Although root disease caused by Phytophthora cinnamomi is considered to be the most frequent and damaging disease associated with Quercus spp. decline in southwestern Spain, cankers commonly are observed on branches of declining Mediterranean Quercus spp. in this region. In surveys carried out in eight declining Quercus forests, strips of necrotic inner bark were common on diseased branches. Botryosphaeria stevensii, B. dothidea, and Diplodia sarmentorum consistently were isolated from these branches. Isolates of all three species caused cankers when inoculated onto excised Quercus branches. Inoculations on healthy branches in the field also induced canker development, but only B. stevensii caused lesions that girdled and killed the branches. The optimum temperature for in vitro growth of B. stevensii and B. dothidea was above 25°C, with slow growth at 35°C. In contrast, D. sarmentorum had an optimum temperature for growth of about 21°C, and did not grow at 35°C. The common occurrence and wide distribution of these pathogens, their association with cankers, and their ability to infect Quercus spp. suggest that they may contribute to the Quercus spp. decline in southwestern Spain.
Summary Abies pinsapo, a fir endemic to a small area in southernmost Spain, is frequently attacked in natural stands by Heterobasidion root rot. To identify the Heterobasidion species causing the disease, pure cultures of the fungus were isolated from symptomatic trees in five localities in Sierra de las Nieves Natural Park and identified by pairing tests. In addition, genets of the fungus were identified in two pure stands of A. pinsapo. All the Heterobasidion specimens collected belonged to the species Heterobasidion abietinum. The largest genet found was 57 m long, and had colonized 10 trees. The large size of the main genets implied that H. abietinum had spread via root contacts from old infections generated before the establishment of the Sierra de las Nieves National Park in 1989. Exceptionally dry summers in the last 20 years may have weakened A. pinsapo and favoured spread of the disease.
1. Conservation bias towards flagship species sometimes threatens other species of chief concern. Long-term studies of potential harm by favoured species on other sensitive species, though seldom adopted, are required to fairly evaluate the suitability of management and restoration efforts. 2. We illustrate the potential detrimental outcomes of conservation biased towards birds by investigating the long-term ) impact of a large waterbird colony (up to 13 000 pairs) on a remnant cork oak Quercus suber population at a World Biosphere Reserve in south-western Spain (the Doñana National Park). To this end, we compared changes in performance (growth, crown vigour and survival) of oaks occupied and unoccupied by the waterbird colony. 3. After 46 years of occupation, the risk of death to centenarian oaks in the area occupied by the colony was over twofold higher than for trees outside the area. Non-centenarian planted and naturally regenerated oaks showed similar trends, leading to restoration failure. 4. Synthesis and applications. Our long-term study reveals that waterbirds and centenarian oaks cannot coexist, at the most local scale, but they can at a regional scale including within the Doñana area. We propose immediate planting efforts in suitable colony-free areas, while managers evaluate the feasibility of relocating colonial waterbirds to an alternative location. To preserve the Doñana oak genetic pool, such reforestation should be accomplished using local seeds and seedlings. New trees should not be planted in close proximity of colony-occupied trees since it significantly reduces their survival. Doñana stakeholders should both overcome current conservation bias in favour of birds and enter into a process of settlement to best preserve the overall biodiversity of the system.
Some people remain healthier throughout life than others but the underlying reasons are poorly understood. Here we hypothesize this advantage is attributable in part to optimal immune resilience (IR), defined as the capacity to preserve and/or rapidly restore immune functions that promote disease resistance (immunocompetence) and control inflammation in infectious diseases as well as other causes of inflammatory stress. We gauge IR levels with two distinct peripheral blood metrics that quantify the balance between (i) CD8+ and CD4+ T-cell levels and (ii) gene expression signatures tracking longevity-associated immunocompetence and mortality-associated inflammation. Profiles of IR metrics in ~48,500 individuals collectively indicate that some persons resist degradation of IR both during aging and when challenged with varied inflammatory stressors. With this resistance, preservation of optimal IR tracked (i) a lower risk of HIV acquisition, AIDS development, symptomatic influenza infection, and recurrent skin cancer; (ii) survival during COVID-19 and sepsis; and (iii) longevity. IR degradation is potentially reversible by decreasing inflammatory stress. Overall, we show that optimal IR is a trait observed across the age spectrum, more common in females, and aligned with a specific immunocompetence-inflammation balance linked to favorable immunity-dependent health outcomes. IR metrics and mechanisms have utility both as biomarkers for measuring immune health and for improving health outcomes.
Summary Brassicaceous plants rich in glucosinolates have been used as biofumigants for the management of soilborne pathogens. Efficacy of Brassica plant tissue has mainly been attributed to toxic isothiocyanates released upon the hydrolysis of glucosinolates. Management of Phytophthora cinnamomi, the causal agent of oak root rot in rangeland ecosystems using biofumigation, is promising, but requires further validation. The biofumigation activity of 14 brassicaceous plants was evaluated under experimental conditions. All evaluated plants rich in sinigrin suppressed (100%) the mycelial growth of P. cinnamomi, while plants rich in aromatic or other aliphatic glucosinolates had little or no suppressive effect. Simulating soil amendment in field conditions, the effects on natural soil artificially infested with P. cinnamomi chlamydospores were examined with Brassica juncea, Eruca vesicaria and Lepidium sativum, three species with different glucosinolate profiles. Only B. juncea decreased the viability of chlamydospores significantly in comparison with untreated soil only 1 day after biofumigation, whereas E. vesicaria needed 8 days to reach significance and L. sativum had no effect at all. Despite the decreases in soil inoculum, biofumigation with B. juncea did not prevent the root infections in a highly susceptible host (Lupinus luteus). However, biofumigation with plants rich in sinigrin, such as B. juncea, decreased P. cinnamomi soil inoculum under the experimental minimum threshold for oak disease expression. Although biofumigation should be considered as an effective measure to be incorporated in integrated control of the oak disease, biofumigation by itself would not be effective enough for the substantial suppression of P. cinnamomi inoculum.
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