Cytological Variability in <Emphasis Type="Italic">Artemisia</Emphasis> L. inhabiting North-West Himalayas: B Chromosomes in <Emphasis Type="Italic">Artemisia gmelini</Emphasis> Weber ex Stechm

Present work is a part of our studies on the cytological details of some species of Artemisia L. inhabiting Ladakh region of Jammu and Kashmir state. Of the six populations investigated for three different species (Artemisia sieversiana Ehrh. ex Willd., A. tournefortiana L. and A. gmelinii Weber ex Stechm.), some variations were noticed only for Artemisia gmelinii. The species occurring in Leh region at altitudinal range of 3992 masl is diploid with 2n = 18 (n = 9). In one of the population of the species, sprawling in Hemis region (4009 masl), В chromosome was found to be present in addition to the diploid chromosome complement. Comparison of the different morphological and reproductive features revealed that the population with В chromosome had reduced vigour.     

Facilitative interactions among co-flowering <Emphasis Type="Italic">Primula</Emphasis> species mediated by pollinator sharing

We investigated flowering phenology, pollinator visitation and visitor community composition in communities of self-incompatible sympatric Primula species in a high-elevation Himalayan ecosystem. Within the tight constraints imposed by short growing seasons in such ecosystems, interactions among co-occurring plants for pollinators may vary from competition to facilitation, depending on the specifics of the system. We found that pollinator community composition changed with elevation in this system: lepidopterans were the dominant visitors at lower elevations (2200–3000 masl), bees (other than bumblebees) dominated at mid-elevations (3000–3800 masl) and bumblebees dominated at higher elevations (3800–4600 masl). However, within an elevation zone, there were no significant differences in pollinators amongst co-occurring Primula species. At a focal study site where multiple Primula species co-occurred, our results showed that even while the overall flowering periods of these species broadly overlapped, the peak flowering periods of different Primula species were temporally segregated. Upon further inferring the nature of interaction amongst co-flowering Primula species, we found that plots with higher Primula diversity (≥?2 species) and density (80–100 individuals) experienced significantly higher pollinator visitation, compared with plots with single species and low flower densities (40–50 individuals). Our results suggest that in this community of sympatric, self-incompatible Primula species, a broadly aggregated, synchronous floral display of multiple species results in pollinator facilitation by attracting a greater number of pollinator visitors. Within this broadly synchronous display, the temporal segregation of peak flowering period of individual species may reduce competition for pollinators and limit heterospecific pollen transfer.     

An endangered hemiparasitic shrub is the only host plant of the little-known Neotropical hairstreak <Emphasis Type="Italic">Strymon flavaria</Emphasis> (Lepidoptera: Lycaenidae) in the arid Andes

Larval host plants can be the main resource underlying the distribution (including altitudinal ranges) of specialized phytophagous insects such as butterflies. Strymon flavaria (Ureta) (Lepidoptera: Lycaenidae: Theclinae: Eumaeini) is a little-known hairstreak endemic to the arid belt at about 3000–3500 m elevation on the western slopes of the Andes of northern Chile. The hemiparasitic shrub Krameria lappacea (Dombey) Burdet and Simpson is here recorded as the first host plant known for S. flavaria, representing also the first record of the association of a species of Strymon Hübner with the plant family Krameriaceae. Females of S. flavaria lay eggs on flower buds and unripe fruits of K. lappacea; the larva eats mostly these plant organs. Field observations revealed that S. flavaria is a host-specialist hairstreak, since females lay eggs only on K. lappacea. These findings suggest that the altitudinal range of S. flavaria could be the result of its specialized association with K. lappacea, as this shrub is also mostly restricted to elevations above 3000 m in the Andes of northern Chile. The implications of this finding for the ecology and conservation of S. flavaria are discussed.     

Detection of <Emphasis Type="Italic">Diaphorina citri</Emphasis> Kuwayama (Hemiptera: Liviidae) in Kenya and potential implication for the spread of Huanglongbing disease in East Africa

The Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera: Liviidae) is a damaging pest of citrus globally and has recently been detected in Tanzania. Although direct damage by the pest is seldom of economic importance, the insect is more notorious for its ability to vector the fastidious phloem-limited bacterium Candidatus Liberibacter asiaticus (CLas), the putative causal bacterium of Huanglongbing or Asian citrus greening disease. For many years, Trioza erytreae (Del Guercio) (Hemiptera: Triozidae) was known to be the main vector of the African citrus greening disease caused by Candidatus Liberibacter africanus (CLaf), but the recent arrival of D. citri on the continent adds to the dynamics of infection and spread of both diseases on mainland Africa. Following the recent report of the presence of D. citri in Tanzania, an additional delimiting survey was carried out in the region, focusing on Kenya, mainland Tanzania and Zanzibar to detect the presence and ascertain the extent of spread of D. citri. We employed molecular tools based on the use of DNA barcoding to confirm the identity of D. citri. In addition to D. citri, the occurrence of T. erytreae in the same sampling locations is also reported. Adults and nymphs of either D. citri or T. erytreae were collected from citrus at many of the surveyed sites ranging from 19 to 668 m above sea level (masl) in Tanzania, 20–1666 masl in Kenya, and 42–48 masl in Zanzibar. Diaphorina citri was sympatric with T. erytreae at the mid to higher elevations of 1375–1666 masl and no T. erytreae or its open-gall symptoms were detected below 523 masl. Sequences obtained were queried via BLAST and all linked to D. citri of different accession numbers already available on GenBank. This is the first report of the presence of D. citri in Kenya and Zanzibar. The potential implication of the detection and spread of the two pathogens, CLaf and CLas to the citrus industry in East Africa and movement of suitable host plants is discussed.     

Variation in the Presence of Anti-<Emphasis Type="Italic">Batrachochytrium dendrobatidis</Emphasis> Bacteria of Amphibians Across Life Stages and Elevations in Ecuador

Amphibian populations are decreasing worldwide due to a variety of factors. In South America, the chytrid fungus Batrachochytrium dendrobatidis (Bd) is linked to many population declines. The pathogenic effect of Bd on amphibians can be inhibited by specific bacteria present on host skin. This symbiotic association allows some amphibians to resist the development of the disease chytridiomycosis. Here, we aimed (1) to determine for the first time if specific anti-Bd bacteria are present on amphibians in the Andes of Ecuador, (2) to monitor anti-Bd bacteria across developmental stages in a focal amphibian, the Andean marsupial tree frog, Gastrotheca riobambae, that deposits larvae in aquatic habitats, and (3) to compare the Bd presence associated with host assemblages including 10 species at sites ranging in biogeography from Amazonian rainforest (450 masl) to Andes montane rainforest (3200 masl). We sampled and identified skin-associated bacteria of frogs in the field using swabs and a novel methodology of aerobic counting plates, and a combination of morphological, biochemical, and molecular identification techniques. The following anti-Bd bacteria were identified and found to be shared among several hosts at high-elevation sites where Bd was present at a prevalence of 32.5%: Janthinobacterium lividum, Pseudomonas fluorescens, and Serratia sp. Bd were detected in Gastrotheca spp. and not detected in the lowlands (sites below 1000 masl). In G. riobambae, recognized Bd-resistant bacteria start to be present at the metamorphic stage. Overall bacterial abundance was significantly higher post-metamorphosis and on species sampled at lower elevations. Further metagenomic studies are needed to evaluate the roles of host identity, life-history stage, and biogeography of the microbiota and their function in disease resistance.     

Ectomycorrhizal pre-inoculation of <Emphasis Type="Italic">Pinus hartwegii</Emphasis> and <Emphasis Type="Italic">Abies religiosa</Emphasis> is replaced by native fungi in a temperate forest of central Mexico

Few studies have focused on analyzing the effect of native inoculated ectomycorrhizal (ECM) fungal strains on seedlings under field conditions in temperate forests. However, it is crucial to verify that the positive effects of ECM under nursery conditions also occur in the field, favoring their performance. We evaluated the short-term effect of ECM on three-year-old seedlings of Pinus hartwegii and Abies religiosa in central Mexico by subjecting them to four treatments: inoculation with Inocybe splendens, inoculation with Suillus brevipes (both native strains), inoculation with forest soil, and non-inoculated plants. Percentage of ECM colonization, plant growth (shoot height and stem diameter), and physiological (osmotic potential, stomatal conductance, CO₂ assimilation and water use efficiency) responses were evaluated. We found that these two ECM species were partial (P. hartwegii) or totally (A. religiosa) replaced after one and a half years in the field. P. hartwegii seedlings increased their water use efficiency during the dry season, but in A. religiosa seedlings, a clear strategy for avoiding water stress was not detected. This ECM replacement had a negative effect on the physiological performance Of A. religiosa. Our results emphasize the importance of selecting compatible fungal-host species combinations for nursery inoculation and of using sources of inoculum adapted to the environmental conditions of the transplant site, ensuring root colonization prior to field transplanting to minimize seedling mortality due to water stress.     

Seasonal and altitude effects on the structure of arthropod communities associated with <Emphasis Type="Italic">Tillandsia violacea</Emphasis> Baker (Bromeliaceae) in a temperate forest of Mexico

The canopy of forests has been considered “the last biotic frontier,” and study of its elements is very important in explaining the global functionality in ecosystems. Epiphytic plants and arthropods are essential elements in canopy habitats, and their relationships have been studied in order to understand the high diversity in tropical forests. Nevertheless, there are few studies on this development in temperate forests. The arthropod community was studied during the rainy and dry seasons at two altitudes, and a total of 240 T. violacea plants of three sizes were collected from Abies religiosa and Quercus spp. host trees. A total of 163,043 arthropods were collected and about 200 morphospecies identified. The highest abundance was obtained during the dry season, while high diversity was found during the rainy season. There was a significant effect of plant size, host trees and collecting season on abundance and diversity, and there were seasonal variations in community composition. The community hosted on A. religiosa epiphytes showed higher abundance and density than that of Quercus.     

Distributional and ecophysiological study on the Antarctic lichens species pair <Emphasis Type="Italic">Usnea antarctica</Emphasis>/<Emphasis Type="Italic">Usnea aurantiaco</Emphasis>-<Emphasis Type="Italic">atra</Emphasis>

The factors that control lichen distribution in Antarctica are still not well understood, and in this investigation we focused on the distribution, local and continental, and gas exchange of a species pair, closely related lichens with differing reproductive strategies, Usnea aurantiaco-atra (fertile) and Usnea antarctica (sterile, sorediate). The local distributions of these species were recorded along an altitudinal gradient of nearly 300 m at South Bay, Livingston Island, and microclimate was also recorded over 1 year. The photosynthetic responses to temperature, light and thallus water content were determined under controlled conditions in the laboratory. The species were almost identical in their photosynthetic profiles. Locally, on Livingston Island, U. antarctica was confined to low altitude sites which were warmer and drier, whilst U. aurantiaco-atra was present at all altitudes. This contrasts with its distribution across Antarctica where U. antarctica grows 9° latitude further south than U. aurantiaco-atra. Temperature appears not to be the main controller of distribution in these species, but dryness of habitat, which will influence length of activity periods, may be important.     

Morphological and molecular investigations of <Emphasis Type="Italic">Gagea</Emphasis> (Liliaceae) in southeastern Kazakhstan with special reference to putative altitudinal hybrid zones

The most important center of speciation in the genus Gagea is thought to be in Central Asia. Here, we focus on species diversity in southeastern Kazakhstan (around Almaty, Ili-Alatau range of the Western Tian-Shan mountains). We studied an elevational transect, reaching from lowland steppes to the alpine zone (500–2750 m a. s. l.), and carried out detailed morphological and molecular investigations for populations of Gagea spp. Nine species were identified in different altitudinal zones; one of these (Gagea almaatensis) is described as new to science. We could detect two altitudinal contact zones between closely related species: G. filiformis and G. granulosa (sect. Minimae), and G. almaatensis and G. kuraminica (sect. Gagea). Morphological and molecular investigations (ITS data and cpDNA networks) indicate ongoing hybridization of co-occurring G. filiformis into G. granulosa and putative bidirectional hybridization events between G. almaatensis and G. kuraminica.     

Growth and photosynthetic activity of <Emphasis Type="Italic">Botryococcus braunii</Emphasis> biofilms

Botryococcus braunii is a green microalga capable of producing large amounts of external long-chain hydrocarbons suitable as a source of biofuel. There have been several studies indicating that cultures of B. braunii can reduce the energy and water requirement for mass biofuel production, especially if non-destructive extraction methods for milking hydrocarbons are used. Growing microalgae as a raw material for biofuel using conventional liquid-based cultivation (i.e., raceway ponds) has yet to be shown to be economically successful. An alternative solid growth (biofilm) cultivation method can markedly reduce the energy requirements and costs associated with the harvesting and dewatering processes. We evaluated the growth of biofilms of several strains of B. braunii (from races A, B, L and S) and found that three of the four tested races successfully grew to stationary phase in 10 weeks with no contamination. Among all races, B. braunii BOT22 (race B) reached the highest biomass and lipid yields (3.80 mg dry weight cm^?2 day^?1 and 1.11 mg dry weight cm^?2). Irrespective of the race, almost all photosynthetic parameters (F _V /F ₀ , PI_ABS and the OJIP curve) showed that the biofilm cultures were more stressed during lag and stationary phases than in logarithmic phase. We also studied the Botryococcus biofilm profiles using confocal microscopy and found that this method is suitable for estimating the overall biomass yield when compared with gravimetric measurement. In conclusion, the growth characteristics (biomass and lipid) and photosynthetic performance of all races indicated that B. braunii BOT22 is the most promising strain for biofilm cultivation.     

Light-harvesting complexes of <Emphasis Type="Italic">Botryococcus braunii</Emphasis>

The colonial green alga Botryococcus braunii (BB) is a potential source of biofuel due to its natural high hydrocarbon content. Unfortunately, its slow growth limits its biotechnological potential. Understanding its photosynthetic machinery could help to identify possible growth limitations. Here, we present the first study on BB light-harvesting complexes (LHCs). We purified two LHC fractions containing the complexes in monomeric and trimeric form. Both fractions contained at least two proteins with molecular weight (MW) around 25 kDa. The chlorophyll composition is similar to that of the LHCII of plants; in contrast, the main xanthophyll is loroxanthin, which substitutes lutein in most binding sites. Circular dichroism and 77 K absorption spectra lack typical differences between monomeric and trimeric complexes, suggesting that intermonomer interactions do not play a role in BB LHCs. This is in agreement with the low stability of the BB LHCII trimers as compared to the complexes of plants, which could be related to loroxanthin binding in the central (L1 and L2) binding sites. The properties of BB LHCII are similar to those of plant LHCII, indicating a similar pigment organization. Differences are a higher content of red chlorophyll a, similar to plant Lhcb3. These differences and the different Xan composition had no effect on excitation energy transfer or fluorescence lifetimes, which were similar to plant LHCII.     

Carbon assimilation,nitrogen, and photochemical efficiency of different Himalayan tree species along an altitudinal gradient

In the area of Jumla region in Western Nepal, measurements of saturated leaf net photosynthetic rate (P_sat), nitrogen content, leaf fluorescence, carbon isotopic composition, and water status were performed on woody coniferous (Pinus wallichiana, Picea smithiana, Abies spectabilis, Juniperus wallichiana, Taxus baccata), evergreen (Quercus semecarpifolia, Rhododendron campanulatum), and deciduous broadleaved species (Betula utilis, Populus ciliata, Sorbus cuspidata) spreading from 2 400 m up to the treeline at 4 200 m a.s.l. With the exception of J. wallichiana, P_sat values were lower in coniferous than broadleaved species. Q. semecarpifolia, that in this area grows above the coniferous belt between 3 000 and 4 000 m, showed the highest P_sat at saturating irradiance and the highest leaf N content. This N content was higher and P_sat lower than those of evergreen oak species of tempe forests at middle and low altitudes. For all species, P_sat and N content were linearly correlated, but instantaneous nitrogen use efficiency was lower than values measured in lowland and temperate plant communities. The values of carbon isotopic composition, estimated by δ₁₃C, showed the same range reported for temperate tree species. The ranking of δ₁₃C values for the different tree types was conifers < evergreen broadleaved<deciduous, suggesting tighter stomatal closure and higher water use efficiency for the evergreen types, confirming trends found elsewhere. No relevant differences of δ₁₃C were found along the altitudinal gradient. Quantum yield of photochemistry at saturating irradiance, measured by leaf fluorescence (δF/F_m’), was highest in J. wallichiana and lowest in T. baccata. Overall, photochemical efficiency was more strongly related to species than to altitude. Interestingly, changes of .δF/F_m’ along the altitudinal gradient correlated well with the reported altitudinal distribution of the species.     

Fossil wood of <Emphasis Type="Italic">Betula erkovetskiensis</Emphasis> sp. nov. (Betulaceae) from the Miocene of the Erkovetskii Brown Coal Field,Amur Region,Russia

A new species, Betula erkovetskiensis Blokhina et O.V. Bondarenko (Betulaceae), from the deposits of the Sazanka Formation (upper Middle?Upper Miocene) of the Erkovetskii Brown Coal Field (Amur Region, Russia) is described based on anatomical features of fossil wood. The new species shows some wood anatomical characters of the extant birch subgenus Betula, B. davurica, B. nigra (section Dahuricae), and B. papyrifera (section Betula). Fossil wood of Betula is found in the Amur Region for the first time.     

Genotypic differences in phosphorus use physiology in producers (<Emphasis Type="Italic">Chlamydomonas reinhardtii</Emphasis>) and consumers (<Emphasis Type="Italic">Daphnia pulex</Emphasis>) interact to alter primary and secondary production

By considering the relative abundance of elements in trophic interactions, ecological stoichiometry makes predictions about key ecological processes such as biomass production and consumer-driven nutrient recycling. Theoretical and empirical work has focused on interspecific variation in elemental composition, and stoichiometric imbalances between resources and consumers in determining productivity, particularly at the base of foodwebs. Recent work has found considerable intraspecific variation in elemental composition. We know little about the ecological relevance of such variation, and whether predictions of stoichiometric theory hold at the intraspecific level. Here, we used two genotypes of a primary producer Chlamydomonas reinhardtii, and two genotypes of a primary consumer Daphnia pulex, which are already known to vary considerably in their phosphorus (P) use physiology, under conditions of P abundance and limitation, to explore whether such intraspecific differences alter primary as well as secondary production. Specifically, we tested whether there are intraspecific differences in the carbon: phosphorus (C:P) stoichiometry of Chlamydomonas genotypes, whether such differences affect growth and abundance of the two Daphnia genotypes, and whether the two Daphnia genotypes had distinct effects on primary production and growth of the two Chlamydomonas genotypes. We found significant differences in C:P stoichiometry between the two Chlamydomonas genotypes in both P supply conditions. Such intraspecific differences altered the growth of Daphnia genotypes, and affected the outcome of genotypic competition. Finally, Daphnia genotype affected primary production, and interacted with P supply to distinctly affect the growth of the two Chlamydomonas genotypes. Together, our results highlight the potential ecological relevance of intraspecific differences in nutrient use physiology and elemental composition, and the utility of ecological stoichiometry in understanding such consequences.     

On the taxonomic rank of <Emphasis Type="Italic">ciscaucasicus</Emphasis> and its relationships with the pygmy wood mouse <Emphasis Type="Italic">Sylvaemus uralensis</Emphasis> inferred from the mtDNA cytochrome b gene sequence

To specify the taxonomic rank of form ciscaucasicus (independent species Sylvaemus ciscaucasicus, or intraspecific form of pygmy wood mouse, S. uralensis), a 402-bp the mtDNA cytochrome b gene fragment (402 bp) was examined in ciscaucasicus individuals from six geographic localities of the Caucasus and Ciscaucasus (Krasnodar krai and Adygeya Republic) and 17 S. uralensis individuals from seven localities of the Russian Plain (Saratov oblast, Smolensk oblast, Voronezh oblast, Tula oblast, Moscow oblast, Tver’ oblast, and northern Krasnodar krai). For comparison, the cytochrome b gene was partly sequenced in the samples of yellow necked, S. flavicollis (n = 2, Samara oblast), and Caucasian, S. ponticus (n = 6, Krasnodar krai), wood mice. One Mus musculus specimen from Western Europe, whose nucleotide sequences were deposed in the GenBank, was used as intergeneric outgroup. Phylogenetic trees for the forms examined were constructed based on the mtDNA sequence variation and using the neighbor joining and maximum parsimony methods. The network of the cytochrome b haplotypes was also constructed. The level of genetic divergence was evaluated using Kimura’s two-parameter algorithm. Based on the data on the sequence variation in a 402-bp mtDNA cytochrome b gene fragment, the hypothesis on the species status of the ciscaucasicus form was. The mean intergroup distances (d) between the geographic groups of S. uralensis varied from 0.0036 to 0.0152. At the same time, the distances between the pygmy wood mice and the group of S. flavicollis-S. ponticus varies in the range from 0.0860 to 0.0935, and the level of intergeneric genetic differentiation (Sylvaemus-Mus) is higher than the latter index (d = 0.142). Ciscaucasicus should be considered as geographic substitution form of S. uralensis. Furthermore, the Caucasian populations of S. uralensis (= ciscaucasicus) were characterized by a threefold lower value of intergroup genetic divergence (d = 0.0062) than the East European populations (d = 0.0179). This finding pointed to some isolation of Caucasian populations of pygmy wood mouse and depletion of their gene pool. However other molecular genetic data (similarity of nucleotide composition and consistence of the levels of intra-and intergroup distances) suggest the absence of geographic subdivision between Caucasian and East European populations of S. uralensis relative to the molecular marker examined.     

<Emphasis Type="Italic">Scenedesmus</Emphasis> sp. cultivation using commercial-grade ammonium sources

The use of commercial-grade nutrients such as agricultural fertilizers is important for commercial microalgae cultivation, and this is particularly the case for biofuel production which is associated with low added value. Nitrogen is a very important macronutrient in microalgae cultivation, and ammonium sources are cheaper than nitrate sources. However, the growth response and cellular composition can be altered by the different nutrient sources. In the study reported here, we investigated the effects of different ammonium doses and commercial-grade macronutrients from agricultural fertilizers on the growth of Scenedesmus sp. BR003, a promising genus for biofuel production. Five growth media were developed using fertilizers and evaluated during Scenedesmus sp. cultivation under autotrophic conditions. The growth media differed in terms of their composition and concentration of macronutrients. We found that all commercial-grade media supported equal or higher cell concentrations, dry weight, water-soluble proteins, neutral carbohydrates, and total lipid production compared to the conventional BG11 medium. However, the commercial-grade growth medium with the highest ammonium content affected the coenobium pattern of Scenedesmus sp. BR003. Commercial-grade nutrient sources were a low-cost alternative to improve the growth of Scenedesmus sp. BR003. The different fertilizers also allowed for manipulation of microalgae chemical composition and phenotypic plasticity to target traits of commercial interest. Our results demonstrate the potential of using ammonium from agricultural fertilizers as a nitrogen source in combination with other commercial-grade macronutrients sources. In addition, this work demonstrates the ability of a robust Scenedesmus strain to grow in media of different compositions, even when a high dosage of ammonium was used.     

Measurement of individual cell strength of <Emphasis Type="Italic">Botryococcus braunii</Emphasis> in cell culture

Botryococcus braunii is a microalga considered for biofuel production and may require physical disruption of cells/colonies for efficient hydrocarbon extraction. In this study, the strength of individual cells of B. braunii was measured using a nanoindenter. From the load and cell size, the pressure for bursting the cell was calculated to be 56.9 MPa. This value is 2.3–10 times those of Saccharomyces cerevisiae and Chlorella vulgaris found in another research, because B. braunii has two types of cell walls with different thicknesses. The energy required to disrupt 1 g of dry B. braunii cells, estimated by load-displacement curves, is 3.19 J g^?1 which is 0.19–1.2 times higher than those of S. cerevisiae and C. vulgaris. When using a high-pressure homogenizer for disrupting B. braunii cells, the cell disruption degree increased with the treatment pressure at above 30 MPa, and 70% of cells were disrupted at 80 MPa.     

Fossil wood of <Emphasis Type="Italic">Pinus priamurensis</Emphasis> sp. nov. (Pinaceae) from the Miocene deposits of the Erkovetskii Brown Coal Field,Amur Region

New species of the pine fossil wood, Pinus priamurensis sp. nov. (Pinaceae) from the Sazanka Formation (upper Middle Miocene–Upper Miocene) of the Erkovetskii Brown Coal Field (Amur Region) is described. The new species shares some wood anatomical features with modern species of the subsection Pinus (section Pinus, subgenus Pinus). This is the first record of fossil wood of Pinus in the Amur Region.     

Xylem anatomy and calculated hydraulic conductance of four <Emphasis Type="Italic">Nothofagus</Emphasis> species with contrasting distribution in South-Central Chile

Nothofagus obliqua, N. dombeyi, N. alpina and N. antarctica are characteristic tree species of the temperate forests on the western slopes of the Andes with centres of distribution that differ in their temperature and moisture regimes. We tested branch wood from co-occurring specimens of these species for the inherent differences in xylem anatomy and theoretical hydraulic conductance to evaluate their resistance to drought or frost. The hydraulic conductivity of the xylem was calculated using a modified Hagen–Poiseuille equation and related to wood density. Conduit dimensions were used to predict the water potential that would cause 50 % loss of hydraulic conductivity (Ψ ₅₀). Nothofagus alpina, which mainly grows at sites with low frost frequency, exhibited the largest conduits and the highest mean values for conduit area, fraction of conduit area in the cross-section and hydraulic conductivity, but the lowest wood density. Opposite relationships were found in the plastic N. antarctica, whose xylem seems to be least vulnerable to freezing-induced, but also to drought-induced embolism. Calculated Ψ ₅₀ was highest (least negative) in N. alpina, indicating a relatively high susceptibility to cavitation. The xylem of the thermophilic N. obliqua and of N. dombeyi, which mainly occurs under oceanic climate, but can also survive at sporadically dry and warm sites, is not particularly adapted to periods of drought stress. Across all species, wood density was negatively correlated with the calculated hydraulic conductance. The xylem traits of N. alpina might contribute to its relatively high growth rate and facilitate its spread into forest gaps.     

QTL Mapping of Wood FT-IR Chemotypes Shows Promise for Improving Biofuel Potential in Short Rotation Coppice Willow (<Emphasis Type="Italic">Salix</Emphasis> spp.)

An increasing interest to convert lignocellulosic biomass into biofuels has highlighted the potential of using willows for this purpose, due to its fast growth in short rotation coppice systems. Here, we use a mapping population of 463 individuals of a cross between Salix viminalis and S. viminalis × S. schwerinii to investigate the genetic background of different wood chemical traits, information of importance for breeding towards different uses of wood. Furthermore, using a subset of the mapping population, the correlation between biogas production and chemical traits was investigated. The phenotyping of wood was carried by Furrier-transformed-Infrared spectrometry (FT-IR) and water content analysis. Quantitative trait loci (QTLs) analysis was used to identify regions in the genome of importance for the phenotypic variation of these chemical traits. We found 27 QTLs for various traits. On linkage group (LG) VI-1, QTLs for signals assigned to G-lignin, lignin, and the S/G ratio were collocated and on LG XIV we found a cluster of QTLs representing signals assigned to lignin, cellulose, hemicellulose, and water. The QTLs explained from 3.4 to 6.9% of the phenotypic variation indicating a quantitative genetic background where many genes influence the traits. For the biogas production, a positive and negative correlation was seen with the signals assigned to acetyl and lignin, respectively. This study represents a first step in the understanding of the genetic background of wood chemical traits for willows, information needed for complementary studies, mapping of important genes, and for breeding of varieties for biofuel production purposes.