Arthrocladiella mougeotii causing powdery mildew on goji berry plants (Lycium barbarum and L. chinense) and mixed infections with Phyllactinia chubutiana in California.

Goji berries (Lycium barbarum and L. chinense) have a rich historical significance in traditional Chinese medicine and have gained popularity as a superfood in Western cultures. From 2021 to 2023, powdery mildew was observed on goji plants of both species in community and residential gardens in Yolo County, California (USA). Disease severity varied from 20 to 100% of infected leaves per plant. Powdery mildew was characterized by the presence of white fungal colonies on both sides of leaves and fruit sepals. Additionally, a brownish discoloration was observed in infected mature leaves, resulting in further defoliation. Morphologically, the fungus matched the description of Arthrocladiella mougeotii. The pathogen identity was confirmed by phylogenetic analyses of the rDNA internal transcribed spacer and the 28S rDNA gene sequences. Pathogenicity was confirmed by inoculating healthy L. barbarum plants using infected leaves and successfully reproducing powdery mildew symptoms after 28 days (22°C, 60% RH), with A. mougeotii colonies confirmed by morphology. Control leaves remained symptomless. Co-infection with Phyllactinia chubutiana was detected on plants from two separate gardens, with A. mougeotii observed first in late spring (May to June) and P. chubutiana later in the summer (July to August). These results revealed that both A. mougeotii and P. chubutiana constitute causal agents of powdery mildew on goji berry plants, often infecting the same plant tissues simultaneously. To our knowledge, this is the first report of A. mougeotii causing powdery mildew on L. barbarum and L. chinense in California, which provides a better understanding of the etiology of powdery mildew of goji plants in California.

Microbial symbionts buffer hosts from the demographic costs of environmental stochasticity.

Species' persistence in increasingly variable climates will depend on resilience against the fitness costs of environmental stochasticity. Most organisms host microbiota that shield against stressors. Here, we test the hypothesis that, by limiting exposure to temporally variable stressors, microbial symbionts reduce hosts' demographic variance. We parameterized stochastic population models using data from a 14-year symbiont-removal experiment including seven grass species that host Epichloë fungal endophytes. Results provide novel evidence that symbiotic benefits arise not only through improved mean fitness, but also through dampened inter-annual variance. Hosts with "fast" life-history traits benefited most from symbiont-mediated demographic buffering. Under current climate conditions, contributions of demographic buffering were modest compared to benefits to mean fitness. However, simulations of increased stochasticity amplified benefits of demographic buffering and made it the more important pathway of host-symbiont mutualism. Microbial-mediated variance buffering is likely an important, yet cryptic, mechanism of resilience in an increasingly variable world.

Botulinum toxin therapy for management of phantom and residual limb pain following amputation: A systematic review.

Chronic pain following amputation is debilitating. Due to its mechanisms in modulating muscle contraction and pain, botulinum toxin has been investigated as a treatment option for phantom limb pain (PLP) and residual limb pain (RLP). The objective of this study was to determine the efficacy of botulinum toxin injection in the management of PLP and RLP following major limb amputation using a systematic review of the literature. The databases Medline, CINAHL, EMBASE, Scopus, Web of Science, and Cochrane were searched from inception through October 30, 2023. The search identified 50 articles; 37 underwent full-text review, and 11 were included in the final review. Eighty-nine individuals with pain were investigated by the included studies; 53 had RLP and 63 had PLP. There was significant variation in botulinum toxin type, injection method, and dosage. Twenty-one (53.9%) and 27 (64.3%) participants had improvement in PLP and RLP following botulinum toxin injection, respectively. Therefore, there is potential for use of botulinum toxin for the treatment of PLP and RLP. However, due to the minimal number of studies, small sample sizes, and heterogenous methodologies, our ability to conclude with certainty the efficacy of botulinum toxin injection on the treatment of PLP and RLP following amputation is limited.

First report of Phyllactinia chubutiana causing powdery mildew on Goji berry plants (Lycium barbarum and L. chinense) in the United States.

Goji berries, both Lycium barbarum, and L. chinense, are native to Asia and have been highly valued for food and medicinal purposes for more than 2,000 years (Wetters et al. 2018). These species are difficult to distinguish due to the extensive cultivar development of the former and the plasticity of the latter's phenotypes. During the summers (from July to September) of 2021 and 2022, powdery mildew was observed in Goji berry plants (L. barbarum and L. chinense) in both community and residential gardens, in Yolo Co., California. Disease severity varied between 30 and 100% of infected leaves per plant. Host identity was confirmed by phylogenetic analysis using sequences of the psbA-trnH intergenic region (Wetters et al. 2018). Powdery mildew was characterized by the presence of white fungal colonies on both sides of the leaves and the fruit sepals. Colorless adhesive tape mounts of the fungal structures were examined in drops of 3% KOH. Epidermal strips of infected leaves were peeled off for analysis of the mycelia. Hyphae were both external and internal, hyaline, septate, branched, smooth, and 2.5 to 5.8 (4.3) µm wide (n = 50). Appressoria were nipple-shaped to irregularly branched and solitary or opposite in pairs. Conidiophores were hyaline, erect, and simple. Foot cells were cylindrical, straight, 13.1 to 48.9 (29.8) × 5.0 to 8.2 (6.8) µm (n = 20), followed by 0 to 2 cells. Conidia lacked fibrosin bodies, were borne singly, unicellular, hyaline, and ellipsoid when young. Mature conidia were either cylindrical or slightly centrally constricted to dumb-bell-like, and 36.2 to 51.8 (44.9) × 15.1 to 22.0 (18.9) µm (n = 50), with conspicuous subterminal protuberances. Germ tubes were subterminal, either short with multilobate apex or moderately long with a simple end. Chasmothecia were not observed. Morphologically the fungus matched the description of Phyllactinia chubutiana Havryl., S. Takam. & U. Braun (Braun and Cook, 2012). The pathogen identity was further confirmed by amplifying and sequencing the rDNA internal transcribed spacer (ITS) and the 28S rDNA gene using the primer pairs ITS1/ITS4 (White et al. 1990) and PM3/TW14 (Takamatsu and Kano 2001, Mori et al. 2000). The resulting sequences (GenBank OP434568 to OP434569; and OP410969 to OP410970) were compared with the NCBI database using BLAST, showing 99% similarity to the ex-type isolate of P. chubutiana (BCRU 4634, GenBank AB243690). Maximum parsimony phylogenetic analysis clustered our isolates with reference sequences of P. chubutiana from various hosts deposited in GenBank. Pathogenicity was confirmed by inoculating two two-year-old L. barbarum potted plants. Four leaves per plant were surface disinfected (75% ethanol, 30 s) before gently rubbing powdery mildew infected leaves onto healthy leaves. Healthy leaves were used for mock inoculations. All plants were maintained in a growth chamber at 22°C and 80% relative humidity (RH) for five days and then 60% RH thereafter. Inoculated leaves developed powdery mildew symptoms after 28 days, and P. chubutiana colonies were confirmed by morphology, hence fulfilling Koch's postulates. Control leaves remained symptomless. Phyllactinia chubutiana (= Oidium insolitum, Ovulariopsis insolita) was first described on L. chilense in Argentina (Braun et al. 2000, Havrylenko et al. 2006), and later reported on L. chinense in China (Wang Yan et al. 2016). To our knowledge, this is the first report of P. chubutiana causing powdery mildew on L. barbarum and L. chinense in the United States, which provides crucial information for developing effective strategies to monitor and control this newly described disease.

Nectar resources affect bird-dispersed microbial metacommunities in suburban and rural gardens.

As cities expand, understanding how urbanization affects biodiversity is a key ecological goal. Yet, little is known about how host-associated microbial diversity responds to urbanization. We asked whether communities of microbial (bacterial and fungal) in floral nectar and sugar-water feeders and vectored by nectar-feeding birds-thus forming a metacommunity-differed in composition and diversity between suburban and rural gardens. Compared to rural birds, we found that suburban birds vectored different and more diverse bacterial communities. These differences were not detected in the nectar of common plant species, suggesting that nectar filters microbial taxa and results in metacommunity convergence. However, when considering all the nectar sources present, suburban beta diversity was elevated compared to rural beta diversity due to turnover of bacterial taxa across a plant species and sugar-water feeders. While fungal metacommunity composition and beta diversity in nectar were similar between suburban and rural sites, alpha diversity was elevated in suburban sites, which mirrored the trend of increased fungal alpha diversity on birds. These results emphasize the interdependence of host, vector, and microbial diversity and demonstrate that human decisions can shape nectar microbial diversity in contrasting ways for bacteria and fungi.

Two-Sex Demography, Sexual Niche Differentiation, and the Geographic Range Limits of Texas Bluegrass (Poa arachnifera).

AbstractUnderstanding the mechanisms that generate biogeographic range limits is a long-standing goal of ecology. It is widely hypothesized that distributional limits reflect the environmental niche, but this hypothesis is complicated by the potential for intraspecific niche heterogeneity. In dioecious species, sexual niche differentiation may cause divergence between the sexes in their limits of environmental suitability. We studied range boundary formation in Texas bluegrass (Poa arachnifera), a perennial dioecious plant, testing the alternative hypotheses that range limits reflect the niche limits of females only versus the combined contributions of females and males, including their interdependence via mating. Common garden experiments across a longitudinal aridity gradient revealed female-biased flowering approaching eastern range limits, suggesting that mate limitation may constrain the species' distribution. However, a demographic model showed that declines in λ approaching range limits were driven almost entirely by female vital rates. The dominant role of females was attributable to seed viability being robust to sex ratio variation and to low sensitivity of λ to reproductive transitions. We suggest that female-dominant range limits may be common to long-lived species with polygamous mating systems and that female responses to environmental drivers may often be sufficient for predicting range shifts in response to environmental change.

Does ant-plant mutualism have spillover effects on the non-partner ant community?

Mutualism benefits partner species, and theory predicts these partnerships can affect the abundance, diversity, and composition of partner and non-partner species. We used 16 years of monitoring data to determine the ant partner species of tree cholla cacti (Cylindropuntia imbricata), which reward ants with extrafloral nectar in exchange for anti-herbivore defense. These long-term data revealed one dominant ant partner (Liometopum apiculatum) and two less common partners (Crematogaster opuntiae and Forelius pruinosus). We then used short-term characterization of the terrestrial ant community by pitfall trapping to sample partner and non-partner ant species across ten plots of varying cactus density. We found that the dominant ant partner tended a higher proportion cacti in plots of higher cactus density, and was also found at higher occurrence within the pitfall traps in higher density plots, suggesting a strong positive feedback that promotes ant partner occurrence where plant partners are available. Despite the strong association and increased partner occurrence, ant community-wide effects from this mutualism appear limited. Of the common ant species, the occurrence of a single non-partner ant species was negatively associated with cactus density and with the increased presence of L. apiculatum. Additionally, the composition and diversity of the ant community in our plots were insensitive to cactus density variation, indicating that positive effects of the mutualism on the dominant ant partner did not have cascading impacts on the ant community. This study provides novel evidence that exclusive mutualisms, even those with a strong positive feedback, may be limited in the scope of their community-level effects.

Mammalian herbivores restrict the altitudinal range limits of alpine plants.

Although rarely experimentally tested, biotic interactions have long been hypothesised to limit low-elevation range boundaries of species. We tested the effects of herbivory on three alpine-restricted plant species by transplanting plants below (novel), at the edge (limit), or in the centre (core) of their current elevational range and factorially fencing-out above- and belowground mammals. Herbivore damage was greater in range limit and novel habitats than in range cores. Exclosures increased plant biomass and reproduction more in novel habitats than in range cores, suggesting demographic costs of novel interactions with herbivores. We then used demographic models to project population growth rates, which increased 5-20% more under herbivore exclosure at range limit and novel sites than in core habitats. Our results identify mammalian herbivores as key drivers of the low-elevation range limits of alpine plants and indicate that upward encroachment of herbivores could trigger local extinctions by depressing plant population growth.

Lagged and dormant season climate better predict plant vital rates than climate during the growing season.

Understanding the effects of climate on the vital rates (e.g., survival, development, reproduction) and dynamics of natural populations is a long-standing quest in ecology, with ever-increasing relevance in the face of climate change. However, linking climate drivers to demographic processes requires identifying the appropriate time windows during which climate influences vital rates. Researchers often do not have access to the long-term data required to test a large number of windows, and are thus forced to make a priori choices. In this study, we first synthesize the literature to assess current a priori choices employed in studies performed on 104 plant species that link climate drivers with demographic responses. Second, we use a sliding-window approach to investigate which combination of climate drivers and temporal window have the best predictive ability for vital rates of four perennial plant species that each have over a decade of demographic data (Helianthella quinquenervis, Frasera speciosa, Cylindriopuntia imbricata, and Cryptantha flava). Our literature review shows that most studies consider time windows in only the year preceding the measurement of the vital rate(s) of interest, and focus on annual or growing season temporal scales. In contrast, our sliding-window analysis shows that in only four out of 13 vital rates the selected climate drivers have time windows that align with, or are similar to, the growing season. For many vital rates, the best window lagged more than 1 year and up to 4 years before the measurement of the vital rate. Our results demonstrate that for the vital rates of these four species, climate drivers that are lagged or outside of the growing season are the norm. Our study suggests that considering climatic predictors that fall outside of the most recent growing season will improve our understanding of how climate affects population dynamics.

Affinity purification of human alpha galactosidase utilizing a novel small molecule biomimetic of alpha-D-galactose.

Alpha galactosidase (a-Gal) is an acidic hydrolase that plays a critical role in hydrolyzing the terminal alpha-galactoyl moiety from glycolipids and glycoproteins. There are over a hundred mutations reported for the GLA gene that encodes a-Gal that result in reduced protein synthesis, protein instability, and reduction in function. The deficiencies of a-Gal can cause Fabry disease, a rare lysosomal storage disorder (LSD) caused by the failure to catabolize alpha-d-galactoyl glycolipid moieties. The current standard of care for Fabry disease is enzyme replacement therapy (ERT) where the purified recombinant form of human a-Gal is given to patients. The manufacture of a-Gal is currently performed utilizing traditional large-scale chromatography processes. Developing an affinity resin for the purification of a-Gal would reduce the complexity of the manufacturing process, reduce costs, and potentially produce a higher quality a-Gal. After the evaluation of many small molecules, a commercially available small molecule biomimetic, N-5-Carboxypentyl-1-deoxygalactonojirimycin (N5C-DGJ), was utilized for the development of a novel small molecule biomimetic affinity resin for a-Gal. Affinity purified a-Gal demonstrated a purity greater than 90%, exhibited expected thermal stability and specific activity. Complementing this affinity purification is the development of an elution buffer system that confers an increased thermal stability to a-Gal. The N5C-DGJ affinity resin tolerated sodium hydroxide sanitization with no loss of binding capacity, making it amenable to large scale purification processes and potential use in manufacturing. This novel method for purifying the challenging a-Gal enzyme can be extended to other enzyme replacement therapies.

Eco-evolutionary dynamics of range expansion.

Understanding the movement of species' ranges is a classic ecological problem that takes on urgency in this era of global change. Historically treated as a purely ecological process, range expansion is now understood to involve eco-evolutionary feedbacks due to spatial genetic structure that emerges as populations spread. We synthesize empirical and theoretical work on the eco-evolutionary dynamics of range expansion, with emphasis on bridging directional, deterministic processes that favor evolved increases in dispersal and demographic traits with stochastic processes that lead to the random fixation of alleles and traits. We develop a framework for understanding the joint influence of these processes in changing the mean and variance of expansion speed and its underlying traits. Our synthesis of recent laboratory experiments supports the consistent role of evolution in accelerating expansion speed on average, and highlights unexpected diversity in how evolution can influence variability in speed: results not well predicted by current theory. We discuss and evaluate support for three classes of modifiers of eco-evolutionary range dynamics (landscape context, trait genetics, and biotic interactions), identify emerging themes, and suggest new directions for future work in a field that stands to increase in relevance as populations move in response to global change.

Effect of summer warming on growth, photosynthesis and water status in female and male Populus cathayana: implications for sex-specific drought and heat tolerances.

Effects of climate warming on tree growth and physiology may be driven by direct thermal effects and/or by changes in soil moisture. Dioecious tree species usually show sexual spatial segregation along abiotic gradients; however, few studies have assessed the sex-specific responses to warming in dioecious trees. We investigated the sex-specific responses in growth, photosynthesis, nonstructural carbohydrate (NSC), water-use efficiency and whole-plant hydraulic conductance (KP) of the dioecious tree species Populus cathayana Rehd. under +4 °C elevated temperature with and without supplemental water. For both sexes, high-temperature treatments significantly decreased growth (height and biomass), photosynthetic rate (A), the ratio of A to dark respiration rate, stomatal conductance (gs), transpiration rate, NSC, leaf water potential and KP, but increased water-use efficiency (estimated from carbon isotope composition). Under warming with supplemental water, most traits of females did not change relative to ambient conditions, but traits of males decreased, resulting in greater sexual differences. Females showed a lower KP, and their gs and A responded more steeply with water-related traits than males. These results show that the effect of summer warming on growth and photosynthesis was driven mainly by soil moisture in female P. cathayana, while male performance was mainly related to temperature. Females may experience less thermal stress than males due to flexible water balance strategy via stomata regulation and water use.

Demography-Dispersal Trait Correlations Modify the Eco-Evolutionary Dynamics of Range Expansion.

Spreading populations are subject to evolutionary processes acting on dispersal and reproduction that can increase invasion speed and variability. It is typically assumed that dispersal and demography traits evolve independently, but abundant evidence points to correlations between them that may be positive or negative and genetic, maternal, or environmental. We sought to understand how demography-dispersal correlations modify the eco-evolutionary dynamics of range expansion. We first explored this question with the beetle Callosobruchus maculatus, a laboratory model in which evolutionary acceleration of invasion has been demonstrated. We then built a simulation model to explore the role of trait correlations in this system and more generally. We found that positive correlations amplify the positive influence of evolution on speed and variability while negative correlations (such as we found empirically) constrain that influence. Strong negative genetic correlations can even cause evolution to decelerate invasion. Genetic and nongenetic (maternal and environmental) correlations had similar effects on some measures of invasion but different effects on others. Model results enabled us to retrospectively explain invasion dynamics and trait evolution in C. maculatus and may similarly aid the interpretation of other field and laboratory studies. Nonindependence of demography and dispersal is an important consideration for understanding and predicting outcomes of range expansion.

Simulated folivory increases vertical transmission of fungal endophytes that deter herbivores and alter tolerance to herbivory in Poa autumnalis.

BACKGROUND AND AIMS: The processes that maintain variation in the prevalence of symbioses within host populations are not well understood. While the fitness benefits of symbiosis have clearly been shown to drive changes in symbiont prevalence, the rate of transmission has been less well studied. Many grasses host symbiotic fungi (Epichloë spp.), which can be transmitted vertically to seeds or horizontally via spores. These symbionts may protect plants against herbivores by producing alkaloids or by increasing tolerance to damage. Therefore, herbivory may be a key ecological factor that alters symbiont prevalence within host populations by affecting either symbiont benefits to host fitness or the symbiont transmission rate. Here, we addressed the following questions: Does symbiont presence modulate plant tolerance to herbivory? Does folivory increase symbiont vertical transmission to seeds or hyphal density in seedlings? Do plants with symbiont horizontal transmission have lower rates of vertical transmission than plants lacking horizontal transmission? METHODS: We studied the grass Poa autumnalis and its symbiotic fungi in the genus Epichloë. We measured plant fitness (survival, growth, reproduction) and symbiont transmission to seeds following simulated folivory in a 3-year common garden experiment and surveyed natural populations that varied in mode of symbiont transmission. KEY RESULTS: Poa autumnalis hosted two Epichloë taxa, an undescribed vertically transmitted Epichloë sp. PauTG-1 and E. typhina subsp. poae with both vertical and horizontal transmission. Simulated folivory reduced plant survival, but endophyte presence increased tolerance to damage and boosted fitness. Folivory increased vertical transmission and hyphal density within seedlings, suggesting induced protection for progeny of damaged plants. Across natural populations, the prevalence of vertical transmission did not correlate with symbiont prevalence or differ with mode of transmission. CONCLUSIONS: Herbivory not only mediated the reproductive fitness benefits of symbiosis, but also promoted symbiosis prevalence by increasing vertical transmission of the fungus to the next generation. Our results reveal a new mechanism by which herbivores could influence the prevalence of microbial symbionts in host populations.

How Evolution Modifies the Variability of Range Expansion.

Eco-evolutionary theory suggests that rapid evolution can accelerate range expansion speed. In addition to average speed, recent experimental studies reveal that evolution can also influence the amount of variability across replicates of spreading populations, but in contrasting ways. Here we develop a predictive framework, drawing on ideas from population genetics and spread theory, to understand when, why, and in what direction evolution will modify the variability of range expansion. Our framework revolves around the balance of variance-generating (drift) and variance-reducing (selective) evolutionary processes, and factors that may tip this balance, including population size at the leading edge and mating system. We suggest hypotheses to clarify contrasting experimental results and highlight a way forward for studying eco-evolutionary dynamics of range expansion.

Salinity tolerance of a rare and endangered unionid mussel, Popenaias popeii (Texas Hornshell) and its implications for conservation and water management.

Unionid mussels are considered sensitive to salinity and there is growing concern in arid and semi-arid regions that declining flows coupled with anthropogenic impacts are amplifying natural salinity levels. In this study, we tested the effects of varying salinity concentrations (3.0, 4.0, 5.0, 6.0, 7.0 and 10.0 ppt NaCl) on survival of adult Popenaias popeii, (Texas Hornshell). This species occurs in the Rio Grande basin of Texas and northern Mexico, an arid to semi-arid stream plagued by salinization, and was recently listed as Endangered under the U.S. Endangered Species Act. We performed 2, 4, and 10-day toxicity tests on individuals from two disjunct populations: Laredo, TX, and the Lower Canyons of the Rio Grande near Big Bend National Park. We found no significant differences in LC50 estimates between populations at 96-hrs or 10-days but significant differences in TUD50s at 5 ppt between populations, which indicates that tolerance does not vary but sensitivity may between these populations. Overlaying LC50 estimates at 10-days for both populations on plots of salinity (ppt) measured over time, we show parts of the Rio Grande periodically approach or exceed 4.0 ppt, indicating these reaches are becoming unsuitable for P. popeii and populations within them at risk.

Testing the roles of vertical transmission and drought stress in the prevalence of heritable fungal endophytes in annual grass populations.

Beneficial inherited symbionts are expected to reach high prevalence in host populations, yet many are observed at intermediate prevalence. Theory predicts that a balance of fitness benefits and efficiency of vertical transmission may interact to stabilize intermediate prevalence. We established populations of grass hosts (Lolium multiflorum) that varied in prevalence of a heritable fungal endophyte (Epichloё occultans), allowing us to infer long-term equilibria by tracking change in prevalence over one generation. We manipulated an environmental stressor (elevated precipitation), which we hypothesized would reduce the fitness benefits of symbiosis, and altered the efficiency of vertical transmission by replacing endophyte-positive seeds with endophyte-free seeds. Endophytes and elevated precipitation both increased host fitness, but symbiont effects were not stronger in the drier treatment, suggesting that benefits of symbiosis were unrelated to drought tolerance. Reduced transmission suppressed the inferred equilibrium prevalence from 42.6% to 11.7%. However, elevated precipitation did not modify prevalence, consistent with the result that it did not modify fitness benefits. Our results demonstrate that failed transmission can influence the prevalence of heritable microbes and that intermediate prevalence can be a stable equilibrium due to forces that allow symbionts to increase (fitness benefits) but prevent them from reaching fixation (failed transmission).

Issues and Opportunities on Implementing an Online Faculty Review System.

Intensifying accountability pressures have led to an increased attention to assessments of teaching, but teaching generally represents only a portion of faculty duties. Less attention has been paid to how evaluations of faculty members can be used to gather data on teaching, research, clinical work, and outreach to integrate clinical and academic contributions and fill in information gaps in strategic areas such as technology transfer and commercialization where universities are being pressed to do more. Online reporting systems can enable departments to gather comprehensive data on faculty activities that can be aggregated for accreditation assessments, program reviews, and strategic planning. As detailed in our case study of implementing such a system at a research university, online annual reviews can also be used to publicize faculty achievements, to document departmental achievements, foster interdisciplinary and community collaborations, recognize service contributions (and disparities), and provide a comprehensive baseline for salary and budgetary investments.