On the question of natural hybridization between Pinus discolor and Pinus cembrides

Sixty Pinus cembroides and P. discolor trees from two mixed stands and eight pure stands were analysed for the composition of their wood monoterpenes, number of abaxial and adaxial stomatal rows and the number of needles per fascicle. While by far the majority of the characters analysed showed highly significant differences between the two species, only the sum of thujene, sabinene, γ-terpenene, terpinolene and p-cymene percentages, the sum of myrcene and cis-ocimene percentages, the number of abaxial stomatal rows, and the number of needles per fascicle could be used to evaluate the potential intermediacy of trees from the common sites. The results indicated the absence of any hybridization in the Sierra de la Catarina Mountains of Chihuathua (Mexico) and either a possible minute introgression of P. cembroides into P. discolor in the San Miguelito Mountains of San Luis Potosi (Mexico) or a slightly different genetic composition of the trees from this site. The results strongly support the proposal of Bailey and Hawksworth to regard P. discolor as a distinct species.     

Characterization of α-pinene synthase gene in <Emphasis Type="Italic">Pinus pinaster</Emphasis> and <Emphasis Type="Italic">P. pinea</Emphasis> in vitro cultures and differential gene expression following <Emphasis Type="Italic">Bursaphelenchus xylophilus</Emphasis> inoculation

Pinus pinaster and P. pinea are two important pine species in Portugal. These two pine species show different susceptibility to Bursaphelenchus xylophilus, the nematode causing pine wilt disease, as well as a diverse volatile composition. To clarify the role of terpenes in plant–nematode interactions, the α-pinene synthase gene expression was studied, using P. pinaster and P. pinea in vitro axenic shoot cultures. Identification and isolation of α-pinene synthase genes from both pine species was performed, together with functional characterization of the genes, revealing that the translated amino acid sequences between both species shared 97.3 % pairwise identity. Heterologous expression of full and truncated sequences, devoid of the 48 amino acids of the transit peptide, proved the functionality of both, with the production of α-pinene as the major final product. Relative quantification of protein activity showed a twofold increase of α-pinene production at 4 °C in comparison to assays performed at 21 and 37 °C. Both MnCl₂ and KCl were required for substrate conversion. Furthermore, the variation in gene expression was studied by RT-PCR, using both axenic in vitro shoot pine cultures and co-cultures with B. xylophilus. In P. pinaster there was no difference between co-cultures and control cultures, while in P. pinea α-pinene synthase gene was upregulated in the co-cultures, with a peak of expression at 24 hpi (h post inoculation).     

Genetic structure of Pinus pinaster Ait. populations in Morocco revealed by nuclear microsatellites

Pinus pinaster is one of the most popular conifers used for reforestation in Morocco and represents an economically and ecologically important species for the region. In this study, nuclear microsatellites (ncSSRs) are used to compare genetic structure and diversity estimates of natural populations of Moroccan maritime pine. Samples were collected among 10 natural populations distributed in three biogeographically different regions, the Rif Mountain, the Middle and the High Atlas. Forty-five nuclear alleles at seven variable loci were found with a mean of 6.4 alleles per locus. A number of private alleles (17.1%) were shown in populations from Rif and Middle Atlas. Moreover, in Morocco, P. pinaster showed a lower genetic diversity than in other parts of its geographic range. Significant departures from Hardy–Weinberg equilibrium with excess homozygosity are observed indicating a high level of mating inside populations. Genetic diversity was structured with high variability among populations (Fst = 12%). Results show a correlation between genetic and geographic distances with an R-squared of 0.436. Two clusters were found using STRUCTURE, whereas three main clusters can be distinguished based on genetic distances of phylogenetic tree. Genetic relationships among maritime pine populations in Morocco appear to be related to historical, ecological as well as anthropogenic factors, suggesting the need for conservation strategies at the population level.     

Mevalonate kinase from Pinus pinaster seedlings

Cell-free extracts and acetone powder extracts from Pinus pinaster seedlings contain mevalonate kinase which phosphorylates mevalonic acid (MVA). t     

Breeding performance and longevity of Tomicus destruens on Mediterranean and continental pine species

The pine shoot beetle Tomicus destruens (Wollaston) (Coleoptera: Curculionidae: Scolytinae) is one of the main pests of Mediterranean forests, where it is oligophagous on Mediterranean pines. However, possible global warming may make the insect move to higher latitudes and altitudes, allowing it to attack new pine species. In this respect, the aim of the present article was to assess both the acceptance and performance of T. destruens offered host and non‐host pine species. A no‐choice breeding experiment was set up under laboratory conditions, using logs of three Mediterranean (Pinus pinea L., Pinus pinaster Miller, and Pinus halepensis Aiton) and two continental (Pinus nigra Arnold and Pinus sylvestris L.) pine species. Log debarking at the end of adult emergence assessed parent fecundity, egg, and larval mortality. The quality of callow adults emerging from each tested pine was evaluated on the basis of their longevity on a semiartificial diet. Tomicus destruens colonised all tested pine species, but did not reproduce in Scots pine, taking about 79 days to complete development with no differences among pines tested. The best breeding performance, evaluated as female fecundity and adult production, was observed in P. halepensis, and the lowest in P. pinaster. On average, adults emerging from P. pinea survived longer (83 days) than from other pines, and adult longevity was the lowest in males emerging from P. nigra. Austrian pine, which under natural conditions is usually not a host of T. destruens, allowed insect development and adult production similar to P. pinea and P. pinaster.     

长白山北坡不同林型内红松年表特征及其与气候因子的关系

运用树木年轮学的基本原理和方法,选取了长白山北坡保存完好的典型性植被阔叶红松林,探讨了杨桦红松林和椴树红松林内建群种红松(Pinus koraiensis)径向生长对气候要素的响应.结果表明,长白山北坡红松的径向生长对降水较为敏感,杨桦红松林和椴树红松林中,红松年轮宽度均与当年7月以及上一年9月的降水呈显著正相关关系.不同林型内红松的生长与气候因子的关系也有差异.椴树红松的年轮宽度还与上年7月的降水显著负相关,与当年3、4月份的平均气温呈显著正相关.而杨桦红松林内红松年轮宽度和平均温度没有显著的相关关系.特征年分析进一步验证了响应函数相关分析的结果,即当年生长季以及上年生长季末的降水充足促进了红松的径向生长;椴树红松林中,初春温度的升高有利于红松的生长.     

Fatty acids of Pinus elliottii tissues

The total fatty constituents of slash pine (Pinus elliottii) tissue cultures, seeds and seedlings were examined by GLC and MS. Qualitatively, the fatty acid composition of these tissues was very similar to that reported for other pine species. The fatty acid contents of the tissue cultures resembled that of the seedling tissues. In addition to the fatty acids common to botanical materials, Δ⁵-C₁₈ and -C₂₀ nonmethy lene-interrupted polyunsaturated acids were present in low relative abundances. The branched-chain C₁₇ acid reported for several other Pinus species was confirmed as the anteiso isomer.     

Variation in needle terpenoids among Pinus sylvestris L. (Pinaceae) provenances from Turkey

Variation of terpenes and resin acids in needles of young Scots pine (Pinus sylvestris L.) seedlings from nine different provenances in Turkey was investigated. The provenances represent 1200-km West to East and 400-km South to North transects. Seven monoterpenes and two sesquiterpenes were reported in the needles of pines studied. Generally, the kinds of terpenes were similar but the relative amount of some compounds differed among the origins. The major components of the monoterpene fraction in Turkish sources were α-pinene (84.8%), β-pinene (4.1%) and limonene (3.0%), corresponding to 91.9% of the crude needle extract. In a PCA-analysis, 3-carene, myrcene and terpinolene in seedlings from Turkish provenances were quite low and thus, they were clearly different from a Northern European Scots pine provenance from Finland. In the resin acid fraction, abietic acid (62.4%) and dehydroabietic acid (16.1%) were the most abundant constituents in the needles of the Scots pine from Turkish provenances.     

Terpene composition of Pinus pinaster seedlings and plants

-The production of essential oils in Pinus pinaster increases with the age of the seedlings, being higher in plants grown under continuous illumination. In the seedlings, nearly all the terpene is α- and β-pinene, the relative proportions of which are completely reversed between the 6th and 10th days of growth, regardless of the illumination period. Another reversion takes place after 60–65 days, the proportion found in the adult pine being very constant with α-pinene as the main component. The amount of oil in seedlings from high resin yielding parent trees was 4-fold higher than that in seedlings of normal (wild type) seeds. This finding is interesting because it can be employed for the preselection at the early stage of seedling of seeds to be used in forestry to obtain plantations of a high resin yield.     

Variability of the wood monoterpenoids from Pinus aristata

Striking differences in turpentine composition between California-Nevada-Utah populations and Colorado-New Mexico-Arizona populations of the Bristlecone pine (Pinus aristata) were demonstrated by GLC analyses of the wood extracts. These differences are in line with Bailey's taxonomic division of Pinus aristata sensu lato into western Pinus longaeva and eastern Pinus aristata sensu stricto.     

Pine volatiles mediate host selection for oviposition by Thaumetopoea pityocampa (Lep., Notodontidae)

The oviposition behaviour and host selection by females of the pine processionary moth, Thaumetopoea pityocampa, was studied under two conditions: in a field insectary and in a pine stand. An oviposition choice test was conducted in an insectary cage, using artificial Christmas trees (ACTs) baited with extracts from four pine species: Pinus pinea, Pinus pinaster, Pinus halepensis and Pinus brutia, plus a control. Females oviposited significantly more egg batches on the ACT baited with a P. brutia extract, while no oviposition occurred on the control ACT. In a large P. pinea stand, two groups of randomly selected trees were marked and baited respectively with an extract of P. brutia, which was the preferred species under insectary conditions and with a solvent, to act as control. Results showed that oviposition in the field followed an aggregated pattern, fitting a negative binomial distribution and that trees baited with P. brutia extracts, received a significantly larger number of egg‐batches than control trees. In parallel, the volatiles emitted by all pine extracts tested where analysed by gas chromatography and mass spectrometry (GC‐MS), coupled to a time‐of‐flight (TOF) mass analyser after solid phase microextraction (SPME), resulting in the identification of 26 compounds. Comparative chromatograms showed qualitative differences among the pine species used, some compounds being present in one of them only. Findings demonstrate for the first time that: (i) T. pityocampa females discriminate among bouquets extracted from different host pine species and exhibit oviposition preferences; and (ii) olfactory cues play an important role in mediating the selection process.     

Le pin pignon (Pinus pinea L.) dans le Wurm recent de Provence

The charcoal analysis of two settlements, one in the Maures massif and the other in the Durance valley, reveals the existence of Pinus pinea L. at the late Würm and gives the evidences of its spontaneousness in Provence.     

Polyisoprenols in Pinus sylvestris needles

A polyisoprenoid fraction was isolated from the needles of Pinus sylvestris and comprised about 1% of the dry weight. MS, IR, GLC and HPLC analyses showed that the fraction consisted of polyisoprenylacetates, with 10–19 isoprene units predominantly in the cis configuration.     

Impact of groundwater salinity on vegetation species richness in the coastal pine forests and wetlands of Ravenna,Italy

In the coastal pine forests (Pinus pinea and Pinus pinaster) of Ravenna (Italy) along the Adriatic coast, many pine trees are stressed or dying. In this paper we present ground elevation, depth to watertable, salinity of groundwater and vegetation species richness data within one of the coastal pine forests and some wetlands north of the Bevano River between LAT. 44°23′10″ and LAT. 44°20′21″ and between LONG. 12°17′25″ and LONG. 12°19′33″. The data are presented areally and along a 50 m long transect perpendicular to the coast to study the cause of distress in the pine forest and in different water pools within the wetlands. The findings were compared to published values of tolerance to salinity for 39 plant species typical of the area and incorporated into a web application to help nature managers in assessing or adjusting water salinity in relation to the vegetation species present. The pine trees are relatively tolerant to salinity (up to 12 g/l) but cannot survive a shallow watertable. On the other hand, species richness or biodiversity in this area is promoted by a shallow watertable and low salinity.     

Terpenoid and morphological variability of Pinus quadrifolia and the natural hybridization with Pinus monophylla in the San Jacinto Mountains in California

Monoterpenoids from wood of Pinus quadrifolia and Pinus monophylla from south of the San Jacinto Mountains in southern California were analysed by gas-liquid chromatography (GLC). The number of needles per fascicle, the number of resin canals, and the number of abaxial and adaxial stomatal rows in the needles were determined. Percentages of mycrene, α-pinene, and to a minor extent of camphene, β-pinene, limonene, and β-phellandrene, the above mentioned morphological characteristics and previously obtained data were all used for identification and characterisation of species intermediacy in the San Jacinto area. It was concluded that many P. quadrifolia trees in the mixed Buck Ridge stand and some trees in two pure stands of the same area were hybrids and that sympatric and to a lesser extent allopatric introgression of P. monophylla into P. quadrifolia takes place in the San Jacinto region. Introgression of P. quadrifolia into P. monophylla could not be demonstrated.     

Monolignol and dilignol glycosides from Pinus contorta leaves

Four monolignol glucosides have been isolated and identified from the needles of Pinus contorta. Chavicol 4-O-α-L-arabinofuranosyl-(1 →     

Resin acids of Pinus resinosa needles

The principal resin acids in the needles of Pinus resinosa are the labdane diterpenes, the new 8,13-epoxy-14-labden-19-oic acid (epimanoyl oxide acid), 8,13β-epoxy-14-labden-19-oic acid (manoyl oxide acid), 8(17),E-12,14-labdatrien-19-oic acid (communic acid) and 15-oxo-8(17)-labden-19-oic acid (imbricataloic acid). A survey of needles from representative populations of P. resinosa showed a limited variability in resin acid composition consistent with the uniformity of other traits. The composition of needle resin acids for putative P. nigra x resinosa hybrids strongly suggests the improbability of P. resinosa as the pollen parent.     

Ontogenetic differentiation between Mediterranean and Eurasian pines (sect. Pinus) at the seedling stage

Heteroblastic development in pine seedlings includes extreme morphological changes with still unclear adaptive and evolutionary significance. In particular, Mediterranean and Eurasian pines (section Pinus) living in the Mediterranean basin seem to follow quite distinct developmental trajectories at the seedling stage. Aiming to confirm this ontogenetic differentiation we performed a nursery experiment with seedlings of five Mediterranean pines (Pinus pinaster, P. brutia, P. halepensis, P. pinea and P. canariensis) and three Eurasian pines (P. sylvestris, P. uncinata, and P. nigra subsp. salzmannii), also including P. radiata as an outgroup. After destructive analyses at two harvest times (9 and 32 weeks), we found sharp differentiation between Mediterranean and Eurasian pines in a combination of traits linked to shoot heteroblasty. In particular, Mediterranean pines showed a marked delay in the proportion of adult needles to total needles in the shoot compared to Eurasian species, especially at the second harvest. However, two Mediterranean pines, P. pinaster and P. brutia showed a slightly higher proportion of secondary needles, and a higher rate of budset at a more advanced stage (68 weeks) compared to the other three Mediterranean species. Meaningfully, the outgroup P. radiata was the only species combining a high proportion of adult foliage since the first harvest with a delayed formation of the first terminal bud. We discussed the adaptive significance of these findings at the light of species’ climatic niches and life histories.     

Epicuticular wax of Pinus radiata needles

Epicuticular wax isolated from the cotyledons and primary needles of 10-week-old Pinus radiata seedlings is similar in composition and contains 86% neutral compounds, viz. alkyl esters (25%, C₂₄–C₆₄), nonacosan-10-ol (52%), heptacosane-5,10-diol (2%), nonacosane-4,10-diol, nonacosane-5,10-diol, and nonacosane-10,13-diol (total 12%) and estolides, MW ca 800 (2%), MW ca 1100 (6%), and MW ca 1500 (1%). The acidic fraction (14%) contains n-acids (78%, C₁₂–C₃₂) and diterpene acids (22%, mainly abieta-8,11,13-trien-18-oic, with lesser amounts of pimara-8(14),15-dien-18-oic, isopimara-7,15-dien-18-oic and hydroxylated aromatic, diene and mono-ene acids). Wax isolated from primary needles of 1-yr-old seedlings had a similar neutral fraction composition, but the acidic fraction contained predominantly the diterpene acid mixture, with only trace amounts of n-acids. The wax from 1-yr-old secondary, needles from P. radiata forest trees aged 5 yr and 40 yr contained an acid fraction (12% 5 yr, 17% 40 yr trees) comprising the diterpene acid mixture, with trace amounts of n-acids together with ω-hydroxy acids (C₁₂, C₁₄ and C₁₆). The neutral fraction from both young and old trees had a similar composition containing alkyl esters (7%, C₂₄–C₆₆), estolides (90%, MW 566-ca 1500), nonacosan-10-ol (2%) and the heptacosane and nonacosane diols (1%). During growth and maturation of P. radiata, the nonacosan-10-ol content of the needle wax decreases while the proportion of estolides and diterpene acids increases, the latter probably being located around the stomatal pore.