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PubMed2003

[Quantitative analysis on sharp-tooth oak stands in Qinling Mountains].

The arbor stratum of Quercus aliena var. acuteserrata stands included two substratums. Phanerophyta synusium was in first position, and hemicryptophyta was inferior to it. The DBH structures of Quercus aliena var. acuteserrata and Pinus armandii were sinister normal school, which could finish self-regeneration under the natural conditions. The small DBH class individuals of Pinus tabulaeformis were dominant, their DBH classes being distributed irregularly and absent very much. The large DBH classes of Toxicodendron vernicifluum took biggish proportion, belonging to declining population. Young trees were the principal individuals of Castanea mollissima, and in transitional age stage from the young to the middle. Populus davidiana was in the transitional stage from progressive to stable and young-middle age stands. The stands DBH structure was mainly influenced by the DBH variety of Quercus aliena var. acuteserrata population. Quantitative classification (ward's method ward) and ordination (PCA) were used to study the community types of sharp-tooth oak. The results showed that the community could be divided into 6 types: 1. Ass. Smilax stans + Rosa multiflora-Quercus variabilis + Ulmus glaucescens-Quercus aliena var. acuteserrata; 2. Ass. Smilax stans + Lespedeza bicolor-Castanea mollissima-Q. aliena var. acuteserrata; 3. Ass. Corylus mandshurica-Populus davidiana + Dendrobenthamia angustata-Q. aliena var. acuteserrata; 4. Ass. Prunus pseudoccrasus + Corylus mandshurica-Toxicodendron vernicifluum-Q. aliena var. acuteserrata; 5. Ass. Corylus mandshurica + Rosa multiflora-Pinus armandii-Q. aliena var. acuteserrata; and 6. Ass. Sinarundinaria nitida-Pinus armandii + Pinus tabulaeformis-Q. aliena var. acuteserrata. Ward's method ward was better for classifying community types than the other clustering analyses in Qinling Mountains. The PCA results were consistent with the clustering, and demonstrated that the sharp-tooth oak stands were influenced by the altitude, site gradient and soil mainly.

China↗

PubMed2006

Light quality treatments enhance somatic seedling production in three southern pine species.

Embryogenic cultures of loblolly pine (Pinus taeda L.), slash pine (Pinus elliottii Engelm.), longleaf pine (Pinus palustris Mill.) and slash pine x longleaf pine hybrids were initiated from immature seeds on an initiation medium containing 13.57 microM 2,4-dichlorophenoxyacetic acid and 2.22 microM benzylaminopurine. Embryogenic cultures proliferated and somatic embryos developed, matured and germinated following a modified protocol and media originally developed for radiata pine (Pinus radiata D. Don.) somatic seedling production. A discrete, light-sensitive pre-germination stage and a later germination (radicle emergence) stage were identified by the differential response of somatic embryos to light of different wavelengths. Different light quality treatments were applied during the pre-germination and germination steps, using cool white fluorescent bulbs or light-emitting diodes (LEDs), or both. In general, red wavelengths provided by LEDs during these steps resulted in higher frequencies of somatic embryo germination (up to 64%) and conversion (up to 50%), longer tap roots and more first-order lateral roots than the standard cool white fluorescent treatments or treatment with blue wavelengths from LEDs. In addition, exposure to red light allowed germination of somatic embryos of some clones that failed to produce germinants under fluorescent light. Germination and conversion were further enhanced by sequential application of cool white fluorescent light and red light, resulting in up to 100% germination and conversion in one experiment. Longleaf pine somatic embryos were especially responsive to the light quality treatments, resulting in the first report of somatic seedling production for this species.

2,4-Dichlorophenoxyacetic Acid↗

PubMed2006

The use of compost in afforestation of Mediterranean areas: Effects on soil properties and young tree seedlings.

In Mediterranean frequently burnt areas, fire and erosion result in the decrease of soil fertility, so afforestation is a major concern. We carried out an in situ experiment of compost amendment to improve survival and growth of planted tree seedlings. One-year-tree seedlings of native species (Quercus ilex, Pinus halepensis and Pinus pinea) were planted on a frequently burnt calcareous site. Three rates of fresh co-composted sewage sludge and greenwastes (control without compost, 20 and 40 kg m(-2) of compost) were incorporated into the soil at each seedling stem. Changes of soil properties and tree development were studied during 3 years (2001-2003) and 2 years (2002-2003) respectively. The compost improved survival of Quercus ilex and Pinus pinea seedlings in severe drought conditions, but had no effect on Pinus halepensis. For all species seedling length and radial growth and NPK nutrition were increased for both rates of amendment. Amendment improved soil fertility, but available P concentration increased 13 fold in the neighbouring soil of seedlings amended at the maximal rate compared to control. However, amendment did not significantly increase concentrations of Cd, Cr, Ni and Pb in soils or tree seedlings. It increased Cu and Zn total and available concentrations in soils, while foliar Cu and Zn concentrations in the seedlings remained similar in all plots. Compost can efficiently help afforestation of dry soils with low organic matter content. However, sewage sludge concentrations in P, and to a lesser extent in Cu and Zn, limit rates of application that can be applied without environmental hazard.

Agriculture↗

PubMedDate not supplied

Fatty acid composition of two Tunisian pine seed oils.

Oils were extracted from fully ripen Pinus pinea L. and Pinus halepensis Mill seeds and fatty acid composition has been established by capillary gas chromatography. Seeds are rich in lipids, 34.63-48.12% on a dry weight basis. Qualitatively, fatty acid composition of both species is identical. For P. halepensis linoleic acid is the major fatty acid (56.06% of total fatty acids) followed by oleic (24.03%) and palmitic (5.23%) acids. For P. pinea, the same fatty acids are found with the proportions 47.28%, 36.56%, and 6.67%, respectively. Extracted fatty acids from both species are mainly unsaturated, respectively, 89.87% and 88.01%. Pinus halepensis cis-5 olefinic acids are more abundant (7.84% compared to 2.24%). Results will be important as a good indication of the potential nutraceutical value of Pinus seeds as new sources of fruit oils rich in polyunsaturated fatty acids and cis-5 olefinic acids.

Fatty Acids↗

PubMed2006

Effectiveness of bifenthrin (Onyx) and carbaryl (Sevin SL) for protecting individual, high-value conifers from bark beetle attack (Coleoptera: Curculionidae: Scolytinae) in the Western United States.

High-value trees, such as those located in residential, recreational, or administrative sites, are particularly susceptible to bark beetle (Coleoptera: Curculionidae: Scolytinae) attack as a result of increased amounts of stress associated with drought, soil compaction, mechanical injury, or vandalism. Tree losses in these unique environments generally have a substantial impact. The value of these individual trees, cost of removal, and loss of esthetics may justify protection until the main thrust of a bark beetle infestation subsides. This situation emphasizes the need for ensuring that effective insecticides are available for individual tree protection. In this study, we assess the efficacy of bifenthrin (Onyx) and carbaryl (Sevin SL) for protecting: ponderosa pine, Pinus ponderosa Dougl. ex. Laws., from western pine beetle, Dendroctonus brevicomis LeConte, in California; mountain pine beetle, Dendroctonus ponderosae Hopkins in South Dakota; and Ips spp. in Arizona; lodgepole pine, Pinus contorta Dougl. ex Loud., from D. ponderosae in Montana; pinyon, Pinus edulis Engelm. in Colorado and Pinus monophylla Torr. and Frem. in Nevada from pinyon ips, Ips confusus (LeConte); and Engelmann spruce, Picea engelmannii Parry ex. Engelm. from spruce beetle, Dendroctonus rufipennis (Kirby) in Utah. Few trees were attacked by Ips spp. in Arizona and that study was discontinued. Sevin SL (2.0%) was effective for protecting P. ponderosa, P. contorta, and P. monophylla for two field seasons. Estimates of efficacy could not be made during the second field season in P. edulis and P. engelmannii due to insufficient mortality in untreated, baited control trees. Two field seasons of efficacy was demonstrated in P. ponderosa/D. brevicomis and P. monophylla for 0.06% Onyx. We conclude that Onyx is an effective individual tree protection tool, but repeated annual applications may be required in some systems if multiyear control is desired.

Animals↗

PubMed2002

[Characteristics of canopy patches related to natural regeneration of broad-leaved Korean pine forest].

The characteristics of canopy patches of dominant tree species in a broad-leaved Korean pine forest at an elevation of 740 m in north slope of Changbai mountain was investigated to understand the effects of canopy patch on the structure and regeneration of the forest. The results showed that the main species that constituted the canopy patches were Pinus koraiensis, Tilia amurese, Acer mono and Quercus mongolica, their canopy patches covered 57.1% of the forest, and 87% of the total area of the canopy. Most canopy patches were less than 100 m2, with irregular shapes. The seedlings and saplings of Acer mono were distributed under almost all canopy patches of Tilia amurense and Pinus koraiensis, and reached the maximum densities under canopy patch of Tilia amurense of 32 m2, and patch of Pinus koraiensis of 28 m2. However, the seedlings and saplings of Tilia amurense were distributed only under a few canopy patches of Tilia amurense and Pinus koraiensis.

Acer↗

PubMed2006

[Species diversity and community structure of forest communities in Lishan Mountain].

Lishan Mountain is belonged to the Zhongtiao Ranges in Southeast Shanxi, and situated between 35 degrees 16'30" - 35 degrees 27'20" N and 111 degrees 51'-- 112 degrees 5'35" E. The climate is cool and arid in winter, but warm and rainy in summer. This paper studied the species diversity and community structure of forest communities there, based on field investigation data and by using diversity, richness and evenness indices. The results showed that the species diversity and evenness of the communities were in the order of Acer davidii + Acer mono > Acer davidii + Carpinus turczaninouii > Quercus liaolugensis > Quercus varibilis > Pinus armandii + Betula albo-sinensis > Pinus tabulaeformis + Quercus glandulifera > Betula platyphylla > Platycladus orientalis + Quercus variabilis > Betula albo-sinensis > Pinus armandii > Platycladus orientalis > Pinus tabulaeformis > Populus davidiana + Betula albo-sinensis. The diversity and richness of shrub layer were higher than those of herb layer and arbor layer, but the evenness of arbor, shrub and herb layers had no significant difference. There were positive correlations (P < 0.05) between Shannon-Wiener index, Hill index, and species richness from 1 000 m to 1 920 m above sea level, but negative correlations (P < 0.05) from 1920 m to the top of the Mountain. The species diversity showed a "mid-altitude bulge" pattern with the change of altitude, and the reason was that the combination of temperature and moisture conditions from 1000 m to 1920 m above sea level was improved, and human disturbance was decreased gradually.

Acer↗

PubMed1994

Construction of genetic maps for some Eurasian coniferous species using allozyme genes.

In an analysis of allozyme genes in three pine and one spruce species distributed in Eurasia, 45 of 87 loci were mapped. Four linkage groups in Pinus sylvestris and Picea abies, three in Pinus pallasiana, and two in Pinus pumila were determined. The order and the locations of homologous genes in the linkage groups in the different species were similar. The data suggest that during the separate development of the Pinus and Picea genera that has lasted for millions of years, there was not any large inversion, translocation, or other significant chromosomal change, at least in the gene blocks analyzed.

Commonwealth of Independent States↗

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↗

PubMed1995

Polymorphic simple sequence repeat regions in chloroplast genomes: applications to the population genetics of pines.

Simple sequence repeats (SSRs), consisting of tandemly repeated multiple copies of mono-, di-, tri-, or tetranucleotide motifs, are ubiquitous in eukaryotic genomes and are frequently used as genetic markers, taking advantage of their length polymorphism. We have examined the polymorphism of such sequences in the chloroplast genomes of plants, by using a PCR-based assay. GenBank searches identified the presence of several (dA)n.(dT)n mononucleotide stretches in chloroplast genomes. A chloroplast (cp) SSR was identified in three pine species (Pinus contorta, Pinus sylvestris, and Pinus thunbergii) 312 bp upstream of the psbA gene. DNA amplification of this repeated region from 11 pine species identified nine length variants. The polymorphic amplified fragments were isolated and the DNA sequence was determined, confirming that the length polymorphism was caused by variation in the length of the repeated region. In the pines, the chloroplast genome is transmitted through pollen and this PCR assay may be used to monitor gene flow in this genus. Analysis of 305 individuals from seven populations of Pinus leucodermis Ant. revealed the presence of four variants with intrapopulational diversities ranging from 0.000 to 0.629 and an average of 0.320. Restriction fragment length polymorphism analysis of cpDNA on the same populations previously failed to detect any variation. Population subdivision based on cpSSR was higher (Gst = 0.22, where Gst is coefficient of gene differentiation) than that revealed in a previous isozyme study (Gst = 0.05). We anticipate that SSR loci within the chloroplast genome should provide a highly informative assay for the analysis of the genetic structure of plant populations.

Base Sequence↗

PubMed2006

Effects of low-carbohydrate diet and Pycnogenol treatment on retinal antioxidant enzymes in normal and diabetic rats.

Because chronic hyperglycemia of uncontrolled diabetes mellitus may lead to increased reactive oxygen species and decreased enzymatic antioxidant defenses responsible for pathological processes in diabetic retinopathy, this study examined the hypothesis that a low-carbohydrate, high-fat diet, either alone or in combination with Pinus maritima can reduce hyperglycemia, restoring a more balanced, oxidative condition. Normal and streptozotocininduced diabetic rats were fed either a regular or low-carbohydrate diet for 30 or 90 d. In addition, normal and diabetic rats on the chronic (90-d) low-carbohydrate diet were treated with daily intraperitoneal Pinus maritima doses (10 mg/kg) for 14 consecutive days. Retinas were fractionated to assay activities of glutathione peroxidase, glutathione reductase, and gamma-glutamyl transferase. After 30 d, the low-carbohydrate diet reduced glycemic parameters and normalized aspartate aminotransferase activity in diabetic animals, suggesting less organ damage. No differences were observed between males and females in any measured glycemic parameters. Whereas all diabetic control animals developed cataracts bilaterally, no treated diabetic animals developed cataracts. There were no deleterious effects on retinal antioxidant defenses with either a 30-d or chronic low-carbohydrate diet. When diet was combined with Pinus maritima treatment, both retinal glutathione peroxidase and glutathione reductase activities increased, suggesting that a low-carbohydrate diet plus Pinus maritima may be an effective antioxidant and antihyperglycemic therapy, reducing the risk of diabetic retinopathy and cataract formation.

Animals↗

PubMed1993

Canopy dynamics and aboveground production of five tree species with different leaf longevities.

Canopy dynamics and aboveground net primary production (ANPP) were studied in replicated monospecific and dual-species plantations comprised of species with different leaf longevities. In the monospecific plantations, leaf longevity averaged 5, 6, 36, 46 and 66 months for Quercus rubra L., Larix decidua Miller, Pinus strobus L., Pinus resinosa Ait. and Picea abies (L.) Karst., respectively. Specific leaf area, maximum net photosynthesis per unit mass (A/mass), leaf N per unit mass (N(leaf)/mass) and maximum net photosynthesis on a leaf N basis (A/N(leaf)) were inversely correlated to leaf longevity (r(2) = 0.92-0.97, 0.91, 0.88 and 0.80, respectively). Maximum net photosynthesis per unit area (A/area) was not correlated to leaf longevity, whereas leaf N per unit area (N(leaf)/area) was positively correlated to leaf longevity (r(2) = 0.95). For a similar-diameter conifer, species with long-lived foliage supported a greater foliage mass than species with short-lived foliage; however, Quercus rubra did not follow this pattern. At the stand level, total foliage mass ranged from 3.3 to 30.5 Mg ha(-1) and was positively correlated (r(2) = 0.97) to leaf longevity. Leaf area index (LAI) was also positively correlated (r(2) = 0.82) to leaf longevity. Production efficiency (ANPP/LAI) was inversely related to leaf longevity and positively related to A/mass. Aboveground biomass and net primary production differed significantly (P < 0.05) among the five species but were not correlated to leaf longevity, total foliage mass or leaf area. In monospecific plantations, stem NPP for Larix decidua was 17% greater than for Pinus strobus and 14% less than for Picea abies, but in mixed-species plantations stem NPP for Larix decidua was 62 and 85% greater than for Pinus strobus and Picea abies, respectively. Similar aboveground net primary production rates can be attained by tree species with different leaf longevities because of trade-offs resulting from different structural and physiological leaf and canopy characteristics that are correlated to each other and to leaf longevity.

Journal Article↗

PubMed1968

Enzymes of glyoxylate in conifers.

The high level of lipids in seeds of some species of conifers suggested that the glyoxylate cycle might have a role in conifer seed metabolism.Six species (Pinus pinea, Pinus pinaster, Pinus canariensis, Pinus strobus, Abies alba, and Cupressus sempervirens) were investigated for their lipid content and malate synthase and isocitrate lyase level. The fatty acid composition of the triglyceride fraction was also investigated. The correlation between lipid content of germinating seed with the presence of the cycle was confirmed. The enzymes of the glyoxylate cycle were not detected in Cupressus sempervirens where the lipid content is very low.

Journal Article↗

PubMed2003

[Dust absorption effect of urban conifers in northeast China].

Dust pollution is much heavier in winter than in other seasons in the cities of Northeast China, because the urban heating system consumes mainly coal as energy resources. Deciduous trees can hardly absorb dust because of their defoliation, and hence, urban conifer trees become more important in dust absorption in winter. This paper studied the dust absorption ability of 7 conifers under the same and different dust pollution status in Shenyang city, Northeast China. The results showed that the dust absorption ability of conifers was decreased in the order of Abies holophilla > Picea mongolica > P. koraiensis > Taxus cupidata > Pinus bungeana > P. armandi > P. tabulaeformis. Different conifers had different surface structures. Pinus bungeana, P. armandi and P. tabulaeformis had smooth surfaces, their cells and stomata arranged in order, and hence, their dust absorption ability was poor. P. koraiensis, Abies holophilla and Taxus cupidata had coarse surfaces, and their cells and stomata arranged out of order. There were even many tubercular things on the surface of P. koraiensis, and hence, their dust absorption ability was stronger. The dust absorption ability of conifers was related the shape of their leaf sections. The upper leaf surface of Pinus bungeana and P. tabulaeformis was arc, not opted to absorb the dust. The leaf section of P. armandi was prism, and its upper surface was narrow, and hence, its dust absorption ability was also poor. The leaves of Picea mongolica and P. koraiensis had four edges, their upper surfaces were broader and flatter than the former three species, and hence, they had stronger dust absorption ability. The leaf section's shape of Abies holophilla and Taxus cupidata was also broad and flat, which made the dust absorption ability of the two latter's was stronger than other three Pinus species and two Picea species.

Absorption↗

PubMed2006

[Pollen assemblage and palaeo-vegetation of Late holocene fen in Dunhua of Jilin Province].

Based on the study of pollen, stratum and 14C dating of Daqiao fen in Dunhua of Jilin Province, four pollen zones were distinguished, i.e., Pinus-Picea-Abies assemblage (2195 +/- 70 to appromimately 2045 +/- 70 B. P., Carex-Pinus-BetulaCorylus-Juglans assemblage (2045 +/- 70 to appromimately 1745 +/- 70 B.P.), Pinus-Corylus-Carpinus-Carex-Ranunculus assemblage (1745 +/- 70 to appromimately 705 +/- 70 B.P.), and Pinus-Picea-Abies-Betula-Carex assemblage (705 +/- 70 to appromimately 1950 AD). The vegetation changed from coniferous forest (similar to the vegetation currently foundover 1100 m a.s. 1. in this area), through conifer-broad-leaved mixed forest (similar to the vegetation currently found between 400-600 m a.s.l.) and conifer-broad-leaved mixed forest (similar to the vegetation currently found between 600-800 m a.s.l.), to conifer-broad-leaved mixed forest (similar to the vegetation currently found between 800-1100 m a.s.l.). Accordingly, Daqiao fen underwent the periods of gestation, fast development, expansion, and dieing out.

China↗

PubMed2003

Complex population genetic structure in the endemic Canary Island pine revealed using chloroplast microsatellite markers.

The Canary archipelago, located on the northwestern Atlantic coast of Africa, is comprised of seven islands aligned from east to west, plus seven minor islets. All the islands were formed by volcanic eruptions and their geological history is well documented providing a historical framework to study colonization events. The Canary Island pine ( Pinus canariensis C. Sm.), nowadays restricted to the westernmost Canary Islands (Gran Canaria, Tenerife, La Gomera, La Palma and El Hierro), is considered an old (Lower Cretaceous) relic from an ancient Mediterranean evolutionary centre. Twenty seven chloroplast haplotypes were found in Canary Island pine but only one of them was common to all populations. The distribution of haplotypic variation in P. canariensis suggested the colonization of western Canary Islands from a single continental source located close to the Mediterranean Basin. Present-day populations of Canary Island pine retain levels of genetic diversity equivalent to those found in Mediterranean continental pine species, Pinus pinaster and Pinus halepensis. A hierarchical analysis of variance (AMOVA) showed high differentiation among populations within islands (approximately 19%) but no differentiation among islands. Simple differentiation models such as isolation by distance or stepping-stone colonization from older to younger islands were rejected based on product-moment correlations between pairwise genetic distances and both geographic distances and population-age divergences. However, the distribution of cpSSR diversity within the islands of Tenerife and Gran Canaria pointed towards the importance of the role played by regional Pliocene and Quaternary volcanic activity and long-distance gene flow in shaping the population genetic structure of the Canary Island pine. Therefore, conservation strategies at the population level are strongly recommended for this species.

Atlantic Islands↗

PubMed2004

Cross-amplification and sequence variation of microsatellite loci in Eurasian hard pines.

Microsatellite transfer across coniferous species is a valued methodology because de novo development for each species is costly and there are many species with only a limited commodity value. Cross-species amplification of orthologous microsatellite regions provides valuable information on mutational and evolutionary processes affecting these loci. We tested 19 nuclear microsatellite markers from Pinus taeda L. (subsection Australes) and three from P. sylvestris L. (subsection Pinus) on seven Eurasian hard pine species ( P. uncinata Ram., P. sylvestris L., P. nigra Arn., P. pinaster Ait., P. halepensis Mill., P. pinea L. and P. canariensis Sm.). Transfer rates to species in subsection Pinus (36-59%) were slightly higher than those to subsections Pineae and Pinaster (32-45%). Half of the trans-specific microsatellites were found to be polymorphic over evolutionary times of approximately 100 million years (ten million generations). Sequencing of three trans-specific microsatellites showed conserved repeat and flanking regions. Both a decrease in the number of perfect repeats in the non-focal species and a polarity for mutation, the latter defined as a higher substitution rate in the flanking sequence regions close to the repeat motifs, were observed in the trans-specific microsatellites. The transfer of microsatellites among hard pine species proved to be useful for obtaining highly polymorphic markers in a wide range of species, thereby providing new tools for population and quantitative genetic studies.

Alleles↗

PubMed2005

Effects of tree phytochemistry on the interactions among endophloedic fungi associated with the southern pine beetle.

We examined the interaction between host trees and fungi associated with a tree-killing bark beetle, Dendroctonus frontalis. We evaluated (1) the response of four Pinus species to fungal invasion and (2) the effects of plant secondary metabolites on primary growth of and secondary colonization of three consistent fungal associates. Two of these fungi, Entomocorticium sp. A and Ophiostoma ranaculosum, are obligate mutualists with D. frontalis, and the third associate is a blue-staining fungus, O. minus, that is commonly introduced by beetles and phoretic mites. O. minus negatively affects beetle larvae and in high abundance can impact D. frontalis population dynamics. Size of lesions formed and quantity of secondary metabolites produced in response to fungal inoculations varied significantly among Pinus species. However, monoterpene composition within infected tissue did not significantly vary across treatments. While all eight tested metabolites negatively affected the growth rate of O. minus, only 4-allylanisole, p-cymene, and terpinene reduced the growth of the mycangial fungi. Surprisingly, growth rates of mycangial fungi increased in the presence of several secondary metabolite volatiles. O. minus out-competed both mycangial fungi, but the presence of secondary metabolites altered the outcome slightly. O. ranaculosum out-performed E. sp. A in the presence of dominant conifer monoterpenes, such as alpha- and beta-pinene. Volatiles from the mycangial fungi, particularly E. sp. A, had a negative effect on O. minus growth. In general, phloem phytochemistry of particular Pinus species appeared to alter the relative growth and competitiveness of mutualistic and non-mutualistic fungi associated with D. frontalis. The outcome of interactions among these fungi likely has important consequences for the population dynamics of D. frontalis.

Animals↗