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Airborne pollen is a major contributor to allergic respiratory diseases. However, the literature on patterns and seasonality of specific pollen types mainly comes from northern hemisphere and developed regions, limiting our ability to extrapolate these findings to other geographical locations. With this research letter, our aim is to contribute to the current knowledge of aerobiology by analyzing the decade-long patterns of airborne tree pollen in the city of Bahia Blanca, Argentina. In general, we found late winter to early spring as the period with the highest Cupressaceae pollen counts. In 2020, the average pollen count during July through September was 78.81 (SD 79.70), the highest recorded during the last 10 years. These months had varying pollen concentrations from moderate (15-89 grains/m3 of air) to high (90-1499 grains/m3 of air). Regardless of such variation, August had consistently been the month with the highest peak concentrations from 2010 to 2020 (61.2, SD 57.3), followed by September (27.1, SD 20.3). We did not find any month with very high (˃1500 grains/m3 of air) peak concentration. Further studies need to be done to expand our knowledge on aerobiology to characterize specific pollen sub-types and determine the exact allergenic potential of airborne pollen in different regions.

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Haematobia irritans is a cosmopolitan obligate blood-feeding ectoparasite of cattle and is the major global pest of livestock production. Currently, H. irritans management is largely dependent on broad-spectrum pesticides, which has led to the development of insecticide resistance. Thus, alternative control methods are needed. Essential oils have been studied as an alternative due to their wide spectrum of biological activities against insects. Thus, the main aim of this study was to evaluate the insecticidal, repellent and antifeedant activity of the essential oils from Blepharocalyx cruckshanksii leaves and Pilgerodendron uviferum heartwood against horn flies in laboratory conditions. The composition of the essential oils was analyzed using gas chromatography coupled to mass spectrometry. Accordingly, α-pinene (36.50%) and limonene (20.50%) were the principal components of the B. cruckchanksii essential oil, and δ-cadinol (24.16%), cubenol (22.64%), 15-copaenol (15.46%) and δ-cadinene (10.81%) were the most abundant compounds in the P. uviferum essential oil. Mortality of flies and feeding behavior were evaluated by non-choice tests, and olfactory response was evaluated using a Y-tube olfactometer. Both essential oils were toxic to horn flies, with LC50 values for B. cruckchanksii essential oil of 3.58 µL L-1 air at 4 h, and for P. uviferum essential oil of 9.41 µL L-1 air and 1.02 µL L-1 air at 1 and 4 h, respectively. Moreover, the essential oils exhibited spatial repellency in the olfactometer using only 10 µg of each oil, and these significantly reduced the horn fly feeding at all doses evaluated. Although further laboratory and field studies related to the insectistatic and insecticide properties of these essential oils against H. irritans are necessary, B. cruckshanksii leaves and P. uviferum heartwood essential oils are promising candidates for horn fly management.

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BACKGROUND: Fitzroya cupressoides, commonly known as alerce, is an endemic conifer unique to southern South America. Alerce wood is renowned for its durability and resistance to biological degradation due to the presence of a particular class of secondary metabolite. Alerce extracts have been used in traditional medicine for different skin lesion treatments. AIMS: To develop a cell culture system to produce alerce extract and evaluate its cytotoxicity and effects on in vitro wound healing. METHODS: Cell cultures and aqueous extracts were prepared from alerce needles. Cytotoxicity was evaluated in keratinocytes (HaCaT line) and melanocites (C32 line) using the XTT assay. Wound healing was assayed with the scratch test in HaCaT cells, using mitomycin C to evaluate the role of cell division in the wound closure. RESULTS: Alerce cell culture extract has a significant effect on wound healing at different concentrations. No positive effects on the viability of normal and cancerous skin cells were observed. These results suggest that alerce extracts stimulate cell division in human skin epidermal cells in the context of wound repair. CONCLUSIONS: Bioactive compounds extracted from alerce cell cultures show promise as ingredients in dermocosmetic formulations, but further clinical studies are required to support these findings at the tissue level.

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PREMISE OF THE STUDY: It is unclear to what extent the co-occurrence of angiosperm and gymnosperm species in some marginal ecosystems is explained by reduced growth in angiosperms due to carbon (C) limitation and by high stress tolerance in gymnosperms associated with lack of vessels and resource conservation. METHODS: We examined growth patterns and traits associated with C balance in four evergreen angiosperm species (including one vesselless species, Drimys winteri) and three gymnosperm tree species of a cold-temperate rainforest in southern Chile. We measured the mean basal area increment for the first 50 (BAI50 ) and the last 10 years (BAI10 ), wood density, leaf lifespan, and nonstructural carbohydrate (NSC) concentrations in different organs. KEY RESULTS: BAI50 was 6-fold higher in angiosperms than in gymnosperms and ca. 4-fold higher in Drimys than in the fastest-growing gymnosperm. BAI10 and aboveground NSC concentrations were significantly higher and leaf lifespan lower in angiosperms than in gymnosperms; these differences, however, were largely driven by the slow growth and low NSC concentrations of the Cupressaceae species (Pilgerodendron uviferum), while the two Podocarpaceae had BAI10 and NSC concentrations similar to angiosperms. In angiosperms, NSC and starch concentrations were generally higher in species with lower BAI10 , indicating no severe C limitation. CONCLUSIONS: The co-occurrence of angiosperms and gymnosperms in cold-temperate rainforests of southern Chile is not explained by growth disadvantages and C limitation in angiosperms. Long leaf longevity, but not lack of vessels, appeared to favor resource conservation and C balance in some gymnosperms (Podocarpaceae).

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Background: Platycladus orientalis has an extremely long life span of several thousands of years, attracting great interests in the mechanisms involved in such successful senescence regulation and resistance at physiological and molecular levels. Results: The levels of reactive oxygen species (ROS) were higher in 3,000-year-old than in 20-year-old P. orientalis, and the activities of GR and GSH demonstrated the same trend. We produced and analyzed massive sequence information from pooled samples of P. orientalis through transcriptome sequencing, which generated 51,664 unigenes with an average length of 475 bp. We then used RNA-seq analysis to obtain a high-resolution age­course profile of gene expression in 20- and 3,000-year-old P. orientalis individuals. Totally, 106 differentially expressed genes were obtained, of which 47 genes were downregulated and 59 upregulated in the old tree. These genes were involved in transcription factors, hormone-related responses, ROS scavengers, senescence-related responses, stress response, and defense and possibly play crucial roles in tackling various stresses in the 3,000-year-old P. orientalis during its life time. The expression patterns of genes related to ROS homeostasis further indicated that the high ability of ROS scavenging could be helpful for the 3,000-year-old P. orientalis to resist senescence. Conclusions: This study provides a foundation for the elucidation of senescence resistance through molecular studies and the discovery of useful genes in P. orientalis.

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Phytophthora austrocedri is causing widespread mortality of Austrocedrus chilensis in Argentina and Juniperus communis in Britain. The pathogen has also been isolated from J. horizontalis in Germany. Isolates from Britain, Argentina, and Germany are homothallic, with no clear differences in the dimensions of sporangia, oogonia, or oospores. Argentinian and German isolates grew faster than British isolates across a range of media and had a higher temperature tolerance, although most isolates, regardless of origin, grew best at 15°C and all isolates were killed at 25°C. Argentinian and British isolates caused lesions when inoculated onto both A. chilensis and J. communis; however, the Argentinian isolate caused longer lesions on A. chilensis than on J. communis and vice versa for the British isolate. Genetic analyses of nuclear and mitochondrial loci showed that all British isolates are identical. Argentinian isolates and the German isolate are also identical but differ from the British isolates. Single-nucleotide polymorphisms are shared between the British and Argentinian isolates. We concluded that British isolates and Argentinian isolates conform to two distinct clonal lineages of P. austrocedri founded from the same as-yet-unidentified source population. These lineages should be recognized and treated as separate risks by international plant health legislation.

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Platycladus orientalis has a lifespan of several thousand years in China, making it a good plant in which to study aging at the molecular level, but this requires sufficient quantities of high-quality P. orientalis RNA. However, no appropriate methods have been reported for total RNA isolation from P. orientalis leaves. The TRIzol method did not extract RNA, while cetyltrimethylammonium bromide, sodium dodecyl sulfate-phenol, and plant RNAout kit (Tianz, Inc., China) protocols resulted in low yields of poor quality RNA. Isolating total RNA using the Spectrum™ Plant Total RNA Kit (Sigma-Aldrich, St. Louis, MO, USA) resulted in a high-quality product but a low yield. However, the two-step removal of polyphenols and polysaccharides in the improved plant RNAout kit protocol resulted in the isolation of RNA with a 28S:18S rRNA ratio of band intensities that was ~2:1, the A260/A280 absorbance ratio was 2.03, and the total RNA yield from P. orientalis leaves was high. This protocol was tested on different P. orientalis tissues of different ages and on leaves of five other Cupressaceae plants. The total RNAs were successfully used in complementary DNA synthesis for transcriptome sequencing and would be suitable to use in additional experiments. The results of this study will benefit future studies in Cupressaceae plants.

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The weevil Aegorhinus superciliosus Guérin (Coleoptera: Curculionidae), which is endemic to Central-Southern Chile and Argentina, is one of the major berry pests in Chile and the most important pest in the La Araucanía Region (38°44'9″S, 72°35'25″W). Due to the poor effectiveness and problems surrounding the implementation of the traditional control methods using organophosphate and carbamate insecticides, new strategies for controlling this pest are needed. In this communication, we evaluated the behavioral responses of male and female A. superciliosus to volatile compounds released from the essential oil (EO) obtained from the heartwood of Pilgerodendron uviferum (D. Don) Florin using olfactometric bioassays. The composition of the EO was analyzed using gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). According to these analyses, δ-cadinol (24.16%), cubenol (22.64%), 15-copaenol (15.46%) and δ-cadinene (10.81%) were the principal components of the EO. The Pilgerodendron uviferum EO, which is almost exclusively composed of sesquiterpenes (99.5%), exhibited a repellent effect against A. superciliosus adults, regardless of the sex or concentration used (56.6 mg/cm³ and 1.58 × 10(-2) mg/cm³). The EO has low volatility and greater persistence than the EOs composed of monoterpenes and is considered a good model in the search for raspberry weevil repellents.

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Fire severity and extent are expected to increase in many regions worldwide due to climate change. Therefore, it is crucial to assess the relative importance of deterministic vs. stochastic factors producing remnant vegetation to understand their function in the persistence of fire-sensitive plants. Vegetation remnants (areas within the landscape that have not burned for a considerable amount of time) may occur stochastically or in more predictable locations (fire refuges) where physical conditions decrease fire severity. Our aim was to determine if remnant forests of the fire-sensitive conifer Austrocedrus chilensis are associated with biophysical attributes that allow persistence in a fire-prone Patagonian landscape. We conducted a multi-scale approach, determining attributes of forest remnants and their surroundings (matrices) through remote sensing and field-based biophysical and functional characteristics, and quantifying how tree survival probability relates to microsite conditions. Trees within remnants displayed abundant fire scars, were twofold older and had threefold larger growth rates than matrix trees. Remnants were associated with high rocky cover and elevated topographical positions. Tree survival increased in hilltops, eastern aspects, and with sparse vegetation. Trees within remnants experienced severe reductions in growth during droughts. Our results suggest that A. chilensis remnants are mainly the result of refuges, where environmental conditions increase fire survival, but also increase susceptibility to drought. A trade-off between fire survival and drought vulnerability may imply that under increasing drought and fire severity, locations that in the past have served as refuges may reduce their ability to allow the persistence of fire-sensitive taxa.

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