ABSTRACT In the current study, hormonal balance and cell wall biosynthesis were determined as responses related to defense mechanisms during infection with Phytophthora cinnamomi in avocado. The phytohormones jasmonic acid, salicylic acid, phenylpropanoids, and caffeic and ferulic acids were analyzed by liquid chromatography coupled to RP-UPLC-MS2 TQD mass spectrometry. Likewise, polyphenol oxidase enzymatic activity and lignin levels were determined. Data were correlated with the area under the disease progress curve (AUDPC). The analysis showed significant differences between cultivars for jasmonic acid levels and production peaks considering the susceptible cultivar ‘Hass’. During Phytophthora cinnamomi infection, salicylic acid production peaked at 24 h in the resistant cultivar ‘Duke 7’ and only increased gradually, without a clear peak, in the susceptible cultivar ‘Hass’, which suggests a differential response consistent with the role of salicylic acid in plant resistance. Production of caffeic and ferulic acids (activation of the phenylpropanoid pathway) increased over time in ‘Duke 7’, opposite to what was observed in ‘Hass’. Correlation between cultivar virulence assays and early responses in the production of signal-amplifying phytohormones (jasmonic and salicylic acids), as well as the subsequent differential production of caffeic and ferulic acids and the activation of polyphenoloxidase for lignin biosynthesis as defense responses, suggests that these phytohormones play an important role in the defense mechanisms of avocado. Better understanding of the avocado immune response may serve as a tool for early and relatively inexpensive identification of materials potentially resistant to P. cinnamommi infection.

Understanding the dynamics of soil microbial communities and their responses to seasonal fluctuations is crucial for maintaining soil health and predicting the effects of climate change. We investigated seasonal impacts on soil microorganisms in tropical dry forests, Andean forests, and páramos. We characterized bacterial and fungal communities using 16S rRNA and ITS gene metabarcoding, complemented by soil chemical analysis. Proteobacteria, Actinobacteriota, Acidobacteriota, and Chloroflexi dominated bacterial communities. Fungi primarily comprised Ascomycota, Basidiomycota, and Mortierellomycota across all ecosystems. Bacterial Shannon diversity was significantly higher during the dry season at all sites, irrespective of ecosystem type. While fungal communities also showed higher species richness in the dry season, these differences were not statistically significant. Correlations between microbial communities and soil properties were generally stronger in the dry season, particularly in tropical dry forests. These findings suggest bacterial communities are more responsive to seasonal environmental shifts, whereas fungal communities exhibit greater structural stability. The páramo notably exhibited the greatest seasonal variability and highest proportion of unclassified reads, underscoring its ecological sensitivity and need for further research and conservation. This study provides valuable insights into the temporal dynamics of microbes in underexplored ecosystems, which are particularly vulnerable to the effects of climate change.

ABSTRACT The disease caused by the oomycete Phytophthora cinnamomi Rands affects most avocado (Persea americana) varieties, requiring additional tools for the selection of resistant materials. In the present study, induction of defense responses related to the oxidative metabolism in avocado was evaluated as a support for establishing its role in the defense responses during infection by this oomycete. Infection trials were carried out with the avocado clones ‘Duke 7’ (tolerant) and ‘Hass’ (susceptible), which had their stem base inoculated with the pathogen and whole leaves sampled at 0, 3, 24, 48 and 120 hours after infection (hai), for subsequent evaluation of the activities of the enzymes superoxide dismutase (SOD) and ascorbate peroxidase (APX), as well as for assessment of free radical scavenging capacity, total polyphenol content and caspase 3-like activity. The area under the disease progress curve was 1.3 and 14.8 (cm.day-1) for ‘Duke 7’ and ‘Hass’, respectively, and the former showed high resistance to the oomycete, which correlated with higher APX activity, higher free radical scavenger activity, and expression of caspase 3-like activity. Resistance or susceptibility in avocado during interaction with Phytophthora cinnamomi is suggested to be mediated by the participation of induced and innate antioxidants and by the induction of apoptosis responses in the resistant genotype ‘Duke 7’, whereas there is lack of such responses in ‘Hass’, the susceptible genotype.

In this work, the influence of evaporative flux over the atomization driven by surface acoustic waves (SAWs) of a Newtonian water drop is studied. The drop is placed on a heated substrate at constant temperature, higher than the saturation temperature at a given vapor pressure. In this manner, an interfacial temperature distribution arises along the drop free surface in terms evaporative mass flux and vapor recoil, which repercussion over aerosol size is studied by determining the asymptotic evolution equation governing the acoustically driven free surface. At such scenario, the connection between surface tension and temperature is also considered; thus, thermocapillary flow is incorporated into our drop model, described in terms of fundamental parameters, like the evaporation number, Marangoni number, and acoustic capillary number. Numerical solution of the evolution equation led us to obtain a simplified representation of the drop interfacial deformation mechanism, capable of predicting atomization and portraying the influence of evaporation over atomization. Subsequent analysis shows that the incorporation of evaporation at SAW atomization traduces in normal stresses counteracting the acoustic and thermocapillary effect, leading to the development of smaller drop aspect ratios with respect to the no-evaporative case. Being aware that the aerosol size is deeply related to the aspect ratio, we propose an analytical expression to estimate aerosol diameter under evaporative conditions. The results show that aspect ratio reduction leads to a decrement on aerosol size, up to two orders of magnitude, with respect to the no-evaporative case. Our study is a first approach providing insight about the importance of evaporation on aerosol regulation at SAW atomization.

The medicinal Lippia alba and Petiveria alliacea, originating from Central and South America, exhibit a wide range of beneficial properties, including antimicrobial, antifungal, anti-inflammatory, antitumor, analgesic, and antibacterial effects. However, little is known about their population structure and genetic diversity, which may hinder the establishment of their cultivation in different regions of Colombia. In this study, we conducted a comprehensive analysis of the genetic diversity and population structure of 17 samples of L. alba from the departments of Tolima, Valle del Cauca, and Putumayo, as well as 31 samples of P. alliacea from the departments of Cundinamarca, Boyacá, Tolima, and Valle del Cauca. We employed restriction-site associated DNA sequencing (RADseq) with the enzyme PstI. We performed denovo_map and ref_map pipeline for L. alba and identified a total of 17,036 loci and 14,562 SNPs, respectively, revealing a genetic variation of 5.19

A bacterial (16S rRNA) and fungal (ITS rRNA) taxonomic characterization was carried out using metabarcoding along an altitudinal gradient in the western range of the Valle del Cauca, Colombia. This study encompassed Tropical Dry Forests, Andean, and Páramo ecosystems in Laguna de Sonso (900 m.a.s.l), Yotoco (1,800 m.a.s.l), Bosque del Duende (2,400 m.a.s.l), and Páramo del Duende (3,200 m.a.s.l). The physicochemical analyses revealed soils with high organic matter (>10%), non-compacted, extremely acidic pH levels (4.4) at higher altitudes, and slightly to moderately acidic pH in lower areas (5.5-6.1). 59 plant families were identified, with Araceae, Lauraceae, and Fabaceae being the most abundant. The most abundant bacterial taxonomic assignments were Acidobacteriota and Proteobacteria phyla, while for fungi, it was Ascomycota and Basidiomycota. Alpha diversity analysis showed high community diversity, whereas beta diversity reflected composition differences among locations and their heterogeneity. The most abundant functional predictions for bacteria were chemoheterotrophic activity and nitrogen cycle involvement. At the same time, for fungi, it was ecological guilds related to pathogenic activity in both animals and plants, endophytes, and epiphytic saprotrophs. The PLS-PM analysis revealed an indirect influence of altitude on microbial abundance and diversity.

Bidens pilosa L., native to South America and commonly used for medicinal purposes, has been understudied at molecular and genomic levels and in its relationship with soil microorganisms. In this study, restriction site-associated DNA markers (RADseq) techniques were implemented to analyze genetic diversity and population structure, and metabarcoding to examine microbial composition in soils from Palmira, Sibundoy, and Bogotá, Colombia. A total of 2,984,123 loci and 3485 single nucleotide polymorphisms (SNPs) were identified, revealing a genetic variation of 12% between populations and 88% within individuals, and distributing the population into three main genetic groups, FST = 0.115 (p < 0.001) and FIT = 0.013 (p > 0.05). In the soil analysis, significant correlations were found between effective cation exchange capacity (ECEC) and apparent density, soil texture, and levels of Mg and Fe, as well as negative correlations between ECEC and Mg, and Mg, Fe, and Ca. Proteobacteria and Ascomycota emerged as the predominant bacterial and fungal phyla, respectively. Analyses of alpha, beta, and multifactorial diversity highlight the influence of ecological and environmental factors on these microbial communities, revealing specific patterns of clustering and association between bacteria and fungi in the studied locations.

The influence of elevation on natural terrestrial ecosystems determines the arrangements of microbial communities in soils to be associated with biotic and abiotic factors. To evaluate changes of fungi and bacteria at the community level along an elevational gradient (between 1000 and 3800 m.a.s.l.), physicochemical measurements of soils, taxonomic identifications of plants, and metabarcoding sequences of the 16S rRNA gene for bacteria and the ITS1 region for fungi were obtained. The bacterial taxonomic composition showed that Acidobacteriota increased in abundance with elevation, while Actinobacteriota and Verrucomicrobiota decreased. Furthermore, Firmicutes and Proteobacteria maintained maximum levels of abundance at intermediate elevations (1200 and 2400 m.a.s.l.). In fungi, Ascomycota was more abundant at higher elevations, Basidiomycota tended to dominate at lower elevations, and Mortierellomycota had a greater presence at intermediate sites. These results correlated with the edaphic parameters of decreasing pH and increasing organic carbon and available nitrogen with elevation. In addition, the Shannon index found a greater diversity in bacteria than fungi, but both showed a unimodal pattern with maximum values in the Andean Forest at 2400 m.a.s.l. Through the microbial characterization of the ecosystems, the elevational gradient, soil properties, and vegetation were found to exert significant effects on microbial communities and alpha diversity indices. We conclude that the most abundant soil microorganisms at the sampling points differed in abundance and diversity according to the variations in factors influencing ecological communities.

Thermocapillary flow on the mechanism of interfacial destabilization prior to atomization of a sessile Newtonian droplet subjected to surface acoustic waves (SAWs) is analyzed. We assumed that an interfacial temperature distribution is induced on the free surface of the millimeter-sized water droplet since the droplet is on a heated substrate. Given the dependence of surface tension on interfacial temperature, shear stresses combined with SAWs lead to the development of thermocapillary flow. The evolution equation for a small-scale droplet under the combined influence of SAW atomization and thermocapillary flow is derived via an asymptotic approach to the hydrodynamic equations, arising the acoustic capillary and Marangoni numbers. In this limit, our simplified droplet model can predict capillary instability leading to atomization once a critical amplitude is reached for the induced capillary waves at the liquid droplet. In doing so, our model also represents the influence of the thermocapillary effect on the interfacial deformation of the droplet and shows how the Marangoni flow promoted by a heated substrate counteracts the acoustic stress, leading to a virtually uniform droplet aspect ratio and thus larger aerosol diameters compared to the isothermal case. These results are supported by the development of a novel analytical expression that has allowed us to estimate the characteristic aerosol size under thermocapillary flow and SAW excitation, and to postulate thermocapillary flow as a new valuable means of explaining the regulation of the characteristic aerosol size at SAW atomization.

Given the importance of soil as a supplier of nutrients and water for different ecosystems, understanding soil health and quality is necessary for its preservation. Microorganisms, due to their high abundance and their relationship with the degradation of organic matter and biogeochemical cycles, have a rapid response to environmental changes and thus are a discriminating factor that can be used as bioindicators of soil health. However, 97% of microorganisms are unculturable, leaving a gap in their taxonomic and functional knowledge. The development of metagenomics has reduced this problem through the direct extraction of DNA from soil, allowing the characterization of such non-culturable microorganisms, this technique can be considered one of the most impactful in soil health, given that it allows for an exploration of the biodiversity, the community structure, and the potential functions of the microbial communities from distinct environments. In addition to this, metagenomics have had an impact in different areas such as "OneHealth" or EcoGenomics allowing the formation of international projects. The aim of this paper is to show how metagenomics can be used as a technique to assess soil quality and health through the taxonomic and functional identification of the microorganisms present in the soil.

In the present work, we theoretically analyze the influence of thermocapillary flow on the atomization by surface acoustic waves (SAWs) of a sessile water droplet exposed to a high-frequency acoustic field and placed over a substrate with slippage at the wall. Thermocapillary flow is induced by imposing a Gaussian temperature profile along the free surface of the droplet. Such fluid flow in conjunction with the acoustically-driven capillary waves at the free surface prior to atomization under the influence of the slip phenomenon is analyzed by applying the lubrication theory to the flow field governing equations, leading to the derivation of an evolution equation written in terms of the acoustic capillary number, the Marangoni number, and the substrate slip coefficient. The numerical solution of the evolution equation has led us to propose the combined influence of thermocapillary and slip phenomena as a valuable means of assisting in the regulation of aerosol diameter in SAW atomization, capable of exerting a significant influence on the interfacial dynamics of droplets prior to atomization.

With the increasing negative impacts on worldwide food production caused by pests, the recovery of native entomopathogenic nematodes (EPNs) is relevant, since they are adapted to local environments, entomofauna, and significant virulence. Therefore, the present study was designed to recover and understand the phylogenetic diversity of EPNs and their associated bacterial endosymbionts, from banana and plantain crops, as alternatives for the control of weevil species. An extensive sampling of western Colombia covered 325 ha, yielding the recovery of three EPNs’ isolates (0.49% of the samples). The molecular characterization included four mitochondrial and nuclear loci, which, after merging with the sequences of 48 species, confirmed the presence of Steinernema carpocapsae, the first report of S. costaricense in South America, and monophyly in most of the Steinernema clades. The tree topologies were consistent for the nuclear loci but not for mitochondrial, probably due to the high nucleotide substitution rate, deficit in the number of species available for these loci, and incomplete lineage sorting. The endosymbiotic bacteria associated with S. carpocapsae were identified as Xenorhabdus nematophila. However, the S. costaricense bacterial symbiont presented a genetic similarity to X. koppenhoeferi and X. khoisanae, which are still uncertain in their classification. The identification of S. costaricense in South America indicates the wide range distribution of this species in the Americas and its ability to persist in different soil types. For the first time, EPN isolation and phylogenetic characterization are directed to plantain and banana crops. Leveraging EPNs’ diversity promises novel applications for crop protection, while the genetic resources from the bacterial endosymbionts may provide metabolites with a wide spectrum of uses, either for agricultural or medicinal purposes.

Soils play important roles in the proper functioning of agroecosystems. Using molecular characterization methods such as metabarcoding, soils from eight farms (57 samples) belonging to three production system types—agroecological (two farms with twenty-two sampling points), organic (three farms with twenty-one sampling points), and conventional (three farms with fourteen sampling points)—were compared from the rural villages of El Arenillo and El Mesón in Palmira, Colombia. Amplification and sequencing of the hypervariable V4 region of the 16S rRNA gene was performed using next-generation sequencing (Illumina MiSeq) to estimate the bacterial composition and the alpha and beta diversity present. Across all soil samples, we found 2 domains (Archaea and Bacteria), 56 phylum, 190 classes, 386 orders, 632 families, and 1101 genera to be present. The most abundant phyla in the three systems were Proteobacteria, (agroecological 28%, organic 30%, and conventional 27%), Acidobacteria (agroecological 22%, organic 21%, and conventional 24%), and Verrucomicrobia (agroecological 10%, organic 6%, and conventional 13%). We found 41 nitrogen-fixing and phosphate-dissolving genera which promote growth and pathogens. Alpha and beta diversity indices were very similar across the three agricultural production systems, as reflected by shared amplicon sequence variants (ASVs) among them, likely due to the proximity of the sampling sites and recent management changes.

Medicinal plants maintain structures and diversities of bacteria, fungi, and arbuscular mycorrhizal fungi (AMF) that can interact to promote growth and therapeutic properties. Therefore, the purpose of this research was to evaluate the microbiome of Lippia alba and Petiveria alliacea, species known for their high potential for medicinal benefits in Colombia. To achieve this, rhizosphere soils and roots were sampled from five departments in Colombia: Boyacá, Cundinamarca, Tolima, Putumayo, and Valle del Cauca. The results revealed that the dominant bacterial groups in both plants were primarily Proteobacteria, Acidobacteriota, and Actinobacteriota, with the first phylum showing the highest number of differentially abundant genera between the sampling points. In fungi, Ascomycota tended to dominate in most of the sampled locations, while Mortierellomycota was particularly abundant in roots of P. alliacea in Valle. Furthermore, the study of AMF indicated differentiation in the colonization for both plants, with the genera Glomus and Paraglomus being predominant. Differences in the Shannon diversity index were recorded between sampling types within these sampling points, possibly influenced by local and environmental factors. Our findings reveal that the microbiomes of both medicinal plants exhibit distinct community assemblies, which could be a significant factor for their future therapeutic use.

The production of Musa AAB Simmonds (plantain) and M. acuminata AAA (banana) is threatened by different plant-parasitic nematodes (PPN) worldwide. Main PPN such as Radopholus similis, Meloidogyne spp., Pratylenchus spp., Rotylenchulus reniformis, and Helicotylenchus spp. may cause yield losses up to 80%. Most of these nematodes have a wide host range and their dispersal has been favored by planting infested seedlings. This chapter discusses the main aspects of each of the plantain and banana PPN species and the non-conventional tools available for their adequate management. Although some chemical nematicides are efficient in controlling PPN associated with Musa spp. crops, they are being withdrawn from the market for their hazardous to the environment and human health. Thus, the PPN management should consider non-chemical tactics, before and after sowing, including the use of PPN free seeds, the spraying of biocontrol agents, and the use of phytochemical compounds applied via biofumigation, green manures, plant essential oils and extracts, intercropping, cover crops, improved fallow and crops rotation.

La investigación se realizó en Ecuador en los cantones Santo Domingo de los Colorados y El Carmen, pertenecientes a las provincias de Santo Domingo de los Tsáchilas y Manabí respectivamente. El objetivo fue identificar los sistemas agrícolas de producción de plátano (Musa AAB) y caracterizarlos en función de sus componentes. Se aplicó una encuesta a los productores donde se obtuvieron datos de carácter cualitativo que se evaluaron con un análisis multivariado de correspondencia múltiple (ACM), así como un estudio de conglomerados que permitió agrupar los sistemas de producción por afinidad intragrupal y diferencias intergrupales. Se obtuvieron como resultado 5 indicadores representativos de los agrosistemas y dos tipos de producción: uno dedicado exclusivamente al monocultivo de plátano y el otro en asociación de cultivos, con mayor frecuencia combinados con especies perennes frutales y forestales.

The research focused on fine aroma cocoa is a priority for Ecuador.The objective of this work was to identify stable, high-yielding accessions.The genetic base was based on 2222 cocoa accessions from the germplasm bank of the Tenguel Aroma Cocoa Center -Ecuador.An index was applied for selecting 150 accessions based on yield and health status.A descriptive analysis, principal component analysis by the factor extraction method between the meteorological parameters and the variables evaluated, was used.A multiple regression and stability analysis was also performed using the method of Eberhart & Russell (1966) modified by considering the years as the different environments and multivariate principal component analysis.Variables related to high CV % yield ranged from 93 to 112 %.The highest yields were observed in 2003, 2004 and 2005.The flowering intensity was influenced by rainfall, temperature and relative humidity and thus by the yield of the accessions.The predictor variables for yield were healthy pods, diseased pods and flowering intensity with a correlation of 0.95, 0.33 and 0.07, respectively, and an R2 = 0.899.The following were selected for their stability and average yield per tree 2.1 kg tree-1: L17H38, L33H45, L53H4, L49H4, L41H70, L49H4, L21H56, L13H11, L30H1, L30H46, L42H80, L30H45 and L32H72.The characteristics of the selected accessions constitute a contribution to cocoa breeding programs in Ecuador and other cocoa-producing regions.

The Arrayán tree (Calycolpus moritzianus) is an endemic species from northern South America and it is important for its potential in the medical and cosmetic industry. However, to take advantage of its applied potential different biological aspects, such as genetic diversity, must be characterized. We evaluated 5 RAMs markers on 45 individuals of C. moritzianus collected from 5 locations in Norte de Santander, Colombia, to estimate its genetic diversity. The cluster analysis indicated heterogeneity between populations; however, Ocaña individuals were genetically more different, when compared with other populations. A multiple correspondence analysis revealed 2 population groups: the first one including individuals from Ocaña, and the second one that includes individuals from Salazar, Chinácota, Pamplonita and Toledo. This last group showed a higher degree of genetic diversity. We found an average heterozygosity (He) of 0.34 and a fixation index (FST) of 0.13 among populations. These results are likely due to the relatively high genetic distance, observed between Ocaña and the other populations, and because of the effect of geographical barriers in the area. This is the first study in population genetics of this important native timber resource in the northern Andes, and provides relevant information for future conservation strategies and its sustainable use.

The influence of the slippage phenomenon over the interfacial dynamics of a millimeter-order fluid drop exposed to surface acoustic wave atomization is numerically studied under hydrophilic conditions. Implementation of the Navier-slip model into the governing hydrodynamic equations yields an interfacial evolution equation. The solution suggests that slippage at the wall constitutes a valuable phenomenon to manipulate the parent drop geometric aspect ratio and consequently the characteristic aerosol size during the atomization process.

Tepary bean (Phaseolus acutifolius A. Gray) is more heat and drought tolerant than common bean (P. vulgaris L.). Four hundred mutant lines of two tepary accessions (G40068 and G40159) were generated by ethyl methane sulfonate (EMS) treatment. In preliminary studies of the M5 mutant lines under abiotic stress, three mutant lines (CMT 38, CMT 109, CMT 187) were selected from six mutated lines based on morpho-physiological traits and superior yield and advanced to the M6 generation. The M6 mutant lines were uniform and genetically stable. These mutant lines and their original (M0) parents were evaluated for heat and drought tolerance under greenhouse conditions. Their performance was evaluated for morpho-physiological attributes, seed yield and yield components. Under high temperature and drought conditions, the CMT 38 mutant (M6 line) and its original tepary (M0) accession (G40068) showed greater values of pod biomass, pod number and 100-seed biomass than the other lines tested. The CMT 109 and CMT 187 mutant lines and their G40159 original accession (M0) also showed the highest value of seed number under high temperature and drought conditions. This suggests that the previous screening performed during the population advancement of these mutant lines, based on morphological traits like growth habit, was not detrimental to the yield variables evaluated here. Under combined heat and drought conditions, different parameters could be incorporated into tepary breeding programmes, as selection criteria to screen genotypes for tolerance to heat and drought stress. These parameters included: chlorophyll (SPAD) readings, seed biomass, 100-seed biomass and seed number because they explain the observed variance in the principal component analysis. Two additional traits (root biomass and stem diameter) were also identified as useful attributes, based on univariate analysis. The mutant lines evaluated here offer potential for further improvement of tepary bean to high temperature and drought