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Biosynthesis of the hypericins that accumulate in the dark glands of some members of the genus Hypericumis poorly understood. The gene named hyp-1, isolated from Hypericum perforatumL. 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 Hypericumspecies 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-1gene was expressed in all studied species regardless of whether hypericins and emodin were detected in the plants. The coding sequences of hyp-1cDNA were isolated from all species and showed more than 86% similarity to each other. Although, in general, an increased level of the hyp-1gene 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-1gene product as a key enzyme responsible for biosynthesis of hypericins in the genus Hypericum. The function of the hyp-1gene may not be restricted to hypericin biosynthesis only, or some additional factors are necessary for completion of hypericin biosynthesis. [ABSTRACT FROM AUTHOR]

This study represents the first comprehensive analysis of phylogenetic relationships within the Australian water-lilies, Nymphaeasubg. Anecphya. Our 51-accession dataset covers all 10 species of the subgenus, except the newly described N. alexii, and includes information from the nuclear ITS as well as from the chloroplast trnT–trnFregion. The results show that molecular data are consistent with morphology, because the subdivision of subg. Anecphyainto two major clades, a large-seeded and a small-seeded group, could be confirmed. Within the large-seeded group, Nymphaea atransand N. immutabilisseem to form one clade, whereas samples of N. gigantea, N. georginae, N. macrospermaand N. carpentariaeform another. Relationships within the small-seeded group, containing all samples of N. violacea, N. elleniaeand N. hastifolia, are less clear, since the trees obtained from the chloroplast and the nuclear marker are incongruent. The samples of N. violaceado not form a monophyletic group in each of the trees, but—at least in the ITS tree—group with either N. elleniaeor N. hastifolia/Ondinea, respectively. Polymorphisms among ITS paralogues, i.e. substitutions at single nucleotide positions and length polymorphisms, have been observed in some samples of N. violacea.This fact as well as the incongruent phylogenetic signal obtained from the chloroplast and the nuclear genomes point to recent hybridisation or introgression in this group. Remarkably, Ondinea purpureais resolved within the small-seeded group by both markers and seems to have a close relationship to N. hastifolia.Although incomplete lineage sorting cannot be fully excluded to explain high variability in N. violacea, molecular data potentially hint to a case of still imperfect taxonomy. [ABSTRACT FROM AUTHOR]

Flowering pattern and seedling establishment of umbrella bamboo ( Fargesia murieliae (Gamble) Yi) were studied in its native habitat, Mount Shennongjia in Central China. Here in 1996–2000, over 95% of the bamboo plants simultaneously flowered and died, extending from lower elevations to the higher mountains along the altitude and from southwest to northeast along the mountain settings. Bamboo seedlings emerged after the simultaneous flowering, achieving an average density of 5 460 seedlings· m−2 in the autumn of the year following the flowering. After a high mortality throughout the first winter, bamboo seedlings remained a stable density in following 2–4 years (1130–1230 seedlings· m−2). Seedling density positively related to the coverage of parent bamboo, but negatively to the herb layers. [ABSTRACT FROM AUTHOR]

Simultaneous flowering caused a gregarious dieback of umbrella bamboo ( Fargesia murielae) all over the world in 1993–2000. Mountain Shennongjia in Central China’s Hubei Province is the only native home of umbrella bamboo, where it dominates the understorey of the farges fir ( Abies fargesii) forest between 2 400 and 3 100 m, covering the ground for more than one century before a periodically flowering death. Data from 20 quadrats along a vegetation sequence revealed that the density, coverage, and height of umbrella bamboo negatively affected the species richness, diversity, and evenness of vascular plants in the forest. Local climax community of fir-bamboo was the poorest in species diversity, while the bamboo-free communities (i.e. shrubs and meadows) were bearing a higher species diversity. The simultaneous dieback of umbrella bamboo is an ecological release, which can periodically promote the plant diversity in the fir forest. [ABSTRACT FROM AUTHOR]