Palm Species Research Articles

Non-native palm affects arthropod communities and litter decomposition in an ongoing biome shift

The emergence of novel ecosystems, characterized by shifts in species composition and interactions, abiotic conditions and altered ecosystem functioning, is a major and inevitable challenge to contemporary ecosystem management. This study examines the ecological implications of Trachycarpus fortunei, a non-native evergreen palm, currently involved in a biome shift from deciduous temperate forest to evergreen laurophyllous forest in the Southern European Alps. Specifically, we investigated the effects of T. fortunei encroachment in peri-urban forests on flying and ground-dwelling arthropod communities as well as on leaf-litter decomposition. We found that the presence of T. fortunei altered arthropod community composition, mostly by reducing the number of herbivore species. This effect was likely driven by the lower quality of palm leaves as a food source compared to deciduous, dicotyledonous tree leaves and by a lower plant richness in the herb and shrub layer. Furthermore, we observed higher rates of leaf-litter decomposition associated with increasing abundance of young palm trees, which was not explained by predictors commonly associated with litter decomposition (i.e., detritivore abundance, litter depth and air temperature). Hence, the slow decay of palm leaves appears to be counterbalanced by the favourable conditions for litter decomposition within dense palm stands. Overall, our findings indicate that high densities of the non-native palm species (T. fortunei) impacts herbivore arthropod communities in the Southern European Alps, providing first evidence of possible effects on ecosystem functioning of this ongoing biome shift. These outcomes are integral components of the broader process of laurophyllisation in the study region, a phenomenon linked to climate warming and land use change, encompassing both native and non-native species.

Taxonomic significance of seeds and seedling morphology in the threatened Indian endemic palm genus Bentinckia (Arecaceae)

A comparative morphological study was carried out to evaluate the taxonomic significance of seed and seedling traits of Bentinckia condapanna and B. nicobarica (Arecaceae), the threatened endemic palm species. Both species are unique and have specific requirements for seedling recruitment. An effort was made to cultivate these species ex situ at the Botanical Survey of India’s National Orchidarium and Experimental Garden (NOEG) in Yercaud, Tamil Nadu, and Dhanikhari Experimental Garden cum Arboretum (DEGCA), in Andaman & Nicobar Islands. The seeds and seedlings of the two species differ in the beak and ridges on the seed, endosperm colour and the shape of the eophyll.

Identification of Multifunctional Putative Bioactive Peptides in the Insect Model Red Palm Weevil (Rhynchophorus ferrugineus)

Innate immunity, the body’s initial defense against bacteria, fungi, and viruses, heavily depends on antimicrobial peptides (AMPs), which are small molecules produced by all living organisms. Insects, with their vast biodiversity, are one of the most abundant and innovative sources of AMPs. In this study, AMPs from the red palm weevil (RPW) Rhynchophorus ferrugineus (Coleoptera: Curculionidae), a known invasive pest of palm species, were examined. The AMPs were identified in the transcriptomes from different body parts of male and female adults, under different experimental conditions, including specimens collected from the field and those reared in the laboratory. The RPW transcriptomes were examined to predict antimicrobial activity, and all sequences putatively encoding AMPs were analyzed using several machine learning algorithms available in the CAMPR3 database. Additionally, anticancer, antiviral, and antifungal activity of the peptides were predicted using iACP, AVPpred, and Antifp server tools, respectively. Physicochemical parameters were assessed using the Antimicrobial Peptide Database Calculator and Predictor. From these analyses, 198 putatively active peptides were identified, which can be tested in future studies to validate the in silico predictions. Genome-wide analysis revealed that several AMPs have predominantly emerged through gene duplication. Noticeably, we detect a newly originated defensin allele from an ancestral defensin via the deletion of two amino acids following gene duplication in RPW, which may confer an enhanced resilience to microbial infection. Our study shed light on AMP gene families and shows that high duplication and deletion rates are essential to achieve a diversity of antimicrobial mechanisms; hence, we propose the RPW AMPs as a model for exploring gene duplication and functional variations against microbial infection.

Characterization of Atlantic Forest Tucum (Bactris setosa Mart.) Leaf Fibers: Aspects of Innovation, Waste Valorization and Sustainability.

This study investigates the fibers of tucum (Bactris setosa Mart.), a palm species native to the Atlantic Forest. The fibers manually extracted from tucum leaves were characterized to determine important properties that help with the recognition of the material. The fibers were also subjected to pre-bleaching to evaluate their dyeing potential. The extraction and characterization of these fibers revealed excellent properties, making this material suitable not only for manufacturing high-quality textile products but also for various technical and engineering applications. The characterization techniques included SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared Spectroscopy), TGA (Thermogravimetric Analysis), and tensile strength tests. These analyses showed that tucum fibers possess desirable properties, such as high tensile strength, with values comparable to linen but with a much finer diameter. The fibers also demonstrated good affinity for dyes, comparable to cotton fibers. An SEM analysis revealed a rough surface, with superficial phytoliths contributing to their excellent mechanical strength. FTIR presented a spectrum compatible with cellulose, confirming its main composition and highly hydrophilic nature. The dyeing tests indicated that tucum fibers can be successfully dyed with industrial direct dyes, showing good color yield and uniformity. This study highlights the potential of tucum fibers as a renewable, biodegradable, and sustainable alternative for the transformation industry, promoting waste valorization.

Structural and anatomical analysis of rattan (Calamus balansaeanus Becc.)

Abstract Calamus balasaeanus Becc., a climbing palm species, has potential commercial value. Detailed anatomical and chemical analyses of rattan stems at different ages are crucial for their utilization in various industrial applications, particularly eco-friendly products. In this study, rattan stems of different ages were examined using light microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. The results showed that the anatomical structure of rattan stems at different ages are very similar, with vascular bundle sizes ranging from 0.26 to 0.37 mm and a frequency of 8.4 to 13.7 bundles/mm2. The vessel lengths and diameters were 1.87–2.35 mm and 0.10–0.16 mm, respectively. Fiber lengths and diameters were 0.84–1.15 mm and 8.65–11.55 μm, respectively. As C. balasaeanus matured, the secondary wall of fiber cells thickened into the cell lumen, changing from 2 layers to 4 layers, the amount of crystallinity in cellulose increased while the mean microfibril angle decreased. The crystallinity of cellulose was higher in the periphery of the stem compared to the center. Unimodal imaging effectively visualized the distribution of various polysaccharides in C. balasaeanus tissues, with the highest concentrations of cellulose, hemicellulose, and lignin found in the base of the rattan stems.

Recurrent wildfires alter forest structure and community composition of terra firme Amazonian forests

Abstract Wildfires associated with land-use and climate change have considered a key driver to the Amazon forest collapse. However, achieving a detailed understanding of how human-related disturbances impact forest successional trajectories needs comprehensive information spanning forest strata. Here, we investigate the impact of recurrent wildfires on forest structure, species diversity, and composition, making a comprehensive assessment of the regenerating, understory, and canopy tree communities in a sustainable use reserve in the eastern Amazon. Plant communities were described across 16 forest stands (old-growth, burned once and twice) sampling a total of 3620 individuals and 326 tree and palm species. Wildfires affected all attributes of forest structure. Aboveground biomass decreased by 44% in forest burned once, and 71% in twice-burned forest stands. Forest canopy was the most affected strata after the second fire, with a 44%-decrease compared to unburned forest. The same pattern emerged for basal area, which decreased by an average of 27.5% after the first fire and 53.8% following the second fire event. Overall, plant communities experienced a 50%-loss of species richness after two fires, including both dominant and rare species. Plant communities also became more dissimilar as fire events accumulated, with 58%–61% increase in species dissimilarity following two fires events. As wildfires reoccured, the old-growth forests of our focal landscape were converted into a mosaic of regenerating forest stands dominated by local short-lived pioneers (i.e. low-biomass early-regenerating forest stands) and a few tree species less sensitive to fire. Our findings highlight the urgent need to secure a resilient future for Amazonian forests with actions needed to support local livelihoods whilst reducing the prevalence of ignitions sources and allowing forest recovery.

Introducing palmfungi.org, an integrated fungal-host data platform.

Palm fungi are a diverse and unique group mostly found on Arecaceae hosts. They have been studied for approximately 200 years resulting in a large number of known fungal species representing over 700 genera. The timeline of palm fungal studies could be roughly divided into three phases, based on the methods and frequency of reports. They are the "Historical palm fungi era", "Classical palm fungi era" and "Molecular palm fungi era". In the first two periods, the identification of palm fungi was based on morphology, which resulted in a considerable number of morphological species scattered across the data in books, monographs and papers. With the advancement of molecular techniques, studies on palm fungi accelerated. A large number of new species were introduced in the molecular era, especially from Asia, including China and Thailand. However, there is a necessity to link these three generations of studies into a single platform combining data related to host factors, geography and utilisation. Herein, we introduce the palm fungi website: https://palmfungi.org, an integrated data platform for interactive retrieval, based on palm and fungal species. This website is not only a portal for the latest, comprehensive species information on palm fungi, but also provides a new platform for fungal researchers to explore the host-specificity of palm fungi. Additionally, this study uses palmfungi.org and related data to briefly discuss the current status of research on the distribution of palm fungi populations, showing how palmfungi.org links fungi with their palm hosts. Furthermore, the website will act as a platform for collaboration amongst taxonomists, plant pathologists, botanists, ecologists and those who are interested in palms and their relationship with ecological sustainability.

Chemical characterization, neuroprotective effect, and in-silico evaluation of the petroleum ether extract of three palm tree species against glutamate-induced excitotoxicity in rats

The burden of neurological disorders is growing substantially with limited therapeutic options, urging the consideration and assessment of alternative strategies. In this regard, we aimed to elucidate the phytochemical profile of the petroleum ether extract (PEE) of three palm tree species: Aiphanes eggersii Burret, Carpoxylon macrospermum H. Wendl. & Drude, and Jubaeopsis caffra Becc. (Family Arecaceae), and to evaluate their neuroprotective effect in monosodium glutamate (MSG)-induced excitotoxicity model for the first time. We identified a total of 48, 18, and 45 compounds in A. eggersii, C. macrospermum, and J. caffra, constituting 79.41 %, 60.45 %, and 76.35 % of the total detected compounds, respectively. A. eggersii extract was rich in the methyl esters of fatty acids (65.08 %) especially methyl dodecanoate (17.72 %). C. macrospermum was exclusively prolific by the triterpene 3β-methoxy-d:c-friedo-b’:a'-neogammacer-9(11)-ene (40.36 %), while J. caffra was noticeable by hydrocarbons (30.14 %) and lupeol derivatives (19.79 %). The biochemical and histopathological analysis showed that the tested extracts significantly reduced the oxidative stress, especially at the highest tested dose (1000 mg/kg). The extracts also reduced the activity of induced nitric oxide synthetase, Ca+2 level, and NR2B subunit expression and attenuated apoptosis and DNA damage. The docking results show that most active natural compounds bind to SOD-1 and NR2B-NMDARs, verifying the credibility of the biological findings. To sum up, the PEE of the three investigated palm tree species possessed a unique blend of lipophilic bioactive constituents that exert promising neuroprotective potential against MSG-induced excitoneurotoxicity. However, further preclinical investigation and pharmaceutical formulation are needed.

Biochemical and toxicological characteristics of polyphenol oxidase from red palm weevil Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae)

Red palm weevil (RPW) Rhynchophorus ferrugineus is the most destructive insect pests of numerous palm species in the world. The introduction of botanical extract(s) as integral part of an integrated pest management (IPM) programs against RPW will reduce the use of chemical insecticides. Polyphenol oxidase (PPO) is one of the RPW innate immune mechanisms and inhibition of such enzyme could result in a disorder of the insect's immune system. A one single PO isoenzyme has been purified from the hemolymph of the 12th instar larvae of RPW. Using L-DOPA as substrate, R. ferrugineus PPO exhibited specific activity 428 Units/mg proteins with 8.3-fold purification, optimum pH and temperature for activity at 7.5 and 40 °C, respectively and is enhanced by Cu2+ with 1.76-fold. The rank order for oxidizing R. ferrugineus PPO different substrates is catechol > pyrogallol > L-DOPA > pyrocatechuic acid and not tyrosine. The kinetic parameters Km, Vmax and Vmax/Km for L-DOPA are 3.3 mM, 1.3 μmol/ml/min, and 0.39, respectively. The catalytic efficiency of the enzyme towards catechol is 5.3-fold higher than that for L-DOPA. The enzyme completely inhibited by thiourea, ascorbic acid, dithiothreitol, and SDS. R. ferrugineus PPO is a catechol oxidase di-phenol: O2 oxidoreductase. Based on the toxicological studies of various botanical extracts, the IC50 ranged from 20 to 90 mg/ml. The enzyme completely inhibited by 50 mg/ml Cinnamomum camphora. Gallic acid, the major phenolic compound, has IC50 0.8 mM and competitively inhibited the enzyme with Ki 0.54 mM. C. camphora could be a useful natural RPW-controlling agent and used as integral part in IPM programs. This interpretation can be validated in future through an in vivo investigation.

Physicochemical composition and amino acid profile of the beverage of Ungurahua (Oenocarpus bataua) from the Amazonian Region of Ecuador.

Oenocarpus bataua, also known as Ungurahua, is a palm species indigenous to Ecuador's Amazon region. The fruit is used for oil extraction and beverage production. This research aimed to evaluate a beverage made from O. bataua by characterizing its physicochemical properties, amino acid profile, formulation, and sensory and microbiological properties. The research employed quantitative, exploratory, and experimental methodologies utilizing a bifactorial design (3 × 2). This research investigated the effect of cooking and the type of sweetener on the quality of sweetened products. Six treatments were applied, and sensory analysis was performed to determine the optimal treatment. The most effective treatment was a2b2 (cooked for 30 min at 65 ±3°C and sweetened with panela). Upon further analysis, this treatment had a moisture content of 94.7%, ash content of 0.85%, protein content of 0.59%, ethereal extract EE of 2.18%, fiber content of 0.80%, non-nitrogenous extract-ENN of 0.85%, pH of 4.37, Brix of 1.80°, and titratable acidity of 1.92%. A comparison of O. bataua beverages with similar beverages indicated their acceptable nutritional value. Amino acid profile analysis showed the presence of 10 amino acids, of which 8 were essential, and 10 were non-essential. Histidine had the highest concentration in the beverage, with an average of 77%. To ensure the safety and quality of the beverage, a microbiological analysis was performed in compliance with NTE-INEN 3028 standards. No mesophilic aerobes, Salmonella spp., or total coliforms were detected. Therefore, the proposed beverage is safe and nutritionally valuable because of its high amino acid content, balanced physicochemical composition, and sufficient microbiological composition.

In Vitro evaluation of probiotic properties of lactic acid bacteria strains isolated from juçara fruit native to the Atlantic Forest

Lactic acid bacteria (LAB) are the microorganisms most commonly used as probiotics. Since probiotic benefits are strain-dependent, there is a continuous need for research into new cultures with probiotic properties. Fruits such as juçara (Euterpe edulis Martius), a palm species from the Atlantic Forest threatened with extinction, are rich niches for microorganisms, including LAB. This study investigated the probiotic properties of Lactococcus lactis J7 and Leuconostoc pseudomesenteroides JF17 strains isolated from juçara fruits native to the Atlantic Forest. Probiotic characteristics, such as tolerance to simulated gastrointestinal fluids or juices, hydrophobicity, autoaggregation, coaggregation properties, inhibition of pathogenic microorganisms, and technological properties were evaluated. The survival rate of L. lactis J7 and L. pseudomesenteroides JF17 decreased after exposure to simulated gastrointestinal conditions; however, L. lactis J7 was more resistant, maintaining viability at the end of the enteric phase of 6.07 ± 0.16 log CFU mL-1. The J7 strain also exhibited the highest values in hydrophobicity (12.55 ± 0.52%), autoaggregation (25.63 ± 0.75%), and coaggregation capacity with E. coli ATCC 25922 (21.52 ± 0.98%) and S. Enteritidis ATCC 13076 (22.68 ± 1.01%). Both J7 and JF17 strains demonstrated antimicrobial activity, confirmed by the multilayer agar plate system. Additionally, the growth of the strains was temperature-dependent, and they were able to thrive in high concentrations of sodium chloride (6%). Thus, L. lactis J7 is a promising probiotic candidate for the development of functional products. Nevertheless, further studies using animal models are necessary to explore the properties of these probiotic bacteria. Novel strains isolated from fruits should be studied to broaden the application of probiotic microorganisms in the development of foods and medicines.

A hybrid hue saturation lightness, gray level co-occurrence matrix, and k-nearest neighbour for palm-sugar classification

<span lang="EN-US">In recent years, there has been an increasing demand for high-quality raw materials driven by consumers and the food industry. This study aims to build a model to predict the type of </span><span lang="IN">palm</span><span lang="EN-US"> sugar using a hybrid method of hue</span><span lang="IN">-</span><span lang="EN-US">saturation</span><span lang="IN">-l</span><span lang="EN-US">ightness (HSL), gray level co-occurrence matrix (GLCM), and K-nearest neighbor (KNN). The price of palm sugar is determined based on the type and ingredients used. However, due to the lack of public knowledge in distinguishing the types of </span><span lang="IN">palm</span><span lang="EN-US"> sugar, there is the potential for price manipulation that can harm the community. The accuracy rate of 9</span><span lang="IN">7.6</span><span lang="EN-US">% of the palm sugar type prediction results shows that the model that was built has worked very well. The results have practical implications, such as developing automated systems to classify palm species in specific industries to benefit economics and operational efficiency. Future research directions may explore the integration of advanced machine-learning techniques and real-time image processing for further improving classification performance and scalability in industrial applications</span><span lang="IN">.</span>

Unveiling the overlooked: Current and future distribution dynamics of kissing bugs and palm species linked to oral Chagas disease transmission

Chagas disease, a neglected global health concern primarily transmitted through the bite and feces of kissing bugs, has garnered increasing attention due to recent outbreaks in northern Brazil, highlighting the role of oral transmission facilitated by the kissing bugs species Rhodnius robustus and Rhodnius pictipes. These vectors are associated with palm trees with large crowns, such as the maripa palm (Attalea maripa) and moriche palm (Mauritia flexuosa). In this study, we employ maximum entropy (MaxEnt) ecological niche models to analyze the spatial distribution of these vectors and palm species, predicting current and future climate suitability. Our models indicate broader potential habitats than documented occurrences, with high suitability in northern South America, southern Central America, central Africa, and southeast Asia. Projections suggest increased climate suitability by 2040, followed by a reduction by 2080. This study identifies present and future areas suitable for kissing bugs and palm tree species due to climate change, aiding in the design of prevention and management strategies.

Cultural Significance and Sustainable Use of <em>Loxococcus rupicola</em> (Thw.) H. Wendl. and Drude in Sri Lanka: Implications for Conservation and Religious Practices

Loxococcus rupicola (“Ran-Dothalu”), is a nationally endangered palm species found in the southwestern rainforests, central highlands, and Knuckles regions of Sri Lanka. With a predominant Buddhist population, Ran-Dotalu holds sacred reverence among Buddhists. Thus, the present study aimed to elucidate the impact of cultural practices and religious beliefs on their conservation. Comprehensive semi-structured interviews were conducted selecting Buddhist clergy, flower collectors, and devotees(n=114), while data were also extracted from social media platforms. Our findings reveal the multifaceted role of L. rupicola within religious and cultural contexts. Notably, L.rupicola flowers emerge as offerings to the Buddha and deities as an integral component of rituals and medicine, while their seeds are being used as a substitute for the Areca nut. Despite these diverse applications, users were unaware of L.rupicola’s conservation status. Although there are legislative measures, the popularity of L. rupicola as an ornamental species triggers the over-exploitation of seedlings and saplings from natural habitats forming a threat to the population. This study underlines the urgency of aligning conservation strategies with local religious practices, emphasizing the imperative of immediate conservation measures.

Genotyping-by-sequencing informs conservation of Andean palms sources of non-timber forest products.

Conservation and sustainable management of lineages providing non-timber forest products are imperative under the current global biodiversity loss. Most non-timber forest species, however, lack genomic studies that characterize their intraspecific variation and evolutionary history, which inform species' conservation practices. Contrary to many lineages in the Andean biodiversity hotspot that exhibit high diversification, the genus Parajubaea (Arecaceae) has only three species despite the genus' origin 22 million years ago. Two of the three palm species, P. torallyi and P. sunkha, are non-timber forest species endemic to the Andes of Bolivia and are listed as IUCN endangered. The third species, P. cocoides, is a vulnerable species with unknown wild populations. We investigated the evolutionary relationships of Parajubaea species and the genetic diversity and structure of wild Bolivian populations. Sequencing of five low-copy nuclear genes (3753 bp) challenged the hypothesis that P. cocoides is a cultigen that originated from the wild Bolivian species. We further obtained up to 15,134 de novo single-nucleotide polymorphism markers by genotyping-by-sequencing of 194 wild Parajubaea individuals. Our total DNA sequencing effort rejected the taxonomic separation of the two Bolivian species. As expected for narrow endemic species, we observed low genetic diversity, but no inbreeding signal. We found three genetic clusters shaped by geographic distance, which we use to propose three management units. Different percentages of missing genotypic data did not impact the genetic structure of populations. We use the management units to recommend insitu conservation by creating new protected areas, and ex situ conservation through seed collection.

Study on the changes during the fermentation of the wine prepared from palm (Phoenix sylvestris) sap

The sugary sap of different palm trees is fermented to create palm wine, an alcoholic beverage. This work was aimed at studying the changes that occur during the fermentation process of wine made from the sap of the wild date palm species Phoenix sylvestris. At first, the best age of the palm tree was determined by observing total soluble solid and sap yield for 24 h and was found to be middle-aged palm plants (15–40 years old). Pure wine yeast (Saccharomyces cerevisiae SC22) and a natural starter culture were added to the palm saps, adjusting the total soluble solid (TSS) to 21.5° brix (°Bx). Total titratable acidity, pH, volatile acidity, reducing sugar, non-reducing sugar, total sugar, alcohol content, ester content, and aldehyde contents were the parameters under investigation. The statistical analysis showed significant (p ≤ 0.05) changes in the physico-chemical and volatile constituents of palm sap during the fermentation process in both systems. Sensory evaluation revealed that palm wine fermented with pure yeast culture was significantly superior to natural, spontaneously fermented wine. The acceptability test showed that the ideal characteristics of palm wine are cloudy in appearance, fruity in aroma, and sweet in taste.

Molecular Insights into Red Palm Weevil Resistance Mechanisms of Coconut (Cocos nucifera) Leaves.

Red palm weevil (RPW) (Rhynchophorus ferrugineus) threatens most palm species worldwide. This study investigated the molecular responses of coconut (Cocos nucifera) leaves to RPW infestation through metabolomics and transcriptomics analysis. An RPW insect attack model was developed by placing different RPW larval densitiesin coconut plants and measuring the relative chlorophyll content of different leaf positions and physiological indicators of dysfunction after RPW infestation. The metabolomic changes were detected in the leaves of 10, 20, 30, 40, and 50 days after infestation (DAI) using GC-MS. Certain metabolites (glycine, D-pinitol, lauric acid, allylmalonic acid, D-glucaro-1, 4-lactone, protocatechuic acid, alpha, and alpha-trehalose) were found to be possible indicators for distinct stages of infestation using metabolomics analysis. The influence on ABC transporters, glutathione, galactose, and glycolipid metabolism was emphasized by pathway analysis. Differentially expressed genes (DEGs) were identified at 5, 10, 15, and 20 DAI through transcriptomics analysis of infested coconut leaves, with altered expression levels under RPW infestation. The KEGG pathway and GO analysis revealed enrichment in pathways related to metabolism, stress response, and plant-pathogen interactions, shedding light on the intricate mechanisms underlying coconut-RPW interactions. The identified genes may serve as potential markers for tracking RPW infestation progression and could inform strategies for pest control and management.

Towards accurate monitoring of water content in woody tissue across tropical forests and other biomes.

Forest ecosystems face increasing drought exposure due to climate change, necessitating accurate measurements of vegetation water content to assess drought stress and tree mortality risks. Although Frequency Domain Reflectometry offers a viable method for monitoring stem water content by measuring dielectric permittivity, challenges arise from uncertainties in sensor calibration linked to wood properties and species variability, impeding its wider usage. We sampled tropical forest trees and palms in eastern Amazônia to evaluate how sensor output differences are controlled by wood density, temperature and taxonomic identity. Three individuals per species were felled and cut into segments within a diverse dataset comprising five dicotyledonous tree and three monocotyledonous palm species on a wide range of wood densities. Water content was estimated gravimetrically for each segment using a temporally explicit wet-up/dry-down approach and the relationship with the dielectric permittivity was examined. Woody tissue density had no significant impact on the calibration, but species identity and temperature significantly affected sensor readings. The temperature artefact was quantitatively important at large temperature differences, which may have led to significant bias of daily and seasonal water content dynamics in previous studies. We established the first tropical tree and palm calibration equation which performed well for estimating water content. Notably, we demonstrated that the sensitivity remained consistent across species, enabling the creation of a simplified one-slope calibration for accurate, species-independent measurements of relative water content. Our one-slope calibration serves as a general, species-independent standard calibration for assessing relative water content in woody tissue, offering a valuable tool for quantifying drought responses and stress in trees and forest ecosystems.

Detection of different groups of phytoplasma in palm species of Puerto Rico

Palm trees play important cultural, ecological, and economic roles in the tropics. Native palm species such as the royal palm, Roystonea borinquena O.F. Cook, are extensively planted in landscapes and urban areas of Hispaniola, Puerto Rico and the Virgin Islands. Worldwide, palms are affected by a disease commonly known as lethal yellowing, linked to the presence of phytoplasmas. Coconut Lethal Yellowing (CLY) is the most devastating disease of palms, associated with the 16SrIV phytoplasma group in the Americas. In Puerto Rico, palms displayed symptoms such as leaf chlorosis or yellowing, inflorescence and fruit necrosis, and eventual death. The objective of this research was to identify and characterize phytoplasmas in palms and their potential insect vectors, focusing on a native palm, R. borinquena. To fulfill this objective, 69 palms belonging to the species: Cocos nucifera (n=15), Gaussia attendata (n=1), Leucothrinax morrisii (n=1), Pseudophenix sargentii (n=1), Roystonea borinquena (n=50) and Washingtonia robusta (n=1) were sampled within three transects across the island. Ninety percent of palms sampled displayed typical lethal yellowing symptoms. In addition, 12 different insect species (Auchenorrhyncha: Fulgoroidea) that could act as potential phytoplasma vectors were sweep-collected from palms and grasses near the study area. The 16S ribosomal region of phytoplasmas was amplified using nested polymerase chain reaction (PCR) and subjected to restriction fragment length polymorphism (RFLP) analyses to allow their ribosomal grouping. Overall, 17 palm samples were positive to phytoplasmas. These are C. nucifera (n = 1), L. morrisii (n = 1) and R. borinquena (n = 15). Phytoplasmas detected belong to six ribosomal groups: 16SrII, 16SrIII, 16SrIV, 16SrVI, 16SrIX and 16SrX. The most frequent phytoplasma detected (59%) is enclosed in the 16SrII group. Samples from nine royal palms (R. borinquena) and one key thatch palm (L. morrisii) were positive to the 16SrII-related group. Only one insect specimen, the cixiid Haplaxius crudus collected from a phytoplasma positive R. borinquena palm, was positive for a 16SrII-related group phytoplasma. Another significant epidemiological finding was the detection of a phytoplasma related to CLY in the 16SrIV group in one individual of R. borinquena. This native species is the most abundant palm on the island. To our knowledge this is the first report of a phytoplasma related to the 16SrII group in R. borinquena in Puerto Rico and the world. Detection for the first time of other phytoplasmas related to 16Sr groups -III, -IX and -X in palms deserves further studies.

Towards Pathogen-Free Coconut Germplasm Exchange.

Coconut (Cocos nucifera L.) is an important palm species that serves as the mainstay of several industries and contributes to the livelihoods of millions of smallholder farmers. International exchange of coconut germplasm has been undertaken for several decades to facilitate the conservation of selected varieties within global genebanks and for the distribution to farmers and scientists. In vitro systems are a convenient and an efficient method for the exchange of coconut germplasm. However, it is possible that these tissue culture systems can transfer lethal pathogens causing a threat to the importing countries. In this review, the following topics are discussed: the major disease-causing agents of concern, the various tissues that could be used for coconut germplasm exchange, and the techniques available for the detection and elimination of disease-causing agents from various transmission systems. Additionally, the lack of clear, science-backed guidelines to facilitate the exchange of in vitro coconut materials is raised, along with recommendations for future studies to ensure the safe movement of coconut germplasm without biosecurity risks.