Plants flower in response to many varied cues, such as temperature, photoperiod, and age. The floral transition of Cardamine flexuosa, a herbaceous biennial-to-perennial plant, requires exposure to cold temperature, a treatment known as vernalization. C. flexuosa younger than 5 weeks old are not fully responsive to cold treatment. We demonstrate that the levels of two age-regulated microRNAs, miR156 and miR172, regulate the timing of sensitivity in response to vernalization. Age and vernalization pathways coordinately regulate flowering through modulating the expression of CfSOC1, a flower-promoting MADS-box gene. The related annual Arabidopsis thaliana, which has both vernalization and age pathways, does not possess an age-dependent vernalization response. Thus, the recruitment of age cue in response to environmental signals contributes to the evolution of life cycle in plants.

ORCID IDs: 0000-0002-8950-6643 (J.Z-L.); 0000-0002-7658-0844 (K.M.).This article describes the use of cytogenomic and molecular approaches to explore the origin and evolution of Cardamine schulzii, a textbook example of a recent allopolyploid, in its ;110-year history of human-induced hybridization and allopolyploidy in the Swiss Alps. Triploids are typically viewed as bridges between diploids and tetraploids but rarely as parental genomes of high-level hybrids and polyploids. The genome of the triploid semifertile hybrid Cardamine 3 insueta (2n = 24, RRA) was shown to combine the parental genomes of two diploid (2n = 2x = 16) species, Cardamine amara (AA) and Cardamine rivularis (RR). These parental genomes have remained structurally stable within the triploid genome over the >100 years since its origin. Furthermore, we provide compelling evidence that the alleged recent polyploid C. schulzii is not an autohexaploid derivative of C. 3 insueta. Instead, at least two hybridization events involving C. 3 insueta and the hypotetraploid Cardamine pratensis (PPPP, 2n = 4x22 = 30) have resulted in the origin of the trigenomic hypopentaploid (2n = 5x22 = 38, PPRRA) and hypohexaploid (2n = 6x22 = 46, PPPPRA). These data show that the semifertile triploid hybrid can promote a merger of three different genomes and demonstrate how important it is to reexamine the routinely repeated textbook examples using modern techniques.

The Alyssum montanum–A. repens polyploid complex is a group of related perennial taxa with a diversity centre in the European (Sub)Mediterranean, controversial taxonomic treatments, and a poorly known evolutionary history. In the present study, morphological, ploidy level and genetic (AFLPs and chloroplast DNA sequences) data were collected to address the taxonomy and evolution of a sublineage of this complex distributed in southwestern Europe and Morocco. As a result, a new taxonomic treatment, differing substantially from recent concepts, is presented, including an identification key, synonymy and typifications. The recognition of several previously described but recently not accepted endemics is favoured (A. flexicaule, A. orophilum, A. rhodanense), whereas the existence of southern Iberian endemics is not supported. Most of the Iberian Peninsula is occupied by a single species for which the name A. fastigiatum is applicable. Populations from the summit areas of the Pyrenees represent a separate species, which is described here as A. cacuminum. Populations from coastal sand dunes in the Basque country (Bay of Biscay) and Galicia, recently recognised as two subspecies of A. loiseleurii, are elevated to species rank according to their genetic and morphological divergence. Alyssum atlanticum is resolved as a species confined to northern Africa and not reaching southern Spain. The distribution of A. montanum in a strict sense is much more restricted than previously reported, being delimited by the Pyrenees in the south, and the Alps in the northeast. The species complex studied here is composed of several polyploid stenoendemics confined to different mountain ranges or specific lowland habitats, and a few relatively widely distributed species. We infer that hybridisation and polyploidisation events, along with ecological and geographic isolation, have stimulated speciation in this complex. Hypotheses about the origin and evolutionary history of the species are discussed.

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We provide evidence for the presence of Mediterranean refugia for the studied Alyssum montanum-A. repens complex located in central and southern Italy, which, however, did not contribute to the postglacial colonization of Central Europe. Past extinctions, genetic bottlenecks, and recent expansion were inferred in Central Europe, while long-term accumulation of diversity as well as polyploidization occurred in the Apennines.

The phylogeographical history of mid-altitude woodland herbs that depend on moist and shaded forest habitats is poorly understood. Here, we analysed the genetic structure of Cyclamen purpurascens, a mountainous calcicolous perennial, to test hypotheses regarding its glacial survival in single or multiple refugia and postglacial colonization routes, and to explore how they are congruent with the histories inferred for temperate trees and other mountainous herbs. We gathered AFLP data and chloroplast DNA sequences (trnD-trnT region) from 68 populations spanning the entire distribution range (the Jura Mountains, Alps, western Carpathians, Dinarides). Both genetic markers revealed two main phylogeographical groups (phylogroups) in C. purpurascens. Additionally, AFLP data detected a more detailed structure of five phylogroups: two widespread, showing east-west geographical separation, and three local ones, restricted to somewhat disjunct, marginal regions of the species range. We suggest that C. purpurascens survived the last glaciation in two main regions, the foothills of the Southern Limestone Alps and the Karst area of the north-western Dinarides, and possibly also in microrefugia in the Western Carpathians. The glacial persistence and colonization routes of this woodland herb are highly concordant with those inferred for several temperate trees, especially the European beech.

The observed spatial and genetic patterns likely reflect the evolutionary and colonization history of the two cytotypes and have been maintained by multiple factors such as ecological divergence, limited gene flow between the cytotypes, and the restricted dispersal capacity.