Expression and Function Studies of CYC/TB1-Like Genes in the Asymmetric Flower Canna (Cannaceae, Zingiberales)

The asymmetric flower, lacking any plane of symmetry, is rare among angiosperms. Canna indica L. has conspicuously asymmetric flowers resulting from the presence of a half-fertile stamen, while the other androecial members develop as petaloid staminodes or abort early during development. The molecular basis of the asymmetric distribution of fertility and petaloidy in the androecial whorls remains unknown. Ontogenetic studies have shown that Canna flowers are borne on monochasial (cincinnus) partial florescences within a racemose inflorescence, with floral asymmetry likely corresponding to the inflorescence architecture. Given the hypothesized role of CYC/TB1 genes in establishing floral symmetry in response to the influence of the underlying inflorescence architecture, the spatiotemporal expression patterns of three Canna CYC/TB1 homologs (CiTBL1a, CiTBL1b-1, and CiTBL1b-2) were analyzed during inflorescence and floral development using RNA in situ hybridization and qRT-PCR. In the young inflorescence, both CiTBL1a and CiTBL1b-1 were found to be expressed in the bracts and at the base of the lateral florescence branches, whereas transcripts of CiTBL1b-2 were mainly detected in flower primordia and inflorescence primordia. During early flower development, expression of CiTBL1a and CiTBL1b-1 were both restricted to the developing sepals and petals. In later flower development, expression of CiTBL1a was reduced to a very low level while CiTBL1b-1 was detected with extremely high expression levels in the petaloid androecial structures including the petaloid staminodes, the labellum, and the petaloid appendage of the fertile stamen. In contrast, expression of CiTBL1b-2 was strongest in the fertile stamen throughout flower development, from early initiation of the stamen primordium to maturity of the ½ anther. Heterologous overexpression of CiTBL genes in Arabidopsis led to dwarf plants with smaller petals and fewer stamens, and altered the symmetry of mature flowers. These data provide evidence for the involvement of CYC/TB1 homologs in the development of the asymmetric Cannaceae flower.

Moldenhawera congestiflora: a new species of Leguminosae from the Brazilian Atlantic Forest

Moldenhawera is a small genus of Caesalpinioideae (Leguminosae), characterized by biramous (T-shaped) trichomes, compoundly pinnate stipules, hypanthium absence, clawed petals, dimorphic androecium, and anther connective of the fertile stamen pubescent. Moldenhawera congestiflora, a new species from the Atlantic Forest in Bahia State, Brazil is described and illustrated. It is distinguished from other species of the M. sect. Brasilianae by the combination of its tree habit, leaves relatively long (rachis > 24 cm long), leaflets elliptic to oblong with apex acuminate, flower buds densely grouped at the inflorescence apex, flowers pentamerous, petal blades relatively small (6–8 × 4–5 mm), and base of fertile stamen villous. Additionally we provide a new identification key for the section Brasilianae.

The correct assignment of the lectotype of Vochysia guianensis (Vochysiaceae)

Vochysia Aublet (1775: 18) encompasses ca. 140 species, distributed from Mexico to southern Brazil. They are mainly large trees, with spurred yellow flowers, usually 3-petaled and with a single fertile stamen (Kawasaki 2007). The genus was described by Aublet (1775) in his work on plants from French Guiana as ‘Vochy’, taken from a native name among the Caribs, and after several latinizations the form ‘Vochysia’, proposed by Poiret (1808), was conserved.

A new species of Moldenhawera (Leguminosae) from Brazilian Atlantic Forest

Moldenhawera is a small genus of caesalpinioid legumes from eastern Brazil, characterized by the presence of T-shaped trichomes, flowers lacking a hypanthium, clawed petals with wrinkled margins, and dimorphic androecium with only one fertile stamen. Moldenhawera longipedicellata is described as a new species from the Atlantic Forest phytogeographical domain in Espírito Santo State, Brazil. It is similar to M. floribunda, M. polysperma and M. papillanthera by presenting slender staminodia filaments, longer than the anthers. However, it can be distinguished from those related species by the once-pinnate leaves (vs. bipinnate), flowers with long pedicels (2–5.9 cm long) and larger sepals (16–25 × 4–8 mm) and petals (petal claw 10–19 mm long and petal blade 14–24 × 13–23 mm).