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At least 19 recordsLinked to original sources
PubMed2003

Volatile compounds from leaf-buds of Populus nigra L (Salicaceae).

Volatile components from fresh and air-dried leaf-buds of Populus nigra L. (Salicaceae) were isolated by Likens-Nickerson apparatus and analyzed using GC/MS. Forty-eight components (ca. 95% of the total isolate) were identified among black poplar bud volatiles. Sesquiterpene alcohols beta-eudesmol and alpha-eudesmol represented 26.3-28.7% of the oil. Other major sesquiterpene compounds were gamma-selinene (7.6-8.8%), delta-cadinene (7.8-8.6%), alpha-elemene (3.3-5.2%) and gamma-cadinene (3.9-4.2%). Hemiterpenes were also identified (2.2-7.6%). Monoterpenes were present in low percentages (1.6-5.7%). Aliphatic and aromatic alcohols, carbonyl compounds and aliphatic acids were identified among non-terpene volatiles (9.8-13.5%). The fresh buds contained 0.27% and dried 0.12% essential oil. Air-drying moderately effected the volatiles qualitative and quantitative composition.

Gas Chromatography-Mass Spectrometry↗
PubMed1992

The enzymatic decomposition of salicin and its derivatives obtained from Salicaceae species.

The enzymatic catalysis of the decomposition of Salicaceae phenolic glucosides was tested using almond beta-glucosidase and rabbit and porcine liver esterases. The beta-glucosidase catalyzed the complete hydrolysis of salicin and salicortin, yielding saligenin and glucose. Salicortin also produced (+)-6-hydroxycyclohexen-2-one (6-HCH). The acylglucosides were not decomposed by the beta-glucosidase. Both esterases catalyzed the decomposition of tremulacin, salicortin, and 2'-O-acetylsalicortin, releasing tremuloidin, salicin, and 2'-O-acetylsalicin as the main products, accompanied by 6-HCH and catechol. Tremuloidin and 2'-O-acetylsalicin were quite stable under the esterase hydrolysis, and salicin was not decomposed at all.

Animals↗
PubMed2000

Phylogenetic relationships of Salix (Salicaceae) based on rbcL sequence data.

Nucleotide sequences of the chloroplast-encoded rbcL gene were used to examine phylogenetic relationships of the genus Salix together with other allied genera of the family Salicaceae. Phylogenetic analyses of rbcL sequences strongly suggest the monophyly of three commonly recognized genera (Chosenia, Salix, and Toisusu). Two monophyletic groups are recognized within the larger monophyletic group. They do not correspond with any infrageneric taxa proposed so far. With regard to character evolution, it is thought that the reduction of stamen number from more than two stamens to two might occur in at least three lineages and that fused bud scales evolved several times and/or the reverse evolution occurred from fused to free. Some types of pollen surfaces are considered to have evolved independently.

Journal Article↗
PubMed2005

Phylogenetic relationships in some Melampsora rusts on Salicaceae assessed using rDNA sequence information.

The 5' end of the large subunit (LSU) region and the entire internal transcribed spacer (ITS) region of ribosomal DNA were sequenced from 11 species or special forms of Melampsora on Salix, and three species on Populus. For all the species, except for M. larici-epitea and M. coleosporioides, the sequences in both the examined regions were identical within a species. Within M. larici-epitea, f. sp. larici-epitea typica and f. sp. larici-retusae shared the same sequences which slightly differed from that of f. sp. larici-daphnoides. In the LSU region, M. larici-epitea, M. capraearum and the stem-infecting form on S. viminalis shared the same sequence and the Far-Eastern species M. epiphylla differed from them only slightly (p distance 0.006), indicating that they may share a common ancestral lineage. M. amygdalinae and M. coleosporioides formed a distict group (bootstrap value 100% for combined ITS and LSU data). M. larici-epitea and M. ribesii-purpurea, both belonging to the M. epitea complex, appeared to be distinct. The molecular data also suggest that the differences in certain characteristics, such as the thickness of teliospore walls and host specificity, may have evolved relatively recently.

Basidiomycota↗
PubMed2000

Leaves of Salicaceae (Salix and Populus) from Oligocene Sediments Near Tepexi de Rodríguez, Puebla, Mexico.

Eleven new salicaceous taxa based on fossil leaves, seven Salix and four Populus species, are described from the Oligocene Los Ahuehuetes locality, Pie de Vaca Formation, near Tepexi de Rodríguez in Puebla, Mexico. They are characterized by the presence of typical salicoid teeth, camptodromous secondary venation, and elliptic or lanceolate shape. Morphological differences between these new fossil plants and those reported previously from the United States and elsewhere indicate that diversification among these taxa occurred early during their differentiation. Furthermore, the limited morphological similarities of the fossil and extant plants growing naturally in Mexico also indicate a high rate of evolution. Documenting the expansion of high-latitude North American taxa into lower latitudes at the time of deposition of the Pie de Vaca Formation confirms that at least some of the typical boreal taxa were part of dry tropical communities in low-latitude North America and underscores the need to reevaluate the origin of this southern vegetation.

Journal Article↗
PubMed2005

Molecular population genetics of herbivore-induced protease inhibitor genes in European aspen (Populus tremula L., Salicaceae).

Plants defend themselves against the attack of natural enemies by using an array of both constitutively expressed and induced defenses. Long-lived woody perennials are overrepresented among plant species that show strong induced defense responses, whereas annual plants and crop species are underrepresented. However, most studies of plant defense genes have been performed on annual or short-lived perennial weeds or crop species. Here I use molecular population genetic methods to survey six wound-inducible protease inhibitors (PIs) in a long-lived woody, perennial plant species, the European aspen (Populus tremula), to evaluate the likelihood of either recurrent selective sweeps or balancing selection maintaining amino acid polymorphisms in these genes. The results show that none of the six PI genes have reduced diversities at synonymous sites, as would be expected in the presence of recurrent selective sweeps. However, several genes show some evidence of nonneutral evolution such as enhanced linkage disequilibrium and a large number of high-frequency-derived mutations. A group of at least four Kunitz trypsin inhibitor genes appear to have experienced elevated levels of nonsynonymous substitutions, indicating allelic turnover on an evolutionary timescale. One gene, TI1, has enhanced levels of intraspecific polymorphism at nonsynonymous sites and also has an unusual haplotype structure characterized by two divergent haplotypes occurring at roughly equal frequencies in the sample. One haplotype has very low levels of intraallelic nucleotide diversity, whereas the other haplotype has levels of diversity comparable to other genes in P. tremula. Patterns of sequence diversity at TI1 do not fit a simple model of either balancing selection or recurrent selective sweeps. This suggests that selection at TI1 is more complex, possibly involving allelic cycling.

Base Sequence↗
PubMed2004

Nucleotide polymorphism and linkage disequilibrium within and among natural populations of European aspen (Populus tremula L., Salicaceae).

Populus is an important model organism in forest biology, but levels of nucleotide polymorphisms and linkage disequilibrium have never been investigated in natural populations. Here I present a study on levels of nucleotide polymorphism, haplotype structure, and population subdivision in five nuclear genes in the European aspen Populus tremula. Results show substantial levels of genetic variation. Levels of silent site polymorphisms, pi(s), averaged 0.016 across the five genes. Linkage disequilibrium was generally low, extending only a few hundred base pairs, suggesting that rates of recombination are high in this obligate outcrossing species. Significant genetic differentiation was found at all five genes, with an average estimate of F(ST) = 0.116. Levels of polymorphism in P. tremula are 2- to 10-fold higher than those in other woody, long-lived perennial plants, such as Pinus and Cryptomeria. The high levels of nucleotide polymorphism and low linkage disequilibrium suggest that it may be possible to map functional variation to very fine scales in P. tremula using association-mapping approaches.

Genes, Plant↗
PubMed1999

Genotypic variation for condensed tannin production in trembling aspen (POPULUS TREMULOIDES, salicaceae) under elevated CO2 and in high- and low-fertility soil.

The carbon/nutrient balance hypothesis suggests that leaf carbon to nitrogen ratios influence the synthesis of secondary compounds such as condensed tannins. We studied the effects of rising atmospheric carbon dioxide on carbon to nitrogen ratios and tannin production. Six genotypes of Populus tremuloides were grown under elevated and ambient CO(2) partial pressure and high- and low-fertility soil in field open-top chambers in northern lower Michigan, USA. During the second year of exposure, leaves were harvested three times (June, August, and September) and analyzed for condensed tannin concentration. The carbon/nutrient balance hypothesis was supported overall, with significantly greater leaf tannin concentration at high CO(2) and low soil fertility compared to ambient CO(2) and high soil fertility. However, some genotypes increased tannin concentration at elevated compared to ambient CO(2), while others showed no CO(2) response. Performance of lepidopteran leaf miner (Phyllonorycter tremuloidiella) larvae feeding on these plants varied across genotypes, CO(2), and fertility treatments. These results suggest that with rising atmospheric CO(2), plant secondary compound production may vary within species. This could have consequences for plant-herbivore and plant-microbe interactions and for the evolutionary response of this species to global climate change.

Journal Article↗