Generic level phylogeny of Thalictroideae (Ranunculaceae) — implications for the taxonomic status of Paropyrum and petal evolution

Abstract

The subfamily Thalictroideae, which is clearly defined by its chromosome characters, contains nine or ten genera. Here we use sequences of chloroplast rbcL and matK genes as well as non‐coding trnL‐F and nuclear ITS regions to reconstruct the generic level phylogeny of this subfamily. Our data recognize three major groups within Thalictroideae: (1) Thalictrum, Leptopyrum, Paropyrum, and Paraquilegia; (2) Urophysa, Semiaquilegia, and Aquilegia; and (3) Dichocarpum, Enemion, and Isopyrum. Isopyrum anemonoides, the sole species of Paropyrum, and Paraquilegia form a clade sister to Leptopyrum; together they make up the first group. Isopyrum manshuricum and I. thalictroides form another clade within the third group. Isopyrum anemonoides is sister to the monophyletic Paraquilegia. Our data suggest that Isopyrum is polyphyletic and support the segregate genus Paropyrum. Reconstruction of petal evolution suggests a secondary loss of petals in Enemion and Thalictrum, in contrast with the view that apetalous taxa are the most primitive. Petals with longer stalks in Dichocarpum are shown to be derivative, refuting the viewpoint that this type is a primitive condition. The flat petals in Paraquilegia may be derived from the tubular‐type petals in Paropyrum and Leptopyrum, and spurred petals are thought to have originated from a single ancestor.

Within and between Whorls: Comparative Transcriptional Profiling of Aquilegia and Arabidopsis

“…Another aim was to identify genes co-expressed with floral identity genes and characterize the transcriptional signature of petaloid sepals. Lastly, we were interested in generating hypotheses regarding the evolution and ecological function of staminodia, a floral organ type recently evolved in Aquilegia and its close relatives Semiaquilegia and Urophysa [17], [18].…”

“…It has a bipartite perianth with petaloid sepals and petals that possess nectar-producing spurs, followed by four to seven whorls of stamens, one whorl of staminodia and one whorl of free carpels (Figure 1). Spurs and staminodia evolved only recently [17], [18] and while spurs are a modification of petals and produce a nectar reward for pollinators, the underlying developmental program and any specific function of staminodia are still a matter of debate. The sepals of Aquilegia are petaloid owing to their bright coloration and papillated epidermal cells [19].…”

An ortholog of MIXTA‐like2 controls epidermal cell shape in flowers of Thalictrum

“…Evidence from closely related genera in the phylogeny of Ranunculaceae suggests that loss of petals occurred before the diversification of Thalictrum (Wang & Chen, 2007). Following this event, petaloidy of the sepals, which is found throughout the family, was further lost in association with transitions to wind pollination.…”

Semiaquilegia quelpaertensis (Ranunculaceae), a new species from the Republic of Korea

“…Recently, Wang and Chen (2007) showed that Semiaquilegia , Urophysa Ulbrich and Aquilegia form a monophyletic group, with Semiaquilegia as sister to Aquilegia . These three genera are characterised by the presence of membranous staminodes, most frequently 5 carpels and spurred petals, but can be distinguished from each other by their habitat, flowering season, flower size, floral structure with the petals divided into lamina and spur, the colour of sepals, the number of staminodia, the presence of spur, seed surface etc.…”