Terpenoid and morphological variability of Pinus quadrifolia and its natural hybridization with Pinus monophylla in Northern Baja California and adjoining United States

Mono- and sesquiterpenoids from wood of P. quadrifolia and that of the southwestern form of P. monophylla were analysed by GLC. Concurrently the number of needles per fascicle, the number of resin canals, and the number of abaxial and adaxial stomatal rows towards the tip, in the middle, and towards the base of the needles were determined. The data covered 90 trees from 8 pure populations from southernmost California and northern Baja California and 21 trees from a mixed stand in Baja California.α-Pinene, mycene, α-amorphene, γ-muurolene, germacrene D, and to a very minor extent camphene, β-pinene, limonene, β-phellandrene and β-ylangene percentages could be used for species identification. The number of needles per fascicle, the number of resin canals, and the number of abaxial stomatal rows afforded appreciably sharper identification, however. Statistical treatment of chemical and morphological data from pure stands did not give evidence for introgression of the two species. A definite intermediacy, rather limited in extent, could be demonstrated for the mixed stand, however.     

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.     

Monoterpenoid and morphological differentiation within Pinus cembroides

Wood of Pinus cembroides from 232 trees sampled in 23 localities throughout its range in the United States and Mexico has been analysed for monoterpenes. With a few exceptions the trees of the continental populations from the state of Hidalgo northward produced α-pinene as the main monoterpene. The majority of trees of the southern populations (subsp. orizabensis) from the state of Puebla and adjoining regions of the neighboring Veracruz and Tlaxcala produced 3-carene in appreciable amounts. The population from Baja California (subsp. lagunae) produced monoterpenes of the sabinene family (thujene, sabinene, γ-terpinene, terpinolene and $\text{p-}\text{cymene}$) as the main constituents. The variations in morphological characters, including number of needles per fascicle, number of stomatal rows in needles, number of resin canals in needles, as well as other characters of the internal needle morphology, needle length and thickness, needle retention, thickness of seed shells, bark and cone characteristics, rate of growth and cotyledon number either paralleled or did not contradict the chemical variations. The evolution of the southern populations (subsp. orizabensis) into a separate group most likely resulted from geographic separation and climatic differences, while the evolutionary separation of the Baja California trees (subsp. lagunae) was connected with northwestern movement of the California coastal region from Miocene onward and the formation of Sierra Madre Occidental resulting in separation of this population from the mainland populations by the gap of the Gulf of California and the coastal mountain ranges.     

A new species of Arceuthobium (Viscaceae) from central Mexico

Arceuthobium pendens, a parasite of the pinyonsPinus discolor andP. cembroides, is described from San Luis Potosí and Veracruz, Mexico. This andA. divaricatum Engelm. are the only dwarf mistletoes known to parasitize pinyons.Arceuthobium pendens is distinct fromA. divaricatum Engelm. in its long, slender, greenish shoots, formation of systemic witches brooms, and frequency on various species of pinyons. With the discovery of this new species, 19 dwarf mistletoes are known from Mexico.     

Variability in essential oils and needle resin canals of Pinus longaeva from Eastern California and Western Nevada in relation to other members of subsection Balfourianae

Mono- and sesquiterpenoids from wood and leaves of Pinus longaeva trees collected in various localities of eastern California and western Nevada were quantitatively analyzed by GLC. Concurrently the number and size of resin canals in foliage of the same trees and as well as Pinus aristata trees from Arizona, Colorado and New Mexico were determined. While some monoterpenes (mainly α-pinene and 3-carene) suggest that P. longaeva trees from the Panamint Mountains of California are P. aristata-like, the total chemical data and morphological data indicate that Panamint trees should be grouped with P. longaeva. A chemical latitudinal gradient is evidenced by the appearance of trees producing 3-carene in large amounts along the line joining the Panamint, Inyo and White Mountains of California. Pinus rzedowskii, well separated geographically and morphologically from the accepted members of subsection Balfourianae, is shown to be sufficiently distinct chemically, as to leave its suggested membership in the subsection an open question.     

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.     

Differences between Pinus pinea and Pinus pinaster as bioindicators of polycyclic aromatic hydrocarbons

The potential of Univariate and Multivariate Analysis and specifically Principal Components Analysis (PCA), has been employed to assess the performance of pine needles as bioindicators of polycyclic aromatic hydrocarbons (PAHs) and particularly emphasize the crucial importance of making a distinction between different pine species if more than one is sampled. Four sampling sessions were done in 29 sites and needles of two common pine species (Pinus pinaster Ait. in 19 sites and Pinus pinea L. in 12) were collected and analysed using gas chromatography-mass spectrometry (GC-MS) and PCA. The results obtained indicated significant differences between species, attributed to their different morphology. The mean total PAH concentration of the P. pinaster needles are over two times higher than P. pinea's. This difference is lower when the results are presented in lipid weight, but still statistically significant. Samples from the two sites with adjacent trees reinforce these conclusions, showing significant differences in terms of PAH mean concentration and aromatic ring patterns.     

Variability in the essential oils of wood and foliage of Pinus aristata and Pinus longaeva

Variations in the monoterpenoid composition of the essential oil of wood, and of the mono- and sesquiterpenoids of foliage collected from more than 200 specimens of pines of subsection Balfourianae (P. aristata, P. longaeva and P. balfouriana) substantiate the previously reported morphological and chemical separation of P. aristata and P. longaeva and suggest a restricted intermediacy in northern Arizona and eastern California. On the basis of wood essential oil the limited population of P. aristata in northern Arizona, while exhibiting to a slight degree morphological intermediacy, is found to be practically identical to the main populations of P. aristata in Colorado and New Mexico. On the basis of foliage oil, however, the same population is clearly intermediate, but closer to P. aristata. The detailed chemical data suggest a distinct chemical status for the Arizona population, with selection for the present-day chemophenotypes being the dominant factor in their evolution. Analysis of monoterpenoids from P. balfouriana × longaeva hybrids indicates that incomplete selective elimination of 3-carene-producing P. longaeva chemophenotypes rather than gene exchange with P. balfouriana is responsible for the presence of abnormal P. aristata-like 3-carene-producing trees in eastern California. The latter trees could have resulted from limited gene exchange between P. aristata and P. longaeva by routes no longer available to them lying to the south of the Grand Canyon.     

Non-linear response of stomata in Pinus koraiensis to tree age and elevation

Knowledge on variations in stomata is useful in reflecting leaf physiological characteristics of CO₂ uptake and water transpiration, and predicting the responses of plants to future climate change. Stomatal density and number of stomatal rows (current-year, 1- and 2-year-old needles) in relation to tree age (ranging from 25 to 320 years old), elevation (ranging from 738 to 1,380 m a.s.l.), and sun exposure (sun and shade exposure) were investigated in Pinus koraiensis trees. Stomatal density and number of stomatal rows in relation to tree age and elevation showed a humped curve with the maximum values at intermediate levels of tree age (210 years old) and elevation (1,050 m a.s.l.), respectively. Needle age but not sun exposure significantly affected the stomatal density across tree ages and elevations. Our results suggest that variations in stomatal density of Pinus koraiensis needles are related to ontogenetic growth and environmental factors.     

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.     

Monoterpenoid differentiation in relation to the morphology of Pinus remota

Wood of Pinus remota from 126 trees sampled in 13 localities throughout of its ranges in the United States and Mexico has been analysed for monoterpenes. The trees of P. remota produced mainly α-pinene and limonene with ranges for population means of 68.0–92.3% and 3.2–16.9%, respectively. Limonene was useful for distinguishing this species from subsp. cembroides. Small chemical differences were found between the eastern and western variants of P. remota. The chemical differences between the trees of P. remota from the United States and the trees of the newly described species, P. catarinae, from Mpo Santa Catarina near Saltillo, Mexico, were also very few and quantitatively small. The variations in morphological characteristics paralleled the chemical differentiation. The chemical and morphological data substantiated the species status of P. remota, and suggested the status of a mere marginal variant for P. catarinae.     

Carbon isotope discrimination and stomatal responses of mature Pinus sylvestris L. trees exposed in situ for three years to elevated CO2 and temperature

The Climate Change Experiment (CLIMEX) is a unique large scale facility in which an entire undisturbed catchment of boreal vegetation has been exposed to elevated CO₂ (560 ppm) and temperature (+3°C summer, +5°C winter) for the past three years with all the soil-plant-atmosphere linkages intact. Here, carbon isotope composition and stomatal density have been analysed from sequential year classes of needles of mature Scots pine trees (Pinus sylvestris L.) to investigate the response of time-integrated water-use efficiency (UWE) and stomatal density to CO₂ enrichment and climate change. Carbon isotope discrimination decreased and WUE increased in cohorts of needles developing under increased CO₂ and temperature, compared to needles on the same trees developing in pretreatment years. Mid-season instantaneous gas exchange, measured on the same trees for the past four years, indicated that these responses resulted from higher needle photosynthetic rates and reduced stomatal conductance. Needles of P. sylvestris developing under increased CO₂ and temperature had consistently lower stomatal densities than their ambient grown counterparts on the same trees. The stomatal density of P. sylvestris needles was inversely correlated with δ¹³C-derived WUE, implying some effect of this morphological response on leaf gas exchange. Future atmospheric CO₂ and temperature increases are therefore likely to improve the water economy of P. sylvestris, at least at the scale of individual needles, by affecting stomatal density and gas exchange processes.     

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.     

The role of anthropogenic influences in a mixed-conifer forest mortality episode

Abstract. Anthropogenic influences on recent tree mortality in mid-montane mixed conifer forests of southern California, USA, and northern Baja California, Mexico, were investigated. The Pinus jeffreyi-Abies concolor phase of the mixed-conifer montane community was sampled at three sites, characterized by: (1) low levels of air pollution and long-term fire suppression (Holcomb Valley in the San Bernardino Mountains, California); (2) chronic, severe air pollution and long-term fire suppression (Barton Flats in the San Bernardino Mountains, California); and (3) little air pollution and no fire suppression (La Corona Arriba in the Sierra San Pedro Martir in Baja California, Mexico). Similar percentages of dead standing trees, around 14 %, were found at both San Bernardino sites, but a comparatively low level, 4 %, was found in the Mexican forest. Anthropogenic effects, in particular fire suppression, may play an important role in enhancing the impact of natural stresses on the dynamics of mixed conifer forests.     

秦岭火地塘林区油松和华山松林乔木层净生产力与气候因子的关系

以秦岭火地塘林区油松(Pinus tabulaeformis)和华山松(Pinus armandi)林为研究对象,以其生物量及树高-胸径模型为基础,运用树木年轮宽度方法推算出1973年至2011年生物量和生产力年际动态,并通过相关分析和多元逐步回归分析探讨了油松和华山松林乔木层净生产力与温度、降水之间的关系。结果显示,该林区油松林和华山松林乔木层生物量39a间增长迅速,分别从1973年的15.32 t/hm2和7.53 t/hm2增长到2011年的175.97 t/hm2和130.98 t/hm2,平均年净生产力分别为4.18 t hm-2a-1和3.20 t hm-2a-1,油松林乔木层生物量和生产力均高于华山松林;气候分析表明年净生产力与降水关系不明显,与温度关系较为密切,随气温升高呈波动上升趋势:单月气候因子中上年7月温度、当年7月温度与油松林乔木层净生产力显著正相关,上年7月温度与华山松林乔木层净生产力显著正相关;油松林乔木层净生产力动态变化主要受1—7月平均温度影响,华山松林主要受5—7月平均温度影响;油松林生产力与温度因子的相关性高于华山松林。两种林型的生物量和生产力差异是由油松和华山松生物学特性所致。     

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 →     

In vitro regeneration of adult Pinus sylvestris L. trees

The propagation of adult conifer trees by tissue culture has been studied for the last twenty years, but problems related to the juvenile to adult phase change of trees have limited the practical applications of these tissue culture procedures. This paper describes a micropropagation protocol for the in vitro propagation of mature Scots pine trees. In this study, dormant shoot buds, which had not started to elongate, were collected from twenty-one adult Pinus sylvestris trees (> 15 years old) during the winter. The sampled buds were cut transversely into slices of 0.5 to 1 cm in thickness and were cultured on three types of culture media (DCR, WP and LPm) supplemented with four cytokinins (BA, mT, Tdz and Z), at two different concentrations (25 and 50 µM), except for Tdz, whose concentrations were diluted to 5 µM and 2.5 µM. The evaluated culture media did not show significant differences in the bud organogenesis capacity. In fact, the highest organogenic response was obtained with buds cultured on DCR and WP media and by explants cultured on medium supplemented with 25 µM meta-topolin. This protocol is a successful and efficient biotechnological approach to the micropropagation of adult P. sylvestris trees.     

Light-dependent monoterpene synthesis in Pinus radiata cultures

Callus cultures of Pinus radiata that synthesized monoterpenes de novo and which were stable for at least 1 year have been established. The products differed from those of parent plants in that α-pinene (87–100%) rather than β-pinene was the main component. The best lines accumulated monoterpenes (ca 2 × 10^?3% wt/wet wt)in yields 40–20% of that in the parent stem and needles. The composition of the extractable oil depended on the light regime. After culture in total darkness toluene and acetone accumulated. These compounds also occurred (at low levels) in dark-grown seedlings and in seeds of P. radiata and a route for their formation from α-pinene is suggested. Cell-free extracts of the culture lines converted [¹⁴C] IPP into geraniol, nerol and α- and β-pinenes in up to 46% total yield. These are the most active crude extracts for monoterpene biosynthesis that have been reported from either tissue cultures or higher plants.     

Analysis of 3-indole carboxylic acid in Pinus sylvestris needles

3-Indole carboxylic acid (ICA) has been characterized as an endogenous constituent of Pinus sylvestris needles. Quantitative estimates of 3-indole acetic acid (IAA) and ICA, corrected for both sample losses and the conversion of IAA to ICA occurring during purification, indicate that Pinus needles contain 24.5 ± 6.5 ng IAA/g and 2.3 ± 0.4 ng ICA/g.