Arid Land Plants Research Articles

Biomass production of 14 accessions of cactus pear (Opuntia spp.) under semi‐arid land conditions

AbstractIncreased food, feed, and biofuel demands of the future will require a greater reliance upon crop production systems in arid and semi‐arid regions around the world. Diminishing freshwater resources and hotter and drier climatic conditions will also necessitate the use of highly drought tolerant and water‐use efficient crops. Cactus pear (Opuntia ficus‐indica) is a low‐water input, climate‐resilient crop capable of high biomass production due to its use of crassulacean acid metabolism (CAM). Cactus pear produces both food and forage/fodder, a wide variety of high‐value byproducts, and serves as a bioenergy feedstock for biogas or bioethanol production. Here, we evaluated the biomass productivity of 14 Opuntia spp. accessions from the National Arid Land Plant Genetic Resources Unit (NALPGRU) in Parlier, CA under semi‐arid conditions with a planting density of 6667 plants ha−1 over a 3‐year period to identify high‐yielding biomass producers. Mean annual cladode fresh weight (CFW) (73.7 Mg ha−1 year−1), cladode dry weight (CDW) (5.2 Mg ha−1 year−1), and cladode count (CC) (10.5 cladodes plant−1) increased by 2.9‐, 2.8‐, and 2.8‐fold in year 3 compared with year 1. PARL 845, hybrid no. 46 (O. ficus‐indica × O. lindheimerii), showed the highest annual mean CFW (152.8 Mg ha−1 year−1), CDW (13.3 Mg ha−1 year−1), CC (22.1 cladodes plant−1), and dry matter content (DMC, 11.2%) among all accessions tested. Non‐hybrid accessions PARL 242 (O. cochenillifera), PARL 582 (Opuntia sp.), and PARL 584 (Opuntia sp.) showed 100% cladode establishment rates and CDW productivity of >6 Mg ha−1 year−1. Such biomass productivity results indicate that cactus pear displays great potential as a crop with many uses with lower water inputs than conventional crops for arid and semi‐arid environments.

The benefits of woody plant stem photosynthesis extend to hydraulic function and drought survival in Parkinsonia florida.

As climate change exacerbates drought stress in many parts of the world, understanding plant physiological mechanisms for drought survival is critical to predicting ecosystem responses. Stem net photosynthesis, which is common in arid environments, may be a drought survival trait, but whether the additional carbon fixed by stems contributes to plant hydraulic function and drought survival in arid land plants is untested. We conducted a stem light-exclusion experiment on saplings of a widespread North American desert tree species, Parkinsonia florida L., and after shading acclimation, we then subjected half of the plants to a drought treatment to test the interaction between light exclusion and water limitation on growth, leaf and stem photosynthetic gas exchange, xylem embolism assessed with micro-computed tomography and gravimetric techniques, and survival. Growth, stem photosynthetic gas exchange, hydraulic function and survival all showed expected reductions in response to light exclusion. However, stem photosynthesis mitigated the drought-induced reductions in gas exchange, xylem embolism (percent loss of conductivity, PLC) and mortality. The highest mortality was in the combined light exclusion and drought treatment, and was related to stem PLC and native sapwood-specific hydraulic conductivity. This research highlights the integration of carbon economy and water transport. Our results show that additional carbon income by photosynthetic stems has an important role in the growth and survival of a widespread desert tree species during drought. This shift in function under conditions of increasing stress underscores the importance of considering stem photosynthesis for predicting drought-induced mortality not only for the additional supply of carbon, but also for its extended benefits for hydraulic function.

A New Discrete Mycorrhiza Optimization Nature-Inspired Algorithm

This paper presents the discrete version of the Mycorrhiza Tree Optimization Algorithm (MTOA), using the Lotka–Volterra Discrete Equation System (LVDES) formed by the Predator–Prey, Cooperative and Competitive Models. The Discrete Mycorrhizal Optimization Algorithm (DMOA) is a stochastic metaheuristic that integrates randomness in its search processes. These algorithms are inspired by nature, specifically by the symbiosis between plant roots and a fungal network called the Mycorrhizal Network (MN). The communication in the network is performed using chemical signals of environmental conditions and hazards, the exchange of resources, such as Carbon Dioxide (CO2) that plants perform through photosynthesis to the MN and to other seedlings or growing plants. The MN provides water (H2O) and nutrients to plants that may or may not be of the same species; therefore, the colonization of plants in arid lands would not have been possible without the MN. In this work, we performed a comparison with the CEC-2013 mathematical functions between MTOA and DMOA by conducting Hypothesis Tests to obtain the efficiency and performance of the algorithms, but in future research we will also propose optimization experiments in Neural Networks and Fuzzy Systems to verify with which methods these algorithms perform better.

Cactaceae plants as sources of active bioavailable phytochemicals.

Arid-land plants from the Cactaceae family are endemic to the Americas and cultivated worldwide. Cactaceous plants and their fruits contain phenolic compounds, betalains, vitamins, carotenoids, minerals, and soluble fiber. Edible cactaceous matrices can be considered functional foods since their consumption may confer health benefits. These plants could be a source of novel bioactive compounds relevant to the area of phytomedicine. However, consumption of high concentrations of active molecules is not necessarily correlated to beneficial physiological effects because phytochemicals must be released from the food matrices under physiological conditions, resist digestion-associated chemical transformations, and remain in their active state in systemic circulation until the target tissues are reached. Notably, although digestion may either increase or decrease the bioactive phytochemicals' activity and stability, non-absorbed compounds may also be relevant for human health. Additionally, food matrices' type and composition and their technological processing operations may influence the compounds' release, stability, and accessibility. Thus, this review provides insights on the feasibility of using Cactaceae plants as sources of functional compounds. It is focused on compounds' bioactivity, bioaccessibility, and overall bioavailability after their metabolic transformation. Also, it addresses the influence of food processing on bioactive compounds. Many Cactaceae species are unexplored, and our understanding of how they confer health benefits is limited. To better understand the physiological relevance, nutraceutical potential, and therapeutic feasibility of cactaceous bioactive phytochemicals, future research should focus on the metabolic stability and safety of these compounds, as well as their assimilation mechanisms (absorption, distribution, and metabolic fate).

What are the demographic consequences of a seed bank stage for columnar cacti?

AbstractThe dynamics of plant populations are often limited by the early stages in their life cycles. However, information regarding seed bank dynamics and how these may influence the whole life cycle of plant species is remarkably scarce or not considered explicitly. This lack of knowledge is due mainly to the challenges in quantifying seed vital rates. Studies of arid land plant species have historically been focused on the drivers of sporadic recruitment. However, little attention has been given to the demographic consequences of early developmental stages, and how seed banks affect their dynamics. Here, we evaluate the effects of seed bank survival and seedling recruitment vital rates on the population dynamics and viability of 12 columnar cacti species. Recent evidence suggests that cacti seeds may remain viable for the short‐term. We assess how changes in the vital rates of these processes and the inclusion of a seed bank affect population growth rate (λ). We found that a seed bank in the examined matrix population models significantly increased λ as well as the vital rate elasticities of λ to growth and fecundity, whereas that of overall survival decreased. Our numerical simulations showed that seed survival had a more considerable effect on λ than seedling recruitment and establishment. We suggest that the seed bank may explain the structure and population dynamics. Thus, we reconsider that this early stage in demographic models will generate more informed decisions on the conservation and management of columnar cacti.

Increasing aridity shapes beta diversity and the network dynamics of the belowground fungal microbiome associated with Opuntia ficus-indica

AimsThe effects of aridity on soil and water-use efficient (WUE) crop species are relatively well known. However, the understanding of its impacts on the dynamics of below-ground microorganisms associated with plant roots is less well understood. MethodsTo investigate the influence of increasing aridity on the dynamics of the fungal communities, samples from the root endosphere and rhizosphere associated with the prickly pear cactus trees (Opuntia ficus-indica) growing along the aridity gradient were collected and the internal transcribed spacer (ITS) were sequenced. The diversity and network analyses of fungal taxa were determined along with standard measurements of soil parameters. ResultsWe found that (i) the fungal community exhibited similar alpha diversity and shared a set of core taxa within the rhizosphere and endosphere, but there was significant beta diversity differences; (ii) the relative abundance of major phyla was higher in the rhizosphere than in the endosphere; (iii) arbuscular endomycorrhizal colonization was highest in the humid climate and decreased under lower-arid, and was negatively correlated with increased concentration of Ca2+ in the soil; (iv) increased aridity correlated with increased connectivity of the soil microbial-root fungal networks in the arid soils, producing a highly cohesive network in the upper-arid area; and (v) distinct fungal hubs sculpt the fungal microbiome network structure in the rhizosphere and endosphere within each bioclimatic zone. ConclusionsOur findings highlight the importance of gradient analysis-based correlation network as a powerful approach to understand changes in the diversity, the dynamics, and the structure of fungal communities associated with the rhizosphere-endosphere interaction and led to the identification of microbes at each bioclimatic zone that are potentially involved in promoting the survival, protection, and growth of Opuntia trees. The variability of fungal hubs composition depending on plant compartment and bioclimatic zone will give key implications for the application of rhizospheric fungi and endophytes as microbial inoculants in agriculture, as well as in the conservation and restoration of cacti plants in arid and semi-arid lands against the backdrop of climate change. Overall, this study will enhance our understanding of the microbiomes'dynamic of CAM plants in nature.

Insights into the aridification history of Central Asian Mountains and international conservation strategy from the endangered wild apple tree

AbstractAimEvolutionary processes of mountain plants in arid lands remain poorly understood. Here, we investigate population genomics of the endangered wild apple tree to interpret the effects of long‐term aridification on plant diversification and demographical history in Central Asian Mountains.LocationThe Tianshan Mountains, spanning north‐western China, Kazakhstan, Kyrgyzstan and Tajikistan.TaxonMalus sieversii (Rosaceae)MethodsUsing genome‐wide single nucleotide polymorphisms, we assessed genetic diversity and genetic structure of 15 populations across the species' range. Demographical history was simulated with approximate Bayesian computation and species distribution modelling. We used a general linear model to identify key environmental factors affecting population genetic diversity and structure.ResultsWe separated the 15 populations into three groups: the eastern group of western Junggar Mountains in China; the central group of the Ili Valley, the Talas Alatau Mountains in Kazakhstan and Kyrgyzstan; and the western group of Tajikistan and the Dzungarian Alatau in Kazakhstan. Central populations had higher genetic diversity and effective population size than eastern and western populations. The three groups split at the late Miocene and subsequently experienced extensive admixture. We detected a significant pattern of isolation by distance, but not isolation by environment, among these populations. Population genetic diversity was significantly associated with longitudinal and current environmental gradients.Main conclusionsLong‐term aridification promoted distribution fragmentation and plant lineage divergence of relict broad‐leaved forests in Central Asian Mountains. Both geographical isolation and environmental heterogeneity shaped spatial patterns in genetic variation among M. sieversii populations. To maintain genetic integrity, we propose the establishment of an international network for the conservation of this endangered wild apple tree.

Molecular Diversity from Arid‐Land Plants: Valorization of Terpenes and Biotransformation Products

Asteraceae plants from arid lands are a source of biomass, resin and latex rich in terpenoids with diverse biological effects. Thirty-six previously isolated terpenes, comprising sesquiterpenes, diterpenes, triterpenes and quassinoids, isolated from arid-land plants and a series of metabolites from the biotransformation of some lead compounds were evaluated against insect pests (Spodoptera littoralis, Leptinotarsa decemlineata, Myzus persicae and Rhopalosiphum padi), cells (insect, hamster, murine and human tumoral cells) and parasites (Trypanosoma cruzi and Leishmania infantum). Among the insecticidal sesquiterpenes, maalian-1α,8α-diol (12) and γ-eudesmol (17) were antifeedant against L. decemlineata, M. persicae and cytotoxic to Sf9 insect cells, and (-)-maali-3-en-8α-ol (10), (+)-maaliane-5α,8α,9α-triol (11), chrysothame (31) and holacanthone (35) were antifeedant against S. littoralis. The parasite L. infantum was slightly more sensitive than T. cruzi to the test compounds (39 % vs. 33 % of active compounds) with compound 17 and the biotransformed diterpene 27 being antiparasitic to L. infantum, with no cytotoxic effects on mammalian cells. Moreover, sesquiterpenes 3 and 17, and grindelane diterpenes 22, 23 and 26 showed selective activity against chemoresistant human colon, cervical and melanoma cancer cells. Thus, considering our results, the best candidates for future studies are compounds 17 and 3, due to their activity on insect pests, parasites (17) and tumoral cells (3, 17, 22, 23 and 26).

Spectral Signature for Detecting Pest Infestation of Some Cultivated Plants in the Northern West Coast of Egypt.

Early detection of pest infestation is essential for determining the optimal time for control application. Many studies indicated the effectiveness of remote sensing technology as a tool to identify plants stressed by pest infestation. In the current study, we observed using hyper spectral remotely sensed data for discrimination between healthy and pest infested plants. Three arid-land plants were selected in the current study: sweet almond, citrus lemon trees and olives. As the first step of the analysis, spectral reflectance pattern for the three plants healthy and infected was identified. The optimal waveband and wavelength/s to differentiate between healthy and infected plants were identified. Different vegetation indices: Modified Chlorophyll Absorption in Reflectance Index (MCARI), Transformed Chlorophyll Absorption in Reflectance Index (TCARI), and Normalized Pigment Chlorophyll Index (NPCI) were calculated and compared between the values of these indices under infestation stress was examined. The results showed that healthy plants give higher reflectance values in visible spectral bands than infected plants with olives, however, healthy plants showed higher reflectance than infected plants throughout the whole spectrum with the other two plants. Vegetation indices values showed less value with healthy plants with sweet almond and citrus lemon but an opposite trend was found with olives. Blue and red spectral zones were optimal to differentiate between healthy and infected sweet almond and citrus lemon trees when all spectral zones except SWIRI were effective to differentiate between healthy and infected olives.

Three-dimensional digitization of the arid land plant Haloxylon ammodendron using a consumer-grade camera.

Plant structural parameters are important for ecological studies and for monitoring the environment. Terrestrial laser scanning has become a widely accepted technique for acquiring accurate high‐density three‐dimensional information about plant surfaces; however, this instrument is expensive, technically challenging to operate, heavy, and difficult to transport to hard‐to‐reach areas such as dense forests and undeveloped areas without easy vehicle access. Using Haloxylon ammodendron, a plant widely distributed in arid lands, as an example, we used a consumer‐grade handheld camera to take a series of overlapping images of this plant. Computer vision and photogrammetric software were used to reconstruct highly detailed three‐dimensional data of the plant surface. This surface data was compared to the point cloud of the plant acquired from concomitant terrestrial laser scanning. We demonstrated that the accuracy and degree of completeness of the image‐derived point clouds are comparable to that of laser scanning. Plant structural parameters (such as tree height and crown width) and three‐dimensional models extracted from the point clouds also agree well with a relative difference of less than 5%. Our case study shows that a common camera and image processing software can be an affordable, highly portable, and viable option for acquiring accurate and detailed high‐density and high‐resolution three‐dimensional information about plant structure in the environment. This digitization technique can record the plant and its surrounding environment effectively and efficiently, and it can be applied to many ecological fields and studies.

Climate variability affects the germination strategies exhibited by arid land plants.

Spatial and temporal environmental variability can lead to variation in selection pressures across a landscape. Strategies for coping with environmental heterogeneity range from specialized phenotypic responses to a narrow range of conditions to generalist strategies that function under a range of conditions. Here, we ask how mean climate and climate variation at individual sites and across a species' range affect the specialist-generalist spectrum of germination strategies exhibited by 10 arid land forbs. We investigated these relationships using climate data for the western United States, occurrence records from herbaria, and germination trials with field-collected seeds, and predicted that generalist strategies would be most common in species that experience a high degree of climate variation or occur over a wide range of conditions. We used two metrics to describe variation in germination strategies: (a) selectivity (did seeds require specific cues to germinate?) and (b) population-level variation (did populations differ in their responses to germination cues?) in germination displayed by each species. Species exhibited distinct germination strategies, with some species demonstrating as much among-population variation as we observed among species. Modeling efforts suggested that generalist strategies evolve in response to higher spatial variation in actual evapotranspiration at a local scale and in available water in the spring and annual precipitation at a range-wide scale. Describing the conditions that lead to variation in early life-history traits is important for understanding the evolution of diversity in natural systems, as well as the possible responses of individual species to global climate change.

Bacterial endophytes from arid land plants regulate endogenous hormone content and promote growth in crop plants: an example of Sphingomonas sp. and Serratia marcescens

ABSTRACTThe objective of the present study was to determine the potential plant growth-promoting action of bacterial endophytes isolated from arid land-dwelling plants under normal conditions. Overall, five bacterial endophytes LK11 (Sphingomonas sp. LK11), TP5 (Bacillus subtilis), MPB5.3 (B. subtilis subsp. Subtilis), S9 (B. subtilis subsp. Subtilis), and TP1 (Serratia marcescens) were evaluated based on morphological characteristics after isolation and purification. Phytohormonal analysis of these endophytes predicted indole acetic acid (IAA) production 12.31 ± 0.45 , 6.8 ± 0.59, and 10.5 ± 1.02 μM/mL in the culture broths of LK11, MPB5.3, and TP1, respectively. Under controlled greenhouse conditions, these endophytes were inoculated into soybean, and their growth-promoting characteristics were compared with those of non-phytohormone-producing endophytes. In terms of plant growth promotion, among IAA-producing endophytes, LK11 and TP1 greatly improved physiological characteristics such as shoot/root length, fresh/dry weight, and chlorophyll contents. However, the non-phytohormone-producing endophytes TP5 and S9 did not show a growth-promoting effect. Based on these results, plants inoculated with LK11 and TP1 along with a control were subjected to endogenous hormonal analysis and showed a significant increase in abscisic acid (457.30–398.55 vs. 205.93 ng/g D.W.) and a decrease in jasmonic acid content (50.07–85.07 vs. 93.90 ng/g D.W.), respectively. Total gibberellin content was found to significantly increase in endophyte-inoculated plants (155.43–146.94 ng/g D.W.) as compared to that in controls (113.76 ng/g D.W.). In summary, bacterial endophytes might be used to enhance crop plant physiological characteristics isolated from arid land-inhabiting plants under normal conditions.

Paleorelicts or archaeophytes: Enigmatic trees in the Middle East

Plants in arid lands with long histories of use by humans may shed light on the past and help decide on management policies, especially with regards agroforestry design and landscape-scale ecological restoration. We focus on five woody species that occur in unexpected sites and habitats in southern Arabia, and the southern Levant (Israel, Jordan, and Lebanon), namely Adansonia digitata L., Dalbergia sissoo Roxb. ex DC., Faidherbia albida (Delile) A.Chev., Lawsonia inermis L., and Tamarindus indica L.. Little study has been conducted on these taxa in these areas, despite their past and present importance to people in the Middle East, Africa, Asia, and elsewhere. Based on herbarium records from 12 major herbaria, field observations, and extensive literature review, we suggest that two of the five taxa are clearly archaeophytes in the Middle East (Adansonia digitata and Lawsonia inermis) introduced as early as 1500–2500 years BP. In contrast, D. sissoo is probably a neophyte, introduced in the last 135 years. We call for focused research on them as these trees of ancient heritage have value for agricultural, agroforestry and ecological restoration programmes going forward.

English

Climatic changes have induced the spread of aridity in many parts of the globe. Eucalyptus plantations show wide variations in productivity due to several factors, including climatic changes. Therefore, Eucalyptus genotypes that can adapt to such conditions is very welcome. Thus, an evaluation was done by comparing the physiological responses of two Eucalyptus genotypes, tolerant and drought-sensitive. They were assessed in different stages of experimental period and the rate of chlorophyll and chlorophyll fluorescence (minimal fluorescence and maximal fluorescence) were recorded. The potential photosystem II (PSII) quantum efficiency was then calculated. A decline in the rate of total chlorophyll (values below 25) and in the minimal fluorescence (values below 190) in clone sensitive due to the water stress was observed, while an increase was noted in clone tolerant to aridity. A reduction in the maximal fluorescence and photochemical efficiency was recorded in the genotype not being irrigated, with an earlier and more severe effect being verified for the sensitive genotype with values below 300 and 0.40, respectively. The variables studied confirm that clone tolerant exhibits greater drought tolerance, thus indicating that the photochemical efficiency of photosystem II is a reliable tool that enables the nondestructive choice of genotypes naturally tolerant to water scarcity conditions.  Key words: Abiotic stress, arid land plants, chlorophyll, ecophysiology, photochemical efficiency, tree drought tolerance, water deficit, water potential.

Anti-allergy and Melanogenesis Regulatory Effects of Semi-arid and Arid Land Plants

Anti-allergy and Melanogenesis Regulatory Effects of Semi-arid and Arid Land Plants

Phenolic Content And Antioxidant Activity Of Cytisus Villosus And Hypericum Afrum Extracts

Oxidative stress plays an important role in the progression of neurodegenerative conditions, including rheumatic and cardiovascular disorders, metabolic syndrome, and other maladies. Natural antioxidants from plants have played an important role from ancient to recent times in the management and treatment of many of these disorders. The combined effect of environmental conditions such as moisture and ultraviolet radiation induce biochemical mechanisms in plants that regulate the production of antioxidant agents as secondary metabolites. The objectives of this study were to determine the phenolic content using a modified Folin-Ciocalteau method, the DPPH method of measuring antioxidant effects, and a HPLC profile of the aerial part of two endemic North Africa plants Cytisus villosus and Hypericum afrum [1 – 2]. The ethyl acetate and n-butanol fractions of these arid land plants were investigated. The butanol fraction from C. villosus and the ethyl acetate fraction of H. afrum showed the highest DPPH scavenging activity with IC50 values of 0.164 ± 0.004 and 0.049 ± 0.008 g of extract/mmol DPPH, respectively. These results suggest that the polyphenols compositions of both plants are closely associated to its antioxidant potentials.

Hydrothermal Carbonization (HTC) and Pelletization of Two Arid Land Plants Bagasse for Energy Densification

In this study, bagasse from two arid land plants, grindelia and rabbitbrush, were hydrothermally carbonized (HTC) along with their raw biomass at 200–260 °C for 5 min. Prior to HTC, biocrude was extracted from grindelia (Grindelia squarrosa), whereas rubber was extracted from rabbitbrush (Ericameria nauseosa). Solid hydrochars and HTC process liquids of extracted feedstocks were characterized by ultimate, proximate, fiber, FTIR, higher heating value (HHV), and GC–MS analyses and the results were compared with their corresponding unextracted conditions. Hydrochars were pelletized in a single-press pelletizer and mass and energy densities of the pellets were measured. From the proximate, ultimate, FTIR, and fiber analyses, the bagasse show similar properties of the raw biomass, although the HHV was slightly increased with crude extraction from grindelia and decreased with rubber extraction from rabbitbrush. With the increase of HTC temperature, solid mass yield was decreased up to 44% for grindelia bagasse ...

A study on the porosity development for biomass based carbonaceous materials

This study deals with the structural and morphological changes occurring during pyrolysis and activation steps for the production of porous carbons from an arid-land plant Euphorbia rigida. A fixed-bed retort was used for slow pyrolysis and for further activation processes. Effect of pyrolysis atmosphere was examined at 550 °C and char yields were calculated to be 22.6, 23.1 and 17.5% under static, nitrogen and steam atmospheres respectively. Solid product obtained under static atmosphere was then impregnated with different chemicals (HCl, KOH, K2CO3, H2SO4, H3PO4, NaOH, ZnCl2) and a second thermal treatment was applied under different activation atmospheres. It was observed that the impregnation material, impregnation ratio and activation technique showed a strong influence on the yield and porous texture of the resulting carbons. On the basis of BET surface areas, most effective chemical agent was selected as K2CO3 giving a specific surface area of 1079 m2/g and microspore volume of 0.443 cm3/g. The physical–chemical properties of the chars and activated carbons were investigated by proximate and ultimate analyses, FT-IR, SEM, EDX, XRD and iodine number. In addition, surface functional groups were classified by Boehm titration method. Results suggest that chemical activation of E. rigida char produces valuable activated carbons under proper conditions.

Yucca aloifolia oil methyl esters

Yucca aloifolia Linn (Y. aloifolia) is a drought-resistant arid land plant that grows in most soil types. In this work, Y. aloifolia seed oil (YAO) was evaluated for the first time as a potential biodiesel feedstock, which contains 16.23% oil (w/w) whereas the acidity of the oil was 11%. Two step processes i.e. acid-catalyzed esterification to reduce the acid value of YAO and then standard base-catalyzed transesterification procedure were used to synthesis the Y. aloifolia methyl esters (Yame) at optimization conditions. YAO has a high content of linoleic acid (70.77 %) followed by oleic acid (12%), and palmitic acid (8.59%). The fuel properties of biodiesel derived from YAO including density, iodine value, kinematic viscosity, cetane number, flash point, pour point, cloud point, and gross heating value were evaluated and compared with the limits of ASTM D6751 standards. The comparison showed that the biodiesel obtained from Y. aloifolia oil could be used as an alternative fuel for diesel engines.

Fungal endophytes in aboveground tissues of desert plants: infrequent in culture, but highly diverse and distinctive symbionts.

In hot deserts, plants cope with aridity, high temperatures, and nutrient-poor soils with morphological and biochemical adaptations that encompass intimate microbial symbioses. Whereas the root microbiomes of arid-land plants have received increasing attention, factors influencing assemblages of symbionts in aboveground tissues have not been evaluated for many woody plants that flourish in desert environments. We evaluated the diversity, host affiliations, and distributions of endophytic fungi associated with photosynthetic tissues of desert trees and shrubs, focusing on nonsucculent woody plants in the species-rich Sonoran Desert. To inform our strength of inference, we evaluated the effects of two different nutrient media, incubation temperatures, and collection seasons on the apparent structure of endophyte assemblages. Analysis of >22,000 tissue segments revealed that endophytes were isolated four times more frequently from photosynthetic stems than leaves. Isolation frequency was lower than expected given the latitude of the study region and varied among species a function of sampling site and abiotic factors. However, endophytes were very species-rich and phylogenetically diverse, consistent with less arid sites of a similar latitudinal position. Community composition differed among host species, but not as a function of tissue type, sampling site, sampling month, or exposure. Estimates of abundance, diversity, and composition were not influenced by isolation medium or incubation temperature. Phylogenetic analyses of the most commonly isolated genus (Preussia) revealed multiple evolutionary origins of desert-plant endophytism and little phylogenetic structure with regard to seasonality, tissue preference, or optimal temperatures and nutrients for growth in vitro. Together, these results provide insight into endophytic symbioses in desert-plant communities and can be used to optimize strategies for capturing endophyte biodiversity at regional scales.