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The distribution of n-alkanes of foliar epicuticular waxes of Psidium guajava (Myrtaceae) exposed to air pollutants was determined by GC-EIMS. Saplings were exposed for two periods of one year (July 2000-June 2001 and December 200...
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The distribution of n-alkanes of foliar epicuticular waxes of Psidium guajava (Myrtaceae) exposed to air pollutants was determined by GC-EIMS. Saplings were exposed for two periods of one year (July 2000-June 2001 and December 2000-November 2001) in two experimental sites: Piloes River Valley (PV), where the contamination of air pollutants is relatively low, and Mogi River Valley (MV), which is severely affected by pollutants released by chemical, fertilizer, ceramic, iron and steel industries. On average, total leaf waxes were higher for plants that were exposed initially in the rainy season (December). Leaf waxes showed different n-alkane composition comparing both sites, especially during the first period of exposure (July 2000-June 2001). The main n-alkane waxes in both areas were C25, C26 and C27. However, in both experimental periods, an increase of the relative amounts of homologous of shorter carbon chains (C18-C23) under pollutants influence was observed. While the total percents of such homologues were on average 9.5 and 10.2 at PV for the first and second experimental periods, the observed percents at MV were on average 15.6 and 13.7, respectively. The results of the present work are in agreement with previous findings that air pollutants affect the synthesis of surface waxes, leading to alterations of the distribution of wax constituents..
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Four cytokinins (CKs), indole-3-acetic acid (IAA) and its ester and amino conjugates, and abscisic acid (ABA) levels of two bromeliads, Ananas comosus (L.) Merril and Vriesea gigantea Gaudich., grown in 5 mM (NH_4)_2SO_4 or urea a...
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Four cytokinins (CKs), indole-3-acetic acid (IAA) and its ester and amino conjugates, and abscisic acid (ABA) levels of two bromeliads, Ananas comosus (L.) Merril and Vriesea gigantea Gaudich., grown in 5 mM (NH_4)_2SO_4 or urea as th sole nitrogen (N) form, were investigated. In both bromeliads, zeatin (Z) and zeatin riboside ([9R]Z) were the most abundant CKs. In A. comosus, CKs levels decreased drastically (approx= 12 times) after 7 and 30 d in media with ammonium and urea, respectively. After 3d in media with N, V. gigantea CK levels decreased 30 and 20 times in the presence of ammonium and urea, respectively. N-starved A. comosus and V. gigantea exhibited similar ABA levels, but ABA decreased faster in V. gigantea when plants were transferred to media with N. Free IAA levels decreased until the 15th and 30th day when A. comosus was transferred to a medium with ammonium and urea, respectively. N-starved A. comosus amide, ester, and free IAA amounted to 81%, 14%,and 4%, respectively. There was a transient increase in the proportion of amide IAA and a corresponding decrease of the ester and the free IAA proportion when N-starved plants were transferred to media with N. The relationship between the internal hormonal patterns and the different ecological adaptations of the two bromeliads are discussed.
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In this work,two new flavonoids,oblongifolioside A(1)and oblongifolioside B(2),along with eight known compounds(3-10),are isolated from the leaves of Baccharis oblongifolia(Asteraceae).The new structures are established through sp...
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In this work,two new flavonoids,oblongifolioside A(1)and oblongifolioside B(2),along with eight known compounds(3-10),are isolated from the leaves of Baccharis oblongifolia(Asteraceae).The new structures are established through spectroscopic data and the known compounds are identified by comparison with data reported in the literature.The compounds(1-10)are evaluated in relation to their antiradical properties.Compounds 1 and 2 are found to exhibit high antiradical activity compared to their respective non-acylated flavonoids.
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This paper is part of an extensive study on the biodiversity of the macroalgal flora of Sao Paulo state, SE Brazil. Previous assessments were based only on morphological descriptions. Here, we tested the effectiveness of DNA barco...
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This paper is part of an extensive study on the biodiversity of the macroalgal flora of Sao Paulo state, SE Brazil. Previous assessments were based only on morphological descriptions. Here, we tested the effectiveness of DNA barcoding, in comparison with morphological observations for the recognition and cataloging of species. The focus of this study is the genus Porphyra, which is a conspicuous component of the upper intertidal on rocky shores of this region. With five currently accepted species, we have sequenced three short markers: cox1, cox2-3 spacer and UPA to establish the first DNA barcode database for the Porphyra species from the Brazilian coast. The three markers, although with different evolution rates, recovered a cryptic species (Porphyra sp. 77), grouped two different species (Porphyra drewiana and Porphyra spiralis) that are being synonymized, and finally indicated that varieties within P. acanthophora and P. spiralis are merely morphological, with no sequence divergence in the studied molecular markers.
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We have studied the effects of nitrate supply under photosynthetic active radiation (PAR) plus ultraviolet radiation (UVR) exposure on photosynthetic pigments (chlorophyll a and carotenoids), photoprotective UV screen mycosporine-...
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We have studied the effects of nitrate supply under photosynthetic active radiation (PAR) plus ultraviolet radiation (UVR) exposure on photosynthetic pigments (chlorophyll a and carotenoids), photoprotective UV screen mycosporine-like amino acids (MAAs), and photosynthetic parameters, including the maximum quantum yield (Fv/Fm) and electron transport rate (ETR) on the red agarophyte Gracilaria tenuistipitata. Apical tips of G. tenuistipitata were cultivated under ten different concentrations of NO3- for 7 days. It has been shown that G. tenuistipitata cultured under laboratory conditions has the ability to accumulate high amounts of MAAs following a nitrate concentration-dependent manner under PAR+UVR. Two MAAs were identified, shinorine and porphyra-334. The relative concentration of the first increased under high concentrations of nitrate, while the second one decreased. The presence of antheraxanthin is reported for the first time in this macroalgae, which also contains zeaxanthin, lutein, and beta -carotene. The accumulation of pigments, photoprotective compounds, and photosynthetic parameters of G. tenuistipitata is directly related to N availability. All variables decreased under low N supplies and reached constant maximum values with supplements higher than 0.5 mM NO3-. Our results suggest a high potential to acclimation and photoprotection against stress factors (including high PAR and UVR) directly related to N availability for G. tenuistipitata.
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In the light of taxonomic studies of Chamaecrista sect. Chamaecrista ser. Coriaceae the status of several varieties is reevaluated: Three former varieties are recognized at the specific level, two new combinations and one synonymi...
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In the light of taxonomic studies of Chamaecrista sect. Chamaecrista ser. Coriaceae the status of several varieties is reevaluated: Three former varieties are recognized at the specific level, two new combinations and one synonymization are here proposed. The geographic distribution and taxonomic affinities of these species are discussed. Chamaecrista Moench (1794: 272) is one of the largest genera of the subfamily Caesalpinioideae, with more than 330 species distributed mainly in tropical America (Lewis 2005). In Brazil 252 species are known, of which 203 are restricted to the country (Souza & Bortoluzzi 2013); many are narrow endemics. This high diversity of Chamaecrista is centered in the Cerrado Domain, mainly in the campos rupestres (Souza & Bortolluzi 2013) that are highland areas with many rock outcrops surrounded by sandy or rocky soils, which are mostly covered by a low, herbaceous or shrubby vegetation (Giulietti et al. 1997).
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Species of the suborder Portulacineae (Caryophyllales) often possess succulent leaves with wide morphological diversity, including flat and terete leaves. Terete leaves are described as not developing a marginal meristem during th...
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Species of the suborder Portulacineae (Caryophyllales) often possess succulent leaves with wide morphological diversity, including flat and terete leaves. Terete leaves are described as not developing a marginal meristem during their growth, but in Portulacineae little is known about anatomical development in this particular leaf type. To better understand the mechanisms underlying the development of different leaf morphologies within this group, we examined leaf histogenesis in species of four families with succulent leaves-Basellaceae, Didiereaceae, Por-tulacaceae, and Talinaceae-through optical microscopy. We observed two morphological patterns (terete and flat leaves) and three developmental patterns regarding blastozone positioning. While species with flat leaves always show the expected pattern of marginal blastozone activity, terete leaves of Didiereaceae present marginal blastozones for only a very brief period. On the other hand, terete leaves of Portulacaceae show a persistent peripheral blastozone enveloping the entire leaf during its development. We also demonstrate anatomical evidence suggesting that the terete leaves of Portulacaceae are adaxialized, i.e., their entire surface is homologous to the adaxial side, while terete leaves of Didiereaceae seem to result from a less severe modification.
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Premise of research. Phyllanthus is a pantropical genus and the largest in Phyllanthaceae with a wide diversity of habits and floral morphologies. The flowers are considered monochlamydeous, but some divergences are found in the l...
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Premise of research. Phyllanthus is a pantropical genus and the largest in Phyllanthaceae with a wide diversity of habits and floral morphologies. The flowers are considered monochlamydeous, but some divergences are found in the literature. The aim of this study was to investigate the floral structure of Phyllanthus urinaria based on ontogenetic, structural, and vascular analyses. Methodology. Flowers and buds of P. urinaria were embedded in Paraplast and sectioned using a rotatory microtome for analysis under LM. SEM was performed for additional structural and ontogenetic data. Pivotal results. The primordia of the sepals are the first structures to be formed in a counterclockwise direction, followed by the petals, which arise in a clockwise direction. Nectaries are formed on the base of the corolla in the staminate and pistillate flowers; then, the two perianth whorls merge, fusing at the base of the adult flowers. The three stamens have filaments postgenitally fused and free anthers. The ovary has three carpels congenitally connate with two ovules hemitropous with one long nucellar beak per locule and styles partially fused. Conclusions. Our results demonstrate for the first time the petaliferous nature of the inner whorl of the perianth in Phyllanthus, based on ontogenetic and anatomical evidence. The presence of a perianth with sepals and petals is a possible synapomorphy of the clade formed by Phyllanthus sect. Emblica + Phyllanthus sect. Urinaria and Breynia, Glochidion, and Sauropus, now under Phyllanthus in the current phylogenetic circumscription of the tribe Phyllantheae.
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The circumscription of genera belonging to tribe Bignonieae (Bignoniaceae) has traditionally been complex, with only a few genera having stable circumscriptions in the various classification systems proposed for the tribe. The gen...
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The circumscription of genera belonging to tribe Bignonieae (Bignoniaceae) has traditionally been complex, with only a few genera having stable circumscriptions in the various classification systems proposed for the tribe. The genus Lundia, for instance, is well characterized by a series of morphological synapomorphies and its circumscription has remained quite stable throughout its history. Despite the stable circumscription of Lundia, the circumscription of species within the genus has remained problematic. This study aims to reconstruct the phylogeny of Lundia in order to refine species circumscriptions, gain a better understanding of relationships between taxa, and identify potential morphological synapomorphies for species and major clades. We sampled 26 accessions representing 13 species of Lundia, and 5 outgroups, and reconstructed the phylogeny of the genus using a chloroplast (ndhF) and a nuclear marker (PepC). Data derived from sequences of the individual loci were analyzed using parsimony and Bayesian inference, and the combined molecular dataset was analyzed with Bayesian methods. The monophyly of Lundia nitidula, a species with a particularly complex circumscription, was tested using Shimodaira-Hasegawa (SH) test and the approximately unbiased test for phylogenetic tree selection (AU test). In addition, 40 morphological characters were mapped onto the tree that resulted from the analysis of the combined molecular dataset in order to identify morphological synapomorphies of individual species and major clades. Lundia and most species currently recognized within the genus were strongly supported as monophyletic in all analyses. One species, Lundia nitidula, was not resolved as monophyletic, but the monophyly of this species was not rejected by the AU and SH tests. Lundia sect. Eriolundia is resolved as paraphyletic in all analyses, while Lundia sect. Eulundia is monophyletic and supported by the same morphological characters traditionally used to circumscribe this section. The phylogeny of Lundia contributed important information for a better circumscription of species and served as basis the taxonomic revision of the genus.
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Lianas are one of the most important components of tropical forest, and yet one of the most poorly known organisms. Therefore, our paper addresses questions on the environmental and developmental aspects that influence the growth ...
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Lianas are one of the most important components of tropical forest, and yet one of the most poorly known organisms. Therefore, our paper addresses questions on the environmental and developmental aspects that influence the growth of lianas of Bignoniaceae, tribe Bignonieae. In order to better understand their growth, we studied the stem anatomy, seasonality of formation and differentiation of secondary tissues, and the influence of the cambial variant in xylem development on a selected species: Tynanthus cognatus. Afterwards, we compared the results found in T. cognatus with 31 other species of Bignonieae to identify general patterns of growth in lianas of this tribe. We found that cambial activity starts toward the end of the rainy season and onset of the dry season, in contrast to what is known for tropical trees and shrubs. Moreover, their pattern of xylem formation and differentiation is strongly influenced by the presence of massive wedges of phloem produced by a variant cambium. Thus, the variant cambium is the first to commence its activity and only subsequently does cambial activity progress towards the center of the regular region, leading to the formation of confluent growth rings. In summary, we conclude that: the cambium responds to environmental changes; the xylem growth rings are annual and produced in a brief period of about 2 months, something that may explain why lianas possess narrow stems; and furthermore, phloem wedges greatly influence cambial activity.Digital Object Identifier http://dx.doi.org/10.1007/s00468-010-0476-z
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