A new species of Metrodorea (Rutaceae) from Brazil: morphology, molecular phylogenetics, and distribution

A new species of Metrodorea (Rutaceae), M. concinna, is described and illustrated, and morphological, molecular phylogenetic, and distributional support for the new taxon and its relationships with morphologically similar species, as well as with sympatric ones, are explored. The new species is endemic to semideciduous forests of southeastern Bahia, eastern Brazil. It is distinct from other species of the genus mainly by the combination of shrubby to treelet habit, (sub)sessile leaves, sessile leaflets without conspicuous, dark glands on the abaxial surface, and by each carpel bearing one dorsal apophysis. In addition to the diagnostic morphological features, molecular data provide further support to the new taxon.

The hyp-1 gene is not a limiting factor for hypericin biosynthesis in the genus Hypericum

Biosynthesis of the hypericins that accumulate in the dark glands of some members of the genus Hypericum is poorly understood. The gene named hyp-1, isolated from Hypericum perforatum L. has been proposed as playing an important role in the final steps of hypericin biosynthesis. To study the role of this candidate gene in relation to the production of hypericins, the expression of this gene was studied in 15 Hypericum species with varying ability to synthesise hypericin. While the accumulation of hypericins and emodin, an intermediate in the respective pathway, was associated with the dark glands in the hypericin-producing species, the hyp-1 gene was expressed in all studied species regardless of whether hypericins and emodin were detected in the plants. The coding sequences of hyp-1 cDNA were isolated from all species and showed more than 86% similarity to each other. Although, in general, an increased level of the hyp-1 gene transcript was detected in hypericin-producing species, several of the hypericin-lacking species expressed comparable levels as well. Our results question the role of the hyp-1 gene product as a key enzyme responsible for biosynthesis of hypericins in the genus Hypericum. The function of the hyp-1 gene may not be restricted to hypericin biosynthesis only, or some additional factors are necessary for completion of hypericin biosynthesis.

Seasonal Variation of Hypericin and Pseudohypericin Contents in Hypericum Scabrum L. Growing Wild in Turkey

The present study was conducted to determine ontogenetic and morphogenetic variations of hypericin and pseudohypericin contents in Hypericum scabrum growing in Turkey. Plants were harvested at vegetative, floral budding, full flowering, fresh fruiting and mature fruiting stages and observed for the presence of dark glands. Subsequently, they were dissected into stem, leaf and reproductive tissues, which were dried separately, and subsequently assayed for hypericin and pseudohypericin contents by HPLC. No hypericins were detected in stem tissues, while leaves and reproductive parts accumulated both compounds at different levels depending on growth stages. In general, higher levels of hypericin and pseudohypericin accumulation were observed in reproductive parts. Content of both hypericin forms decreased with advancing of plant development and reached their highest levels at floral budding stage.