Alejandro Cabello-Pasini

Marine heatwaves (MHWs) are intensifying under climate change, yet the physiological limits that constrain seagrass resilience remain poorly defined. We experimentally tested the responses of the surfgrass Phyllospadix scouleri, a foundation species of the north-east Pacific coast, to simulated MHWs of contrasting intensity. In a 27-day mesocosm experiment, plants were exposed to fluctuating temperatures representing a severe MHW (23.5±1.5 °C) and an extreme MHW (26.5±1.5 °C), and photosynthetic performance, respiration, nitrogen metabolism, oxidative stress, and growth were monitored during and after warming. Phyllospadix scouleri maintained photosynthetic capacity and carbon balance under severe warming but exhibited pronounced physiological disruption at extreme temperatures, including sustained photoinhibition, reduced nitrate assimilation, elevated respiration, and negative daily productivity. These effects persisted after heat stress, leading to reduced growth and indicating incomplete recovery. Multivariate analysis revealed a transition from tolerance to functional breakdown near 26.5 °C, suggesting a potential physiological tipping point only 5–6 °C above current summer maxima in the area of the studied population. Our findings indicate that intensifying MHWs may rapidly erode the thermal safety margin of temperate seagrasses, pushing foundational coastal ecosystems toward metabolic instability under continued ocean warming.

Marine heatwaves (MHWs) are intensifying under climate change, yet the physiological limits that constrain seagrass resilience remain poorly defined. We experimentally tested the responses of the surfgrass Phyllospadix scouleri , a foundation species of the Northeast Pacific coast, to simulated MHWs of contrasting intensity. In a 27-day mesocosm experiment, plants were exposed to fluctuating temperatures representing a severe MHW (23.5 ± 1.5 °C) and an extreme MHW (26.5 ± 1.5 °C), while photosynthetic performance, respiration, nitrogen metabolism, oxidative stress, and growth were monitored during and after warming. Phyllospadix scouleri maintained photosynthetic capacity and carbon balance under severe warming but exhibited pronounced physiological disruption at extreme temperatures, including sustained photoinhibition, reduced nitrate assimilation, elevated respiration, and negative daily productivity. These effects persisted after heat stress, leading to reduced growth and indicating incomplete recovery. Multivariate analyses revealed a distinct transition from tolerance to functional breakdown near 26.5 °C, suggesting a physiological tipping point only 5–6 °C above current summer maxima in the area of the studied population. Our findings demonstrate that intensifying MHWs may rapidly erode the thermal safety margin of temperate seagrasses, pushing foundational coastal ecosystems toward metabolic instability and potential regime shifts under continued ocean warming. Highlight: Extreme marine heatwave disrupts photosynthesis, nitrogen metabolism, and carbon balance in the seagrass Phyllospadix scouleri , suggesting a narrow thermal safety margin in the face of ocean warming.

Background/Objectives: Botrytis cinerea is a necrotrophic fungal plant pathogen responsible for the gray mold disease, affecting several crops of economic importance worldwide. The primary line of control for the disease in the field and post-harvest fruits includes the application of fungicides. However, the emergence of fungal populations resistant to one or more fungicides has increased their application and diminished their effectiveness. Looking at new control strategies, metallic nanoparticles have appeared as a promising alternative for disease treatment. Green-synthesized copper oxide nanoparticles (CuONPs) are considered a feasible alternative, aiming to reduce the generation of environmentally toxic waste through chemical methods. Methods: In this work, CuONPs biosynthesized using the supernatant of Trichoderma asperellum and Trichoderma ghanense were evaluated to determine their antifungal activity against B. cinerea. Results: Four different formulations of CuONPs were obtained: Ta1, Ta2, Tg1, and Tg2. All formulations displayed antifungal properties, with Tg2 being the most effective and having a high potential in controlling the phytopathogen. CuONPs in the Tg2 formulation were quasi-spherical, ranging in size from 1 to 2.7 nm. Conclusions: Furthermore, Tg2 demonstrated greater efficacy than the copper-based commercial fungicide NORDOX^® 75W, which showed no inhibitory effect on B. cinerea mycelial growth. In summary, the CuONPs reported in this work offer a sustainable and effective alternative for managing the gray mold disease.

Grape production is one of the most agronomically important activities worldwide. However, it is threatened by diseases caused by phytopathogenic microorganisms, which cause severe economic losses. The primary strategy to control phytopathogenic fungi is the application of fungicides; however, they affect the environment and induce resistance in fungi. Nanomaterials, especially those green-synthesized, emerge as an eco-friendly and sustainable alternative to control fungal pathogens. The objective of this work is to evaluate the sensitivity of fungal phytopathogens to biosynthesized copper-oxide nanoparticles (CuONPs). Nanoparticles were evaluated as preventive and corrective treatments in grapevine green tissues and fruits under field conditions, using in vitro and in vivo experimental approaches. Interestingly, corrective treatment was highly effective and showed little accumulation of Cu on the fruits, even less than a commercial copper-based fungicide. Moreover, we report that Aspergillus niger causes lesions in photosynthetic tissues and severe disease symptoms in grapes. We also describe for the first time the presence of Alternaria alternata causing lesions, mainly on the stems and young leaves of grapevine plants in Mexico. These pathogens were inhibited by the biosynthesized CuONPs. All these findings show the effectiveness of using CuONPs to control phytopathogenic fungi, even under field conditions, shedding light on their potential use in agriculture with a less environmental impact than the commercial fungicides and agrochemicals currently used.

El uso de portainjertos en la viticultura moderna es una práctica común para evitar el impacto de la filoxera y nemátodos sobre los viñedos. Sin embargo, el uso de los portainjertos afecta procesos metabólicos de la planta incluso la asimilación de agua y iones del suelo. En México, al igual que en otros países productores de uva, el uso de portainjertos se ha generalizado para proteger los viñedos contra microorganismos nocivos. No obstante, poco se conoce cuál es el impacto del uso de los portainjertos sobre la fisiología de las variedades de vid. Por lo anterior, el objetivo de este estudio fue el evaluar el efecto de los portainjertos 110-R, 101-14, 1103-P y 3309-C sobre la asimilación de nitrógeno, fósforo, sodio, cobre, hierro, manganeso y zinc en vides Merlot, Shiraz y Cabernet Sauvignon de Chihuahua, México. La concentración de nitrógeno no varió en relación con el portainjerto usado ni la variedad cultivada. Además, la concentración de N en las hojas de vid disminuyó a lo largo del tiempo. Lo anterior es el resultado de la movilización de iones a zonas de almacenaje durante el periodo de senescencia foliar. Por otro lado, la concentración de fósforo, sodio, cobre, hierro y zinc en las hojas de las variedades y portainjertos estudiadas no presentaron diferencias significativas. Sin embargo, la concentración de Mn en las hojas de Merlot fue 30% mayor en las vides con portainjerto 1103-P en comparación a las vides con portainjerto 3309-C. En este estudio se demostró que el portainjerto impacta la asimilación de iones en las variedades de uva para vino.

The effects of temperature, irradiance, and other environmental variables on photosynthesis in seagrasses are well understood. However, little information is available regarding the effects of the nitrate concentration in seawater on the photosynthetic characteristics of marine vegetation. Thus, the aim of this study was to determine the effect of the nitrate concentration in seawater on the effective quantum yield of the seagrass Cymodocea nodosa. Cymodocea nodosa shoots were incubated under different irradiance levels and with different nitrate concentrations. In contrast, a decrease in transmittance and an exponential increase in the absorptance of the shoots were observed as a function of increasing nitrate levels. Furthermore, the effective quantum yield of photosystem II (Φ_PSII) in C. nodosa shoots increased exponentially as the nitrate concentration in the media increased. The Φ_PSII values in the shoots decreased as irradiance increased and reached minimum values at solar noon or 2 h afterward. However, the decrease of Φ_PSII values was 4-fold greater in shoots incubated under full solar radiation (100% natural incident irradiance, E_o) compared to those of shoots incubated with 20% E_o. The Φ_PSII values decreased to almost zero in shoots pre-incubated with no nitrate (0 μM NO₃^–), whereas Φ_PSII values in shoots pre incubated with 25 and 100 μM NO₃^– decreased by approximately 25% of their initial values. Collectively, these results indicate that nitrogen levels in seawater regulate the effective quantum yield values of C. nodosa, which suggests that the photosynthetic characteristics of this seagrass might be regulated by fluctuating nitrate levels in the water column such as those that are observed in upwelling regions.

Collagen from the swim bladder of sturgeon has been historically used to precipitate polyphenols in wine. However, little is known about the wine polyphenol precipitation potential of protein from other fishes. Consequently, the objective of this study was to evaluate the polyphenol precipitation potential of collagen extracted from other fish (Rocot, Sebastes sp. and Curvina, Atractoscion nobilis). There were no differences in the complexation time between wine polyphenols and clarifying proteins. However, collagen from fishes from Baja California was more effective in precipitating wine polyphenols than ovalbumin or sturgeon swim bladder collagen. The polyphenol precipitation was specific to the protein added to the wine. The addition of Baja California fish collagen did not change the biochemical structure (pH, total acidity, volatile acidity, and free and total sulfur dioxide) of the clarified wine.

High concentrations of calcium (Ca), magnesium (Mg), potassium (K), and sodium (Na) are often responsible for imparting a salty character in wines that is often described as a negative sensory attribute. The wines of Mexico have been described as salty; however, the origin of the salty character of these wines is unknown. The objective of this study was to evaluate the concentrations of Ca, Mg, K, and Na in wines from Mexico and compare them to those found in wines from other countries. In general, concentrations were higher in the wines from Mexico. Specifically, levels of Na in red and white wines from Mexico were two-to three-fold higher than those in wines from other wine-producing countries. Thus, it is likely that the salty character described in some Mexican wines is, in part, the result of high concentrations of ions, especially Na.