Rafflesia
produces the largest single flowers in the world, at the expense of its host vine,
Tetrastigma,
yet it begins as an inconspicuous endophyte. It is unknown how the
Rafflesia
seed gets into ...the host and germinates. Multiple locals claim to have successfully grown the holoparasitic flower from seeds resulting in blooms. Using available morpho-histological studies, combined with descriptions from local
Rafflesia
seed growers, as well as unpublished details of our own work, we filled in the missing details of
Rafflesia’s
life cycle from seed germination to endophyte inside the host before it transitions to its flowering stage. Post-germination, the
Rafflesia
endophyte forms a clonal network of vegetative meristematic cells, separated by the dividing host tissue, each meristematic cell cluster eventually developing into the primordial floral bud or protocorm. We propose future work involving mass spectrometry imaging to characterize the metabolites that allow communication between distant endophytic clusters and floral bud induction without destroying the histology of the sample.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Context: Cardiovascular disease (CVD) is the number one cause of death globally, responsible for over 17 million (31%) deaths in the world. Novel pharmacological interventions may be needed given the ...high prevalence of CVD.
Objective: In this study, we aimed to find potential new sources of cardiovascular (CV) drugs from phylogenetic and pharmacological analyses of plant species that have experimental and traditional CV applications in the literature.
Materials and methods: We reconstructed the molecular phylogeny of these plant species and mapped their pharmacological mechanisms of action on the phylogeny.
Results: Out of 139 plant species in 71 plant families, seven plant families with 45 species emerged as phylogenetically important exhibiting common CV mechanisms of action within the family, as would be expected given their common ancestry: Apiaceae, Brassicaceae, Fabaceae, Lamiaceae, Malvaceae, Rosaceae and Zingiberaceae. Apiaceae and Brassicaceae promoted diuresis and hypotension; Fabaceae and Lamiaceae had anticoagulant/thrombolytic effects; Apiaceae and Zingiberaceae were calcium channel blockers. Moreover, Apiaceae, Lamiaceae, Malvaceae, Rosaceae and Zingiberaceae species were found to possess anti-atherosclerotic properties.
Discussion and conclusions: The phylogeny identified certain plant families with disproportionately more species, highlighting their importance as sources of natural products for CV drug discovery. Though there were some species that did not show the same mechanism within the family, the phylogeny predicts that these species may contain undiscovered phytochemistry, and potentially, the same bioactivity. Evolutionary pharmacology, as applied here, may guide and expedite our efforts in discovering sources of new CV drugs.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Rafflesia is a genus of holoparasitic plants endemic to Southeast Asia that has lost the ability to undertake photosynthesis. With short-read sequencing technology, we assembled a draft sequence of ...the mitochondrial genome of Rafflesia lagascae Blanco, a species endemic to the Philippine island of Luzon, with ∼350× sequencing depth coverage. Using multiple approaches, however, we were only able to identify small fragments of plastid sequences at low coverage depth (<2×) and could not recover any substantial portion of a chloroplast genome. The gene fragments we identified included photosynthesis and energy production genes (atp, ndh, pet, psa, psb, rbcL), ribosomal RNA genes (rrn16, rrn23), ribosomal protein genes (rps7, rps11, rps16), transfer RNA genes, as well as matK, accD, ycf2, and multiple nongenic regions from the inverted repeats. None of the identified plastid gene sequences had intact reading frames. Phylogenetic analysis suggests that ∼33% of these remnant plastid genes may have been horizontally transferred from the host plant genus Tetrastigma with the rest having ambiguous phylogenetic positions (<50% bootstrap support), except for psaB that was strongly allied with the plastid homolog in Nicotiana. Our inability to identify substantial plastid genome sequences from R. lagascae using multiple approaches--despite success in identifying and developing a draft assembly of the much larger mitochondrial genome--suggests that the parasitic plant genus Rafflesia may be the first plant group for which there is no recognizable plastid genome, or if present is found in cryptic form at very low levels.
Psychoactive plants contain chemicals that presumably evolved as allelochemicals but target certain neuronal receptors when consumed by humans, altering perception, emotion and cognition. These ...plants have been used since ancient times as medicines and in the context of religious rituals for their various psychoactive effects (e.g., as hallucinogens, stimulants, sedatives). The ubiquity of psychoactive plants in various cultures motivates investigation of the commonalities among these plants, in which a phylogenetic framework may be insightful. A phylogeny of culturally diverse psychoactive plant taxa was constructed with their psychotropic effects and affected neurotransmitter systems mapped on the phylogeny. The phylogenetic distribution shows multiple evolutionary origins of psychoactive families. The plant families Myristicaceae (e.g., nutmeg), Papaveraceae (opium poppy), Cactaceae (peyote), Convolvulaceae (morning glory), Solanaceae (tobacco), Lamiaceae (mints), Apocynaceae (dogbane) have a disproportionate number of psychoactive genera with various indigenous groups using geographically disparate members of these plant families for the same psychoactive effect, an example of cultural convergence. Pharmacological traits related to hallucinogenic and sedative potential are phylogenetically conserved within families. Unrelated families that exert similar psychoactive effects also modulate similar neurotransmitter systems (i.e., mechanistic convergence). However, pharmacological mechanisms for stimulant effects were varied even within families suggesting that stimulant chemicals may be more evolutionarily labile than those associated with hallucinogenic and sedative effects. Chemically similar psychoactive chemicals may also exist in phylogenetically unrelated lineages, suggesting convergent evolution or differential gene regulation of a common metabolic pathway. Our study has shown that phylogenetic analysis of traditionally used psychoactive plants suggests multiple ethnobotanical origins and widespread human dependence on these plants, motivating pharmacological investigation into their potential as modern therapeutics for various neurological disorders.
Main conclusion
Metabolites in
Rafflesia
-infected and non-infected
Tetrastigma
were compared which may have applications in
Rafflesia
propagation. Benzylisoquinoline alkaloids, here reported for the ...first time in Vitaceae, were abundant in non-infected shoots and may be a form of defense. In
Rafflesia
-infected shoots, oxylipins, which mediate immune response, were elevated.
Endemic to the forests of Southeast Asia,
Rafflesia
(Rafflesiaceae) is a genus of holoparasitic plants producing the largest flowers in the world, yet completely dependent on its host, the tropical grape vine,
Tetrastigma
.
Rafflesia
species are threatened with extinction, making them an iconic symbol of plant conservation. Thus far, propagation has proved challenging, greatly decreasing efficacy of conservation efforts. This study compared the metabolites in the shoots of
Rafflesia
-infected and non-infected
Tetrastigma loheri
to examine how
Rafflesia
infection affects host metabolomics and elucidate the
Rafflesia
infection process. Results from LC–MS-based untargeted metabolomics analysis showed benzylisoquinoline alkaloids were naturally more abundant in non-infected shoots and are here reported for the first time in the genus
Tetrastigma,
and in the grape family, Vitaceae. These metabolites have been implicated in plant defense mechanisms and may prevent a
Rafflesia
infection. In
Rafflesia
-infected shoots, oxygenated fatty acids, or oxylipins, and a flavonoid, previously shown involved in plant immune response, were significantly elevated. This study provides a preliminary assessment of metabolites that differ between
Rafflesia
-infected and non-infected
Tetrastigma
hosts and may have applications in
Rafflesia
propagation to meet conservation goals.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Asian wild rice (Oryza rufipogon) that ranges widely across the eastern and southern part of Asia is recognized as the direct ancestor of cultivated Asian rice (O. sativa). Studies of the geographic ...structure of O. rufipogon, based on chloroplast and low‐copy nuclear markers, reveal a possible phylogeographic signal of subdivision in O. rufipogon. However, this signal of geographic differentiation is not consistently observed among different markers and studies, with often conflicting results. To more precisely characterize the phylogeography of O. rufipogon populations, a genome‐wide survey of unlinked markers, intensively sampled from across the entire range of O. rufipogon is critical. In this study, we surveyed sequence variation at 42 genome‐wide sequence tagged sites (STS) in 108 O. rufipogon accessions from throughout the native range of the species. Using Bayesian clustering, principal component analysis and amova, we conclude that there are two genetically distinct O. rufipogon groups, Ruf‐I and Ruf‐II. The two groups exhibit a clinal variation pattern generally from north‐east to south‐west. Different from many earlier studies, Ruf‐I, which is found mainly in China and the Indochinese Peninsula, shows genetic similarity with one major cultivated rice variety, O. satvia indica, whereas Ruf‐II, mainly from South Asia and the Indochinese Peninsula, is not found to be closely related to cultivated rice varieties. The other major cultivated rice variety, O. sativa japonica, is not found to be similar to either O. rufipogon groups. Our results support the hypothesis of a single origin of the domesticated O. sativa in China. The possible role of palaeoclimate, introgression and migration–drift balance in creating this clinal variation pattern is also discussed.
See also the Perspective by Gross
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
ABSTRACTRafflesia is an endangered endophytic holoparasitic plant that lives the majority of its life inside the tissues of its sole plant host, Tetrastigma. Rafflesia floral buds emerge to produce ...the world’s largest single flower. Like other plants, holoparasites harbor a diverse microbiome, the role(s) of which has remained largely unstudied. We characterized the bacterial microbiome of seeds of Rafflesia speciosa and cuttings of its host. We found evidence that R. speciosa seed has similar bacterial profiles to its infected host, which suggests that seeds sequester certain host bacteria, as well as acquire unique bacterial taxa from biotic associates of the fruit. We did not find evidence of mycorrhizal taxa in the microbiome. This is the first study of the microbial endophytes associated with any Rafflesia species and its host, a tripartite holobiont, and provides insights on its cryptic microbial partners. We discuss how this may aid horticultural propagation of Rafflesia.
I observed the floral biology of three Leea morphospecies in a Philippine natural forest habitat. The red‐flowered morphospecies Leea guineensis limits selfing through synchronized dichogamy, with ...male and female flowers temporally separated in the same inflorescence, whereas the two morphospecies of the white‐flowered Leea indica might be prone to geitonogamous selfing. Light and soil pH are correlated with phenology. In addition to bees and flies, Leea is visited by wasps, butterflies, beetles, bugs and spiders.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
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