Population genetics of <Emphasis Type="Italic">Cedrela fissilis</Emphasis> (Meliaceae) from an ecotone in central Brazil

Cedrela fissilis is an endangered timber species associated with seasonal forests throughout South America. We investigated a population of C. fissilis (PAN) located toward central Brazil to uncover insights on how an ecotone may have shaped the evolutionary history of this species at the local scale. PAN consisted of 18 mother trees and their 283 offspring (18 families), which were genotyped with ten microsatellite loci. We supplemented our dataset with equivalent microsatellite data from 175 specimens representing the east and west lineages of C. fissilis. An array of complementary methods assessed PAN for genetic diversity, population structure, and mating system. In PAN, the gene pool of the east lineage combined with a third (previously unidentified) lineage to form an admixture population. PAN is under inbreeding (Ho?=?0.80 and 0.74, uHe?=?0.85 and 0.82, Ap?=?1.1 and 7.1, F?=?0.06 and 0.10, for mother trees and offspring, respectively). Mother trees were predominantly outcrossing (t_m?=?0.95), with some selfing (1???t_m?=?0.05), and crossing between related individuals (t_m–t_s?=?0.07); they received pollen from few donors (N_ep?=?9). Restricted gene flow within PAN gave rise to a strong population structure, which split the 18 families into six groups. Some mother trees were reproductively isolated. Conservation perspectives are discussed.     

Population genetics of the naturally rare tree <Emphasis Type="Italic">Dimorphandra wilsonii</Emphasis> (Caesalpinioideae) of the Brazilian Cerrado

Naturally rare species have a higher probability of stochastic extinction due to genetic, demographic, or environmental hazards; human disturbance may intensify these threats. Rare species may therefore be in need of short-term intervention to survive. The ecosystem with the second highest biodiversity in Brazil, the Cerrado, is suffering from fragmentation and threats to its flora. Dimorphandra wilsonii, a 30-m tall endemic tree of the Brazilian Cerrado, is listed as critically endangered; only 21 adult trees have been identified. We carried out mating system and pollen flow analyses to understand the current gene flow and limitations in the reproduction of D. wilsonii. With seven fluorescently labelled microsatellite primers, we genotyped 20 adult trees and 269 progeny from 13 mother trees. D. wilsonii displayed low levels of genetic diversity; bottleneck events are likely to have occurred (H _e ?=?0.60 and 0.29; H _o ?=?0.71 and 0.33, for adults and progeny, respectively). This species is predominantly outcrossing (t _m ?=?0.88), with some selfing (1-t _m ?=?0.12), as well as crossing between related individuals (t _m -t _s ?=?0.11). None of the studied trees was reproductively isolated; a high proportion of pollen (55 %) came from trees yet to be discovered. Two genetic clusters (Northern and Southern) were identified, with high values of genetic divergence among the Southern sites. Planting of seedlings and monitoring of seed dispersion in order to maintain the genetic diversity and genetic structure of D. wilsonii are strategies that may ensure the continuation of D. wilsonii, but this species does not seem to require reproductive intervention to remain viable.     

Breeding system,gene dispersal and small-scale spatial genetic structure of a threatened food tree species, <Emphasis Type="Italic">Pentadesma butyracea</Emphasis> (Clusiaceae) in Benin

Pentadesma butyracea Sabine, a rain forest food tree species, plays a vital role in the socio-economic livelihood of some West African rural communities due to its various products. However, its scattered populations are threatened in Benin. Defining appropriate conservation strategies requires a good knowledge of mating patterns and their consequences for population genetics. The outcrossing rate, levels of correlated paternity and fine-scale spatial genetic structure of adults and maternal sibships were estimated for one small population and three large populations in Benin using microsatellite markers. Similar outcrossing rates (88–95%) were found in all populations, showing that P. butyracea is mainly an outbreeding species. We found no evidence of inbreeding depression from a decay of inbreeding with age. The spatial genetic structure within the large populations (Sp statistic?=?0.003–0.038) was consistent with isolation-by-distance expectations, showing that gene dispersal is spatially limited. Limited pollen dispersal is highlighted by the decay of the degree of correlated paternity between sibships with spatial distance. The mean pollen dispersal distance was estimated between 50 m and 450 m, but up to 21% pollen may migrate from external sources. The smallest population displayed slightly higher correlated paternity than the large populations (r _p ?=?0.37 vs. r _p ?=?0.17–0.30). In conclusion, our results suggest that small populations may show a reduction in sire numbers in seed, while the fragmented populations, large and small, are connected through gene flow. There is little inbreeding and no evidence of inbreeding depression.     

Short-distance pollen dispersal for an outcrossed, wind-pollinated southern beech (Nothofagus nervosa (Phil.) Dim. et Mil.)

The mating system (outcrossing, selfing, and biparental inbreeding) and the extent of pollen flow are two of the most important genetic features that determine the genetic structure of plant populations, and both are crucial for the design of conservation strategies. The objectives here were to estimate mating system parameters and to fit the pollen dispersal kernel for the southern beech, Nothofagus nervosa. We sampled 25 mothers and 372 progeny from two stands in the Tromen Lake region of Argentina. We registered spatial positions of the maternal trees, and genotyped mothers and offspring for five simple sequence repeat markers. We estimated single-locus (t _s?=?0.95) and multilocus (t _m?=?0.99) outcrossing rates and biparental inbreeding (t _m-t _s?=?0.04). The species is strongly outcrossing, but correlated paternity within maternal sibships (r _p?=?0.10) indicates that each maternal parent is sampling a different and restricted array of pollen donors. We used two protocols (twogener and kindist) to fit an exponential power dispersal kernel to the structure of pollen clouds sampled by different mothers. The estimated effective number of pollen donors contributing to a single mother was N _ep?=?9.9. The twogener and kindist analyses yielded slightly different estimates, but both indicated short average distances for pollen dispersal (<35?m), indicating that the dispersal kernel was strongly leptokurtic (???=?0.36). While short-distance pollen dispersal predominates, there remains a nontrivial probability of long-distance dispersal. The results are discussed in the context of ongoing conservation and management programs.     

Mating pattern and pollen dispersal in the wild olive tree (<Emphasis Type="Italic">Olea europaea</Emphasis> subsp. <Emphasis Type="Italic">cuspidata</Emphasis>)

In this study, the mating system, contemporary pollen flow, and landscape pollen connectivity of the wild olive tree (Olea europaea subsp. cuspidata) were analyzed in a fragmented landscape of less than 4-km diameter located in north-western Ethiopia. Four remnant populations of different sizes were investigated. Eight highly polymorphic microsatellite markers were used to genotype 534 adults and 704 embryos. We used contrasting sampling schemes and different methodological approaches to analyze the pollen flow. We observed a lower rate of inbreeding and correlated mating in the fragmented vs. the non-fragmented subpopulation. Using parentage analysis, we detected a bidirectional pollen movement across subpopulations. Pollen flow was found to be directed towards small subpopulations based on parentage and anisotropic analysis. Pollen immigration amounted to more than 50%. Although most pollination occurred within a distance of less than 200 m, longer distance pollen movements of more than 3 km were also detected. Pollen dispersal in the large and dense subpopulation was reduced, and a smaller number of effective pollen sources were detected compared to a smaller fragmented subpopulation. We obtained consistent estimates for the number of effective pollen donors (approximately 6 per mother tree) using three different methods. The average pollen dispersal distance at the landscape level amounted to 276 m while at the local level, 174 m was estimated. Bigger trees were better pollen contributors than smaller trees. We showed here for the first time that pollen dispersal in wild olive follows a leptokurtic distribution.     

Fine-scale spatial genetic structure in the frankincense tree <Emphasis Type="Italic">Boswellia papyrifera</Emphasis> (Del.) Hochst. and implications for conservation

The fine-scale genetic structure and how it varies between generations depends on the spatial scale of gene dispersal and other fundamental aspects of species’ biology, such as the mating system. Such knowledge is crucial for the design of genetic conservation strategies. This is particularly relevant for species that are increasingly fragmented such as Boswellia papyrifera. This species occurs in dry tropical forests from Ethiopia, Eritrea and Sudan and is an important source of frankincense, a highly valued aromatic resin obtained from the bark of the tree. This study assessed the genetic diversity and fine-scale spatial genetic structure (FSGS) of two cohorts (adults and seedlings) from two populations (Guba-Arenja and Kurmuk) in Western Ethiopia and inferred intra-population gene dispersal in the species, using microsatellite markers. The expected heterozygosity (H _E) was 0.664–0.724. The spatial analyses based on kinship coefficient (F _ij) revealed a significant positive genetic correlation up to a distance of 130 m. Spatial genetic structure was relatively weak (Sp = 0.002–0.014) indicating that gene dispersal is extensive within the populations. Based on the FSGS patterns found, we estimate indirectly gene dispersal distances of 103 and 124 m for the two populations studied. The high heterozygosity, the low fixation index and the low Sp values found in this study are consistent with outcrossing as the (predominant) mating system in B. papyrifera. We suggest that seed collection for ex situ conservation and reforestation programmes of B. papyrifera should use trees separated by distances of at least 100 m but preferably 150 m to limit genetic relatedness among seeds from different trees.     

Understanding the effects of isolation on seed and pollen flow,spatial genetic structure and effective population size of the dioecious tropical tree species <Emphasis Type="Italic">Myracrodruon urundeuva</Emphasis>

This study examines the levels of gene flow, the distance and the patterns of pollen and seed dispersal, the intra-population spatial genetic structure (SGS) and the effective population size of a spatially isolated Myracrodruon urundeuva population using five microsatellite loci. The study was carried out in the Paulo de Faria Ecological Station, São Paulo State, Brazil and included the sampling and mapping of 467 adult-trees and 149 juveniles. Open-pollinated seeds (514) from 29 seed-trees were also sampled and genotyped. Significant SGS was detected in both adult (S _p  = 0.0269) and juveniles trees (S _p  = 0.0246), indicating short-distance seed dispersal. Using maternity analysis, all juveniles had the mother-tree assigned within the stand. A father-tree within the stand was also assigned for 97.3% of the juveniles and 98.4% of offspring. The average pollen dispersal distance measured in juveniles \( \left( {\hat{\delta } = 1 3 8\pm 1 6 9 {\text{ m}},{\text{ mean}} \pm {\text{SD}}} \right) \) and offspring \( \left( {\hat{\delta } = 2 5 2\pm 20 4 {\text{ m}}} \right) \) were higher than the average seed dispersal distance measured in juveniles \( \left( {\hat{\delta } = 1 2 4\pm 1 50{\text{ m}}} \right) \). About 70% of the pollen from juveniles and 51% from offspring traveled less than 200 m and, 72% of the seeds traveled less than 50 m. The effective population size of the studied sample indicates that the 467 adult-trees and 145 juveniles correspond respectively to 335 and 63 individuals that are neither inbred nor relatives. The results are discussed in relation to their impact on seed collection practices and genetic conservation.     

<Emphasis Type="Italic">UGP</Emphasis> gene expression and UDP-glucose pyrophosphorylase enzymatic activity in grafting annonaceous plants

Grafting is commonly used to propagate commercial fruit species to ensure that the genetic characteristics of selected clones are maintained. However, the biochemical and molecular mechanisms involved in the graft incompatibility of woody trees are not well understood. We investigated the effect of grafting in vegetative growth, UDP-glucose pyrophosphorylase expression and activity of Annonaceous grafted plants: atemoya (Annona cherimola Mill. x Annona squamosa L.) ‘Thompson’ grafted onto different rootstocks, araticum-de-terra-fria (Annona emarginata Schltdl. H. Rainer “var. terra-fria”), araticum-mirim (Annona emarginata Schltdl. H. Rainer “var. mirim”) and biribá (Annona mucosa Schltdl. H. Rainer) at different post-grafting times. The growth of atemoya grafted onto araticum-mirim was lower than that of the rootstocks araticum-de terra-fria and biribá. The results also indicated that grafting alters UGPase gene expression; showing the combination atemoya grafted onto araticum-de-terra-fria (a compatible union) the higher levels of gene expression during the early stages of grafting development. However, no significant differences were detected in UGPase enzyme activity between the graft combinations. In addition, SDS-PAGE and MALDI-TOF analyses detected similar UGPase amino acid sequences in ungrafted atemoya samples to cherimoya (Annona cherimola Mill.), a female parent of the atemoya hybrid. These findings suggest that expression of the UGPase protein is related to graft compatibility in grafted Annona plants.     

Assessment of genetic diversity and structure in cocoa trees (<Emphasis Type="Italic">Theobroma cacao</Emphasis> L.) in Côte d’Ivoire with reference to their susceptibility to Cocoa swollen shoot virus disease (CSSVD)

Resistance to Cocoa Swollen Shoot Virus disease (CSSVD) is becoming an increasingly important criterion for selection of new cocoa cultivars in Côte-d’Ivoire, where the disease resurfaced since 2003. This virus can seriously affect the yield of trees with a loss of 25%, 1 year after infection, to around 100% 3 years after. In order to find tolerant plant material, 337 farm accessions have been collected on fields affected by CSSVD, according to the status of accessions potentially tolerant (APT) or susceptible (APS). Both phenotypic groups were genotyped using 30 microsatellite markers (SSR) in the presence of representative clones of the ten genetic groups of cocoa. This study revealed 214 alleles with the set of primer pairs used. The number of alleles per locus was between 3 and 16 with an average of 7.13 alleles per locus. The results showed a high contribution of genetic diversity within population (H_s?=?0.51) to the total genetic diversity (H_t?=?0.53) for the two studied groups. There was no significant difference between tolerant and susceptible groups (Fst?=?0.05). These results suggest that APT could be a potential genetic reservoir for other traits of interest associated with virus resistance. The phylogenetic tree, as the STRUCTURE analysis of Ivorian cocoa population, showed a distribution of individuals following four groups marked by a high contribution of group 4 (Nanay, Maranon, Guiana) followed by group 2 (Criollo), and group 1 (Amelonado), and a lower contribution of group 3 (Iquitos, Purus, Nacional, Curaray, Contamana).     

Gene flow among <Emphasis Type="Italic">Hancornia speciosa</Emphasis> (Apocynaceae) varieties and hybrid fitness

The fate of hybrids and the temporal and spatial dynamics of hybrid zones depend on hybrid fitness in comparison to non-hybrids. We studied cross-pollination among Hancornia speciosa varieties and compared progeny fitness in a nursery to address whether hybrid fitness differed from non-hybrids and whether maternal and paternal taxa contribute differentially to offspring fitness. This species has edible fruit pulp that is used as a raw material for candies, ice cream, and juice by small- and medium-sized enterprises in Central-West and Northeast Brazil. We genotyped 258 adults from a germplasm collection and 320 seeds using seven microsatellite loci to estimate genetic parameters and determine pollen donors. Fitness components, days to shoot, growth rate (mm/day), leaf width (mm), leaf length (mm), stem diameter (mm), and plant height (cm) were analyzed in 200 individuals. Genetic diversity and polymorphism did not differ neither between adults and progeny arrays nor among the four varieties. Genetic differentiation among varieties (F _CT?=?0.019, p?<?0.001) and among populations within varieties (F _SC?=?0.053, p?<?0.001) was significant but low. We detected mating among the four varieties, and no self-pollination was observed in parentage analysis, confirming that H. speciosa is self-incompatible with a high outcrossing rate (t _m?=?0.990, SE?=?0.007). No significant effect of heterosis or exogamic depression was detected for any fitness component, but maternal contribution significantly affected plant height.     

Unreduced gamete formation in wheat × <Emphasis Type="Italic">Aegilops</Emphasis> spp. hybrids is genotype specific and prevented by shared homologous subgenomes

Key message

The presence of homologous subgenomes inhibited unreduced gamete formation in wheat × Aegilops interspecific hybrids. Unreduced gamete rates were under the control of the wheat nuclear genome.

Abstract

Production of unreduced gametes is common among interspecific hybrids, and may be affected by parental genotypes and genomic similarity. In the present study, five cultivars of Triticum aestivum and two tetraploid Aegilops species (i.e. Ae. triuncialis and Ae. cylindrica) were reciprocally crossed to produce 20 interspecific hybrid combinations. These hybrids comprised two different types: T. aestivum × Aegilops triuncialis; 2n = ABDU^tC^t (which lack a common subgenome) and T. aestivum × Ae. cylindrica; 2n = ABDD^cC^c (which share a common subgenome). The frequency of unreduced gametes in F₁ hybrids was estimated in sporads from the frequency of dyads, and the frequency of viable pollen, germinated pollen and seed set were recorded. Different meiotic abnormalities recorded in the hybrids included precocious chromosome migration to the poles at metaphase I and II, laggards in anaphase I and II, micronuclei and chromosome stickiness, failure in cell wall formation, premature cytokinesis and microspore fusion. The mean frequency of restitution meiosis was 10.1 %, and the mean frequency of unreduced viable pollen was 4.84 % in T. aestivum × Ae. triuncialis hybrids. By contrast, in T. aestivum × Ae. cylindrica hybrids no meiotic restitution was observed, and a low rate of viable gametes (0.3 %) was recorded. This study present evidence that high levels of homologous pairing between the D and D^c subgenomes may interfere with meiotic restitution and the formation of unreduced gametes. Variation in unreduced gamete production was also observed between T. aestivum × Ae. triuncialis hybrid plants, suggesting genetic control of this trait.

     

Significant patterns of fine-scale spatial genetic structure in a narrow endemic wind-dispersed tree species, <Emphasis Type="Italic">Cedrus brevifolia</Emphasis> Henry

Cedrus brevifolia is a narrowly distributed conifer species, currently limited to a single mountain in Cyprus, growing in restricted habitats on sites of different densities and sizes. This study assessed the influence of seed and pollen dispersal, as well as the effect of demographic and genetic features on the magnitude of fine-scale spatial genetic structure (SGS). Sampling was performed in 11 plots where 50 neighboring adult trees were sampled from each plot, while biparentally and paternally inherited genomes were used for analysis with microsatellites. Fine-scale SGS was significant but showed contrasting patterns among plots. Although the magnitude of SGS in C. brevifolia mainly results from restricted seed dispersal, short-distance pollen dispersal could also explain fine-scale SGS in some plots, which is rather uncommon in wind-pollinated conifer species. The lack of a general and consistent trend of SGS among plots and between genomes indicates that pollen and seed dispersal varies at plot level. The complex SGS patterns in C. brevifolia may result from the unequal ratio of male and female strobilies of trees within the same plots, at different reproductive periods. Demographic features such as habitat fragmentation did not influence the magnitude of SGS in C. brevifolia, whereas low tree aggregation reduced it. Further, the significant correlation observed between linkage disequilibrium (LD) and plots with significant SGS supports the assumption that under specific conditions, LD is likely to be caused by the magnitude of SGS.     

Sap flow of the southern conifer, <Emphasis Type="Italic">Agathis australis</Emphasis> during wet and dry summers

Key message

Analysis of sap flux density during drought suggests that the large sapwood and rooting volumes of larger trees provide a buffer against drying soil.

Abstract

The southern conifer Agathis australis is amongst the largest and longest-lived trees in the world. We measured sap flux densities (F _d) in kauri trees with a DBH range of 20–176 cm to explore differences in responses of trees of different sizes to seasonal conditions and summer drought. F _d was consistently higher in larger trees than smaller trees. Peak F _d was 20 and 8 g m^?2 s^?1 for trees of diameters of 176 and 20 cm, respectively, during the wet summer. Multiple regression analysis revealed photosynthetically active radiation (PAR) and vapour pressure deficit (D) were the main drivers of F _d. During drought, larger trees were more responsive to D whilst smaller trees were more responsive to soil drying. Our largest tree had a sapwood area of 3,600 cm². Preliminary analysis suggests stem water storage provides a buffer against drying soil in larger trees. Furthermore, F _d of smaller trees had higher R ² values for soil moisture at 30 and 60 cm depth than soil moisture at 10 cm depth (R ² = 0.68–0.97 and 0.55–0.67, respectively) suggesting that deeper soil moisture is more important for these trees. Larger trees did not show a relationship between F _d and soil moisture, suggesting they were accessing soil water deeper than 60 cm. These results suggest that larger trees may be better prepared for increasing frequency and intensity of summer droughts due to deeper roots and/or larger stem water storage capacity.

     

How are anatomical and hydraulic features of the mangroves <Emphasis Type="Italic">Avicennia marina</Emphasis> and <Emphasis Type="Italic">Rhizophora mucronata</Emphasis> influenced by siltation?

Key message

This article provides significant data in the debate on whether siltation might have a negative impact on the hydraulic functioning of two widespread mangrove tree species Avicennia marina and Rhizophora mucronata.

Abstract

Elevated sediment addition, or siltation, within mangrove ecosystems is considered as being negative for trees and saplings, resulting in stress and higher mortality rates. However, little is known about how siltation influences the hydraulic functioning of mangrove trees. Comparing two mangrove tree species (Avicennia marina Vierh. Forsk. and Rhizophora mucronata Lam.) from low and high-siltation plots led to the detection of anatomical and morphological differences and tendencies. Adaptations to high siltation were found to be either mutual among both species, e.g., significant smaller single leaf area (p _A.marina  = 0.058, F1.38 = 3.8; p _R.mucronata  = 0.005, F1.38 = 8.7; n = 20 × 20) and a tendency towards smaller stomatal areas (p _A.marina  = 0.131, F1.8 = 2.8; p _R.mucronata  = 0.185, F1.8 = 2.1, n = 5 × 60), or species-specific trends for A. marina, such as higher phloem band/growth layer ratios (p = 0.101, F1.8 = 3.4, n = 5 × 3) and stomatal density (p = 0.052, F1.8 = 5.2, n = 5 × 4). All adaptations seemingly contributed to a comparable hydraulic conductivity independent of the degree of siltation. These findings indicate that silted trees level off fluctuations in their hydraulic performance as a survival mechanism to cope with this less favourable environment. Most of the trees’ structural adaptations to cope with siltation are similar to known drought stress-imposed adaptations.

     

Genetic variability of maternal plants and embryos of their seeds in the populations of <Emphasis Type="Italic">Pinus kochiana</Emphasis> Klotzsch ex Koch in Crimea

Samples of trees and seed embryos of five Pinus kochiana Klotzsch ex Koch populations in Crimea were comparatively studied at 12 allozymic loci for its genetic variability and mating system. It has been shown that the embryos of seeds reproduce the allelic diversity of maternal plants, but the level of their observed heterozygosity (H_o) is significantly lower, i.e., 0.286 vs. 0.189, respectively. Unlike maternal trees, embryos are characterized by a significant divergence between the observed distribution of genotypes and the theoretically expected one according to the Hardy–Weinberg law for the majority of analyzed loci. The frequency of cross pollination in populations varied from 0.384 to 0.673 according to single-locus (t_s) estimates and from 0.639 to 0.841 according to multilocus (t_m) estimates.     

Synchronous fruiting and common seed dispersers of two endemic columnar cacti in the Caatinga,a dry forest in Brazil

This study evaluates the fruiting phenology, fruit traits, and seed dispersal in two Pilosocereus (Cactaceae) species that are widely distributed in Caatinga vegetation. We monitored the fruiting phenology of Pilosocereus gounellei and Pilosocereus chrysostele on a monthly basis for a period of 4 years (45 months from March 2009 to November 2012), including 30 individuals of each species. We also carried out focal observations, captured dispersers, and conducted germination tests, to identify the effective seed dispersers of these species. Both species exhibited sub-annual fruiting patterns and high fruiting synchrony index (O _jk 0.62), with peaks occurring from February to May for P. gounellei and February to April for P. chrysostele. In all, 248 visits by seven bird and two lizard species were recorded for P. gounellei, and 104 visits by five bird species were recorded for P. chrysostele. The two species shared five seed dispersers. The finch Lanio pileatus was the most frequently visiting bird species. The number of visits to the fruits of P. gounellei was higher than to the fruits of P. chrysostele. Passage of seeds through the digestive tracts of all bird species significantly increased the germination rate for P. chrysostele, whereas for P. gounellei, the birds Forpus xanthopterygius and L. pileatus decreased germination rates. Sub-annual fruiting patterns, similar fruit morphology, and high synchronous fruiting are factors that favor resource sharing among the dispersers of Pilosocereus in the Caatinga.     

A novel series of C<Subscript>18</Subscript>–C<Subscript>22</Subscript><Emphasis Type="Italic">trans</Emphasis> ω3 PUFA from Northern and Southern Hemisphere strains of the marine haptophyte <Emphasis Type="Italic">Imantonia rotunda</Emphasis>

A series of novel C₁₈–C₂₂ trans ω3 polyunsaturated fatty acids (PUFA) with a single trans double bond in the ω3 position was found in Northern and Southern Hemisphere strains of the marine haptophyte Imantonia rotunda. The novel ω3 PUFA were identified as 18:3(9c,12c,15t) (0.2–1.8 % of total fatty acids), 18:4(6c,9c,12c,15t) (1.9–4.1 %), 18:5 (3c,6c,9c,12c,15t) (0.7–8.8 %), 20:5(5c,8c,11c,14c,17t) (1.2–4.1 %) and 22:6(4c,7c,10c,13c,16c,19t) (0.3–4.3 %), and were accompanied by larger proportions of the all cis isomers: 18:3ω3(9,12,15) (2.7–3.5 %), 18:4ω3(6,9,12,15) (9.3–14.3 %), 18:5ω3(3,6,9,12,15) (7.8–18.5 %), 20:5ω3(5,8,11,14,17) (3.2–3.9 %), 22:5ω3(7,10,13,16,19) (0.1–0.3 %) and 22:6ω3(4,7,10,13,16,19) (2.3–5.2 %). GC analysis of FAME using a non-polar column did not reveal the trans isomers as they coeluted with the all cis PUFA. However, GC using a polar column resolved the trans PUFA from the all cis PUFA, with the trans isomers eluting before the all cis isomers. GC-MS of FAME fractionated by argentation solid-phase chromatography confirmed the molecular ions of all components. FAME were derivatized to form 4,4-dimethyloxazoline (DMOX) derivatives, and GC-MS revealed the same double bond positions for each trans and cis FAME. The results suggest that the ω3 trans double bond originated from the Δ15/ω3 desaturation of 18:2(9c,12c), suggesting that this desaturase has dual cis/trans activity in these species. These results indicate that 18:3(9c,12c,15?t) was the precursor trans isomer produced for the trans series and further desaturation by the common Δ6 desaturase to produce the trans tetraene and successive elongations and desaturations led to the subsequent series of trans ω3 PUFA isomers. To our knowledge, this is the first report of these trans ω3 isomers occurring in strains of I. rotunda. These trans ω3 PUFA may be used as biomarkers in marine food webs for this species and with their unique structure may be biologically active.     

Extensive pollen flow in a natural fragmented population of Patagonian cypress Austrocedrus chilensis

Habitat fragmentation might significantly affect mating and pollen dispersal patterns in plant populations, contributing to the decline of remnant populations. However, wind-pollinated species are able to disperse pollen at longer distances after opening of the canopy. Our objectives were to characterize the mating system parameters and to estimate the average distance of effective pollen dispersal in the wind-pollinated conifer Austrocedrus chilensis. We sampled 19 “mother trees,” 200 progeny, and 81 additional adults (both male and female), in a fragmented population at the Argentinean Patagonian steppe. We registered the spatial positions of individuals and genotyped all samples with five microsatellite markers. We found a high genetic diversity, a moderated rate of biparental inbreeding (t _m? ??t _s?=?0.105), and a complete absence of correlated paternity (r _p?=??0.015). The effective number of pollen donors contributing to a single mother (N _ep) was 13.9. Applying TWOGENER, we estimated a low but significant differentiation among the inferred pollen pools (Φ_FT?=?0.036, p?=?0.001) and a very large average pollen dispersal distance (d?=?1,032.3 m). The leptokurtic distribution (b?=?0.18) presumes a potential for even larger dispersal distances. The high genetic diversity, the mating patterns, and the extensive pollen dispersal presume that habitat fragmentation did not have a negative impact on pollen movement in this population of A. chilensis. Genetic connectivity among fragmented populations scattered in the Patagonian region is possible, and we stress the need of management policies at the landscape level.