Botanical Journal of the Linnean Society

, ; Chase, M. W.; Christenhusz, M. J. M.; Fay, M. F.; Byng, J. W.; Judd, W. S.; Soltis, D. E.; Mabberley, D. J.; Sennikov, A. N.; Soltis, P. S.; Stevens, P. F.

doi: 10.1111/boj.12385pmid: N/A

AbstractAn update of the Angiosperm Phylogeny Group (APG) classification of the orders and families of angiosperms is presented. Several new orders are recognized: Boraginales, Dilleniales, Icacinales, Metteniusiales and Vahliales. This brings the total number of orders and families recognized in the APG system to 64 and 416, respectively. We propose two additional informal major clades, superrosids and superasterids, that each comprise the additional orders that are included in the larger clades dominated by the rosids and asterids. Families that made up potentially monofamilial orders, Dasypogonaceae and Sabiaceae, are instead referred to Arecales and Proteales, respectively. Two parasitic families formerly of uncertain positions are now placed: Cynomoriaceae in Saxifragales and Apodanthaceae in Cucurbitales. Although there is evidence that some families recognized in APG III are not monophyletic, we make no changes in Dioscoreales and Santalales relative to APG III and leave some genera in Lamiales unplaced (e.g. Peltanthera). These changes in familial circumscription and recognition have all resulted from new results published since APG III, except for some changes simply due to nomenclatural issues, which include substituting Asphodelaceae for Xanthorrhoeaceae (Asparagales) and Francoaceae for Melianthaceae (Geraniales); however, in Francoaceae we also include Bersamaceae, Ledocarpaceae, Rhynchothecaceae and Vivianiaceae. Other changes to family limits are not drastic or numerous and are mostly focused on some members of the lamiids, especially the former Icacinaceae that have long been problematic with several genera moved to the formerly monogeneric Metteniusaceae, but minor changes in circumscription include Aristolochiaceae (now including Lactoridaceae and Hydnoraceae; Aristolochiales), Maundiaceae (removed from Juncaginaceae; Alismatales), Restionaceae (now re-including Anarthriaceae and Centrolepidaceae; Poales), Buxaceae (now including Haptanthaceae; Buxales), Peraceae (split from Euphorbiaceae; Malpighiales), recognition of Petenaeaceae (Huerteales), Kewaceae, Limeaceae, Macarthuriaceae and Microteaceae (all Caryophyllales), Petiveriaceae split from Phytolaccaceae (Caryophyllales), changes to the generic composition of Ixonanthaceae and Irvingiaceae (with transfer of Allantospermum from the former to the latter; Malpighiales), transfer of Pakaraimaea (formerly Dipterocarpaceae) to Cistaceae (Malvales), transfer of Borthwickia, Forchhammeria, Stixis and Tirania (formerly all Capparaceae) to Resedaceae (Brassicales), Nyssaceae split from Cornaceae (Cornales), Pteleocarpa moved to Gelsemiaceae (Gentianales), changes to the generic composition of Gesneriaceae (Sanango moved from Loganiaceae) and Orobanchaceae (now including Lindenbergiaceae and Rehmanniaceae) and recognition of Mazaceae distinct from Phrymaceae (all Lamiales).

Landrein, Sven; Prenner, Gerhard

doi: 10.1111/boj.12396pmid: N/A

AbstractLinnaeeae is a small tribe of Caprifoliaceae consisting of six genera and c. 20 species. In Linnaeeae, floral nectaries are located on the corolla-filament-tube and nectar is produced from unicellular glandular hairs. We studied 23 taxa using scanning electron microscopy (SEM), light microscopy (LM) and transmission electron microscopy (TEM) and found two distinct nectary morphologies, zonate and gibbous types, and two distinct types of glandular hair, clavate and smooth base types. Plesiomorphic characters associated with the nectary and identified in the tribe include hypocrateriform corollas, dichogamous flowers, zonate nectaries, wet papillate stigmas, vestigial nectary disc and smooth pollen grains. Apomorphic characters include bilabiate corollas, homogamous flowers, bulging nectaries, dry papillate stigmas and echinulate pollen grains. The nectary structure is similar in Vesalea and Linnaea and differs from the rest of the tribe, in accordance with recent phylogenetic results. Nectar secretion is typically granulocrine with subcuticular accumulation of nectar, which we compared with the secretion in multicellular hairs of Adoxa moschatellina. The cuticle on the hair becomes detached from the cell wall and large subcuticular spaces filled with nectar are formed. Nectar is probably released in areas with a thin cuticle. In Zabelia, the smooth basal part of the hair could help to build up the hydrostatic pressure.

Rosato, Marcela; Ferrer-Gallego, Pablo; Totta, Chiara; Laguna, Emilio; Rosselló, Josep A.

doi: 10.1111/boj.12392pmid: N/A

AbstractUsing micropropagation through tissue culture has become the most used approach worldwide for mass production for the conservation of endangered species. However, the screening of somaclonal variations generated using in vitro culture is usually restricted to the first generation of micropropagated plants, when they have not yet been released in the field. Accordingly, the fate of genetically modified regenerants after sexual reproduction is usually not assessed and changes in the genetic structures of species are unknown. In this work, we assess the cytogenetic stability of two rDNA gene families in the offspring of experimental crosses between accessions generated after in vitro culture and wild individuals of Cistus heterophyllus (Cistaceae). The cytogenetic rDNA profiles (45S rDNA, 5S rDNA) of 118 accessions including wild and in vitro micropropagated individuals and bi-directional artificial crosses between wild and in vitro-generated plants were assessed by fluorescence in situ hybridization (FISH) and Ag-NOR staining. Plants regenerated by micropropagation showed a lower size of the FISH signals in a 45S rDNA site, but this condition was not present in the wild accessions. Three new cytogenetic and cytological variants were present in 36% of the experimental progeny, involving the amplification of one additional 45S rDNA site and the presence of heteromorphic nucleoli. rDNA-based genomic instability was present after sexual reproduction between wild and in vitro-generated plants. The results of this study discourage the use of micropropagated materials for plant conservation unless comprehensive surveys of the genetic integrity and stability of the regenerants are performed after crossing between wild and micropropagated plants.

Bello, María A.; Martínez-Asperilla, Aránzazu; Fuertes-Aguilar, Javier

doi: 10.1111/boj.12391pmid: N/A

AbstractThe epicalyx is a structure below the calyx that is often integrated in floral display. In Malvales, the epicalyx is interpreted to be formed by bracts derived from inflorescence reduction. In this study, we compare the epicalyx and flower development of Lavatera trimestris and Malva hispanica, which are close relatives but show contrasting morphologies. Both species exhibit cymose branching, stipulate subtending leaves, a short plastochron between the appearance of the alternating epicalyx and calyx, a centrifugally developing androecium and a multicarpellar gynoecium. The predominantly trimerous structure and leafy morphology of the epicalyx suggest its origin from a former subtending leaf with leaf-like stipules. The bilobed epicalyx in M. hispanica represents a loss of the adaxial epicalyx lobe rather than modified bracts. In Malvoideae, the bracts and bracteoles in the flowering branches can be completely absent and are variable in position and number when present. Individual bracts and bracteoles could correspond to further reductions of former subtending leaves instead of precursors of the epicalyx. Although the centrifugal androecium behaves as a branched-like structure, it is a dynamic complex floral whorl with extended growth capacity. The umbrella in L. trimestris is a swollen part of the style without a well-understood role in floral or fruit morphology.

Sullivan, Alexis R.; Owusu, Sandra A.; Weber, Jaime A.; Hipp, Andrew L.; Gailing, Oliver

doi: 10.1111/boj.12393pmid: N/A

AbstractOaks (Quercus: Fagaceae) commonly interbreed yet retain their morphological, genetic and ecological distinctiveness. Post-zygotic isolation mechanisms, such as ecologically dependent selection on adaptive loci, may therefore limit introgression. To test this hypothesis, we quantified hybridization and genetic divergence across the contact zone of four red oaks (Quercus section Lobatae) in the Great Lakes region of North America using a suite of 259 amplified fragment length polymorphisms and 27 genic and genomic microsatellite markers. First, we identified hybrids using genetic structure analysis and confirmed the reliability of our assignments via simulations. Then, we identified candidate loci for species maintenance with three complementary tests for selection and obtained partial gene sequences linked to an outlier locus and three other loci. We detected evidence of recent hybridization among all species and considerable gene flow between Q. ellipsoidalis and Q. velutina. Overall, c. 20% of Q. velutina had recent ancestry from Q. ellipsoidalis, whereas nearly 30% of Q. ellipsoidalis had a Q. velutina ancestor. Most loci were negligibly to weakly differentiated among species, but two gene-linked microsatellites deviated significantly from neutral expectations in multiple, complementary outlier tests. Both outlier loci were located in the same 15-cM bin on an existing Q. robur linkage map, a region under divergent selection in other oak species. Adaptive loci in this highly differentiated genomic region may contribute to ecological divergence among species and limit introgression.

Correa Ribeiro, Priciane; Lemos‐Filho, José P.; Oliveira Buzatti, Renata S.; Lovato, Maria B.; Heuertz, Myriam

doi: 10.1111/boj.12394pmid: N/A

The Brazilian Cerrado is the most diverse savanna in the world. Phylogeographical patterns for Cerrado tree species are relatively congruent; however, the causes of these patterns are not clear. Ours aims were to investigate phylogeographical patterns in two co‐distributed Annona spp. in the Cerrado and identify the factors responsible for their genetic structure. We sequenced non‐coding plastid DNA regions and estimated divergence times using a Bayesian Markov chain Monte Carlo method implemented in BEAST. Generalized linear mixed models (GLMMs) were used to relate genetic divergence with spatial, climatic and phytogeographic data. Annona crassiflora possessed only one haplotype, whereas A. coriacea possessed nine haplotypes constituting two groups: western and eastern. Haplotype diversification first occurred in the Pliocene; the split between eastern and western groups was dated to the Early Pleistocene. GLMMs detected a weak association of genetic distance with current climatic factors, represented mainly by precipitation in the warmest months. In A. coriacea, the north of central Cerrado (around Serra Geral de Goiás) is suggested as a putative Pleistocene refugium. The current climate and dispersal and local adaptation processes probably contribute to maintaining the east–west genetic structure in A. coriacea. Both Annona spp. show idiosyncratic population histories, reminiscent of the complex biogeography of the Cerrado.

Schoonderwoerd, Kristel M.; Friedman, William E.

doi: 10.1111/boj.12409pmid: N/A

AbstractIn Franklinia alatamaha (Theaceae) an extended period of dormancy, associated with winter, separates pollination in the late summer and autumn from observable fruit growth, which occurs during the subsequent summer season. Here, ovule and early seed development were examined to decipher the timing of reproductive events that underlie this unusual phenological pattern. Female gametophytes were found to be mature before pollination. Evidence for double fertilization was observed soon after pollination. Early endosperm development progresses for up to 3 months after fertilization but comes to a standstill at the onset of winter. The zygote becomes dormant shortly after fertilization and does not divide during the autumn or winter. At the start of the following growing season, endosperm development is reinitiated and the first events associated with the formation of an embryo occur. Seed development is completed roughly at the same time as new flowers are opening, a full year after pollination and fertilization. Dehiscence of fruits does not occur until later in autumn. The prolonged zygotic dormancy in Franklinia is exceedingly rare among angiosperms and differs markedly from patterns of delayed fertilization that typically underlie extended periods between pollination and seed maturation in other temperate, perennial species.

Correa Ribeiro, Priciane; Lemos-Filho, José P.; de Oliveira Buzatti, Renata S.; Lovato, Maria B.; Heuertz, Myriam

doi: 10.1111/boj.12394pmid: N/A

AbstractThe Brazilian Cerrado is the most diverse savanna in the world. Phylogeographical patterns for Cerrado tree species are relatively congruent; however, the causes of these patterns are not clear. Ours aims were to investigate phylogeographical patterns in two co-distributed Annona spp. in the Cerrado and identify the factors responsible for their genetic structure. We sequenced non-coding plastid DNA regions and estimated divergence times using a Bayesian Markov chain Monte Carlo method implemented in BEAST. Generalized linear mixed models (GLMMs) were used to relate genetic divergence with spatial, climatic and phytogeographic data. Annona crassiflora possessed only one haplotype, whereas A. coriacea possessed nine haplotypes constituting two groups: western and eastern. Haplotype diversification first occurred in the Pliocene; the split between eastern and western groups was dated to the Early Pleistocene. GLMMs detected a weak association of genetic distance with current climatic factors, represented mainly by precipitation in the warmest months. In A. coriacea, the north of central Cerrado (around Serra Geral de Goiás) is suggested as a putative Pleistocene refugium. The current climate and dispersal and local adaptation processes probably contribute to maintaining the east–west genetic structure in A. coriacea. Both Annona spp. show idiosyncratic population histories, reminiscent of the complex biogeography of the Cerrado.

Ojeda, Fernando; van der Niet, Timotheüs; Malan, Michelle C.; Midgley, Jeremy J.; Segarra-Moragues, José G.

doi: 10.1111/boj.12395pmid: N/A

AbstractA higher frequency of natural selection is expected in populations of organisms with shorter generation times. In fire-prone ecosystems, populations of seeder plants behave as functionally semelparous populations, with short generation times compared to populations of resprouter plants, which are truly iteroparous. Therefore, a stronger signature of natural selection should be detected in seeder populations, favoured by their shorter generation times and higher rates of population turnover. Here we test this idea in Erica coccinea from the Cape Floristic Region, which is dimorphic for post-fire regeneration mode. We measured three floral traits supposedly subject to natural selection in seeder and resprouter populations. We then compared phenotypic trait variation with neutral genetic variation in each group of populations using PST–FST comparisons to detect signatures of natural selection in seeders and resprouters. We found a strong signature of selection in seeder populations, but not in resprouters. Furthermore, anthers of seeders were more exserted (and larger) than those of resprouters. These differences were maintained at sites where seeders and resprouters co-occurred, suggesting that phenotypic plasticity or adaptation to different growth environments are unlikely explanations for trait variation. These results provide empirical support for the hypothesis that the genetic signature of natural selection is certainly more intense in seeder than in resprouter populations, favoured by their comparatively faster generation turnovers. Increased frequency of natural selection would increase differentiation among populations, thus promoting speciation in pyrophytic seeder lineages of the Cape flora.