The diversity and evolution of pollination systems in large plant clades: Apocynaceae as a case study

Background and Aims Large clades of angiosperms are often characterized by diverse interactions with pollinators, but how these pollination systems are structured phylogenetically and biogeographically is still uncertain for most families. Apocynaceae is a clade of >5300 species with a worldwide distribution. A database representing >10 % of species in the family was used to explore the diversity of pollinators and evolutionary shifts in pollination systems across major clades and regions. Methods The database was compiled from published and unpublished reports. Plants were categorized into broad pollination systems and then subdivided to include bimodal systems. These were mapped against the five major divisions of the family, and against the smaller clades. Finally, pollination systems were mapped onto a phylogenetic reconstruction that included those species for which sequence data are available, and transition rates between pollination systems were calculated. Key Results Most Apocynaceae are insect pollinated with few records of bird pollination. Almost three-quarters of species are pollinated by a single higher taxon (e.g. flies or moths); 7 % have bimodal pollination systems, whilst the remaining approx. 20 % are insect generalists. The less phenotypically specialized flowers of the Rauvolfioids are pollinated by a more restricted set of pollinators than are more complex flowers within the Apocynoids + Periplocoideae + Secamonoideae + Asclepiadoideae (APSA) clade. Certain combinations of bimodal pollination systems are more common than others. Some pollination systems are missing from particular regions, whilst others are over-represented. Conclusions Within Apocynaceae, interactions with pollinators are highly structured both phylogenetically and biogeographically. Variation in transition rates between pollination systems suggest constraints on their evolution, whereas regional differences point to environmental effects such as filtering of certain pollinators from habitats. This is the most extensive analysis of its type so far attempted and gives important insights into the diversity and evolution of pollination systems in large clades

Two New Combinations in Arisaema (Araceae) from India

Volume: 19Start Page: 391End Page: 39

THREE NEW SPECIES OF ERIOCAULON (ERIOCAULACEAE) FROM PENINSULAR INDIA

Volume: 21Start Page: 625End Page: 63

Combinatorial approach through in vitro regeneration and phytochemical profiling of Ceropegia media (Huber) Ans. : a potential way forward in the conservation of an endangered medicinal plant from the Western Ghats in India

Ceropegia media is an endemic and endangered plant as its propagation through seeds is unreliable due to low germination, slow growth and seedling decay under natural conditions. Also, tubers of this plant are edible serving as carbohydrate source with medicinal values leading to severe population decline in the natural habitat. To provide a sustainable solution, an efficient in vitro propagation protocol along with phytochemical profiling was developed for C. media. Callus cultures were induced from seedling and wild leaf tissues using the most effective Murashige and Skoog’s (MS) medium with 2,4-dichlorophenoxyacetic acid (2,4-D; 2 µM) and sucrose (3%). Somatic embryos were acquired on MS medium with 1 µM 6-Benzylaminopurine (BAP) and 1 µM 2,4-D. Conversion into plantlets was attained only from tissue culture-derived seedling leaf (TCDSL) explant. Further, in vitro tuberization was achieved from TCDSL callus with BAP and Naphthalene acetic acid (NAA). AgNO3 as an elicitor had a positive effect on both fresh and dry weights of callus. Successful acclimatization (58%) was attained after two months resulting in normal phenotype in pots. Further, metabolite profiles of ten different tissues from wild and in vitro plants were compared. Total 82 compounds comprising alkaloids, fatty acids, fatty acid ester, steroids, terpenes and hydrocarbons were identified. Overall, results suggested enhanced production of selected metabolites with in vitro propagation and AgNO3, alleviating the problem of unavailability of planting materials. Thus, the current study might offer potential ways for the conservation of such RED enlisted species as C. media

Generation of novelties in the genus Ocimum as a result of natural hybridization : a morphological, genetical and chemical appraisal

The genus Ocimum is a boutique of a diverse set of specialized metabolites such as terpenoids and phenylpropanoids. Each Ocimum species and its cultivars represent a characteristic chemical profile. The present study explored the two interspecific Ocimum hybrids originating through a serendipitous natural cross between O. kilimandscharicum and O. basilicum. These two novel Ocimum hybrids exhibited intermediate morphological features of two parental species. Inter simple sequence repeats (ISSR) analysis and DNA barcoding with the plastid non-coding trnH-psbA intergenic spacer region reaffirmed unambiguous parental identification and differentiation of these natural hybrids from other available Ocimum species. Consequently, gas chromatography-mass spectrometry-based metabolite profiling of two hybrids identified them as specific chemotypes with the presence of a unique blend of specialized metabolites from the parental species, which are either rich in terpenes or phenylpropanoids. Additionally, expression analysis of key genes from terpenoid and phenylpropanoid pathways corroborated with differential metabolite accumulation. Thus, these two Ocimum hybrids represented the novel chemotypes, which could be useful in commercial cultivation to produce novel essential oil and bioactive constituents. Further, the resulting metabolite diversity could have potential industrial applications in the areas of healthcare, bioremediation, and crop protection

High-throughput metabolomic and transcriptomic analyses vet the potential route of cerpegin biosynthesis in two varieties of Ceropegia bulbosa Roxb.

Main conclusion: Exploration with high-throughput transcriptomics and metabolomics of two varieties of Ceropegia bulbosa identifies candidate genes, crucial metabolites and a potential cerpegin biosynthetic pathway. Abstract: Ceropegia bulbosa is an important medicinal plant, used in the treatment of various ailments including diarrhea, dysentery, and syphilis. This is primarily attributed to the presence of pharmaceutically active secondary metabolites, especially cerpegin. As this plant belongs to an endemic threatened category, genomic resources are not available hampering exploration on the molecular basis of cerpegin accumulation till now. Therefore, we undertook high-throughput metabolomic and transcriptomic analyses using different tissues from two varieties namely, C. bulbosa var. bulbosa and C. bulbosa var. lushii. Metabolomic analysis revealed spatial and differential accumulation of various metabolites. We chemically synthesized and characterized the cerpegin and its derivatives by liquid chromatography tandem–mass spectrometry (LC–MS/MS). Importantly, these comparisons suggested the presence of cerpegin and 5-allyl cerpegin in all C. bulbosa tissues. Further, de novo transcriptome analysis indicated the presence of significant transcripts for secondary metabolic pathways through the Kyoto encyclopedia of genes and genomes database. Tissue-specific profiling of transcripts and metabolites showed a significant correlation, suggesting the intricate mechanism of cerpegin biosynthesis. The expression of potential candidate genes from the proposed cerpegin biosynthetic pathway was further validated by qRT-PCR and NanoString nCounter. Overall, our findings propose a potential route of cerpegin biosynthesis. Identified transcripts and metabolites have built a foundation as new molecular resources that could facilitate future research on biosynthesis, regulation, and engineering of cerpegin or other important metabolites in such non-model plants

Phylogenetic and population studies of geophytic <i>Euphorbia</i> species (subgenus <i>Euphorbia</i>) from some deciduous forests and hill top plateaus in India

<p>Geophytic <i>Euphorbia</i> species are distributed across four sections in subgenus <i>Euphorbia</i> of genus <i>Euphorbia</i>. At least nine Indian geophytic <i>Euphorbia</i> species have been identified, but delimitation of these species is controversial. Phylogenetic studies using nuclear ribosomal internal transcribed spacers (nrITS) and <i>matK</i> sequences showed that the Indian geophytic <i>Euphorbia</i> species lie within the section <i>Euphorbia</i> clade that includes African and Indian non-geophytic species. Ribotype/ haplotype analysis of nrITS and <i>matK</i> sequences revealed that the populations of <i>Euphorbia fusiformis</i> and <i>Euphorbia nana</i> could not be distinguished on this basis. Population studies based on nrITS sequences showed significant gene differentiation between the populations from different localities. The Indian geophytic <i>Euphorbia</i> species showed morphological variation in their leaf and cyathial characters, which correlated with the variation in soil composition of their habitats. Our studies suggest that local adaptation and phenotypic plasticity are responsible for taxonomic ambiguities in the classification of Indian geophytic <i>Euphorbia</i> species.</p

Diversity of Diptera families that pollinate Ceropegia (Apocynaceae) trap flowers: an update in light of new data and phylogenetic analyses

Pollination by flies (Diptera) has been important to the diversification and ecology of the flowering plants, but is poorly understood in contrast to pollination by other groups such as bees, butterflies and birds. Within the Apocynaceae the genera Ceropegia and Riocreuxia temporarily trap flies, releasing them after a fixed, speciesspecific period of time, during which pollination and/or pollen removal occurs. This “trap flower” pollination system shows convergent evolution with unrelated species in other families and fascinated Stefan Vogel for much of his career, leading to groundbreaking work on floral function in Ceropegia (Apocynaceae). In this new study we extend the work of the latest broad analysis published by some of the authors (Ollerton et al., 2009 – Annals of Botany). This incorporates previously unpublished data from India and Africa, as well as recently published information, on the diversity of pollinators exploited by Ceropegia. The analyses are based on a more accurate phylogenetic understanding of the relationships between the major groups, and significantly widens the biogeographic scope of our understanding of fly pollination within Ceropegia. Information about the pollinators of 69 taxa (species, subspecies and natural varieties) of Ceropegia is now available. Twenty five families of Diptera are known to visit the flowers of Ceropegia, of which sixteen are confirmed as pollinators. Most taxa are pollinated by species from a single family. Overall, there were no major biogeographic differences in the types of Diptera that were used in particular regions, though some subtle differences were apparent. Likewise there were no differences between the two major clades of Ceropegia, but clear differences when comparing the range of Diptera exploited by Ceropegia with that of the stapeliads. This clade, one of the largest in the Asclepiadoideae, is a fascinating example of a species radiation driven by an apparently relatively uniform set of pollinators