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We aimed to evaluate the facilitation effects of an aluminum (Al) hyperaccumulator species bearing cluster roots, Gevuina avellana, on the seedling growth and performance of an Al-intolerant and phosphorus (P)-deficient-sensitive plant, Vaccinium corymbosum. For this, seedlings of G. avellana and V. corymbosum were grown alone or together as follows: i) two G. avellana seedlings, ii) one G. avellana + one V. corymbosum and iii) two V. corymbosum, in soil supplemented with Al (as Al2(SO4)3) and in the control (without Al supplementation). We determined relative growth rate (RGR), photosynthetic rate, chlorophyll concentration, lipid peroxidation and Al and nutrient concentration [Nitrogen (N), P, potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), and sulfur (S)] in leaves and roots of both species. The results showed that, in general, G. avellana did not assist V. corymbosum to enhance its RGR nor reduce its Al uptake. However, G. avellana assisted V. corymbosum in enhanced N acquisition and, consequently, to increase its chlorophyll concentration and photosynthetic rate. Besides, V. corymbosum had lower lipid peroxidation in leaves when grown in the soil with high Al supplementation in association with G. avellana. Our results suggest a facilitating effect of G. avellana to V. corymbosum when grown in soils with high Al concentration, by enhancing chlorophyll concentrations and photosynthetic rate, and decreasing the oxidative damage to lipids.

Southern South American Proteaceae thrive on young volcanic substrates, which are extremely low in plant-available phosphorus (P). Most Proteaceae exhibit a nutrient-acquisition strategy based on the release of carboxylates from specialized roots, named cluster roots (CR). Some Proteaceae colonize young volcanic substrates which has been related to CR functioning. However, physiological functioning of other Proteaceae on recent volcanic substrates is unknown. We conducted an experiment with seedlings of five Proteaceae (Gevuina avellana, Embothrium coccineum, Lomatia hirsuta, L. ferruginea, and L. dentata) grown in three volcanic materials. Two of them are substrates with very low nutrient concentrations, collected from the most recent deposits of the volcanoes Choshuenco and Calbuco (Chile). The other volcanic material corresponds to a developed soil that exhibits a high nutrient availability. We assessed morphological responses (i.e., height, biomass, and CR formation), seed and leaf macronutrient and micronutrient concentrations and carboxylates exuded by roots. The results show that G. avellana was less affected by nutrient availability of the volcanic substrate, probably because it had a greater nutrient content in its seeds and produced large CR exuding carboxylates that supported their initial growth. Embothrium coccineum exhibited greater total plant height and leaf P concentration than Lomatia species. In general, in all species leaf macronutrient concentrations were reduced on nutrient-poor volcanic substrates, while leaf micronutrient concentrations were highly variable depending on species and volcanic material. We conclude that Proteaceae from temperate rainforests differ in their capacity to grow and acquire nutrients from young and nutrient-poor volcanic substrates. The greater seed nutrient content, low nutrient requirements (only for G. avellana) and ability to mobilize nutrients help explain why G. avellana and E. coccineum are better colonizers of recent volcanic substrates than Lomatia species.

The effects of a long-term simulated spring-summer UV-B daily course on some anatomical, physiological, and biochemical features were studied in new and old leaves of blueberry (Vaccinium corymbosum L.) cultivars Legacy, Brigitta, and Bluegold. The results show that under UV-B exposure, leaf thickness increased in Bluegold due to an increased intercellular cavities. By contrast, Brigitta maintained its leaf thickness. The net photosynthetic rate was not significantly affected by the UV-B radiation in any of the cultivars; however, Brigitta presented a better photosystem II performance, since this cultivar had more efficient photochemistry under the UV-B radiation. In addition, Brigitta also maintained enhanced total phenol and total anthocyanin content compared to the other cultivars. In conclusion, Brigitta was more resistant to the UV-B radiation than the other two cultivars.

El tétanos es causado por Clostridium tetani, bacteria Gram+ esporulada que produce una potente neurotoxina. Las vacunas parenterales producen IgG antitoxina tetánica (anti TT) protectores en múltiples dosis inductoras y de reactivación; vax-TET® es una vacuna cubana parenteral adsorbida en alúmina. La IgAS (secretora), principal anticuerpo protector mucoso, sólo es inducida por la vía mucosa. La vía oral, la inducción de IgA y su papel protector no han sido exploradas. SinTimVaS se aplica por vía mucosa y parenteral simultánea que induce IgG sistémica similares a la vía parenteral y adiciona de respuesta de IgA mucosa. Evaluamos el efecto de vax-TET® aplicado en SinTimVaS en ratones Balb/c y exploramos la influencia del adyuvante sobre la inducción de IgA anti TT. SinTimVaS indujo similares respuestas de IgG anti TT séricas que dos dosis de vax-TET® intramusculares; pero superiores a una dosis. Tres dosis de vax-TET® orales no indujeron IgG anti TT sérica, mientras que la adyuvación con el adyuvante Finlay Cocleato 1 (AFCo1) sí la indujeron. No se logró determinar la inducción de IgA anti TT mucosa con ninguna de las formulaciones adjuvadas con alúmina; pero si con la formulación AFCo1+TT. Podemos concluir que vax-TET® en SinTimVaS funcionó de forma similar a la inmunización parenteral establecida, por lo que sería posible reducir los esquemas multidosis con formulaciones de adyuvantes más potentes y se confirma que se requieren potentes adyuvantes para inducir IgA mucosa.

Salicylic acid (SA) has been shown to ameliorate drought stress. However, physiological and biochemical mechanisms involved in drought stress tolerance induced by SA in plants have not been well understood. Thus, this study aimed to study the role of SA application on enzymatic and non-enzymatic antioxidants, photosynthetic performance, and plant growth in A. chilensis plants subjected to moderate drought stress. One-year-old A. chilensis plants were subjected to 100% and 60% of field capacity. When plants reached moderate drought stress (average of stem water potential of −1.0 MPa, considered as moderate drought stress), a single SA application was performed on plants. Then, physiological and biochemical features were determined at different times during 14 days. Our study showed that SA application increased 13.5% plant growth and recovered 41.9% AN and 40.7% gs in drought-stressed plants on day 3 compared to drought-stressed plants without SA application. Interestingly, SOD and APX activities were increased 85% and 60%, respectively, in drought-stressed SA-treated plants on day 3. Likewise, SA improved 30% total phenolic content and 60% antioxidant capacity in drought-stressed A. chilensis plants. Our study provides insight into the SA mechanism to tolerate moderate drought stress in A. chilensis plants.

In this study, the physiological performance and fruit quality responses of the highbush blueberry (Vaccinium corymbosum) cultivar Legacy to high temperatures (HTs) were evaluated in a field experiment. Three-year-old V. corymbosum plants were exposed to two temperature treatments between fruit load set and harvest during the 2022/2023 season: (i) ambient temperature (AT) and (ii) high temperature (HT) (5 °C ± 1 °C above ambient temperature). A chamber covered with transparent polyethylene (100 µm thick) was used to apply the HT treatment. In our study, the diurnal temperature was maintained with a difference of 5.03 °C ± 0.12 °C between the AT and HT treatments. Our findings indicated that HT significantly decreased CO2 assimilation (Pn) by 45% and stomatal conductance (gs) by 35.2% compared to the AT treatment. By contrast, the intercellular CO2 concentration (Ci) showed higher levels (about 6%) in HT plants than in AT plants. Fruit quality analyses revealed that the fruit weight and equatorial diameter decreased by 39% and 13%, respectively, in the HT treatment compared to the AT treatment. By contrast, the firmness and total soluble solids (TSS) were higher in the HT treatment than in the AT treatment. Meanwhile, the titratable acidity showed no changes between temperature treatments. In our study, Pn reduction could be associated with stomatal and non-stomatal limitations under HT treatment. Although these findings improve our understanding of the impact of HTs on fruit growth and quality in V. corymbosum, further biochemical and molecular studies are need.

Ascorbic acid (ASC) is an important antioxidant in plant cells, being the main biosynthesis pathway is L-galactose or Smirnoff-Wheeler. ASC is involved in plant growth and development processes, being a cofactor and regulator of multiple signaling pathways in response to abiotic stresses. Aluminum toxicity is an important stressor under acidic conditions, affecting plant root elongation, triggering ROS induction and accumulation of hydrogen peroxide (H 2 O 2 ). To mitigate damage from Al-toxicity, plants have evolved mechanisms to resist stress conditions, such as Al-tolerance and Al-exclusion or avoidance, both strategies related to the forming of non-phytotoxic complexes or bind-chelates among Al and organic molecules like oxalate. Dehydroascorbate (DHA) degradation generates oxalate when ASC is recycled, and dehydroascorbate reductase (DHAR) expression is inhibited. An alternative strategy is ASC regeneration, mainly due to a higher level of DHAR gene expression and low monodehydroascorbate reductase (MDHAR) gene expression. Therefore, studies performed on Fagopyrum esculentum, Nicotiana tabacum, Poncirus trifoliate, and V. corymbosum suggest that ASC is associated with the Al-resistant mechanism, given the observed enhancements in defense mechanisms, including elevated antioxidant capacity and oxalate production. This review examines the potential involvement of ASC metabolism in Al-resistant mechanisms., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest., (Copyright © 2024. Published by Elsevier Masson SAS.)

Plastic covers have been used to prevent environmental constraints negatively affecting sweet cherry production in Southern Chile. However, less information is available on agronomic practices and their effects on fruit quality in sweet cherry covered orchards. Thus, in this study, we evaluated the impact of fruit load regulation on cherries' antioxidant-related parameters and the quality and condition at harvest and postharvest in sweet cherry ( Prunus avium ) cv. Regina that was cultivated under a plastic cover in Southern Chile. For this, four fruit load treatments were manually applied-(i) 100% fruit load (the control), (ii) 80% fruit load, (iii) 60% fruit load, and (iv) 40% fruit load-in a commercial sweet cherry orchard for two seasons (2021/2022 and 2022/2023). The results revealed that the yield and fruit load were not significantly different between the treatments. Interestingly, the 60% and 40% fruit loads increased the fresh weight, fruit size, and firmness (20.3%) compared to the control (the 100% fruit load) during both seasons. Likewise, the 60% and 40% fruit load treatments exhibited the highest fruit size distribution of 30 mm, while the 100 and 80% fruit load treatments showed the highest fruit distribution with fruit sizes between 28 mm and 24 mm. The total soluble solids (TSSs) did not vary among the fruit load treatments, while a significant increase was found in the titratable acidity (TA) in the 60 and 40% fruit load treatments during both seasons. No significant differences in antioxidant activity (AA) and total phenols (TPHs) among the treatments were observed during both seasons. Overall, the results revealed that the fruit load treatments, mainly 40%, increased the fruit weight and firmness and reduced pitting in fruits by 39.4% at postharvest. Thus, fruit thinning might be an important agronomical practice to regulate fruit load, positively affecting fruit quality at harvest and during postharvest storage in sweet cherry cv. Regina cultivated under a plastic cover. However, more biochemical and molecular studies are needed to elucidate the mechanism involved in this improvement.

Main Conclusions: In contrast to Neltuma species, S. tamarugo exhibited higher stress tolerance, maintaining photosynthetic performance through enhanced gene expression and metabolites. Differentially accumulated metabolites include chlorophyll and carotenoids and accumulation of non-nitrogen osmoprotectants. Plant species have developed different adaptive strategies to live under extreme environmental conditions. Hypothetically, extremophyte species present a unique configuration of physiological functions that prioritize stress-tolerance mechanisms while carefully managing resource allocation for photosynthesis. This could be particularly challenging under a multi-stress environment, where the synthesis of multiple and sequential molecular mechanisms is induced. We explored this hypothesis in three phylogenetically related woody species co-occurring in the Atacama Desert, Strombocarpa tamarugo, Neltuma alba, and Neltuma chilensis, by analyzing their leaf dehydration and freezing tolerance and by characterizing their photosynthetic performance under natural growth conditions. Besides, the transcriptomic profiling, biochemical analyses of leaf pigments, and metabolite analysis by untargeted metabolomics were conducted to study gene expression and metabolomic landscape within this challenging multi-stress environment. S. tamarugo showed a higher photosynthetic capacity and leaf stress tolerance than the other species. In this species, a multifactorial response was observed, which involves high photochemical activity associated with a higher content of chlorophylls and β-carotene. The oxidative damage of the photosynthetic apparatus is probably attenuated by the synthesis of complex antioxidant molecules in the three species, but S. tamarugo showed the highest antioxidant capacity. Comparative transcriptomic and metabolomic analyses among the species showed the differential expression of genes involved in the biosynthetic pathways of key stress-related metabolites. Moreover, the synthesis of non-nitrogen osmoprotectant molecules, such as ciceritol and mannitol in S. tamarugo, would allow the nitrogen allocation to support its high photosynthetic capacity without compromising leaf dehydration tolerance and freezing stress avoidance., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Boron (B) is a micronutrient crucial for the growth, development, productivity, and quality of crops. However, in areas characterized by acid soil (pH water < 5.0) and high rainfall, soil B concentration tends to decrease, leading to insufficient supply to crops. This study was aimed at determining the optimal rate of B fertilization to enhance Vaccinium corymbosum L. performance in acid conditions. One-year-old cultivars with contrasting Al resistance (Al-sensitive Star and Al-resistant Cargo) were used. Plants were conditioned in plastic pots containing 18 L of half-ionic-strength Hoagland solution (pH 4.5) for 2 weeks. Thereafter, the following B treatments were applied foliarly: control, without B application (distilled water), 200, 400, and 800 mg L -1 of B as Solubor ® for up to 72 h. Photosynthetic performance, root and shoot B levels, antioxidants, and oxidative stress were evaluated. Root and shoot B concentrations increased with the increasing B application, being higher in leaves than in roots of both cultivars. Net photosynthesis decreased at 800 mg L -1 B supply and effective quantum yield of PSII at 72 h in all B treatments. Lipid peroxidation increased in both cultivars at 800 mg L -1 B treatment. Antioxidant activity increased in all B treatments in both cultivars; while, at 400 and 800 mg L -1 B, total phenols increased in leaves of cultivar Star and decreased in cultivar Cargo. In conclusion, optimal B foliar application for highbush blueberry appears to be around 400 mg L -1 B. The appropriate B foliar application could help mitigate potential stress-induced problems in highbush blueberry cultivation. However, the optimal foliar B application should be confirmed in field experiments to help the farmers manage B nutrition.

We aimed to evaluate the facilitation effects of an aluminum (Al) hyperaccumulator species bearing cluster roots, Gevuina avellana , on the seedling growth and performance of an Al-intolerant and phosphorus (P)-deficient-sensitive plant, Vaccinium corymbosum . For this, seedlings of G. avellana and V. corymbosum were grown alone or together as follows: i) two G. avellana seedlings, ii) one G. avellana + one V. corymbosum and iii) two V. corymbosum , in soil supplemented with Al (as Al 2 (SO 4 ) 3 ) and in the control (without Al supplementation). We determined relative growth rate (RGR), photosynthetic rate, chlorophyll concentration, lipid peroxidation and Al and nutrient concentration [Nitrogen (N), P, potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), and sulfur (S)] in leaves and roots of both species. The results showed that, in general, G. avellana did not assist V. corymbosum to enhance its RGR nor reduce its Al uptake. However, G. avellana assisted V. corymbosum in enhanced N acquisition and, consequently, to increase its chlorophyll concentration and photosynthetic rate. Besides, V. corymbosum had lower lipid peroxidation in leaves when grown in the soil with high Al supplementation in association with G. avellana. Our results suggest a facilitating effect of G. avellana to V. corymbosum when grown in soils with high Al concentration, by enhancing chlorophyll concentrations and photosynthetic rate, and decreasing the oxidative damage to lipids., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Delgado, Barra, Berrios, Mora, Durán, Valentine and Reyes-Díaz.)

Background: Titanium dioxide nanoparticles (TiO 2 NPs) have been reported to have contrasting effects on plant physiology, while their effects on sugar, protein, and amino acid metabolism are poorly understood. In this work, we evaluated the effects of TiO 2 NPs on physiological and agronomical traits of tomato (Solanum lycopersicum L.) seedlings. Tomato seeds were treated with TiO 2 NPs (1000 and 2000 mg L - 1 ), TiO 2 microparticles (µPs, 2000 mg L - 1 ) as the size control, and ultrapure water as negative control., Results: The dry matter of stems (DMs), leaves (DMl) and total dry matter (DMt) decreased as particle concentration increased. This trend was also observed in the maximum quantum yield of light-adapted photosystem II (PSII) (F v ´/F m ´), the effective quantum yield of PSII (ΦPSII), and net photosynthesis (P n ). The concentrations of sugars, total soluble proteins, and total free amino acids were unaffected, but there were differences in the daily dynamics of these compounds among the treatments., Conclusion: Our results suggest that treating tomato seeds with TiO 2 might affect PSII performance, net photosynthesis and decrease biomass production, associated with a concentration- and size-related effect of TiO 2 particles., (© 2024. The Author(s).)

Boron (B) is an essential microelement for plants, and its deficiency can lead to impaired development and function. Around 50% of arable land in the world is acidic, and low pH in the soil solution decreases availability of several essential mineral elements, including B, magnesium (Mg), calcium (Ca), and potassium (K). Plants take up soil B in the form of boric acid (H 3 BO 3 ) in acidic soil or tetrahydroxy borate [B(OH) 4 ] - at neutral or alkaline pH. Boron can participate directly or indirectly in plant metabolism, including in the synthesis of the cell wall and plasma membrane, in carbohydrate and protein metabolism, and in the formation of ribonucleic acid (RNA). In addition, B interacts with other nutrients such as Ca, nitrogen (N), phosphorus (P), K, and zinc (Zn). In this review, we discuss the mechanisms of B uptake, absorption, and accumulation and its interactions with other elements, and how it contributes to the adaptation of plants to different environmental conditions. We also discuss potential B-mediated networks at the physiological and molecular levels involved in plant growth and development., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Vera-Maldonado, Aquea, Reyes-Díaz, Cárcamo-Fincheira, Soto-Cerda, Nunes-Nesi and Inostroza-Blancheteau.)

Salicylic acid (SA) application is a promising agronomic tool. However, studies under field conditions are required, to confirm the potential benefits of SA. Thus, SA application was evaluated under field conditions for its effect on abscisic acid levels, antioxidant related-parameters, fruit quality, and yield in Aristotelia chilensis subjected to different levels of irrigation. During two growing seasons, three-year-old plants under field conditions were subjected to full irrigation (FI: 100% of reference evapotranspiration (ETo), and deficit irrigation (DI: 60% ETo). During each growth season, a single application of 0.5 mM SA was performed at fruit color change by spraying fruits and leaves of both irrigation treatments. The results showed that DI plants experienced moderate water stress (-1.3 MPa), which increased ABA levels and oxidative stress in the leaves. The SA application facilitated the recovery of all physiological parameters under the DI condition, increasing fruit fresh weight by 44%, with a 27% increase in fruit dry weight, a 1 mm increase in equatorial diameter, a 27% improvement in yield per plant and a 27% increase in total yield, with lesser oxidative stress and tissue ABA levels in leaves. Also, SA application significantly increased (by about 10%) the values of fruit trait variables such as soluble solids, total phenols, and antioxidant activity, with the exceptions of titratable acidity and total anthocyanins, which did not vary. The results demonstrated that SA application might be used as an agronomic strategy to improve fruit yield and quality, representing a saving of 40% regarding water use.

The potato ( Solanum tuberosum L) is one of the four most important crops worldwide in production and consumption. It originated from South America along the Andes, where six hotspots of diversity known as subcenters of origin are described from Venezuela to Chiloe Island in Chile, and where the greatest diversity of potatoes in the world is found. Today, the use of ancestral genetic resources has gained significant relevance, recovering and producing foods with a greater nutrient content and beneficial to human health. Therefore, native potatoes possess a set of characteristics with great potential for use in potato breeding guided primarily to produce better feed, especially potatoes of the Chilotanum Group that are easily crossed with conventional varieties. The primary objective of this study was to evaluate 290 accessions of S. tuberosum subsp tuberosum belonging to the Chilotanum Group using a set of molecular markers and correlate them to its phenotypic traits for future use in breeding programs. For this purpose, 290 accessions were analysed through 22 specific microsatellites described previously, correlating them with flesh and skin colour, total phenolic content, and anthocyanin content. A division into groups considering all the 290 accessions resulted in two clusters using STRUCTURE analysis and seven different genetic clusters using UPGMA. The latter exhibited common phenotypic characteristics as well as anthocyanin content, strongly supporting a correlation between phenotypic traits and the genetic fingerprint. These results will enable breeders to focus on the development of potatoes with high polyphenol and anthocyanin content., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Behn, Lizana, Zapata, Gonzalez, Reyes-Díaz and Fuentes.)

In rainy areas, sweet cherries are cultivated under plastic covers, preventing the cracking of the fruit but decreasing the firmness and acidity of the cherries. We evaluated the impact of plastic cover and pre-harvest K foliar application on quality parameters, antioxidant properties, and phenolic and organic acid compositions in fruits of sweet cherry cv. Regina of Southern Chile. Our results showed that K+ increased firmness, total soluble content, size, fruit weight, and titratable acidity at harvest, independent of the cover factor. The positive impacts of foliar K fertilization on anthocyanins, flavonoids, and phenolic acids could explain the higher antioxidant capacity of fruits. Our study revealed that the additional K doses applied increased malic acid, the main organic acid in cherry fruits, but only in fruits from uncovered trees. In covered trees, the effect was reversed. Citric acid was higher in fruit from covered trees. Our results indicated that tartaric acid also increased with the application of higher K doses; however, this acid was detectable only in uncovered tree fruit. Interestingly, all organic acids were lower in fruits produced in the lower canopy than those detected in fruits harvested from the upper canopy. This showed the positive impact of canopy light exposure on maintaining suitable acidity levels in sweet cherry fruits.

Despite men-who-have-sex-with-men (MSM) from Latin America (LA) are still a vulnerable population for known health-related conditions and social problems, availability of comparable data across LA countries for assessment and monitoring purposes is limited. The objective of this article is to present the study design and the questionnaire of LAMIS-2018 (Latin America MSM Internet Survey), its recruitment strategy, rates and sources by country, and the lessons learned from its implementation. LAMIS-2018 was a cross-sectional, internet-based survey targeting MSM living in 18 LA countries (Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Ecuador, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Suriname, Uruguay, and Venezuela) that gathered data about sexual behaviors, HIV/STI and viral hepatitis knowledge, prophylactic use of antiretrovirals, psychosocial health, and access to sexual health services. The survey went online for four months and was available in three languages (Spanish, Portuguese, and Dutch). Promotion was carried out using dating apps, websites, social networks, and by community-based and academic organizations of each participating country directly in gay venues and in their own premises. Overall, 64,655 MSM participated in LAMIS-2018. Dating apps and websites were the most important recruitment source in most countries, except for Honduras, Nicaragua, and Suriname, where community-based organizations recruited most of the participants. Beyond the LAMIS-2018 implementation description, we highlight the feasibility of such a study in this context, based on the collaboration between community-based and academic organizations to obtain a large sample of MSM in the region. LAMIS-2018 data will contribute to identify determinants of risk behaviors and prevention needs of vulnerable MSM populations in each country of the region., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2022 Reyes-Díaz et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

In the Antarctic Peninsula, increases in mean annual temperature are associated with the coverage and population density of the two Antarctic vascular plant species-Deschampsia antarctica and Colobanthus quitensis-potentially modifying critical soil processes. In this study, we characterized the diversity and community composition of active microorganisms inhabiting the vascular plant rhizosphere in two sites with contrasting vegetation cover in King George Island, Western Antarctic Peninsula. We assessed the interplay between soil physicochemical properties and microbial diversity and composition, evaluating the effect of an in situ experimental warming on the microbial communities of the rhizosphere from D. antarctica and C. quitensis. Bacteria and Eukarya showed different responses to warming in both sites, and the effect was more noticeable in microbial eukaryotes from the low vegetation site. Furthermore, important changes were found in the relative abundance of Tepidisphaerales (Bacteria) and Ciliophora (Eukarya) between warming and control treatments. Our results showed that rhizosphere eukaryal communities are more sensitive to in situ warming than bacterial communities. Overall, our results indicate that vegetation drives the response of the active fraction of the microbial communities from the rhizosphere of Antarctic vascular plants to soil warming., (© The Author(s) 2022. Published by Oxford University Press on behalf of FEMS.)

Salinization of soils and freshwater resources by natural processes and/or human activities has become an increasing issue that affects environmental services and socioeconomic relations. In addition, salinization jeopardizes agroecosystems, inducing salt stress in most cultivated plants (nutrient deficiency, pH and oxidative stress, biomass reduction), and directly affects the quality and quantity of food production. Depending on the type of salt/stress (alkaline or pH-neutral), specific approaches and solutions should be applied to ameliorate the situation on-site. Various agro-hydrotechnical (soil and water conservation, reduced tillage, mulching, rainwater harvesting, irrigation and drainage, control of seawater intrusion), biological (agroforestry, multi-cropping, cultivation of salt-resistant species, bacterial inoculation, promotion of mycorrhiza, grafting with salt-resistant rootstocks), chemical (application of organic and mineral amendments, phytohormones), bio-ecological (breeding, desalination, application of nano-based products, seed biopriming), and/or institutional solutions (salinity monitoring, integrated national and regional strategies) are very effective against salinity/salt stress and numerous other constraints. Advances in computer science (artificial intelligence, machine learning) provide rapid predictions of salinization processes from the field to the global scale, under numerous scenarios, including climate change. Thus, these results represent a comprehensive outcome and tool for a multidisciplinary approach to protect and control salinization, minimizing damages caused by salt stress.

In rainy locations, sweet cherry is cultivated under plastic covers, which are useful to prevent fruit cracking but decrease cherry quality such as firmness and acidity. Here we evaluate the impact of pre-harvest K foliar applications on harvest and post-harvest fruit quality and condition of sweet cherry cultivated under plastic covers in southern Chile orchards. The study was performed on two commercial orchards (cv. Regina), located in different regions, during two consecutive seasons. In all cases, a conventional K regime (four sprays) was compared to an intensive K regimen (seven sprays). Results showed that cherries from the most southern region revealed lower acidity but higher soluble solids content weight and size. The intensive K regime improved the firmness and acidity of fruits of covered trees at harvest and post-harvest. Moreover, we found that condition defects were higher in fruits from un-covered trees and that trees grown under intensive K regime showed lower levels of cracking at harvest and pitting at post-harvest compared to trees treated with the conventional K regime. Otherwise, pedicel browning was inconsistently affected by K sprays. Our results revealed that an intensive K regime could improve the quality and condition of fruits at harvest and post-harvest in covered orchards of sweet cherry cv. Regina; however, the impacts can significantly vary depending on season and locality.

Volcanic ash-derived soils are characterized by low pH (pH ≤ 5.5) with increased concentrations of aluminum (Al 3+ ) and manganese (Mn 2+ ), which decreases plant growth, fruit quality, and yield. Methyl jasmonate (MeJA) improves abiotic stress tolerance. Our work aimed to evaluate the application of MeJA's impact on the growth, antioxidant defense, and fruit quality of highbush blueberry grown under Al and Mn toxicity. A field assay was conducted with four-year-old bushes of highbush blueberry cultivar Legacy under eight treatments (Control, Al (87% of Al saturation), Mn (240 mg kg -1 ), and Al-Mn with and without MeJA application). Physiological, biochemical, and fruit quality parameters were measured. Growth rate significantly decreased with Al (20%), Mn (45%), and Al-Mn (40%). MeJA application recovered the growth rate. Photosynthetic parameters were not affected. Antioxidant activity increased under all treatments compared with controls, being higher with MeJA application. Total phenols (TP) were decreased in plants under Al (43%) and Mn (20%) compared with controls. MeJA application increased TP in all treatments. Fruits of bushes under Al and Mn toxicity with MeJA applications exhibited an increase in fruit firmness and weight, maintaining suitable contents of soluble solids. Our results provide insights about the beneficial effect of MeJA application on growth, antioxidant properties, and fruit quality of highbush blueberry plants grown in acid soils under Al and Mn toxicity.

Phosphorus (P) deficiency affects agricultural systems by limiting crop quality and yield. Studies have suggested that silicon (Si) improves P uptake in plants grown under P deficiency. However, the effects of Si on photosynthesis and carbohydrate metabolism under P stress remain unclear. We performed a hydroponic study using two wheat cultivars with contrasting sensitivity to P deficiency (Púrpura, sensitive; Fritz, semi-tolerant) that were exposed to P (0, 0.01, or 0.1 mM) and Si (0 or 2 mM), and we evaluated the photosynthetic performance and metabolic alterations. In plants from the sensitive cultivar undergoing P deficiency, Si application increased sucrose levels, starch breakdown and length of shoots, and also improved plant dry weight. In Fritz (the semi-tolerant cultivar), Si exposure reduced P concentration, and increased shoot length and P use efficiency (PUE) under P shortage. Interestingly, Si application altered cell wall composition, which was associated with higher mesophyll conductance and net CO 2 assimilation in Fritz plants grown under P stress. Together, our results indicate that under P deficiency, Si nutrition positively affects photosynthesis and carbohydrate levels in a genotype-dependent manner. Furthermore, these results suggest that Si plays an important role in maintaining high photosynthetic rates in wheat plants undergoing P deficiency., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

Boron (B) and zinc (Zn) are essential micronutrients of plant nutrition programs in orchards for securing the crop quality and yield. Although orchard supplementation with B and Zn is a common practice to overcome deficiencies or maintain their optimal levels, the efficiency of combined B and Zn spraying in relation to European hazelnut ( Corylus avellana L.) phenological stage has not been investigated so far. Leaf and kernel mineral and functional traits were studied in cultivar Tonda di Giffoni after B and Zn spraying in four phenological stages. During the 2016/2017 season, 9-year-old trees were sprayed with B (0, 800, and 1,600 mg L -1 ) and Zn (0, 400, and 800 mg L -1 ) under three treatments: B 0 +Zn 0 , B 800 +Zn 400 , and B 1600 +Zn 800 implemented in three spring application programs scheduled from October to December (P1: four times, P2: early two times, and P3: late two times). B and Zn treatments in P1 and P3 led to higher Zn concentration both in leaves and in kernels compared with non-sprayed trees. Stabilized nut production increased 2.5-fold under B 800 +Zn 400 in all three programs. Kernel/nut ratio improved in both B+Zn treatments in P1 and P3, while the percentage of blank nuts was reduced compared with B 0 +Zn 0 . Increased radical scavenging activity in B+Zn-treated kernels and leaves was not attributed to the accumulation of phenolics in P3 compared with B 0 +Zn 0 , whereas B and Zn spraying reduced the level of lipid peroxidation in both studied organs. According to the results, combined B and Zn should be sprayed at the end of spring (P3) on hazelnut plantations in temperate areas such as Southern Chile, whereas early applications (P2) showed an irregularity in nut production and functional traits in nuts. Moderate and partialized rates of B and Zn and the time of implementation contribute to improving the quantitative and qualitative features crucial for future sustainable hazelnut production., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Meriño-Gergichevich, Luengo-Escobar, Alarcón, Reyes-Díaz, Ondrasek, Morina and Ogass.)

Embothrium coccineum produces cluster roots (CR) to acquire sparingly soluble phosphorus (P) from the soil through the exudation of organic compounds. However, the physiological mechanisms involved in carbon drainage through its roots, as well as the gene expression involved in the biosynthesis of carboxylates and P uptake, have not been explored. In this work, we evaluated the relationship between carboxylate exudation rate and phosphoenolpyruvate carboxylase (PEPC) activity in roots of E. coccineum seedlings grown in a nutrient-poor volcanic substrate. Second, we evaluated CR formation and the expression of genes involved in the production of carboxylates (PEPC) and P uptake (PHT1) in E. coccineum seedlings grown under three different P supplies in hydroponic conditions. Our results showed that the carboxylate exudation rate was higher in CR than in non-CR, which was consistent with the higher PEPC activity in CR. We found higher CR formation in seedlings grown at 5 μM of P supply, concomitant with a higher expression of EcPEPC and EcPHT1 in CR than in non-CR. Overall, mature CR of E. coccineum seedlings growing on volcanic substrates poor in nutrients modify their metabolism compared to non-CR, enhancing carboxylate biosynthesis and subsequent carboxylate exudation. Additionally, transcriptional responses of EcPEPC and EcPHT1 were induced simultaneously when E. coccineum seedlings were grown in P-limited conditions that favored CR formation. Our results showed, for the first time, changes at the molecular level in CR of a species of the Proteaceae family, demonstrating that these root structures are highly specialized in P mobilization and uptake., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

Southern South American Proteaceae thrive on young volcanic substrates, which are extremely low in plant-available phosphorus (P). Most Proteaceae exhibit a nutrient-acquisition strategy based on the release of carboxylates from specialized roots, named cluster roots (CR). Some Proteaceae colonize young volcanic substrates which has been related to CR functioning. However, physiological functioning of other Proteaceae on recent volcanic substrates is unknown. We conducted an experiment with seedlings of five Proteaceae ( Gevuina avellana , Embothrium coccineum , Lomatia hirsuta , L. ferruginea , and L. dentata ) grown in three volcanic materials. Two of them are substrates with very low nutrient concentrations, collected from the most recent deposits of the volcanoes Choshuenco and Calbuco (Chile). The other volcanic material corresponds to a developed soil that exhibits a high nutrient availability. We assessed morphological responses (i.e., height, biomass, and CR formation), seed and leaf macronutrient and micronutrient concentrations and carboxylates exuded by roots. The results show that G. avellana was less affected by nutrient availability of the volcanic substrate, probably because it had a greater nutrient content in its seeds and produced large CR exuding carboxylates that supported their initial growth. Embothrium coccineum exhibited greater total plant height and leaf P concentration than Lomatia species. In general, in all species leaf macronutrient concentrations were reduced on nutrient-poor volcanic substrates, while leaf micronutrient concentrations were highly variable depending on species and volcanic material. We conclude that Proteaceae from temperate rainforests differ in their capacity to grow and acquire nutrients from young and nutrient-poor volcanic substrates. The greater seed nutrient content, low nutrient requirements (only for G. avellana ) and ability to mobilize nutrients help explain why G. avellana and E. coccineum are better colonizers of recent volcanic substrates than Lomatia species., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Delgado, Zúñiga-Feest, Reyes-Díaz, Barra, Ruiz, Bertin-Benavides, Valle, Pereira and Lambers.)

In acid soils, manganese (Mn) concentration increases, becoming toxic to plants. Mn toxicity differentially affects physiological processes in highbush blueberry (Vaccinium corymbosum L.) cultivars. However, the mechanisms involved in Mn toxicity of the new and traditionally established cultivars are unknown. To understand Mn toxicity mechanisms, four traditionally established (Legacy, Brigitta, Duke, and Star) cultivars and two recently introduced to Chile (Camellia and Cargo) were grown under hydroponic conditions subjected to control Mn (2 μM) and Mn toxicity (1000 μM). Physiological, biochemical, and molecular parameters were evaluated at 0, 7, 14, and 21 days. We found that the relative growth rate was reduced in almost all blueberry cultivars under Mn toxicity, except Camellia, with Star being the most affected. The photosynthetic parameters were reduced only in Star by Mn treatment. Leaf Mn concentrations increased in all cultivars, exhibiting the lowest levels in Camellia and Cargo. Brigitta and Duke exhibited higher β-carotene levels, while Cargo exhibited a reduction under toxic Mn. In Legacy, lutein levels increased under Mn toxicity. Traditionally established cultivars exhibited higher antioxidant activity than the new cultivars under Mn toxicity. The Legacy and Duke cultivars increased VcMTP4 expression with Mn exposure time. A multivariate analysis separated Legacy and Duke from Camellia; Star and Cargo; and Brigitta. Our study demonstrated that Mn toxicity differentially affects physiological, biochemical, and molecular features in the new and traditionally established cultivars, with Legacy, Duke, Camellia, and Cargo as the Mn-resistant cultivars differing in their Mn-resistance mechanisms and Star as the Mn-sensitive cultivar., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

Carotenoids are essential components of the photosynthetic antenna and reaction center complexes, being also responsible for antioxidant defense, coloration, and many other functions in multiple plant tissues. In tomato, salinity negatively affects the development of vegetative organs and productivity, but according to previous studies it might also increase fruit color and taste, improving its quality, which is a current agricultural challenge. The fruit quality parameters that are increased by salinity are cultivar-specific and include carotenoid, sugar, and organic acid contents. However, the relationship between vegetative and reproductive organs and response to salinity is still poorly understood. Considering this, Solanum lycopersicum cv. Micro-Tom plants were grown in the absence of salt supplementation as well as with increasing concentrations of NaCl for 14 weeks, evaluating plant performance from vegetative to reproductive stages. In response to salinity, plants showed a significant reduction in net photosynthesis, stomatal conductance, PSII quantum yield, and electron transport rate, in addition to an increase in non-photochemical quenching. In line with these responses the number of tomato clusters decreased, and smaller fruits with higher soluble solids content were obtained. Mature-green fruits also displayed a salt-dependent higher induction in the expression of PSY1 , PDS , ZDS , and LYCB , key genes of the carotenoid biosynthesis pathway, in correlation with increased lycopene, lutein, β-carotene, and violaxanthin levels. These results suggest a key relationship between photosynthetic plant response and yield, involving impaired photosynthetic capacity, increased carotenoid-related gene expression, and carotenoid biosynthesis., Competing Interests: The authors declare there are no competing interests., (©2020 Leiva-Ampuero et al.)

Gastric cancer is the third main cause of cancerous tumors in humans in Chile. It is well-accepted that a diet rich in antioxidant plants could help in fighting cancer. Blueberry is a fruit crop with a high content of antioxidants. Methyl jasmonate (MeJA) is a phytohormone involved in plant defenses under stress conditions. The exogenous application of MeJA can improve the antioxidant properties in plants. We studied in vitro and in vivo anticancer action on human gastric cancer (cell line AGS) and the antioxidant properties of extracts from blueberry plants untreated and treated with MeJA. The results demonstrated that leaf extracts displayed a higher inhibition of cancer cell viability as well as greater antioxidant properties compared to fruit extracts. Besides, MeJA applications to plants improved the antioxidant properties of leaf extracts (mainly anthocyanins), increasing their inhibition levels on cell viability and migration. It is noteworthy that leaf extract from MeJA-treated plants significantly decreased cancer cell migration and expression of gastric cancer-related proteins, mainly related to the mitogen-activating protein kinase (MAPK) pathway. Interestingly, in all cases the anticancer and antioxidant properties of leaf extracts were strongly related. Despite highlighted outcomes, in vivo results did not indicate significant differences in Helicobacter pylori colonization nor inflammation levels in Mongolian gerbils unfed and fed with blueberry leaf extract. Our findings demonstrated that MeJA increased antioxidant compounds, mainly anthocyanins, and decreased the viability and migration capacity of AGS cells. In addition, leaf extracts from MeJA-treated plants were also able to decrease the expression of gastric cancer-related proteins. Our outcomes also revealed that the anthocyanin-rich fraction of blueberry leaf extracts showed higher in vitro antiproliferative and anti-invasive effects than the crude leaf extracts. However, it is still uncertain whether the leaf extracts rich in anthocyanins of blueberry plants are capable of exerting a chemopreventive or chemoprotective effect against gastric cancer on an in vivo model., Competing Interests: The authors declare no conflict of interest.

Aluminum (Al) toxicity is one of the major factors that limit the growth and production of crops in acid soils. Highbush blueberry (Vaccinium corymbosum L.) cultivars differing in resistance to Al toxicity regarding root growth and photosynthetic performance were used. In this study, we compared the physiological and metabolic strategies to cope with Al toxicity among the highbush blueberry cultivars [two new ones (Camellia and Cargo) and three established ones (Brigitta (Al-resistant), Star and Duke)]. Aluminum concentration in roots and leaves increased in all cultivars after 24 and 48 h of exposure to Al, but less so in roots of cultivar Camellia and leaves of cultivar Cargo. These two cultivars displayed minor effects of Al exposure in terms of photosynthetic activity in comparison with the established cultivars. Furthermore, Cargo did not vary fluorescence parameters, whereas Camellia exhibited a decrease in effective quantum yield (ΦPSII) and electron transport rate (ETR) and a change in non-photochemical quenching (NPQ) and maximum quantum yield (Fv/Fm) under Al after 48 h. The Al treatment increased total phenols in leaves of Brigitta, Cargo, and Camellia, whereas antioxidant activity increased in Star and Cargo after 48 h. Aluminum exposure decreased malate concentration in roots of all cultivars, but no change was noted in fumarate concentration. The antioxidant activity correlated with photosynthetic performance and the total phenol concentration in the leaves of new cultivars exposed to Al, suggesting enhanced resistance in the short-term experiment. The principal component analysis separated the new from the established cultivars. In conclusion, the new cultivars appear to be more Al-resistant than the established ones, with Star being most Al-sensitive. Regarding the Al-resistance mechanisms of the new cultivars, it is suggested that Camellia could have a root Al-exclusion mechanism under Al toxicity. This mechanism could be explained by low Al concentration in roots, suggesting that this cultivar could exude organic acid, allowing to chelate Al in the rhizosphere. Nonetheless, further researches are needed to confirm this assumption.

Introduction: The native potatoes (Solanum tuberosum ssp. tuberosum L.) cultivated on Chiloé Island in southern Chile have great variability in terms of tuber shape, size, color and flavor. These traits have been preserved throughout generations due to the geographical position of Chiloé, as well as the different uses given by local farmers., Objectives: The present study aimed to investigate the diversity of metabolites in skin and pulp tissues of eleven native accessions of potatoes from Chile, and evaluate the metabolite associations between tuber tissues., Methods: For a deeper characterization of these accessions, we performed a comprehensive metabolic study in skin and pulp tissues of tubers, 3 months after harvesting. Specific targeted quantification of metabolites using 96 well microplates, and high-performance liquid chromatography combined with non-targeted metabolite profiling by gas chromatography time-of-flight mass spectrometry were used in this study., Results: We observed differential levels of antioxidant activity and phenolic compounds between skin and pulp compared to a common commercial cultivar (Desireé). In addition, we uncovered considerable metabolite variability between different tuber tissues and between native potatoes. Network correlation analysis revealed different metabolite associations among tuber tissues that indicate distinct associations between primary metabolite and anthocyanin levels, and antioxidant activity in skin and pulp tissues. Moreover, multivariate analysis lead to the grouping of native and commercial cultivars based on metabolites from both skin and pulp tissues., Conclusions: As well as providing important information to potato producers and breeding programs on the levels of health relevant phytochemicals and other abundant metabolites such as starch, proteins and amino acids, this study highlights the associations of different metabolites in tuber skins and pulp, indicating the need for distinct strategies for metabolic engineering in these tissues. Furthermore, this study shows that native Chilean potato accessions have great potential as a natural source of phytochemicals.

Water-use efficiency (WUE) is a quantitative measurement of biomass produced per volume of water transpired by a plant. WUE is an important physiological trait for drought response to mitigate the water deficiency. In this work, a cisgenic construction from Citrus sinensis was developed and its function in the improvement of WUE was evaluated in Arabidopsis. Sequences of the CsMYB61 coding region, a transcription factor implicated in the closure of stomata, together with a putative stomata-specific promoter from CsMYB15, were identified and cloned. The protein encoded in the CsMYB61 locus harbors domains and motifs characteristic of MYB61 proteins. In addition, a 1.2 kb promoter region of the gene CsMYB15 (pCsMYB15) containing regulatory elements for expression in guard cells and in response to Abscisic Acid (ABA) and light was isolated. In Arabidopsis, pCsMYB15 directs the expression of the reporter gene GUS in stomata in the presence of light. In addition, transgenic lines expressing the CsMYB61 coding region under transcriptional control of pCsMYB15 have a normal phenotype under in vitro and greenhouse conditions. These transgenic lines exhibited a smaller opening of the stomata pore, lower stomatal conductance and respiration rate, enhanced sensitivity to exogenous ABA, and high drought stress tolerance. Our results indicate that stomata-specific expression of CsMYB61 enhances water use efficiency under drought conditions in Arabidospis., (Copyright © 2018. Published by Elsevier Masson SAS.)

Plants from the Proteaceae family can thrive in old, impoverished soil with extremely low phosphorus (P) content, such as those typically found in South Western Australia (SWA) and South Africa. The South Western (SW) Australian Proteaceae species have developed strategies to deal with P scarcity, such as the high capacity to re-mobilize P from senescent to young leaves and the efficient use of P for carbon fixation. In Southern South America, six Proteaceae species grow in younger soils than those of SWA, with a wide variety of climatic and edaphic conditions. However, strategies in the nutrient use efficiency of Southern South (SS) American Proteaceae species growing in their natural ecosystems remain widely unknown. The aim of this study was to evaluate nutrient resorption efficiency and the photosynthetic nutrients use efficiency by SS American Proteaceae species, naturally growing in different sites along a very extensive latitudinal gradient. Mature and senescent leaves of the six SS American Proteaceae species ( Embothrium coccineum, Gevuina avellana, Orites myrtoidea Lomatia hirsuta, L. ferruginea , and L. dentata ), as well as, soil samples were collected in nine sites from southern Chile and were subjected to chemical analyses. Nutrient resorption (P and nitrogen) efficiency in leaves was estimated in all species inhabiting the nine sites evaluated, whereas, the photosynthetic P use efficiency (PPUE) and photosynthetic nitrogen (N) use efficiency (PNUE) per leaf unit were determined in two sites with contrasting nutrient availability. Our study exhibit for the first time a data set related to nutrient use efficiency in the leaves of the six SS American Proteaceae, revealing that for all species and sites, P and N resorption efficiencies were on average 47.7 and 50.6%, respectively. No correlation was found between leaf nutrient (P and N) resorption efficiency and soil attributes. Further, different responses in PPUE and PNUE were found among species and, contrary to our expectations, a higher nutrient use efficiency in the nutrient poorest soil was not found. We conclude that SS American Proteaceae species did not show a general pattern in the nutrient use efficiency among them neither with others Proteaceae species reported in the literature.

Main Conclusion: Aluminum toxicity and sulfate deprivation both regulate microRNA395 expression, repressing its low-affinity sulfate transporter ( SULTR2;1 ) target. Sulfate deprivation also induces the high-affinity sulfate transporter gene ( SULTR12 ), allowing enhanced sulfate uptake. Few studies about the relationships between sulfate, a plant nutrient, and aluminum, a toxic ion, are available; hence, the molecular and physiological processes underpinning this interaction are poorly understood. The Al-sulfate interaction occurs in acidic soils, whereby relatively high concentrations of trivalent toxic aluminum (Al 3+ ) may hamper root growth, limiting uptake of nutrients, including sulfur (S). On the other side, Al 3+ may be detoxified by complexation with sulfate in the acid soil solution as well as in the root-cell vacuoles. In this review, we focus on recent insights into the mechanisms governing plant responses to Al toxicity and its relationship with sulfur nutrition, emphasizing the role of phytohormones, microRNAs, and ion transporters in higher plants. It is known that Al 3+ disturbs gene expression and enzymes involved in biosynthesis of S-containing cysteine in root cells. On the other hand, Al 3+ may induce ethylene biosynthesis, enhance reactive oxygen species production, alter phytohormone transport, trigger root growth inhibition and promote sulfate uptake under S deficiency. MicroRNA395, regulated by both Al toxicity and sulfate deprivation, represses its low-affinity Sulfate Transporter 2;1 (SULTR2;1) target. In addition, sulfate deprivation induces High Affinity Sulfate Transporters (HAST; SULTR1;2), improving sulfate uptake from low-sulfate soil solutions. Identification of new microRNAs and cloning of their target genes are necessary for a better understanding of the role of molecular regulation of plant resistance to Al stress and sulfate deprivation.

UV-B radiation induces several physiological and biochemical effects that can influence regulatory plant processes. Vaccinium corymbosum responds differently to UV-B radiation depending on the UV-B resistance of cultivars, according to their physiological and biochemical features. In this work, the effect of two levels of UV-B radiation during long-term exposure on the phenylpropanoid biosynthesis, and the expression of genes associated with flavonoid biosynthesis as well as the absolute quantification of secondary metabolites were studied in two contrasting UV-B-resistant cultivars (Legacy, resistant and Bluegold, sensitive). Multivariate analyses were performed to understand the role of phenylpropanoids in UV-B defense mechanisms. The amount of phenylpropanoid compounds was generally higher in Legacy than in Bluegold. Different expression levels of flavonoid biosynthetic genes for both cultivars were transiently induced, showing that even in longer period of UV-B exposure; plants are still adjusting their phenylpropanoids at the transcription levels. Multivariate analysis in Legacy indicated no significant correlation between gene expression and the levels of the flavonoids and phenolic acids. By contrast, in the Bluegold cultivar higher number of correlations between secondary metabolite and transcript levels was found. Taken together, the results indicated different adjustments between the cultivars for a successful UV-B acclimation. While the sensitive cultivar depends on metabolite adjustments to respond to UV-B exposure, the resistant cultivar also possesses an intrinsically higher antioxidant and UV-B screening capacity. Thus, we conclude that UV-B resistance involves not only metabolite level adjustments during the acclimation period, but also depends on the intrinsic metabolic status of the plant and metabolic features of the phenylpropanoid compounds., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

We studied physiological traits and Mn transporter genes expression in ryegrass genotypes (One-50, Banquet-II, Halo-AR1 and Nui) under increasing Mn (2.4-750 μM) at short-term (8-24 h) in nutrient solution. An increment in Mn concentration occurred early in roots of all genotypes at increased Mn doses relative to control. Banquet-II and Nui roots showed the greatest Mn concentration at the highest Mn supply. Net photosynthesis (Pn) of Banquet-II and Halo-AR1 were not perturbed by Mn doses, whereas One-50 and Nui, decayed strongly at the highest Mn dose, concomitant with reduced total chlorophyll concentration. A high accumulation of Mn in roots together the maintained Pn under increased Mn doses in Banquet-II and Halo-AR1 suggest a higher Mn resistance of these genotypes. Stomatal conductance (gs) of all genotypes did not vary in presence of Mn. In roots of Banquet-II an augment of lipid peroxidation (LP) by Mn excess was observed earlier decreasing afterwards, being attenuated by the augment of the radical scavenging activity (RSA) and total phenols (TP) of this genotype. Mn concentration and LP in tissues of One-50 and Nui genotypes rose together, may be due to its Mn sensitivity. Differential expression of Mn transporter genes were found in the studied genotypes grown under increasing supplies of Mn, being MTP8.1 expressed in shoots and NRAMP2-like in roots. We concluded that Banquet-II showed greater Mn concentration associated to high roots NRAMP2-like gene expression, without changes in photosynthetic performance. Despite, this genotype showed an increase of LP at the first hours of Mn-excess, it was decreased by the RSA and TP. Halo-AR1 appears to be Mn-resistant in the short-term due to its photosynthetic performance was unchanged by Mn-toxicity, whilst One-50 and Nui were Mn-sensitive., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Despite the Montreal protocol and the eventual recovery of the ozone layer over Antarctica, there are still concerns about increased levels of ultraviolet-B (UV-B) radiation in the Southern Hemisphere. UV-B induces physiological, biochemical and morphological stress responses in plants, which are species-specific and different even for closely related cultivars. In woody plant species, understanding of long-term mechanisms to cope with UV-B-induced stress is limited. Therefore, a greenhouse UV-B daily course simulation was performed for 21 days with two blueberry cultivars (Legacy and Bluegold) under UV-B BE irradiance doses of 0, 0.07 and 0.19 W m -2 . Morphological changes, photosynthetic performance, antioxidants, lipid peroxidation and metabolic features were evaluated. We found that both cultivars behaved differently under UV-B exposure, with Legacy being a UV-B-resistant cultivar. Interestingly, Legacy used a combined strategy: initially, in the first week of exposure its photoprotective compounds increased, coping with the intake of UV-B radiation (avoidance strategy), and then, increasing its antioxidant capacity. These strategies proved to be UV-B radiation dose dependent. The avoidance strategy is triggered early under high UV-B radiation in Legacy. Moreover, the rapid metabolic reprogramming capacity of this cultivar, in contrast to Bluegold, seems to be the most relevant contribution to its UV-B stress-coping strategy., (© 2016 Scandinavian Plant Physiology Society.)

We studied resistance to manganese (Mn) toxicity under acidic conditions and its relationship with nutrients such as calcium (Ca) and magnesium (Mg) in new perennial ryegrass (Lolium perenne L.) genotypes (One-50, Banquet-II and Halo-AR1) introduced in southern Chile, using the Nui genotype as the reference. Plants were grown in nutrient solution at increased Mn concentrations (0-750 μM) at pH 4.8, and physiological and biochemical features were determined. Under higher Mn concentration, the One-50 genotype had a significantly lower relative growth rate (RGR) of shoots and roots, whereas in the other cultivars this parameter did not change under variable Mn treatments. Increasing the Mn concentration led to an increased Mn concentration in roots and shoots, with Banquet-II and Halo-AR1 having higher Mn in roots than shoots. Shoot Mg and Ca concentrations in all genotypes (except Banquet-II) decreased concomitantly with increasing Mn applications. In contrast to the other genotypes, Banquet-II and Halo-AR1 maintained their net CO 2 assimilation rate regardless of Mn treatment, whereas the chlorophyll concentration decreased in all genotypes with the exception of Banquet-II. In addition, lipid peroxidation in Banquet-II roots increased at 150 μM Mn, but decreased at higher Mn concentrations. This decrease was associated with an increase in antioxidant capacity as well as total phenol concentration. Banquet-II and Halo-AR1 appear to be the most Mn-resistant genotypes based on RGR and CO 2 assimilation rate. In addition, Mn excess provoked a strong decrease in Ca and Mg concentrations in shoots of the Mn-sensitive genotype, whereas only slight variations in the Mn-resistant genotype were noted. When other evaluated parameters were taken into account, we concluded that among the perennial ryegrass genotypes introduced recently into southern Chile Banquet-II appears to be the most Mn-resistant, followed by Halo-AR1, with One-50 being the most sensitive., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Peumus boldus Mol. ("Boldo") and Cryptocarya alba Mol. Looser ("Peumo") are medicinal shrubs with wide geographical distribution in South America. Their leaves and fruits are commonly used in traditional medicine because they exhibit natural medicinal properties for treatment of liver disorders and rheumatism. However, there are no apparent data regarding potential protective effects on cellular genetic components. In order to examine potential mutagenic and/or antimutagenic effects of these medicinal plants, the Drosophila melanogaster (D. melanogaster) wing-spot test was employed. This assay detects a wide range of mutational events, including point mutations, deletions, certain types of chromosomal aberrations (nondisjunction), and mitotic recombination. Qualitative and quantitative analyses of phenolic and anthocyanin compounds were carried out using biochemical and high-performance liquid chromatography methodologies. In addition, the antioxidant capacity of P. boldus and C. alba leaf extracts was also analyzed. P. boldus and C. alba extracts did not induce significant mutagenic effects in the D. melanogaster model. However, simultaneous treatment of extracts concurrently with the mutagen ethyl methane sulphonate showed a decrease of mutant spots in somatic cells of D. melanogaster, indicating desmutagenic effects in this in vivo model. Flavonoids and anthocyanins were detected predominantly in the extracts, and these compounds exerted significant antioxidant capacity. The observed antimutagenic effects may be related to the presence of phytochemicals with high antioxidant capacity, such as flavonoids and antohocyanins, in the extracts.

The impact of increased artificial UV-B radiation on photosynthetic performance, antioxidant and SOD activities and molecular antioxidant metabolism responses in leaves of two highbush blueberry (Vaccinium corymbosum L. cv. Brigitta and Bluegold) genotypes was studied. Plants were grown in a solid substrate and exposed to 0, 0.07, 0.12 and 0.19 W m(-2) of biologically-effective UV-B irradiance for 0-72 h. Our findings show that net photosynthesis (Pn) decreased significantly in Bluegold, accompanied by a reduction in the effective quantum yield (ФPSII) and electron transport rate (ETR), especially at the highest UV-B irradiation. On the other hand, Brigitta showed a better photosynthetic performance, as well as a clear increment in the antioxidant activity response that could be associated with increased superoxide dismutase activity (SOD) in the early hours of induced UV-B stress in all treatments. At the molecular level, the expression of the three antioxidant genes evaluated in both genotypes had a similar tendency. However, ascorbate peroxidase (APX) expression was significantly increased (6-fold) in Bluegold compared to Brigitta. Thus, the reduction of Pn concomitant with a lower photochemical performance and a reduced response of antioxidant metabolism suggest that the Bluegold genotype is more sensitive to UV-B radiation, while Brigitta appears to tolerate better moderate UV-B irradiance in a short-term experiment., (Copyright © 2016 Elsevier Masson SAS. All rights reserved.)

Background: Obstructive Jaundice (OJ) is associated with a significant risk of developing acute renal failure (ARF). The involvement of oxidative stress in the development of cholestasis has been demonstrated in different experimental models. However, its role in the morbidity of human cholestasis is far to be elucidated. The aim of the study was the evaluation of oxidative stress markers in blood from patients with OJ and its relation to complications and benign/malignant evolution of cholestasis., Methods: A prospective cross-sectional study of 105 patients with OJ and 34 control subjects were included. Several markers of liver function and oxidative stress, such as lipoperoxides (LPO), as well as reduced glutathione (GSH), catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were assessed., Results: The patients with OJ showed a marked increase in plasma levels of LPO, SOD and GSH, while GSH-Px levels were decreased. The increase in lipid peroxidation products and the depletion of SOD activity in blood were also related to renal dysfunction. The highest level of LPO was associated with malignant etiology of the disease. The logistic regression analysis showed that the age of the patient and the levels of LPO in blood were predictors of renal dysfunction in OJ patients., Conclusions: This study demonstrates a correlation between oxidative stress and renal dysfunction patients with OJ., (Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.)