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BACKGROUND: Many mitochondrial genes, especially ribosomal protein genes, have been frequently transferred as functional entities to the nucleus during plant evolution, often by an RNA-mediated process. A notable case of transfer involves the rps14 gene of three grasses (rice, maize, and wheat), which has been relocated to the intron of the nuclear sdh2 gene and which is expressed and targeted to the mitochondrion via alternative splicing and usage of the sdh2 targeting peptide. Although this transfer occurred at least 50 million years ago, i.e., in a common ancestor of these three grasses, it is striking that expressed, nearly intact pseudogenes of rps14 are retained in the mitochondrial genomes of both rice and wheat. To determine how ancient this transfer is, the extent to which mitochondrial rps14 has been retained and is expressed in grasses, and whether other transfers of rps14 have occurred in grasses and their relatives, we investigated the structure, expression, and phylogeny of mitochondrial and nuclear rps14 genes from 32 additional genera of grasses and from 9 other members of the Poales. RESULTS: Filter hybridization experiments showed that rps14 sequences are present in the mitochondrial genomes of all examined Poales except for members of the grass subfamily Panicoideae (to which maize belongs). However, PCR amplification and sequencing revealed that the mitochondrial rps14 genes of all examined grasses (Poaceae), Cyperaceae, and Joinvilleaceae are pseudogenes, with all those from the Poaceae sharing two 4-NT frameshift deletions and all those from the Cyperaceae sharing a 5-NT insertion (only one member of the Joinvilleaceae was examined). cDNA analysis showed that all mitochondrial pseudogenes examined (from all three families) are transcribed, that most are RNA edited, and that surprisingly many of the edits are reverse (U-->C) edits. Putatively nuclear copies of rps14 were isolated from one to several members of each of these three Poales families. Multiple lines of evidence indicate that the nuclear genes are probably the products of three independent transfers. CONCLUSION: The rps14 gene has, most likely, been functionally transferred from the mitochondrion to the nucleus at least three times during the evolution of the Poales. The transfers in Cyperaceae and Poaceae are relatively ancient, occurring in the common ancestor of each family, roughly 80 million years ago, whereas the putative Joinvilleaceae transfer may be the most recent case of functional organelle-to-nucleus transfer yet described in any organism. Remarkably, nearly intact and expressed pseudogenes of rps14 have persisted in the mitochondrial genomes of most lineages of Poaceae and Cyperaceae despite the antiquity of the transfers and of the frameshift and RNA editing mutations that mark the mitochondrial genes as pseudogenes. Such long-term, nearly pervasive survival of expressed, apparent pseudogenes is to our knowledge unparalleled in any genome. Such survival probably reflects a combination of factors, including the short length of rps14, its location immediately downstream of rpl5 in most plants, and low rates of nucleotide substitutions and indels in plant mitochondrial DNAs. Their survival also raises the possibility that these rps14 sequences may not actually be pseudogenes despite their appearance as such. Overall, these findings indicate that intracellular gene transfer may occur even more frequently in angiosperms than already recognized and that pseudogenes in plant mitochondrial genomes can be surprisingly resistant to forces that lead to gene loss and inactivation.
Surveys were completed in Eritrea, Ethiopia, Kenya, Madagascar, Mozambique, Tanzania, Uganda and Zanzibar to assess the lepidopteran stem borer species diversity on wild host plants. A total of 24,674 larvae belonging to 135 species were collected from 75 species of wild host plants belonging to the Poaceae, Cyperaceae and Typhaceae. Amongst them were 44 noctuid species belonging to at least nine genera, 33 crambids, 15 pyralids, 16 Pyraloidea species not yet identified, 25 tortricids and three cossids. The noctuid larvae represented 73.6% of the total number of larvae collected, with 66.3, 3.5 and 3.8% found on Poaceae, Cyperaceae and Typhaceae, respectively. The Crambidae, Pyralidae, Tortricidae and Cossidae represented 19.8, 1.9, 2.5 and 0.1% of the total larvae collected, respectively, with 90.4% of the Crambidae and Pyralidae collected from Poaceae, and 99.7% of the Tortricidae collected from Cyperaceae. The lepidopteran stem borer species diversity in the wild host plants was far more diverse than previously reported.
The phylogenetic affinities of the grass family (Poaceae) have long been debated. The chloroplast genomes of at least some grasses have been known to possess three inversions relative to the typical gene arrangement found in most flowering plants. We have surveyed for the presence of these inversions in grasses and other monocots by polymerase chain reaction amplification with primers constructed from sequences flanking the inversion end points. Amplification phenotypes diagnostic for the largest inversion (28 kilobase pairs) were found in genera representing all grass subfamilies, and in the nongrass families Restionaceae, Ecdeiocoleaceae, and Joinvilleaceae, but not in any other monocots--notably, Flagellariaceae, Anarthriaceae, Cyperaceae, or Juncaceae. This finding is consistent with one of the two principal views of grass phylogeny in suggesting that Poaceae and Cyperaceae (sedges) are not closest relatives. A second (approximately 6 kilobases) inversion appears to occur in a subset of the families possessing the 28-kilobase inversion and links Joinvilleaceae and Poaceae, while the smallest inversion appears unique to grasses. These inversions thus provide a nested set of phylogenetic characters, indicating a hierarchy of relationships in the grasses and allies, with Joinvilleaceae identified as the likely sister group to the Poaceae.
This paper proposes a new interpretation for primary thickening in monocotyledons. The anatomy of the vegetative organs of the following species was examined: Cephalostemon riedelianus (Rapataceae), Cyperus papyrus (Cyperaceae), Lagenocarpus rigidus, L. junciformis (Cyperaceae), Echinodorus paniculatus (Alismataceae) and Zingiber officinale (Zingiberaceae). The endodermis with meristematic activity was observed in the root of all the species, in the stem of Cyperus, Cephalostemum and Lagenocarpus rigidus, and in the leaf trace of Cyperus and leaf of Echinodorus. Considering the continuity of tissues through the root, stem and leaf, the authors conclude that in the stem the pericycle remains active throughout the life of the plant as the generator of the vascular tissue. The "Primary Thickening Meristem" is in fact the pericycle plus the endodermis and its derivatives (or only the pericycle). Close to the stem apex, the assemblage of seems to be a unique meristem, giving rise to the inner cortex and vascular tissues.
During December/January 1996/97 typical summer syndrome (hyperthermia and a 30% drop in milk yield) occurred in succession in two Holstein dairy herds (n=240 and n=150 milking cows, respectively) on the South African Highveld. These farms are situated in the midst of the prime maize and dairy farming areas of South Africa where this condition had never been diagnosed before. The individual components of the concentrate on both farms were negative for ergot alkaloids. Endophytic fungi and/or ergot infestation of teff and other grasses fed to the cows were then suspected of being involved, but neither endophytes nor ergot alkaloids could be implicated from these sources. By measuring the serum prolactin levels of groups of sheep (n=5) fed the first farm's total mixed ration (TMR) or its three individual fibre components for a period of 11 days, the source of the ergot alkaloids was identified. A statistically significant decrease in the level of this hormone occurred only in the group on maize silage (which constituted 28% on dry matter base of the TMR). The involvement of the maize silage was further chemically confirmed by the high levels of total ergot alkaloids, predominantly ergocryptine, found by LC-MS in the silage as well as in the TMR (115-975 ppb and 65-300 ppb, respectively). The ergot alkaloid content (mainly ergocryptine) of the maize silage on the second affected farm was 875 ppb. Withdrawal of contaminated silage resulted in gradual recovery of stock on both farms. Nut sedge (Cyperus esculentus and Cyperus rotundus of the family Cyperaceae) has a world-wide distribution and is a common weed in annual crops, and can be parasitized by Claviceps cyperi. Careful examination of the maize silage from both farms revealed that it was heavily contaminated with nut sedge and that it contained minute sclerotia, identified as those of Claviceps cyperi, originating from the latter. Nut sedge was abundant on both farms and it is believed that late seasonal rain had resulted in mature, heavily ergotised nut sedge being cut with the silage. Claviceps cyperi sclerotia, collected on the affected fields in the following autumn contained 3600-4000 ppm ergocryptine. That the dominant alkaloid produced by this particular fungus was indeed ergocryptine, was confirmed by negative ion chemical ionization MS/MS. In one further outbreak in another Holstein herd, teff hay contaminated with ergotised nut sedge and containing 1200 ppb alkaloids, was incriminated as the cause of the condition. This is the first report of bovine ergotism not associated with the Poaceae infected with Claviceps purpureum or endophytes but with the family Cyperaceae and this particular fungal phytopathogen.
We studied the composition and seasonal variation of the diet of the capybara (Hydrochaeris hydrochaeris) in the flooded savannas of Caño Limón, Colombia. This was achieved by direct observation of the consumption patterns of these animals. The capybaras only consumed plants, and their diet included 89 species of 22 families. Sixty three percent of these plant species had not been reported before. The most commonly consumed plants (94% of the diet), belonged to the Poaceae, Cyperaceae, Leguminosae and Pontederiaceae. Only seven species represented 60% of the total diet: the grasses Hymenachne amplexicaulis (16.9%), Digitaria bicornis (4.5%) and Panicum maximum (4.4%) and the Cyperaceae Rynchospora corymbosa (4.4%). There was seasonal variation in the diet composition of capybaras.
The forests in northwest Republic of Congo contain a number of herbaceous swamp clearings that provide foraging sites for lowland gorillas (G.g. gorilla). A 10-month study at the Maya Nord clearing (Parc National d'Odzala) showed that feeding activities occupied 72% of the time visiting gorillas spent on the clearing. They fed on four plant species: Enydra fluctuans (Asteraceae), Cyperus sp., Pycreus mundtii, and Rhynchospora corymbosa (Cyperaceae) among the 45 species recorded on the clearing. These clearing food species have higher mineral contents (especially Na and Ca) than the dominant Marantaceae species (Haumania liebrechtsiana) that constituted a staple food plant for gorillas in this forest. They also have higher potassium contents and contain less lignin than non-eaten clearing items/species. Finally, the most actively searched for clearing food (Enydra fluctuans) was characterized by the highest amount of Na and Ca. These results suggest that the mineral content (especially in Na, Ca, and/or K) could determine the feeding selectivity of gorillas at the clearing. They also tend to confirm that the amount of fiber plays a deterrent role in food selectivity, as has been found by many authors. The high density of gorillas in that region could result from the combination of the large areas of Marantaceae forests that provide abundant though monotonous food, and the number of clearings that provide sufficient mineral supplies. Clearings should thus be considered as key habitats for the conservation of gorillas.
Most terrestrial plants associate with root-colonising mycorrhizal fungi, which improve the fitness of both the fungal and plant associates. However, exceptions exist both between and within plant families failing to associate with mycorrhizal fungi or in the incidence and the extent of mycotrophy, which may vary greatly. Sedges are important pioneers of disturbed habitats and often dominate vegetations like wetlands, and arctic and alpine vegetations, in which the mycorrhizal inoculum in the soil is often low or absent. In the past, sedges were often designated as non-mycorrhizal, though limited reports indicated the presence of mycorrhiza in certain species. However, studies since 1987 indicate widespread occurrence of mycorrhiza in sedges. Based on these studies, the family Cyperaceae is no longer a non-mycorrhizal family, but the mycorrhizal status of its members is greatly influenced by environmental conditions. Further, sedges appear to have several morphological adaptations to thrive in the absence of mycorrhizal association. Though mycorrhizal associations have been noted in many sedge species, the ecological role of this association is not well documented and no clear generalisation can be drawn. Similarly, the role of mycorrhizal fungi on sedge growth and nutrient uptake or non-nutritional benefits has yet to be fully ascertained. This paper reviews the current information available on the incidence of mycorrhiza in sedges and the possible reasons for low mycotrophy observed in this family.
Mirabel bog (southern Quebec) was studied with the aim of specifying the past influence of local vegetation on peat accumulation. This influence was essentially translated by the reduction of minerotrophic inputs and peat accumulation induced by the highering of the peatland surface. Extremely rich initial conditions allow to explain the very high accumulations of the beginning of the Holocene, observed in various plant communities, among which Larix forests with ferns and Carex without modern analogues. Moreover, the structure (forest density) and the composition (dominance of Cyperaceae or Ericaceae) of these communities have locally controlled the dynamic of peat accumulation. These results point out the interest of the confrontation between palynological and macrofossil data and the spatialisation of palaeoecological studies.
Silica phytoliths (microscopic remains originating in plant tissues) have been identified on the enamel surface and dental calculus of a sample of teeth selected from well preserved skeletons from a Late Roman necropolis in Tarragona (Spain). Phytoliths were observed by scanning electron microscopy (SEM) and their siliceous nature was confirmed by X-ray microanalysis. The phytoliths were compared to those of soil samples from both the areas of the tombs corresponding to the abdomen and the periphery of the skeletons, and were classified taxonomically by comparison with a large collection of silica particles from modern plants in the Mediterranean area. Most of the phytoliths identified on the enamel and the dental calculus belong to the family of Poaceae, while the phytoliths from the abdominal area belong to Poaceae, Leguminosae, Cyperaceae, and Chenopodiaceae. Results are concordant with archaeological, ecological, and historical data from the same site, and with the human Mediterranean diet. If done properly, the study of phytoliths can provide direct information about the vegetable diet of past human populations, and could be applied to the study of human fossils.
Ethanolic extracts of five traditional Australian medicinal plants, previously shown to display antibacterial activity against laboratory strains of the Gram positive bacteria Staphylococcus aureus and Enterococcus faecalis, were investigated for their abilities to inhibit clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). Using plate-hole diffusion assays, the following results were obtained: (a) extract from the leaves of Eremophila alternifolia (Myoporaceae) showed activity against MRSA; (b) extract from the leaves of Acacia kempeana (Mimosaceae) showed incomplete inhibition of VRE; (c) extracts from the leaves of Amyema quandong (Loranthaceae) and Eremophila duttonii (Myoporaceae) were active against both types of bacteria; (d) extract from the stem base of Lepidosperma viscidum (Cyperaceae) was active against MRSA and exhibited incomplete inhibition of VRE. All active extracts were evaluated using time-kill assays. Most of the extracts showed bactericidal effects and reduced the number of viable cells by 4-6 logs within four hours, while the extracts from Acacia kempeana leaves and Lepidosperma viscidum stem base exhibited bacteriostatic activity against VRE. The extract from the leaves of Eremophila duttonii was the most active and reduced the number of viable cells of MRSA and VRE to undetectable levels within 1 hour.
Separation of the extract of the underground tubers of Cyperus conglomeratus Rottb. (family Cyperaceae) afforded, in addition to known compounds, two novel flavans, which were identified, by one and two dimensional NMR, MS and IR spectra, as 5-hydroxy-7,3',5'-trimethoxyflavan and 5,7-dihydroxy-3',5'-dimethoxy-6-prenylflavan.
This study focused on an ethnopharmacological survey among a group of Brazilian Quilombolas (descended from runaway slaves living in hideouts up-country) whose therapeutic practices involve a combination of healing ceremonies and prescription of medicinal plants consisting of the use of, at least, 48 plants with possible effect on the central nervous system (CNS), cited in 53 formulas prescribed for 17 therapeutic indications, the main ones being: to fortify the brain, for insomnia, as a sedative, for insanity, weight loss, and rejuvenation. The formulas consist of one to ten plants, and each plant may be recommended for up to seven different therapeutic indications, with evidence of non-specificity in the use of plants in this culture. Of these 48 plants, only 31 could be identified to the species level as belonging to 20 taxonomic families, with the Asteraceae, Malpighiaceae, Cyperaceae, and Myrtaceae as the most important families. Only eleven of these species have been previously studied and appear in scientific literature. Some of these plants are at present under study in the Department of Psychobiology of the Federal University of Sao Paulo.
Phylogenetic relationships of the five families of the order Commelinales remain an area of deep uncertainty in higher-level monocot systematics, despite intensive morphological and anatomical study. To test the monophyly of the Commelinales and the subclass Commelinidae, evaluate their relationships, and analyze evolutionary trends in their morphology, ecology, and biogeography, we conducted parsimony analyses on 95 rbcL sequences representing 17 taxa of Commelinales, 16 taxa of other Commelinidae, and 63 taxa from Arecidae, Liliidae, and Zingiberidae. Commelinales is polyphyletic and Commelinidae paraphyletic, with Eriocaulaceae and Xyridaceae sister to Poaceae and its relatives, Rapateaceae sister to Bromeliaceae and Mayacaceae, and Commelinaceae sister to Philydrales and allies. Thurnia is sister to Prionium at the base of Cyperaceae-Juncaceae; only 1 of Cronquist's multifamily commelinoid orders is diagnosed as monophyletic. We propose a revised Commelinidae, incorporating 4 revised superorders (Bromelianae, Commelinanae, Dasypogonanae, Arecanae) and 10 orders ((Poales, Eriocaulales, Cyperales, Typhales, Bromeliales), (Commelinales, Philydrales, Zingiberales), (Dasypogonales), (Arecales)). Morphological and anatomical characters used to define the original Commelinales and Commelinidae appear to be plesiomorphic or to reflect convergence or recurrent mutation; several characters supporting our revised classification are anatomical traits that seem relatively insulated from environmental selection pressures. The Commelinidae distal to the Arecales arose in South America, with amphiatlantic Bromeliaceae-Mayacaceae-Rapateaceae originating in the Guayana Shield. Ecological diversification involved the repeated invasion of shady, infertile, or arid microsites. The numbers of species in families of the revised Commelinidae are related partly to the extent of adaptive radiation in those families, but seem more strongly related to nonadaptive features promoting speciation, such as restricted seed dispersal (especially in forest interior groups with fleshy fruits), polyploidy, aneuploidy, and apomixis. Species diversity is unrelated to the rate/amount of rbcL sequence evolution.
Cercospora caricis is of interest as a potential mycoherbicide for control of purple nutsedge, Cyperus rotundus, which is considered to be the world's worst weed. The genetic variation of a collection of Brazilian Ce. caricis isolated from Cy. rotundus was analyzed by using RAPD, RFLP with a telomeric probe, [TTAGGG]18 and sequencing of the ITS1-5.8S-ITS2 regions of the ribosomal RNA gene. The Brazilian isolates were also compared with a Ce. caricis isolate from Florida, USA and with some other Cercospora species. A cluster of isolates from the Brazilian cerrado region was identified showing high genetic similarity. In contrast, isolates originating in other geographic regions of Brazil were less than 50% and 25% related to the former group according to similarity estimates produced from RAPD and telomeric RFLP analyses respectively. ITS sequence analysis did not support taxonomic division of the Brazilian strains, but did confirm the distant relatedness of these strains to the Ce. caricis isolate from Florida. The data indicate a need for an extensive molecular survey of Cercospora species associated with the Cyperaceae.
Mangroves are climax formation of hydrohalophytes inhabiting estuarine or marine salt marshes in the tropics and subtropics. As a terrestrial plant community inhabiting tidally inundated estuarine or marine sediments, mangroves show considerable adaptation to salinity, water-logging and nutrient stress. Thirty-one species of mangrove and mangrove associates and 23 species of transported flora, belonging to 25 families at four physiographic stages of succession of the mangrove plant community at the terminal part of the Ganges river estuary in India were examined for arbuscular mycorrhizal (AM) root association. Dominant members of the mangrove plant community were all AM, mostly with 'Paris' type structures. Many of the known non-mycotrophic plant families, except the Cyperaceae, also showed AM association, with intracellular hyphae and vesicles as the most discernible endophyte structures. Intensity of AM colonization varied both with the species and situations of their occurrence, being more intense and also more extensive in less saline dry ridge mangroves than in more saline formative and developed swamp mangroves. Introduced exotic trees on the ridges and embankments were infected by AM, but less than the declining mangroves in the same location. Seven species of AM fungi in common with those of the upstream mesophytic plants were isolated from root-free rhizosphere soils of the mangroves, three of which predominated in root association. These species, individually and as mixtures, infected roots of salinity tolerant herbs and trees in both locational silt and upstream alluvial soil with obvious improvements in their biomass yield and phosphorus nutrition. AM infective potential of root-free rhizosphere soils of the dominant members of the mangrove community were negatively related to salinity level of the sediment soil of the successional stages. The evidences of AM association of mangroves and other salt marsh plants obtained here and those reported elsewhere are discussed.
1. The hepatoprotective activity of aqueous-methanolic extract of Cyperus scariosus (Cyperaceae) was investigated against acetaminophen and CCl4-induced hepatic damage. 2. Acetaminophen produced 100% mortality at a dose of 1 g/kg in mice while pretreatment of animals with plant extract (500 mg/kg) reduced the death rate to 30%. 3. Acetaminophen at a dose of 640 mg/kg produced liver damage in rats as manifested by the rise in serum levels of alkaline phosphatase (ALP), glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) to 430 +/- 68, 867 +/- 305 and 732 +/- 212 IU/l (n = 10) respectively, compared to respective control values of 202 +/- 36, 59 +/- 14 and 38 +/- 7. 4. Pretreatment of rats with plant extract (500 mg/kg) significantly lowered (P < 0.05) the respective serum ALP; GOT and GPT levels to 192 +/- 31, 63 +/- 9 and 35 +/- 8. 5. The hepatotoxic dose of CCl4 (1.5 ml/kg; orally) raised serum ALP, GOT and GPT levels to 328 +/- 30, 493 +/- 102 and 357 +/- 109 IU/l (n = 10) respectively, compared to respective control values of 177 +/- 21, 106 +/- 15 and 47 +/- 12. 6. The same dose of plant extract (500 mg/kg) was able to significantly prevent (P < 0.05) CCl4-induced rise in serum enzymes and the estimated values of ALP, GOT and GPT were 220 +/- 30, 207 +/- 95 and 75 +/- 38, respectively. 7. The plant extract also prevented CCl4-induced prolongation in pentobarbital sleeping time confirming hepatoprotectivity.(ABSTRACT TRUNCATED AT 250 WORDS)