Tropical Palm Species Research Articles

Acclimatization of Tropical Palm Species Associated with Leaf Morpho-Physiological Traits to the Understorey Environment of Hevea Rubber Farms

Hevea rubber farm is viable for agroforestry systems since its canopy lessens extreme weather conditions and contributes to the adaptation of shade-tolerant plants. However, some limitations in the availability of soil water and shades vary with the age of rubber trees and affect the understorey plants’ acclimatization. Tropical palms are potentially associated plants for the rubber-based agroforestry systems because they are rainforest species adaptable to understorey environments. Two rubber farms, ages 12 and 25 years, intercropped with tropical palms were selected to investigate the acclimatization of the palms to the seasonal abiotic variations in the mature rubber farms. The studied palm species were Chrysalidocarpus lutescens and Rhapis excelsa in the 12-year-old rubber farm and Livistona speciosa and Licuala spinosa in the 25-year-old rubber farm, respectively. Leaf area, stomatal conductance, photosynthesis pigments, and leaf nitrogen content were identified as the palms’ morpho-physiological traits. The 12-year-old rubber farm had a marked soil water deficit in all soil depths at the beginning of the rainy season, reaching around 200 kPa at the 80 cm soil depth, while the 25-year-old rubber farm received greater light transmissions, ranging between 37 and 46% in the late dry season. All palms adjusted leaf area to balance the photosynthetic capacity. The Rhapis palm had greater acclimatization with significant responses of stomatal conductance. Other than the Licuala palm, all palms exhibited the allocation of chlorophyll pigments and nitrogen content significantly in their leaves in response to the different intensities of abiotic stresses in the understorey of the rubber farms.

Identification and dereplication of endophytic Colletotrichum strains by MALDI TOF mass spectrometry and molecular networking

The chemical diversity of biologically active fungal strains from 42 Colletotrichum, isolated from leaves of the tropical palm species Astrocaryum sciophilum collected in pristine forests of French Guiana, was investigated. The collection was first classified based on protein fingerprints acquired by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) correlated with cytotoxicity. Liquid chromatography coupled to high-resolution tandem mass spectrometry (LC-HRMS/MS) data from ethyl acetate extracts were acquired and processed to generate a massive molecular network (MN) using the MetGem software. From five Colletotrichum strains producing cytotoxic specialized metabolites, we predicted the occurrence of peptide and cytochalasin analogues in four of them by MN, including a similar ion clusters in the MN algorithm provided by MetGem software. Chemoinformatics predictions were fully confirmed after isolation of three pentacyclopeptides (cyclo(Phe-Leu-Leu-Leu-Val), cyclo(Phe-Leu-Leu-Leu-Leu) and cyclo(Phe-Leu-Leu-Leu-Ile)) and two cytochalasins (cytochalasin C and cytochalasin D) exhibiting cytotoxicity at the micromolar concentration. Finally, the chemical study of the last active cytotoxic strain BSNB-0583 led to the isolation of four colletamides bearing an identical decadienamide chain.

Pseudophoenix ekmanii (Arecaceae) seeds at suboptimal temperature show reduced imbibition rates and enhanced expression of genes related to germination inhibition.

Pseudophoenix ekmanii is a critically endangered palm species that can be found in the southeast of the Dominican Republic. The temperatures to which P. ekmanii seeds are exposed upon dispersal range from 32 to 23°C (max and min) and can reach a low of approximately 20°C in January. Our aim was to analyse the effect of suboptimal (20°C) and optimal (30°C) germination temperature on seed imbibition, moisture content, embryo growth and gene expression patterns in this tropical palm species. Seed imbibition was tracked using whole seeds, while moisture content was assessed for individual seed sections. Embryo and whole seed size were measured before and after full imbibition. For transcriptome sequencing, mRNA was extracted from embryo tissues only and the resulting reads were mapped against the Elaeis guineensis reference genome. Differentially expressed genes were identified after statistical analysis and subsequently probed for enrichment of Gene Ontology categories 'Biological process' and 'Cellular component'. Our results show that prolonged exposure to 20°C slows whole seed and embryo imbibition and causes germination to be both delayed and inhibited. Embryonic transcriptome patterns associated with the negative regulation of germination by suboptimal temperature include up-regulation of ABA biosynthesis genes, ABA-responsive genes, as well as other genes previously related to physiological dormancy and inhibition of germination. Thus, our manuscript provides the first insights into the gene expression patterns involved in the response to suboptimal temperature during seed imbibition in a tropical palm species.

Isolation and characterization of microsatellites for the neotropical dioecious palm Chamaedorea tepejilote (Arecaceae) and cross-amplification in other Chamaedorea species.

Palms are important components of tropical and subtropical ecosystems and have even been considered keystone plant resources that can support a large array of pollinators and frugivores. Palms are also economically important. Chamaedorea tepejilote Liebm. is a widely distributed palm with important bioeconomic potential for food, traditional medicine and ornamental purposes. Eighteen microsatellite primers were developed for C. tepejilote. Polymorphism and genetic diversity were evaluated in 71 individuals from four populations in Costa Rica. Thirteen loci were polymorphic and the number of alleles in the pooled sample ranged between 5 and 20, the average number of alleles was 10.61. Average observed heterozygosity was Ho=0.607±0.04 (SD) and the average expected heterozygosity was He=0.600±0.03. The exclusion probability of the combined 13 loci, was PE=0.998. We tested transferability of the markers in the congeneric C. costaricana, C. pinnantifrons and C. macrospadix. Dioecious species are common in tropical forests; however, few studies have analyzed gene flow patterns in these species. The markers developed for C. tepejilote are an important tool to quantify gene flow patterns and the distribution of genetic diversity within populations. This information will be useful for the development of conservation and management practices of this dioecious tropical palm species.

Rivers shape population genetic structure in Mauritia flexuosa (Arecaceae).

The Mauritia flexuosa L.f. palm is known as the “tree of life” given its importance as fundamental food and construction resources for humans. The species is broadly distributed in wet habitats of Amazonia and dry habitats of the Amazon and Orinoco river basins and in the Cerrado savanna. We collected 179 individuals from eight different localities throughout these habitats and used microsatellites to characterize their population structure and patterns of gene flow. Overall, we found high genetic variation, except in one savanna locality. Gene flow between populations is largely congruent with river basins and the direction of water flow within and among them, suggesting their importance for seed dispersal. Further, rivers have had a higher frequency of human settlements than forested sites, contributing to population diversity and structure through increased human use and consumption of M. flexuosa along rivers. Gene flow patterns revealed that migrants are sourced primarily from within the same river basin, such as those from Madeira and Tapajós basins. Our work suggests that rivers and their inhabitants are a critical element of the landscape in Amazonia and have impacted the dispersal and subsequent distribution of tropical palm species, as shown by the patterns of genetic variation in M. flexuosa.

Rain-borne fungi in stemflow and throughfall of six tropical palm species.

Rain-borne fungi in stemflow and throughfall of six tropical palm species.

Impacto del tamaño del fragmento de bosque en la estructura de la población de tres especies de palmas del Bosque Atlántico Brasileño

The main threats to natural populations in terrestrial ecosystems have been widly recognized to be the habitat fragmentation and the exploitation of forest products. In this study, we compared the density of the populations and the structure of three tropical palm species, Astrocaryum aculeatissimum, Euterpe edulis and Geonoma schottiana. For this, we selected five forest fragments of different sizes (3 500ha, 2 400ha, 57ha, 21ha and 19ha) where palms were censused in nine 30 x 30m plots. We tracked the palms survival from 2005 to 2007, and recorded all new individuals encountered. Each individual was assigned in one of the five ontogenetic stages: seedling, infant, juvenile, immature and reproductive. The demographic structure of each palm species was analyzed and compared by a generalized linear model (GLM). The analysis was performed per palm species. The forest fragment area and the year of observation were explanatory variables, and the proportion of individuals in each ontogenetic class and palm density were response variables. The total number of individuals (from seedlings to reproductives, of all species) monitored was 6 450 in 2005, 7 268 in 2006, and 8 664 in 2007. The densities of two palm species were not influenced by the size of the fragment, but the population density of A. aculeatissimum was dependent on the size of the fragment: there were more individuals in the bigger than in the smaller forest fragments. The population structure of A. aculeatissimum, E. edulis, and G. schottiana was not altered in the smaller fragments, except the infants of G. schottiana. The main point to be drawn from the results found in this study is that the responses of density and population structure seem not to be dependent on fragment size, except for one species that resulted more abundant in bigger fragments.

Container Production of Palms

This document summarizes all the good practices for growing palms in containers. Container-grown palms are raised for essentially three markets: liners for field production wholesale or mass market retail sales for landscapes, and interior specimens, both mass market houseplants and interiorscape use. The largest market for container grown palms is the interior. Palms are outstanding plants for the interior environment. When properly acclimated, a large number of subtropical and tropical palm species are capable of residing under low light conditions for a relatively long period of time.

Arbuscular mycorrhizal inoculation increases biomass of Euterpe edulis and Archontophoenix alexandrae after two years under field conditions

Inoculation with arbuscular mycorrhizal fungi (AMF) of tree seedlings in the nursery is a biotechnological strategy to improve growth, survival after transplanting, biomass production and to reduce the use of fertilizers. Archontophoenix alexandrae and Euterpe edulis are palm species used in southern Brazil to produce the palm heart, the latter being included in the list of threatened species due to the overexploitation of its native population. The purpose of this paper was to evaluate the effect of mycorrhizal inoculation on growth and physiological parameters of A. alexandrae and E. edulis. After germination, the seedlings were inoculated (AMF) or not (CTL) with AMF in the treatments. Values of chlorophyll content, biomass and shoot phosphorus were not statistically different between the AMF and CTL treatments, after five months in the greenhouse. Inoculation with AMF significantly increased the levels of starch and soluble carbohydrates in shoots and roots of both species. Under field conditions, AMF had no effect on stem diameter and height after 12 and 24 months, but total plant biomass and leaf, stem and root biomass were greater in AMF than in CTL plants. The data indicated that AMF inoculation in the nursery has a strong effect on biomass accumulation after growing for 24 months under field conditions. Therefore, AMF inoculation should be considered an important strategy to increase growth and production of these economically important tropical palm species.

Caracterização dos estádios ontogenéticos de três espécies de palmeiras: uma proposta de padronização para estudos de dinâmica populacional

The objective of this study was to identify, classify and describe the ontogenetic stages and/or size classes of three tropical palm species, Astrocaryum aculeatissimum (Schott) Burret, Euterpe edulis Mart. and Geonoma schottiana Mart. The populations were sampled in five fragments of Atlantic Rain Forest in 2005. All individuals had their diameter and height measured, and also the number and kind of leaf recorded in each fragment of nine 30 × 30 m plots. Based on these measurements, we assigned each individual to one of five classes. Astrocaryum aculeatissimum and E. edulis change their kind of leaf throughout development. Geonoma schottiana has a high variation in the kind of leaf, and only the seedlings stage displays only one kind of leaf. The appearance of stem and reproductive events also represents class change. The kind of leaf, the surge of the stem and reproductive events were the main characteristics used for the ontogenetic stage identification. However, for E. edulis and G. schottiana class identification, we also used quantitative characteristic because some stages have wide size variation. Studies that characterize and describe species ontogenetic stages are very important for standardization and to allow comparison between studies of population structure and dynamics.

Detection of dehydrin-like proteins in embryos and endosperm of mature Euterpe edulis seeds

Euterpe edulis Martius, a tropical palm species characterized as highly recalcitrant, accumulated dehydrin proteins in both the endosperm and the embryo of the mature seed, as detected by Western blot analysis and immunogold electron microscopy. Three major bands at molecular masses of approximately 16, 18, and 24 kDa were identified in both samples analysed. Immunogold electron microscopy studies detected the presence of dehydrins in the embryo and endosperm. In both cases, dehydrins were immunolocalized in cytoplasm and chromatin. No labelling associated with either membranes or organelles was detected. It is known that dehydrins are produced as part of the developmental program of orthodox seeds and are also present in some recalcitrant seeds of temperate regions. The constitutive presence of dehydrins in embryos of extremely recalcitrant species of tropical origin has not been previously reported.

100-seed test for desiccation tolerance and germination: a case study on eight tropical palm species

100-seed test for desiccation tolerance and germination: a case study on eight tropical palm species

Population dynamics of a tropical palm: use of a genetic algorithm for inverse parameter estimation

The tropical palm species Iriartea deltoidea is an important resource in Amazonian Ecuador. Population models, based on short-term field measurements, have been used to analyze management scenarios for Iriartea sustainable harvesting. An existing matrix population model for Iriartea in secondary and mature forests could not adequately simulate the population dynamics from clearing to 30 years or more. In order to find a better model of the Iriartea population, we used inverse analysis with two optimization techniques (Golden Section search and genetic algorithm (GA)) to find fecundity and seedling demographic parameters that best matched the observed secondary forest (30 years after clearing) and mature forest size class distributions. Re-estimation of fecundity using the Golden Section optimization resulted in a good match to seedling numbers, but a poor fit for other size classes. Genetic algorithm optimization of fecundity and seedling survival and transition parameters found good fits from clearing to age 30 with an exponential or density-dependent model. In order to find a single model that described the population trajectory from clearing to mature forest, we used the genetic algorithm to best fit the observed size class distributions at age 30 and for the mature forest (assumed ages of 65–150 years). The genetic algorithm produced plausible density-dependent models for each of the assumed mature forests ages. Simulated seedling demographic parameters 40–60 years after clearing were similar to field estimates from 30-year-old and mature forest populations.

Pollination Ecology of a Forest-Dominant Palm (Orbignya phalerata Mart.) in Northern Brazil

Pollination Ecology of a Forest-Dominant Palm (Orbignya phalerata Mart.) in Northern Brazil