogenetic levels and cannot help to delimitate taxonomic categories, a conclusion that might also hold for other important families such as Fabaceae.

Gongylolepis martiana, an Asteraceae pollinated by bats in the Amazon.

Most Asteraceae species are pollinated by insects, mainly bees and butterflies, although pollination by birds has been documented and pollination by bats has been suggested for some species. Here, we investigated the pollination of Gongylolepis martiana, a species supposedly pollinated by bats. We assessed floral traits and visitors in a population of G. martiana in the Brazilian Amazon, measuring pollen removal from anthers and deposition on stigmas by diurnal and nocturnal visitors. Florets opened at dusk and lasted for 4 days, with the male phase starting on the first night and the female phase on the third night. Accumulated nectar per capitulum was 69.6 µl per night and sugar concentration was 15%. Nectar-feeding bats and hummingbirds contacted the sexual parts, but pollen removal and deposition were greater throughout the night than during the day, when Meliponini bees considerably reduced pollen availability. Other nocturnal visitors of G. martiana were rare, including nocturnal bees and moths that foraged for pollen and nectar, respectively. Our results support that nectarivorous bats are the main pollinators of G. martiana, confirming Vogel's hypothesis of bat pollination in Asteraceae, particularly in the genus Gongylolepis. Since anthesis and each sexual floral phase started in the evening, nectarivorous bats and diurnal bees caused additive priority effects, preventing hummingbirds from being efficient pollinators. The high density of flowering individuals of G. martiana in patches from white-sand forests likely increases bat attraction, while the small amount of nectar per plant favours cross-pollination.

Genome-Wide Identification of WRKY Transcription Factors in the Asteranae.

The WRKY transcription factors family, which participates in many physiological processes in plants, constitutes one of the largest transcription factor families. The Asterales and the Apiales are two orders of flowering plants in the superorder Asteranae. Among the members of the Asterales, globe artichoke (Cynara cardunculus var. scolymus L.), sunflower (Helianthus annuus L.), and lettuce (Lactuca sativa L.) are important economic crops worldwide. Within the Apiales, ginseng (Panax ginseng C. A. Meyer) and Panax notoginseng (Burk.) F.H. Chen are important medicinal plants, while carrot (Daucus carota subsp. carota L.) has significant economic value. Research involving genome-wide identification of WRKY transcription factors in the Asterales and the Apiales has been limited. In this study, 490 WRKY genes, 244 from three species of the Apiales and 246 from three species of the Asterales, were identified and categorized into three groups. Within each group, WRKY motif characteristics and gene structures were similar. WRKY gene promoter sequences contained light responsive elements, core regulatory elements, and 12 abiotic stress cis-acting elements. WRKY genes were evenly distributed on each chromosome. Evidence of segmental and tandem duplication events was found in all six species in the Asterales and the Apiales, with segmental duplication inferred to play a major role in WRKY gene evolution. Among the six species, we uncovered 54 syntenic gene pairs between globe artichoke and lettuce. The six species are thus relatively closely related, consistent with their traditional taxonomic placement in the Asterales. This study, based on traditional species classifications, was the first to identify WRKY transcription factors in six species from the Asteranae. Our results lay a foundation for further understanding of the role of WRKY transcription factors in species evolution and functional differentiation.

Two new species of Siphocampylus (Campanulaceae, Lobelioideae) from the Central Andes.

Two species of Siphocampylus (Campanulaceae: Lobelioideae) from the Central Andes of Peru and Bolivia are described, illustrated, and discussed with reference to related species. One species, Siphocampylus antonellii, is endemic to high elevation grasslands of Calca, Peru, while the second, Siphocampylus siberiensis, is endemic to cloud forests of Cochabamba, Bolivia. Both species are robust shrubs that produce tubular pink flowers that are likely pollinated by hummingbirds.