Plant proteases in the control of the hypersensitive response

The hypersensitive response (HR) is a plant defence reaction triggered by activation of immune receptors upon pathogen recognition. It results in rapid cell death at the attempted invasion site, confining the pathogen and sending signals to distal parts of the plant that can in turn activate defences for subsequent attacks. HR cell death is a highly controlled phenomenon, requiring the concerted action of diverse plant proteases and regulatory mechanisms to keep it efficient yet confined. Research in the last decade has significantly contributed to a better understanding of the mechanisms leading to HR, although our knowledge about the pathways that regulate this form of programmed cell death (PCD) still remains incomplete. In this review, we explore current knowledge of plant proteases as HR regulators. Proteases are key regulatory enzymes that not only serve degradative purposes, but also have very important signalling roles. In animals, caspases have been shown to be the major regulators and executioners of PCD. Plants do not have caspases, and instead PCD is carried out by the activities of caspase-like and other protease belonging to different protease classes. We summarise the mechanistic roles of plant proteases whose roles in HR regulation are relatively well understood, which includes members of the cysteine, threonine, and serine protease families

Memoria de trabajo, control inhibitorio y flexibilidad cognitiva de niños preescolares en el contexto de la pandemia por Covid-19 Guatemala.

El objetivo general de la investigación fue evaluar las funciones ejecutivas básicas en niños comprendidos entre las edades de 5, 6 y 7 años de preescolar, de la Escuelas Oficiales de Párvulos en tres escuelas del país ubicadas en Guatemala, Jutiapa y Chiquimula. Los objetivos específicos de la investigación: definir los rasgos que presentan los niños con dificultad en la memoria de trabajo, control inhibitorio y flexibilidad cognitiva a causa del confinamiento por la pandemia del COVID-19 e identificar las funciones ejecutivas detectadas por los padres de familia que consideran les ocasiona mayores problemas a los niños, tras la experiencia de adaptación a la nueva modalidad de aprendizaje desde el hogar. La muestra la conformaron parte de los padres de los niños y niñas inscritos en la Escuela Oficial de Párvulos No. 62 de la Colonia Castañas, Zona 11, Ciudad de Guatemala, en donde se obtuvo un porcentaje de participación del 83.33% en los grados de párvulos y preparatoria que asistieron periódicamente los primeros meses antes del cierre de actividades presenciales en la escuela. El enfoque fue cuantitativo, con diseño descriptivo, transaccional. La técnica de muestreo fue no probabilística de tipo homogéneo. Para la recolección de datos se utilizó un único instrumento. El estudio reflejó que un 52% de los niños presentan dificultades leves en las FE básicas las cuales fueron detectadas por los padres, dentro de los rasgos que presentaron los niños con dificultad leve en las funciones ejecutivas: memoria de trabajo, control inhibitorio y flexibilidad cognitiva se encuentra la falta de control de impulsos, y otras dificultades en el aprendizaje que fueron observados en las interacciones con los niños de la escuela. Para el análisis de datos, se utilizó las matrices de datos del programa Excel y fueron presentadas por medio de gráficas de barras

Modulation of plant autophagy during pathogen attack

In plants, the highly conserved catabolic process of autophagy has long been known as a means of maintaining cellular homeostasis and coping with abiotic stress conditions. Accumulating evidence has linked autophagy to immunity against invading pathogens, regulating plant cell death, and antimicrobial defences. In turn, it appears that phytopathogens have evolved ways not only to evade autophagic clearance but also to modulate and co-opt autophagy for their own benefit. In this review, we summarize and discuss the emerging discoveries concerning how pathogens modulate both host and self-autophagy machineries to colonize their host plants, delving into the arms race that determines the fate of interorganismal interaction.Fil: Leary, Alexandre Y. Imperial College London; Reino UnidoFil: Sanguankiattichai, Nattapong. University of Oxford; Reino UnidoFil: Duggan, Cian. Imperial College London; Reino UnidoFil: Tumtas, Yasin. Imperial College London; Reino UnidoFil: Pandey, Pooja. Imperial College London; Reino UnidoFil: Segretin, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Salguero Linares, Jose. Imperial College London; Reino UnidoFil: Savage, Zachary D. Imperial College London; Reino UnidoFil: Yow, Rui Jin. Imperial College London; Reino UnidoFil: Bozkurt, Tolga O.. Imperial College London; Reino Unid

Differences in temperature sensitivity and drought recovery between natural stands and plantations of conifers are species-specific

Forests are being impacted by climate and land-use changes which have altered their productivity and growth. Understanding how tree growth responds to climate in natural and planted stands may provide valuable information to prepare management in sight of climate change. Plantations are expected to show higher sensitivity to climate and lower post-drought resilience than natural stands, due to their lower compositional and structural diversity. We reconstructed and compared the radial growth of six conifers with contrasting ecological and climatic niches (Abies pinsapo, Cedrus atlantica, Pinus sylvestris, Pinus nigra, Pinus pinea, Pinus pinaster) in natural and planted stands subjected to seasonal drought in 40 sites. We quantified the relationships between individual growth variability and climate variables (temperature, precipitation and the SPEI drought index), as well as post-drought resilience. Elevated precipitation during the previous autumn-winter and current spring to early summer enhanced growth in both natural and planted stands of all species. Temperature effects on growth were less consistent: only plantations of A. pinsapo, C. atlantica, P. nigra, P. pinea, P. sylvetris and a natural stand of P. nigra showed negative impacts of summer temperature on growth. Drought reduced growth of all species in both plantations and natural stands, with variations in the temporal scale of the response. Drought constrained growth more severely in natural stands than in plantations of C. atlantica, P. pinaster and P. nigra, whereas the inverse pattern was found for A. pinsapo. Resilience to drought varied between species: natural stands of A. pinsapo, C. atlantica and P. pinaster recovered faster than plantations, while P. pinea plantations recovered faster than natural stands. Overall, plantations did not consistently show a higher sensitivity to climate and a lower capacity to recover after drought. Therefore, plantations are potential tools for mitigating climate warming. © 2021 The AuthorsThis study was supported by project FORMAL ( RTI2018-096884-B-C31 ) from the Spanish Ministry of Science, Innovation and Universities . GS-B was supported by a Spanish Ministry of Economy, Industry and Competitiveness Postdoctoral grant ( IJC2019-040571-I ; FEDER funds)

What drives growth of Scots pine in continental Mediterranean climates: drought, low temperatures or both?

Scots pine forests subjected to continental Mediterranean climates undergo cold winter temperatures and drought stress. Recent climatic trends towards warmer and drier conditions across the Mediterranean Basin might render some of these pine populations more vulnerable to drought-induced growth decline at the Southernmost limit of the species distribution. We investigated how cold winters and dry growing seasons drive the radial growth of Scots pine subject to continental Mediterranean climates by relating growth to climate variables at local (elevational gradient) and regional (latitudinal gradient) scales. Local climate-growth relationships were quantified on different time scales (5-, 10- and 15-days) to evaluate the relative role of elevation and specific site characteristics. A negative water balance driven by high maximum temperatures in June (low-elevation sites) and July (high-elevation sites) was the major constraint on growth, particularly on a 5- to 10-day time scale. Warm nocturnal conditions in January were associated with wider rings at the high-elevation sites. At the regional scale, Scots pine growth mainly responded positively to July precipitation, with a stronger association at lower elevations and higher latitudes. January minimum temperatures showed similar patterns but played a secondary role as a driver of tree growth. The balance between positive and negative effects of summer precipitation and winter temperature on radial growth depends on elevation and latitude, with low-elevation populations being more prone to suffer drought and heat stress; whereas, high-elevation populations may be favoured by warmer winter conditions. This negative impact of summer heat and drought has increased during the past decades. This interaction between climate and site conditions and local adaptations is therefore decisive for the future performance and persistence of Scots pine populations in continental Mediterranean climates. Forecasting changes in the Scots pine range due to climate change should include this site-related information to obtain more realistic predictions, particularly in Mediterranean rear-edge areas

Growth and resilience responses of Scots pine to extreme droughts across Europe depend on predrought growth conditions

Global climate change is expected to further raise the frequency and severity of extreme events, such as droughts. The effects of extreme droughts on trees are difficult to disentangle given the inherent complexity of drought events (frequency, severity, duration, and timing during the growing season). Besides, drought effects might be modulated by trees’ phenotypic variability, which is, in turn, affected by long-term local selective pressures and management legacies. Here we investigated the magnitude and the temporal changes of tree-level resilience (i.e., resistance, recovery, and resilience) to extreme droughts. Moreover, we assessed the tree-, site-, and drought-related factors and their interactions driving the tree-level resilience to extreme droughts. We used a tree-ring network of the widely distributed Scots pine (Pinus sylvestris) along a 2, 800 km latitudinal gradient from southern Spain to northern Germany. We found that the resilience to extreme drought decreased in mid-elevation and low productivity sites from 1980–1999 to 2000–2011 likely due to more frequent and severe droughts in the later period. Our study showed that the impact of drought on tree-level resilience was not dependent on its latitudinal location, but rather on the type of sites trees were growing at and on their growth performances (i.e., magnitude and variability of growth) during the predrought period. We found significant interactive effects between drought duration and tree growth prior to drought, suggesting that Scots pine trees with higher magnitude and variability of growth in the long term are more vulnerable to long and severe droughts. Moreover, our results indicate that Scots pine trees that experienced more frequent droughts over the long-term were less resistant to extreme droughts. We, therefore, conclude that the physiological resilience to extreme droughts might be constrained by their growth prior to drought, and that more frequent and longer drought periods may overstrain their potential for acclimation

Arabidopsis metacaspase MC1 localizes in stress granules, clears protein aggregates and delays senescence

Stress granules (SGs) are highly conserved cytoplasmic condensates that assemble in response to stress and contribute to maintaining protein homeostasis. These membraneless organelles are dynamic, disassembling once the stress is no longer present. Persistence of SGs due to mutations or chronic stress has been often related to age-dependent protein-misfolding diseases in animals. Here, we find that the metacaspase MC1 is dynamically recruited into SGs upon proteotoxic stress in Arabidopsis (Arabidopsis thaliana). Two predicted disordered regions, the prodomain and the 360 loop, mediate MC1 recruitment to and release from SGs. Importantly, we show that MC1 has the capacity to clear toxic protein aggregates in vivo and in vitro, acting as a disaggregase. Finally, we demonstrate that overexpressing MC1 delays senescence and this phenotype is dependent on the presence of the 360 loop and an intact catalytic domain. Together, our data indicate that MC1 regulates senescence through its recruitment into SGs and this function could potentially be linked to its remarkable protein aggregate-clearing activity

Drought Sensitiveness on Forest Growth in Peninsular Spain and the Balearic Islands

Drought is one of the key natural hazards impacting net primary production and tree growth in forest ecosystems. Nonetheless, tree species show different responses to drought events, which make it difficult to adopt fixed tools for monitoring drought impacts under contrasting environmental and climatic conditions. In this study, we assess the response of forest growth and a satellite proxy of the net primary production (NPP) to drought in peninsular Spain and the Balearic Islands, a region characterized by complex climatological, topographical, and environmental characteristics. Herein, we employed three different indicators based on in situ measurements and satellite image-derived vegetation information (i.e., tree-ring width, maximum annual greenness, and an indicator of NPP). We used seven different climate drought indices to assess drought impacts on the tree variables analyzed. The selected drought indices include four versions of the Palmer Drought Severity Index (PDSI, Palmer Hydrological Drought Index (PHDI), Z-index, and Palmer Modified Drought Index (PMDI)) and three multi-scalar indices (Standardized Precipitation Evapotranspiration Index (SPEI), Standardized Precipitation Index (SPI), and Standardized Precipitation Drought Index (SPDI)). Our results suggest that—irrespective of drought index and tree species—tree-ring width shows a stronger response to interannual variability of drought, compared to the greenness and the NPP. In comparison to other drought indices (e.g., PDSI), and our results demonstrate that multi-scalar drought indices (e.g., SPI, SPEI) are more advantageous in monitoring drought impacts on tree-ring growth, maximum greenness, and NPP. This finding suggests that multi-scalar indices are more appropriate for monitoring and modelling forest drought in peninsular Spain and the Balearic Islands

Contrasting growth forecasts across the geographical range of Scots pine due to altitudinal and latitudinal differences in climatic sensitivity

Ongoing changes in global climate are altering ecological conditions for many species. The consequences of such changes are typically most evident at the edge of a species’ geographical distribution, where differences in growth or population dynamics may result in range expansions or contractions. Understanding population responses to different climatic drivers along wide latitudinal and altitudinal gradients is necessary in order to gain a better understanding of plant responses to ongoing increases in global temperature and drought severity. We selected Scots pine (Pinus sylvestrisL.) as a model species to explore growth responses to climatic variability (seasonal temperature and precipitation) over the last century through dendrochronological methods. We developed linear models based on age, climate and previous growth to forecast growth trends up to year 2100 using climatic predictions. Populations were located at the treeline across a latitudinal gradient covering the northern, central and southernmost populations and across an altitudinal gradient at the southern edge of the distribution (treeline, medium and lower elevations). Radial growth was maximal at medium altitude and treeline of the southernmost populations. Temperature was the main factor controlling growth variability along the gradients, although the timing and strength of climatic variables affecting growth shifted with latitude and altitude. Predictive models forecast a general increase in Scots pine growth at treeline across the latitudinal distribution, with southern populations increasing growth up to year 2050, when it stabilises. The highest responsiveness appeared at central latitude, and moderate growth increase is projected at the northern limit. Contrastingly, the model forecasted growth decline at lowland-southern populations, suggesting an upslope range displacement over the coming decades. Our results give insight into the geographical responses of tree species to climate change and demonstrate the importance of incorporating biogeographical variability into predictive models for an accurate prediction of species dynamics as climate changes