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Paleontologists just recently opened their eyes to the wealth of fossil documents relevant to plant – arthropod interaction and are busy now accumulating raw data. Perhaps the richest regional collection of interaction traces cam...
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Paleontologists just recently opened their eyes to the wealth of fossil documents relevant to plant – arthropod interaction and are busy now accumulating raw data. Perhaps the richest regional collection of interaction traces came from the mid-Cretaceous deposits of the Negev Desert, Israel, encompassing the time interval of the rise and basal radiation of angiosperms – the flowering plants. The arthropods (insects and mites) inserting their eggs in the leaves and making leaf mines and galls were discovering new possibilities for endophytic life that the flowering plants provided.
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16 iridoid glucosides and 3 aromatic compounds were isolated from Bulgarian natural populations of Veronica L. and Pseudolysima-chion Opiz species. The distribution of 11 compounds in 34 species (96 samples) was shown. Seven Veron...
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16 iridoid glucosides and 3 aromatic compounds were isolated from Bulgarian natural populations of Veronica L. and Pseudolysima-chion Opiz species. The distribution of 11 compounds in 34 species (96 samples) was shown. Seven Veronica and Pseudolysimachion species were screened for iridoids for the first time and a phenylethanoid glycoside, calceolarioside C, was found for the first time in the genus Veronica. The systematic significance of iridoid glucosides at subspecies, species, sectional, and generic levels is discussed. A correlation between the chemical characters (iridoids and flavonoids) and the chromosome base numbers of the perennial Veronica species was established. Origin of the annual species from the perennials through two evolutionary lines was supposed.
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Results obtained during a light microscopical study revealed the first data on embryo sac development and structure as well as endosperm formation for Achariaceae, a small family of three monotypic genera endemic to southern Afric...
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Results obtained during a light microscopical study revealed the first data on embryo sac development and structure as well as endosperm formation for Achariaceae, a small family of three monotypic genera endemic to southern Africa. For Guthriea capensis Bolus these aspects, as well as the organisation of the sporophytic ovular tissues, are described and depicted in detail. After fertilisation the swollen, branched tip of the pollen tube persists in the embryo sac during the initial stages of endosperm development. A suspensor-less embryo, possibly belonging to the Penaea variation of the Asterad type, is formed. Although both integuments partake in the formation of the seed coat, ontogenetic data show that the inner epidermis of the outer integument contributes most of the mechanical tissue, i.e. the seed coat of Guthriea Bolus is mainly endotestat. The results of the investigation suggest that ovule and seed coat characters In Guthriea and Ceratiosicyos Nees differ considerably. Achariaceae seem well placed within the Malpighiales, but embryological data also show similarities with Cucurbitales and, possibly, Brassicales.
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The extraordinary diversity of angiosperms is the ultimate outcome of the interplay of speciation and extinction, which determine the net diversification of different lineages. We document the temporal trends of angiosperm diversi...
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The extraordinary diversity of angiosperms is the ultimate outcome of the interplay of speciation and extinction, which determine the net diversification of different lineages. We document the temporal trends of angiosperm diversification rates during their early history. Absolute diversification rates were estimated for order-level clades using ages derived front relaxed molecular clock analyses that included or excluded a maximal constraint to angiosperm age. Diversification rates for angiospermsas a whole ranged from 0.0781 to 0.0909 net speciation events per million years, with dates from the constrained analysis. Diversification through time plots show an inverse relationship between clade age and rate, where the younger clades tend to havethe highest rates, Angiosperm diversity is found to have mixed origins: slightly less than half of the living species belong to lineages with low to moderate diversification rates, which appeared between 130 and 102 Mya (Barremian-uppermost Albian: LowerCretaceous). Slightly over half of the living species belong to lineages with moderate to high diversification rates, which appeared between 102 and 77 Mya (Cenomanian-mid Campanian; Upper Cretaceous). Terminal lineages leading to living angiosperm species, however, may have originated soon or long after the phylogenetic differentiation of the clade to which they belong.
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The major challenge of this paper comprises an attempt to compare the wealth of folk-information based on "traditional knowledge" with the efficacy of a chemo-biological background based on scientific knowledge. Surprisingly, corr...
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The major challenge of this paper comprises an attempt to compare the wealth of folk-information based on "traditional knowledge" with the efficacy of a chemo-biological background based on scientific knowledge. Surprisingly, correlations between plant uses (as food and medicine) and evolutionary status according to morphology (as assigned by Sporne indices) and metabolism (as assigned by diversity of phytochemicals) obey strikingly uniform systematic and evolutionary trends. The resulting patterns suggest a dynamic chemical mechanism for the bioactivity in plants regulated by the antagonistic gallate/caffeate pair. This finding is an important step toward the construction of a coherent chemo-biological language by a dynamic holistic quantitative methodology, one of the most potent prospects for understanding the functioning of nature. (C) 2002 Elsevier Science Ltd. All rights reserved. [References: 34]
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A study of fossil and modern pollen of the family Convolvulaceae is presented and five fossil types are identified. Two types, one a large tricolpate of the form species Perfotricolpites digitatus, with similarities to Convolvulus...
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A study of fossil and modern pollen of the family Convolvulaceae is presented and five fossil types are identified. Two types, one a large tricolpate of the form species Perfotricolpites digitatus, with similarities to Convolvulus, Operculina and probably other genera, and the second, a small tricolpate, Tricolpites trioblatus, with affinities to Wilsonia and possibly Cressa, first appear in the late Eocene of southern Australia. Fossil pollen is found worldwide, with the oldest occurrence being Calystegiapollis microechinatus from the early Eocene of Africa. Perfotricolpites digitatus first appears in the mid-Eocene of Brazil, and specimens similar to P. digitatus from Antarctica suggest that it migrated into Australia by the Antarctic route. Wilsonia is endemic to Australia today, but it was in New Zealand in the mid-late Miocene.
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Aquatic Utricularia species usually grow in standing, nutrient-poor humic waters. They take up all necessary nutrients either directly from the water by rootless shoots or from animal prey by traps. The traps are hollow bladders, ...
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Aquatic Utricularia species usually grow in standing, nutrient-poor humic waters. They take up all necessary nutrients either directly from the water by rootless shoots or from animal prey by traps. The traps are hollow bladders, 1-6 mm long with elastic walls and have a mobile trap door. The inner part of the trap is densely lined with quadrifid and bifid glands and these are involved in the secretion of digestive enzymes, resorption of nutrients and pumping out the water. The traps capture small aquatic animals but they also host a community of microorganisms considered as commensals. How do these perfect traps function, kill and digest their prey? How do they provide ATP energy for their demanding physiological functions? What are the nature of the interactions between the traps and the mutualistic microorganisms living inside as commensals? In this mini review, all of these questions are considered from an ecophysiologist's point of view, based on the most recent literature data and unpublished results. A new concept on the role of the commensal community for the plants is presented.
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The sequence of the plastid genome of Amborella trichopoda,the putative sister to all other extant angiosperms, was recentlyreported (Molecular Biology and Evolution 20: 1499–1505).Goremykin et al. used sequence data for 61 pl...
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The sequence of the plastid genome of Amborella trichopoda,the putative sister to all other extant angiosperms, was recentlyreported (Molecular Biology and Evolution 20: 1499–1505).Goremykin et al. used sequence data for 61 plastid genes fromAmborella and 12 other embryophytes in phylogenetic analysesand concluded that Amborella is not the sister to the remainingflowering plants; the monocots instead occupy this position.The authors attributed their results, which differ substantiallyfrom all recent phylogenetic analyses of angiosperms, to theincreased character sampling (30 017 nucleotides in their alignedmatrix) in their analysis relative to published studies thatincluded fewer genes but more taxa. We hypothesized that thedifference in topology is not due to limited character samplingin previous studies but to limited taxon sampling in the analysisby Goremykin et al. To test this, we conducted a series of phylogeneticanalyses using a three-gene, 12 (or more)-taxon data set toevaluate the topological effects of (i) including three vs.61 genes for (nearly) the same set of taxa, (ii) analyzing differentcodon positions, (iii) substituting representatives of otherbasal lineages for Amborella, (iv) replacing the grasses usedto represent the monocots with other monocots, selected eitherfor their phylogenetic position or randomly, and (v) addingother basal taxa—Nymphaea, Austrobaileya, magnoliids,and monocots—to the 12-taxon data set. Our results demonstratethat the "monocots basal" topology obtained by Goremykin etal. is not due to increased character sampling of the plastidgenome; their topology was obtained using only two plastid genesor two plastid genes and one nuclear gene. This topology wasalso retained when either Nymphaea or Austrobaileya was substitutedfor Amborella, demonstrating that any of the three basal lineageswill attach to Calycanthus for lack of any other close branch.Furthermore, the "monocots basal" topology is not robust tochanges in sampling of monocots. Simply adding Oncidium, forexample, places Amborella sister to the other angiosperms. Thus,limited taxon sampling, focusing on organisms with completegenome sequences, can lead to artifactual results.收起
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Genus Alasia GOLOVNEVA, 2006 includes staminate inflorescences repeatedly found together with Trochodendroides type leavesand Trochodendrocarpus - Joffrea type infructescences and is considered as the most probable pollen organ of...
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Genus Alasia GOLOVNEVA, 2006 includes staminate inflorescences repeatedly found together with Trochodendroides type leavesand Trochodendrocarpus - Joffrea type infructescences and is considered as the most probable pollen organ of the Trochodendroides plant.In situ pollen grains were extracted from the anthers of two Alasia flowers and detached stamens of cf. Alasia from the Paleocene of AmurProvince, Russian Far East. The morphology of the flowers was interpreted as the fascicles of stamens with dorsifixed introrse anthersadpressed to the subtending bract before exsertion. The pollen grains are small tricolpate with long colpi and a variably microreticulate toverrucate-scabrate ornamentation. Alasia differs from Cercidiphyllum in both staminate structures and pollen morphology suggesting hama-melid affinities.
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Somatic chromosome numbers of 2n = 24 are reported for all three species of Australian Zostera: Z. capricorni Aschers., Z. muelleri Irmisch ex Aschers, and Z. mucronata den Hartog and 2n = 36 for Heterozostera tasmanica (Martens e...
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Somatic chromosome numbers of 2n = 24 are reported for all three species of Australian Zostera: Z. capricorni Aschers., Z. muelleri Irmisch ex Aschers, and Z. mucronata den Hartog and 2n = 36 for Heterozostera tasmanica (Martens ex Aschers.) den Hartog. All Australian zosteroidean species apparently have similar chromosome morphology: dot-like or rod shaped. It is suggested that the chromosome number and its morphology can be used to distinguish genera and subgenera in the Zosteraceae but not for species identification, and that speciation is not accompanied by changes of chromosome numbers.
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