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At least 19 recordsLinked to original sources
PubMed1999

Frequency of somaclonal variation in plants of black spruce (Picea mariana, Pinaceae) and white spruce (P. glauca, Pinaceae) derived from somatic embryogenesis and identification of some factors involved in genetic instability.

Plants of black spruce (Picea mariana, N = 7047 individuals) and white spruce (P. glauca, N = 3995 individuals) were regenerated from a total of 87 clones over a 5-yr period by somatic embryogenesis to study factors that might be associated with the appearance of variant phenotypes. Morphological evaluation of the plants showed several types of variation. These variations were grouped into nine types: dwarfism (type A), reduced height with various form anomalies (types B, C, and D), needle fasciation (type E), abnormality in tree architecture (type F), variegata phenotype (type G), and plants with an overall regular morphology but smaller than normal plants (type H). Plagiotropic plants were also observed (type I). Each plant from types A to H (except type C where no plants survived more than 6 mo) had retained its phenotype over 4-5 yr of growth. Some of the variant types could be related to chromosomic instability: chromosome counts showed aneuploid cells for type-A and type-D plants. The type I (plagiotropism) was not related to genetic instability but rather to physiological disorders. In total, spruce variants of types A-H were obtained at relatively low frequencies, i.e., 1.0% (39/3995) for white spruce and 1.6% (110/7047) for black spruce. Statistical analyses, conducted with family, clone, and time in maintenance as variables, showed that clone was the most important source of genetic instability followed by time in maintenance.

Journal Article↗
PubMed2001

Spectral reflectance of Picea rubens (Pinaceae) and Abies balsamea (Pinaceae) needles along an elevational gradient, Mt. Moosilauke, New Hampshire, USA.

Relationships among elevation, foliar morphology, spectral reflectance, and chlorophyll fluorescence of two co-occurring montane conifers, red spruce (Picea rubens Sarg.) and balsam fir (Abies balsamea [L.] Mill.), were investigated along two transects from 460 to 1460 m on Mt. Moosilauke in the White Mountains of New Hampshire, USA. Spectral reflectance (300-1100 nm wavelengths) and the chlorophyll fluorescence F(v)/F(m) ratio were measured on dark-adapted needles. Foliar morphology (needle size, shape, and mass) and nitrogen concentrations were measured in the laboratory. Reflectance spectra varied between species and with elevation. Two chlorophyll measures, red edge position and a chlorophyll-based difference index (Chl NDI = R750 - R705/R750 + R705), indicated more chlorophyll in fir than in spruce and decreasing chlorophyll with increasing elevation in both species. The structure-independent pigment index (SIPI = R800 - R445/R800 - R680) increased with elevation, indicating an increasing carotenoid : chlorophyll ratio. The photochemical reflectance index (PRI = R531 - R570/R531 + R570), a measure of photosynthetic radiation use efficiency, decreased with increasing elevation up to 1370 m. In the highest elevation site, within the stunted alpine krummholz at 1460 m, PRI was higher than at 1370 m, but still lower than at 1070 m. This same pattern was evident in the chlorophyll fluorescence F(v)/F(m) measurements. These independent indices indicate higher stress in spruce than fir, which may be related to the "spruce decline" reported in the northeastern USA. Results also indicate progressively increasing stress with increasing elevation up to 1370 m. Stress appears to be lower at 1460 m than at 1370 m, despite the harsher conditions at the very summit of Mt. Moosilauke. This may be a consequence of stress-tolerant physiology and/or prostrate architecture.

Journal Article↗
PubMed2001

The evolutionary split of Pinaceae from other conifers: evidence from an intron loss and a multigene phylogeny.

The second intron in the mitochondrial gene nad1 was surveyed using PCR, DNA sequencing, or Southern hybridization in 323 species (313 genera, 212 families) of seed plants. The intron was absent in all 22 species (22 genera, 8 families) of non-Pinaceae conifers studied, in Welwitschia mirabilis, and in seven angiosperms. Whereas absence of the intron in seven angiosperms and Welwitschia is likely due to seven independent losses when evaluated against the recently published multigene phylogenies, the lack of the intron in all non-Pinaceae conifers can be best explained by a single loss. These data suggest that the non-Pinaceae conifers represent a monophyletic group. We also conducted a phylogenetic analysis of seed plants using a combined data set of the partial exon and intron sequences of nad1 generated from this study and published sequences of mitochondrial cox1 and small subunit (SSU) rDNA, chloroplast rbcL, and nuclear 18S rDNA. The results supported the split of conifers into two groups: Pinaceae and non-Pinaceae conifers. The Gnetales were sister to Pinaceae, in agreement with the conclusion from other recent molecular phylogenetic studies that refute the anthophyte hypothesis.

Base Sequence↗
PubMed2002

Abietoid seed fatty acid compositions--a review of the genera Abies, Cedrus, Hesperopeuce, Keteleeria, Pseudolarix, and Tsuga and preliminary inferences on the taxonomy of Pinaceae.

The seed fatty acid (FA) compositions of Abietoids (Abies, Cedrus, Hesperopeuce, Keteleeria, Pseudolarix, and Tsuga) are reviewed in the present study in conclusion to our survey of Pinaceae seed FA compositions. Many unpublished data are given. Abietoids and Pinoids (Pinus, Larix, Picea, and Pseudotsuga)-constituting the family Pinaceae-are united by the presence of several delta5-olefinic acids, taxoleic (5,9-18:2), pinolenic (5,9,12-18:3), coniferonic (5,9,12,15-1 8:4), keteleeronic (5,11-20:2), and sciadonic (5,11,14-20:3) acids, and of 14-methyl hexadecanoic (anteiso-17:0) acid. These acids seldom occur in angiosperm seeds. The proportions of individual delta5-olefinic acids, however, differ between Pinoids and Abietoids. In the first group, pinolenic acid is much greater than taxoleic acid, whereas in the second group, pinolenic acid is greater than or equal to taxoleic acid. Moreover, taxoleic acid in Abietoids is much greater than taxoleic acid in Pinoids, an apparent limit between the two subfamilies being about 4.5% of that acid relative to total FA. Tsuga spp. appear to be a major exception, as their seed FA compositions are much like those of species from the Pinoid group. In this respect, Hesperopeuce mertensiana, also known as Tsuga mertensiana, has little in common with Abietoids and fits the general FA pattern of Pinoids well. Tsuga spp. and H. mertensiana, from their seed FA compositions, should perhaps be separated from the Abietoid group and their taxonomic position revised. It is suggested that a "Tsugoid" subfamily be created, with seed FA in compliance with the Pinoid pattern and other botanical and immunological criteria of the Abietoid type. All Pinaceae genera, with the exception of Pinus, are quite homogeneous when considering their overall seed FA compositions, including delta5-olefinic acids. In all cases but one (Pinus), variations from one species to another inside a given genus are of small amplitude. Pinus spp., on the other hand, have highly variable levels of delta5-olefinic acids in their FA compositions, particularly when sections (e.g., Cembroides vs. Pinus sections) or subsections (e.g., Flexiles and Cembrae subsections from the section Strobus) are compared, although they show qualitatively the same FA patterns characteristic of Pinoids. Multicomponent analysis of Abietoid seed FA allowed grouping of individual species into genera that coincide with the same genera otherwise characterized by more classical botanical criteria. Our studies exemplify how seed FA compositions, particularly owing to the presence of delta5-olefinic acids, may be useful in sustaining and adding some precision to existing taxonomy of the major family of gymnosperms, Pinaceae.

Abies↗
PubMed2000

Phylogeny and divergence times in Pinaceae: evidence from three genomes.

In Pinaceae, the chloroplast, mitochondrial, and nuclear genomes are paternally, maternally, and biparentally inherited, respectively. Examining congruence and incongruence of gene phylogenies among the three genomes should provide insights into phylogenetic relationships within the family. Here we studied intergeneric relationships of Pinaceae using sequences of the chloroplast matK gene, the mitochondrial nad5 gene, and the low-copy nuclear gene 4CL. The 4CL gene may exist as a single copy in some species of Pinaceae, but it constitutes a small gene family with two or three members in others. Duplication and deletion of the 4CL gene occurred at a tempo such that paralogous loci are maintained within but not between genera. Exons of the 4CL gene have diverged approximately twice as fast as the matK gene and five times more rapidly than the nad5 gene. The partition-homogeneity test indicates that the three data sets are homogeneous. A combined analysis of the three gene sequences generated a well-resolved and strongly supported phylogeny. The combined phylogeny, which is topologically congruent with the three individual gene trees based on the Templeton test, is likely to represent the organismal phylogeny of Pinaceae. This phylogeny agrees to a certain extent with previous phylogenetic hypotheses based on morphological, anatomical, and immunological data. Disagreement between the previous hypotheses and the three-genome phylogeny suggests that morphology of both vegetative and reproductive organs has undergone convergent evolution within the pine family. The strongly supported monophyly of Nothotsuga longibracteata, Tsuga mertensiana, and Tsuga canadensis on all three gene phylogenies provides evidence against previous hypotheses of intergeneric hybrid origins of N. longibracteata and T. mertensiana. Divergence times of the genera were estimated based on sequence divergence of the matK gene, and they correspond well with the fossil record.

Cell Nucleus↗
PubMed2003

Methyl jasmonate induces changes mimicking anatomical defenses in diverse members of the Pinaceae.

Conifers have defenses such as the production of phenolic compounds and resins that can be induced by bark beetles and other invading organisms, but the signaling agents involved are unknown. The anatomical effects of methyl jasmonate (MJ), a potent inducer of certain plant defenses, were compared with wounding of the bark of 12-15-year-old trees of five conifer species. Wounding in all species resulted in tissue necrosis and wound periderm development immediately around the wound site. One cm from the wound, swelling of phloem polyphenolic parenchyma cells and phenolic accumulation were observed in Pseudotsuga menziesii (Mirb.) Franco, Picea pungens Engelman, Larix occidentalis Nutt. and Pinus monticola Douglas ex D. Don, but not in Taxus brevifolia Nutt. Traumatic resin ducts were formed in response to wounding in three species of Pinaceae, but not in P. monticola, which formed irregular clusters of cells rather than ducts. Taxus brevifolia did not form resin ducts in response to either wounding or MJ treatment. In the Pinaceae species studied, surface application of 100 mM MJ caused similar anatomical changes to those observed in response to wounding, including phenolic accumulation, cell swelling and traumatic resin duct formation, but it did not induce a wound periderm. Traumatic resin ducts differed in size among the study species, ranging from small in L. occidentalis to very large in P. menziesii. In P. menziesii, P. pungens and L. occidentalis, traumatic resin ducts were more abundant after MJ treatment than after wounding. We conclude that the octadecanoid pathway is likely involved in defense responses in stems of the Pinaceae, but not necessarily in other taxa.

Acetates↗
PubMed2004

Comparative mapping in the Pinaceae.

A comparative genetic map was constructed between two important genera of the family Pinaceae. Ten homologous linkage groups in loblolly pine (Pinus taeda L.) and Douglas fir (Pseudotsuga menziesii [Mirb.] Franco) were identified using orthologous expressed sequence tag polymorphism (ESTP) and restriction fragment length polymorphism (RFLP) markers. The comparative mapping revealed extensive synteny and colinearity between genomes of the Pinaceae, consistent with the hypothesis of conservative chromosomal evolution in this important plant family. This study reports the first comparative map in forest trees at the family taxonomic level and establishes a framework for comparative genomics in Pinaceae.

Base Sequence↗
PubMed2005

A composite linkage map from two crosses for the species complex Picea mariana x Picea rubens and analysis of synteny with other Pinaceae.

Four individual linkage maps were constructed from two crosses for the species complex Picea mariana (Mill.) B.S.P. x Picea rubens Sarg in order to integrate their information into a composite map and to compare with other Pinaceae. For all individual linkage maps, 12 major linkage groups were recovered with 306 markers per map on average. Before building the composite linkage map, the common male parent between the two crosses made it possible to construct a reference linkage map to validate the relative position of homologous markers. The final composite map had a length of 2,319 cM (Haldane) and contained a total of 1,124 positioned markers, including 1,014 AFLPs, 3 RAPDs, 53 SSRs, and 54 ESTPs, assembled into 12 major linkage groups. Marker density of the composite map was statistically homogenous and was much higher (one marker every 2.1 cM) than that of the individual linkage maps (one marker every 5.7 to 7.1 cM). Synteny was well conserved between individual, reference, and composite linkage maps and 94% of homologous markers were colinear between the reference and composite maps. The combined information from the two crosses increased by about 24% the number of anchor markers compared to the information from any single cross. With a total number of 107 anchor markers (SSRs and ESTPs), the composite linkage map is a useful starting point for large-scale genome comparisons at the intergeneric level in the Pinaceae. Comparisons of this map with those in Pinus and Pseudotsuga allowed the identification of one breakdown in synteny where one linkage group homologous to both Picea and Pinus corresponded to two linkage groups in Pseudotsuga. Implications for the evolution of the Pinaceae genome are discussed.

Chromosome Mapping↗
PubMed2006

Comparative genome mapping among Picea glauca, P. mariana x P. rubens and P. abies, and correspondence with other Pinaceae.

A composite linkage map was constructed from four individual maps for the conifer Picea glauca (Moench) Voss, from anonymous and gene-specific markfers (714 AFLPs, 38 SSRs, and 53 ESTPs). A total of 12 linkage groups were delineated with an average marker density of 2.7 cM. Macro-synteny and macro-colinearity comparisons with two other composite linkage maps developed for the species complex P. mariana (Mill.) B.S.P. x P. rubens Sarg., and for P. abies (L.) Karst. revealed an identical number of linkage groups and a remarkable conservation of the gene content and gene order of linkage groups over the million years since the split between these taxa. Identical gene order among taxa was observed for 10 of the 12 assembled composite linkage groups. The discovery of one breakdown in synteny between P. glauca and the other two taxa indicated the occurrence of an inter-chromosomal rearrangement involving an insertional translocation. Analysis of marker colinearity also revealed a putative segmental duplication. The combined information from these three Picea genomes validated and improved large-scale genome comparisons at the inter-generic level in the family Pinaceae by allowing for the identification of 11 homoeologous linkage groups between Picea and Pinus, and nine such groups between Picea and Pseudotsuga menziesii. Notably, the analysis of synteny among the three genera revealed a putative case of chromosomal fission and an inter-chromosomal rearrangement in the genome of P. menziesii. Both of these changes are inter-connected, indicating much instability in this part of the P. menziesii genome. Overall, the macro-structure of the Pinaceae genome was well conserved, which is notable given the Cretaceous origin of its main lineages.

Genome, Plant↗
PubMed2002

Saturated and unsaturated anteiso-C19 acids in the seed lipids from Hesperopeuce mertensiana (Pinaceae).

Minor uncommon FA from Hesperopeuce mertensiana (a gymnosperm species of the Pinaceae family) seed oil were characterized through a combination of silver ion TLC of their FAME, and GLC coupled with MS of their picolinyl derivatives. These uncommon components have the structures 16-methyloctadecanoic (anteiso-19:0), 16-methyl-cis-9-octadecenoic (anteiso-19:1), and 1 6-methyl-cis-9,cis-12-octadecadienoic (anteiso-19:2) acids. These branched C19 acids were identified earlier in the wood of Picea abies, which would indicate that such acids could be widespread, though minor, components of Pinaceae lipids.

Chromatography, Gas↗
PubMed1997

The unusual occurrence of 14-methylhexadecanoic acid in Pinaceae seed oils among plants.

14-Methylhexadecanoic (14-MHD) acid has been identified in a sample of pine seed oil (Pinus contorta) by gas-liquid chromatography-mass spectrometry of its picolinyl ester derivative. Its identification (through its equivalent chain length) and its distribution in four conifer families have been checked. It occurred only in Pinaceae, where it was found in 72 species belonging to the genera Pinus, Abies, Cedrus, Tsuga, Pseudotsuga, Larix, and Picea, in the range 0.02-1.15%. 14-MHD acid could not be detected in the lipids of Taxaceae (Taxus baccata), Cupressaceae (Juniperus communis), or Taxodiaceae (Sciadopytis verticillata), even after a 10-fold concentration of the saturated acid fraction isolated by argentation thin-layer chromatography. It is concluded that Pinaceae, along with Ginkgo biloba seed lipids, are major exceptions in the plant kingdom with regard to 14-MHD acid, which otherwise occurs almost exclusively in lipids of animals and microorganisms. The biosynthesis and metabolic role of 14-MHD acid, which otherwise also occur in wood and leaf lipids, remain unknown.

Chromatography, Thin Layer↗
PubMed2005

Nuclear ribosomal DNA internal transcribed spacer 1 (ITS1) in Picea (Pinaceae): sequence divergence and structure.

The nrDNA ITS1 of Picea is 2747-3271 bp, the longest known of all plants. We obtained 24 cloned ITS1 sequences from six individuals of Picea glehnii, Picea mariana, Picea orientalis, and Picea rubens. Mean sequence divergence within these individuals (0.018+/-0.009) is more than half that between the species (0.031+/-0.011) and may be maintained against concerted evolution by separation of Picea 18S-26S rDNA repeats on multiple chromosomes. Picea ITS1 contains three subrepeats with a motif (5'-GGCCACCCTAGTC) that is conserved across Pinaceae. Two subrepeats are tandem, remote from the third, and more closely related and significantly more similar to one another than either is to the third subrepeat. This correlation between similarity and proximity may be the result of subrepeat duplication or concerted evolution within rDNA repeats. In inferred secondary structures, subrepeats generally form long hairpins, with a portion of the Pinaceae conserved motif in the terminal loop, and tandem subrepeats pair with one another over most of their length. Coalescence of ITS1 sequences occurs in P. orientalis but not in the other species.

Base Sequence↗
PubMed2000

Cuticle Micromorphology of Pinus krempfii Lecomte (Pinaceae) and Additional Species from Southeast Asia.

Cuticle micromorphology of the unusual Vietnamese pine, Pinus krempfii Lecomte, and three additional endemic southeast Asian species of Pinus L. (Pinaceae) is characterized for the first time. Taxa studied include (1) P. krempfii, typically placed in its own subgenus Ducampopinus (Chevalier) Ferré ex Little & Critchfield; (2) the endemic Vietnamese species Pinus dalatensis Ferré and (3) the southeast Asian species Pinus kwantungensis Chun ex Tsiang, both of subgenus Strobus; and (4) the widespread Asian species Pinus kesiya Royle ex Gordon of subgenus Pinus. The current and previous studies demonstrate that the genus Pinus and its subgenera are delimited by unique combinations of cuticular characters, although some of these characters may occur individually in other conifers. Cuticular micromorphology supports taxonomic assignment of P. krempfii to subgenus Strobus rather than to its own subgenus, a result that is also indicated by other anatomical studies and recent molecular studies. Sectional affinities of P. krempfii are usually with Parrya, subsection Krempfianae. An alternative classification of P. krempfii with subsection Gerardianae can be supported by micromorphological characters including broad cuticular bridges between stomata, details of the intercellular flanges of the epidermal cells, and usually an amphistomatic stomatal distribution. Features of other Asian species studied are consistent with their taxonomic assignments. The study demonstrates the utility of cuticle micromorphology to taxonomic delimitation within the family Pinaceae.

Journal Article↗
PubMed1999

[Terpenoids and steroids from several euphorbiaceae and pinaceae plants].

During the course of a search for biologically active constituents from unexamined plant sources, several biogenetically interesting new di- and tri-terpenes and steroids were isolated from several weeds and shrubs of Euphorbiaceae and the bark, leaves and cones of several Pinaceae trees which had been treated as wastes in the forestry industry. Euphorbia supina contained 3,4-seco-5 alpha- and 5 beta-adian-4(23)-ene-3,5-diols and related oxides, oxygenated fern-8-en-3 beta-ols named supinenolones A-E and unusually migrated oxyfernanes having (9S)- and (9R)-7(8-->9)abeo-9-D:C-friedo-B':A'-neogammacerane skeletons named spirosupinane and neospirosupinane, while E. chamaesyce contained 3,4-seco-oleana-4(23), 18-dien-3-oic acid, 3,4-seco-8 beta H-ferna-4(23),9(11)-dien-3-oic acid and two oxygenated obtusifoliols. The bark of Phyllanthus flexuosus (Euphorbiaceae) contained 11 beta-hydroxy-D:A-friedo-olean-1-en-3-one, lup-20(29)-ene-3 beta, 15 alpha-diol, olean-12-ene-3 beta,15 alpha-diol and olean-12-ene-3 beta,15 alpha,24-triol together with trichadenic acid B for which we revised the structure to 3 beta-hydroxy-D:A-friedo-oleanan-27-oic acid. Two 26-nor-D:A-friedo-olean-14-enes were isolated from P. watsonii. Regarding Pinaceae trees, an unusually migrated abieslactone [(3R, 7S, 9R, 23R)-7-hydroxy-3-methoxy-8-oxo-7(8-->9)abeo-lanost-24-eno-26,23-lactone], named spiroveitchionolide, was isolated from the bark of Abies species, besides nine abieslactone analogues. Two pairs of unusually migrated serratanes, piceanonols A and B and jezananals A and B having novel skeletal systems of 14(13-->12) abeo- and 16(15-->14) abeo-serratanes named piceanane and jezanane, respectively, were also isolated from the stem bark of Picea species, besides three 14 beta,15 beta-epoxyserratanes and two 13 alpha,14 alpha-epoxyserratanes. The leaves of Larix kaempferi contained two deformed abietanes named karamatsuic acid (9,10-seco-9,10 alpha-epoxyabieta-8,11,13-trien-18-oic acid) and larikaempferic acid [9 alpha,13 alpha-epoxy-8-oxo-9(8-->7)abeo-7 beta-abietan-18-oic acid], as well as the cones to contain 8 alpha,12 alpha-epidioxy-15-hydroxyabiet-13-en-18-oic acid, three diepoxy-abietan-18-oic acids and two new dehydroabietic acid analogues. Several of the above compounds exhibited inhibitory effects against tumor-promoting and DNA topoisomerase II activities.

Animals↗
PubMed1999

Internal transcribed spacer region evolution in Larix and Pseudotsuga (Pinaceae).

The nuclear ribosomal DNA (nrDNA) internal transcribed spacer (ITS) region has been characterized in the sister genera Larix and Pseudotsuga (Pinaceae). Complete sequences were obtained for seven species of Larix from North America and Eurasia and five species of Pseudotsuga from western North America and eastern Asia. ITS region lengths ranged from 1759 to 1770 bp in Larix and from 1564 to 1571 bp in Pseudotsuga. In both genera, ITS1 is three times as long as the 5.8S plus ITS2 and contains subrepeats as observed in other genera of Pinaceae. Secondary structure models predicted that the subrepeats fold into terminal stem and loop domains. ITS polymorphism detected within individuals of Larix and Pseudotsuga suggests a slow rate of concerted evolution among nrDNA loci. Except for the placement of L. sibirica, phylogenetic analyses of the ITS region agreed with previously reported restriction site analyses of Larix and Pseudotsuga. The data were not consistent with phylogenetic hypotheses for Larix based primarily upon ovulate cone characters, failing to support a derivation of the North American L. laricina from a short-bracted Eurasian lineage. The phylogenetic hypothesis did not conflict with a stepping stone model of evolution for Pseudotsuga, but a basal lineage could not be inferred for either genus.

Journal Article↗
PubMed1999

Phylogenetic relationships of Eurasian pines (Pinus, Pinaceae) based on chloroplast rbcL, MATK, RPL20-RPS18 spacer, and TRNV intron sequences.

The sequence divergence of chloroplast rbcL, matK, trnV intron, and rpl20-rps18 spacer regions was analyzed among 32 Pinus species and representatives of six other genera in Pinaceae. The total aligned sequence length is 3570 bp. Of the four sequences examined, matK evolved much faster than rbcL in Pinus and in other Pinaceae genera. The two noncoding regions did not show more divergence than the two coding regions, especially within each Pinus subgenus. Phylogenetic analyses based on these four sequences gave consistent results and strongly supported the monophyly hypothesis for the genus Pinus and its two recognized subgenera. Pinus krempfii, the two-flat-needle pine endemic to Vietnam, was placed in subgen. Strobus and showed closer affinity to subsect. Gerardianae. The ancient character of sect. Parrya is further confirmed. However, monophyly of the sect. Parrya is not supported by our data. Among the Eurasian pines of subgen. Pinus, Mediterranean pines formed one clade and the Asian members of subsect. Sylvestres formed another. The Himalayan P. roxburghii showed considerable divergence from all the other hard pines from both regions. Pinus merkusii was distinctly separated from all the Asian members of subsect. Sylvestres. The implications of our results for Pinus classification are discussed.

Journal Article↗
PubMed2001

Fatty acid composition of Pinaceae as taxonomic markers.

Following our previous review on Pinus spp. seed fatty acid (FA) compositions, we recapitulate here the seed FA compositions of Larix (larch), Picea (spruce), and Pseudotsuga (Douglas fir) spp. Numerous seed FA compositions not described earlier are included. Approximately 40% of all Picea taxa and one-third of Larix taxa have been analyzed so far for their seed FA compositions. Qualitatively, the seed FA compositions in the three genera studied here are the same as in Pinus spp., including in particular the same delta5-olefinic acids. However, they display a considerably lower variability in Larix and Picea spp. than in Pinus spp. An assessment of geographical variations in the seed FA composition of P. abies was made, and intraspecific dissimilarities in this species were found to be of considerably smaller amplitude than interspecific dissimilarities among other Picea species. This observation supports the use of seed FA compositions as chemotaxonomic markers, as they practically do not depend on edaphic or climatic conditions. This also shows that Picea spp. are coherently united as a group by their seed FA compositions. This also holds for Larix spp. Despite a close resemblance between Picea and Larix spp. seed FA compositions, principal component analysis indicates that the minor differences in seed FA compositions between the two genera are sufficient to allow a clear-cut individualization of the two genera. In both cases, the main FA is linoleic acid (slightly less than one-half of total FA), followed by pinolenic (5,9,12-18:3) and oleic acids. A maximum of 34% of total delta5-olefinic acids is reached in L. sibirica seeds, which appears to be the highest value found in Pinaceae seed FA. This apparent limit is discussed in terms of regio- and stereospecific distribution of delta5-olefinic acids in seed triacylglycerols. Regarding the single species of Pseudotsuga analyzed so far (P. menziesii), its seed FA composition is quite distinct from that of the other two genera, and in particular, it contains 1.2% of 14-methylhexadecanoic (anteiso-17:0) acid. In the three genera studied here, as well as in most Pinus spp., the C18 delta5-olefinic acids (5,9-18:2 and 5,9,12-18:3 acids) are present in considerably higher amounts than the C20 delta5-olefinic acids (5,11-20:2 and 5,11,14-20:3 acids).

Biomarkers↗
PubMed2003

Marked intragenomic heterogeneity and geographical differentiation of nrDNA ITS in Larix potaninii (Pinaceae).

Nuclear ribosomal DNA (nrDNA) of gymnosperms, especially Pinaceae, is characterized by slow concerted evolution and exhibits substantial ITS-region length variation (975-3663 bp), in sharp contrast to the narrow range (565-700 bp) in angiosperms. Here we examined intra- and intergenomic heterogeneity of the nrDNA internal transcribed spacer (ITS) region in four varieties of Larix potaninii, a species from the mountainous areas of western China. Two clones with more than a 100-bp deletion in ITS1 were detected in L. potaninii var. chinensis and L. potaninii var. australis, respectively. The deletion resulted in the loss of most part, including the motif sequence, of subrepeat 1 (SR1). Sequence divergence and phylogenetic analyses showed that some clones would be pseudogenes given their low GC content, high substitution rates, unique positions in the phylogenetic trees, or significant length variation. These clones might represent orphons or paralogues at minor loci resulting from large-scale gene or chromosome reorganization. Some recombinants characterized by chimeric structure and discordant phylogenetic positions in partitioned sequence analyses indicate that unequal crossing-over plays an important role in the process of nrDNA concerted evolution. In addition, some varieties of L. potaninii might have experienced an nrDNA founder effect parallel to their geographical isolation.

Base Composition↗