Explore the vast range of titles available.

Abstract Bell pepper is a vegetable with beneficial properties for human nutrition. However, salinity is an abiotic factor affecting bell pepper yield in arid and semi-arid areas of Peru. The objective was to determine the combined effect of humic acid (HA) with Trichoderma harzianum (TH) as sustainable alternatives to increase the yield of bell peppers subjected to salt stress. The experiment was carried in field out during the 2023 and 2024 seasons design with a 2 x 3 x 2 factorial scheme, referring to the electrical conductivity (EC) of the irrigation water (0 and 4 dSm-1), HA (0, 15 and 30 L ha-1) and TH (0 and 1 kg ha-1). Agronomic and yield-related parameters were analyzed. The results showed that the saline soil accompanied by irrigations of 0 and 4 dS m-1 of EC, showed a significant decrease in agronomic parameters and an increase in concentration of sodium and chlorine in bell pepper leaves. However, the application of 30 L ha-1 of HA with TH increase in plant height (86.53 y 86,42%), higher root dry weight (95.44 y 95.32%) and plant dry weight (90.46 y 90.41%), also, greatly improved fruit length 64.6 y 63.74%) and width (58.47 y 57.31%), significantly increased fruit content per plant (91.49 y 91.30%), fruit weight per plant (93.29 and 93.15%) and total yield (89.54 and 89.23%) in relation to plants subjected to salt stress. It also significantly increases the concentration of potassium and calcium in the leaves (37.88 and 48.71%), K+/ Na+ ratio (72.07 and 74.93%) and proline content (58.60 and 59.31%) superior to the control, as a defense mechanism against salt stress. Therefore, as the dose of humic acids combined with Trichoderma harzianum is increased, the plant shows tolerance to salinity, being a sustainable alternative of bell pepper to reduce salt stress in arid and semi-arid areas of Peru. Resumo O pimentão é um vegetal com propriedades benéficas para a nutrição humana. No entanto, a salinidade é um fator abiótico que afeta o rendimento do pimentão em áreas áridas e semiáridas do Peru. O objetivo deste estudo foi determinar o efeito combinado do ácido húmico (AH) com o Trichoderma harzianum (TH) como alternativas sustentáveis para aumentar a produção de pimentões submetidos ao estresse salino. O experimento foi realizado em campo durante as estações do ano de 2023 e 2024, com um esquema fatorial 2 x 3 x 2, referente à condutividade elétrica (CE) da água de irrigação (0 e 4 dSm-1), AH (0, 15 e 30 L ha-1) e TH (0 e 1 kg ha-1). Os parâmetros agronômicos e relacionados à produtividade foram analisados. Os resultados mostraram que o solo salino, acompanhado de irrigações de 0 e 4 dS m-1 de CE, apresentou uma redução significativa nos parâmetros agronômicos e um aumento na concentração de sódio e cloro nas folhas do pimentão. No entanto, a aplicação de 30 L ha-1 de AH com aumento de TH na altura da planta (86,53 e 86,42%), maior peso seco da raiz (95,44 e 95,32%) e peso seco da planta (90,46 e 90,41%), também melhorou muito o comprimento do fruto (64,6 e 63,74%) e a largura (58,47 e 57,31%), aumentou significativamente o conteúdo de frutos por planta (91,49 e 91,30%), o peso dos frutos por planta (93,29 e 93,15%) e o rendimento total (89,54 e 89,23%) em relação às plantas submetidas ao estresse salino. Também aumentou significativamente a concentração de potássio e cálcio nas folhas (37,88 e 48,71%), a relação K+/ Na+ (72,07 e 74,93%) e o teor de prolina (58,60 e 59,31%) superior ao controle, como mecanismo de defesa contra o estresse salino. Portanto, à medida que a dose de ácidos húmicos, combinada com Trichoderma harzianum, é aumentada, a planta mostra tolerância à salinidade, sendo uma alternativa sustentável de pimentão para reduzir o estresse salino em áreas áridas e semiáridas do Peru.

Silicon (Si) has beneficial effects on many crops, mainly under biotic and abiotic stress. Silicon can affect biochemical, physiological, and photosynthetic processes and, consequently, reduce drought stress. However, the effects of Si on rice (Oryza sativa L.) plants under drought stress are not well known. The objective of this study was to evaluate the effects of supplemental Si on proline content and peroxidase activity in upland rice plants in the presence and absence of drought stress. The experiment was conducted under greenhouse conditions and was arranged in completely randomized blocks in a 2 × 2 x 2 factorial scheme. Treatments comprised combinations of (1) presence or absence of Si supply (0 or 350 kg ha-1 of Si), (2) presence or absence of a water deficit (-0.050 MPa or -0.025 MPa soil water potential values, respectively), and (3) two upland rice cultivars: Caiapo (traditional type) and Maravilha (modern type), with eight replications. Under water stress conditions, silicon fertilization reduced the proline content in the vegetative and reproductive phases of upland rice plants and increased peroxidase activity in the plants? reproductive phase, which could be indicative of stress tolerance.

Intensive irrigated agriculture relies heavily on nitrogen fertilization, which may cause ammonium accumulation, highly detrimental to sensitive seedlings. Silicon application has emerged as a potential strategy to mitigate this stress, although the underlying mechanisms remain poorly understood. To evaluate this effect, maize seedlings were grown in nutrient solution under five N concentrations (1.4, 3.6, 7.1, 14.3, and 28.6 mmol L−1), applied in the presence or absence of silicon (1.8 mmol L−1 Si). The nitrogen source was a mixture of nitrate and ammonium in a N-NO3−: N-NH4+ ratio of 4:5. Silicon was supplied as monosilicic acid (H2SiO3). Plant growth, leaf area, root morphology (length, diameter, density), N and Si accumulation, uptake and utilization efficiency, SPAD index, nitrate reductase activity, and proline content were evaluated. Silicon supplementation enhanced nitrate reductase activity, SPAD values, leaf area, and root traits, reduced proline in roots and shoots, and improved N uptake and partitioning. Among the tested N concentrations, 14.3 mmol L−1 achieved the highest efficiency of nutrient absorption and biomass production, highlighting silicon as a sustainable strategy to mitigate ammonium stress in maize seedlings.

AIM: To evaluate, in a short-time exposure, the physiological responses of Salvinia auriculata Aubl. under different concentrations of Cu. METHODS: The plants were exposed to treatments with 0.01, 0.1, 1 and 10 mM of Cu in a period of 2 days. Then development variables of S. auriculata (weight, photosynthetic pigments, and soluble carbohydrate), lipid peroxidation (malondialdehyde, aldehydes, and electrolyte leakage) and production of antioxidants (anthocyanins, carotenoids, flavonoids, and proline) were evaluated. RESULTS: It was observed fresh weight reductions in concentrations above 1 mM of Cu. Chlorophyll a decreased with the increase of Cu concentrations unlike chlorophyll b. The ratio chlorophyll a / chlorophyll b was changed due to the degradation of photosynthetic pigments. The reductions of carotenoids were more pronounced than that of total chlorophyll. The values of electrolyte leakage ranged from 14 to 82 % and lipid peroxidation from 7 to 46 nmol.g-1. Flavonoids and soluble carbohydrates showed reductions with the increase of Cu concentration. Anthocyanins, phenolic compounds, and proline when subjected to 0.1 mM of Cu had increased, suggesting adaptability of plant stress caused directly by metal and reactive oxygen species. In higher concentrations, degradation and/or direct modifications of these molecules possibly occurred. CONCLUSIONS: The data suggest that S. auriculata is provided with an efficient mechanism against stress caused by Cu in the concentration of 0.1 mM. As for higher concentrations (1 and 10 mM), despite its role as micronutrients, Cu was toxic to the plant due to the redox behavior of this metal, which leads to the exacerbated formation of reactive oxygen species, inducing to severe damage such as biological membrane degradation and protein denaturation. OBJETIVO: avaliar em curto tempo de exposição às respostas fisiológicas de Salvinia auriculata Aubl. sob diferentes concentrações de Cu. MÉTODOS: as plantas foram expostas a tratamentos com 0,0; 0,01; 0,1; 1 e 10 mM de Cu em um período de 2 dias. Em seguida foram avaliadas variáveis de desenvolvimento de S. auriculata (peso, pigmentos fotossintéticos e carboidratos solúveis), peroxidação lipídica (malonaldeído, aldeídos e extravasamento de eletrólitos) e produção de antioxidantes (antocianinas, carotenóides, flavonóides e prolina). RESULTADOS: Foram verificadas reduções das massas frescas nas concentrações acima de 1 mM de Cu. A clorofila a reduziu com o aumento da concentração de Cu, diferentemente da clorofila b. A razão clorofila a/clorofila b foi alterada, devido à degradação dos pigmentos fotossintéticos. As reduções dos carotenóides foram mais acentuada do que a de clorofila total. Os valores de extravasamento de eletrólitos variaram de 14 a 82 % e peroxidação lipídica de 7 a 46 nmol.g-1. Flavonóides e carboidratos solúveis mostraram reduções com o aumento da concentração de Cu. Antocianinas, compostos fenólicos e prolina quando submetidas a 0.1 mM de Cu apresentaram aumento, sugerindo adaptabilidade da planta ao estresse causado diretamente pelo metal e espécies reativas de oxigênio. Nas concentrações superiores, possivelmente, ocorreram degradação e/ou modificações diretas destas moléculas. CONCLUSÕES: Os dados sugerem que S. auriculata é provida de um mecanismo eficiente contra estresse causado por Cu na concentração de 0.1 mM. Já nas concentrações mais elevadas (1 e 10 mM), apesar de seu papel como micronutriente, Cu foi tóxico para a planta devido ao comportamento redox deste metal, que leva à formação exacerbada de espécies reativas de oxigênio, induzindo danos severos como degradação de membranas biológicas e desnaturação protéica.

Abstract In this study, the activities of antioxidant enzymes, photosynthetic pigments, proline and carbohydrate contents in Pitcairnia encholirioides under ex vitro conditions of water deficit were evaluated. Results show that plants under progressive water stress, previously in vitro cultured in media supplemented with 30 g L-1 sucrose and GA3, accumulated more proline and increased peroxidase (POD) activity and the contents of photosynthetic pigments and carbohydrates. For plants previously in vitro cultured with 15 g L-1 sucrose and NAA, no differences were found for proline content and there were reductions in activities of peroxidase (POD), catalase (CAT) and poliphenoloxidase (PPO), and in contents of carbohydrates, with progress of ex vitro water deficit. After rehydration, plants showed physiological recovery, with enzymatic activities and contents of metabolites similar to those found in the controls not submitted to dehydration, regardless of the previous in vitro culture conditions. These results show that micropropagated P. encholirioides has high tolerance to dehydration once in ex vitro conditions, which can ensure the survival of plants from tissue culture when transferred to its natural environment, emphasizing the importance of such biotechnology for the propagation of endangered species. Resumo Neste estudo, foram avaliadas as atividades de enzimas antioxidantes, pigmentos fotossintéticos, conteúdo de prolina e carboidratos em Pitcairnia encholirioides sob déficit hídrico em condições ex vitro. Os resultados mostraram que as plantas sob estresse hídrico progressivo, previamente cultivadas in vitro em meio de cultura suplementado com 30 g L-1 de sacarose e GA3 acumularam mais prolina e aumentaram a atividade da peroxidase (POD) e os teores de pigmentos fotossintéticos e carboidratos. Para plantas previamente cultivadas in vitro com 15 g L-1 de sacarose e ANA, não foram encontradas diferenças nos conteúdos de prolina e houve reduções nas atividades da peroxidase (POD), catalase (CAT) e polifenoloxidase (PPO), e no conteúdo de carboidratos, com o progresso do déficit hídrico ex vitro. Após a reidratação, as plantas apresentaram recuperação fisiológica, com atividades enzimáticas e conteúdo de metabólitos semelhantes aos encontrados nos controles não sujeitos à desidratação, independentemente das condições de cultivo in vitro. Estes resultados mostram que P. encholirioides micropropagada tem alta tolerância à desidratação uma vez em condições ex vitro, o que pode garantir a sobrevivência de plantas provenientes da cultura de tecidos quando transferidas para seu ambiente natural, enfatizando a importância desta biotecnologia para a propagação de espécies ameaçadas.

Introduction. Drought stress is the major factor affecting growth, development and production of walnut trees. In Iran, approximately 33 Mha of land is affected by salinization and drought stress. Finding genetic resources tolerant to drought stress at different growth stages is important for such semi-arid regions. Our aim was to understand better the adaptive mechanisms that enable different genotypes of walnut population to survive under drought stress, and to provide some useful clues for walnut tree breeding toward improved drought tolerance with utilization of existing drought-tolerant genetic resources. Materials and methods. To study the mechanism(s) involved in drought tolerance of some Persian walnut genotypes, drought stress was induced using polyethylene glycol-6000 to produce water potentials of 0 Mpa (control), –0.10 MPa, –0.50 MPa, –0.75 MPa, –1.00 MPa, –1.50 MPa and –2.00 MPa. The amount of proline and soluble sugar accumulation in four walnut genotypes (‘Panegine20’, ‘Lara’, ‘Serr’ and ‘Chandler’) were determined after being exposed to the various water potential levels. Results. The rates of seed germination in all genotypes were significantly reduced by low external water potentials. Plants exposed to water stress had a higher amount of soluble sugars in roots and shoots of tolerant genotypes (‘Panegine20’ and ‘Chandler’) and a lower amount of starch in their tissues. These results imply the important roles of soluble sugars as solutes conferring resistance to drought in these genotypes. The free proline levels were also increased in response to drought stress. They were higher in drought-tolerant genotypes than in sensitive ones (‘Lara’ and ‘Serr’). Proline increased more in shoots than in roots. However, the soluble sugar and starch fluctuations were higher in the roots. Conclusion. Our results support a direct correlation between the degree of drought stress and proline content. As a consequence, proline concentrations could be used as a biochemical marker of drought stress level in walnut plants. Introduction. Le stress dû à la sécheresse est le principal facteur influant sur la croissance, le développement et la production de noyers. En Iran, environ 33 Mha de terres sont affectées par la salinisation et la sécheresse. Trouver des ressources génétiques tolérantes à la sécheresse à différents stades de croissance est important pour ces régions semi-arides. Notre objectif a été de mieux comprendre les mécanismes adaptatifs qui permettent aux différents génotypes de noyers de survivre en conditions de stress hydrique et de fournir quelques indications utiles pour une amélioration de ces arbres vis-à-vis de la tolérance à la sécheresse en utilisant des ressources génétiques existantes. Matériel et méthodes. Pour étudier les mécanismes de certains génotypes de noyers persans impliqués dans la tolérance à la sécheresse, un stress hydrique a été induit en utilisant du polyéthylène glycol-6000 pour produire des potentiels hydriques de 0 Mpa (témoin), –0.10 MPa, –0.50 MPa, –0.75 MPa, –1.00 MPa, –1.50 MPa et –2.00 MPa. Le niveau d'accumulation de proline et de sucres solubles dans quatre génotypes de noyer ('Panegine20', 'Lara', 'Serr' et 'Chandler') a été déterminé après qu’ils ont été exposés aux différents niveaux de potentiels hydriques. Résultats. Pour les quatre génotypes étudiés, les taux de germination des semences ont été considérablement réduits par les bas potentiels hydriques. Les semis des génotypes tolérants ('Panegine20' et 'Chandler') exposés au stress hydrique ont présenté les plus grandes quantités de sucres solubles dans les racines et les tiges, mais une moindre quantité d’'amidon dans leurs tissus par rapport aux génotypes sensibles. Ces résultats suggèrent l'importance des sucres solubles comme solutés conférant, à ces génotypes, la résistance à la sécheresse. Les niveaux de proline libre ont également été augmentés en réponse à la sécheresse. Ils ont été plus élevés chez les génotypes tolérants à la sécheresse que chez les plus sensibles (‘Lara’ et ‘Serr '). La teneur en proline a davantage augmenté dans les tiges que dans les racines. Toutefois, les fluctuations du sucre soluble et de l'amidon ont été plus élevées dans les racines. Conclusion. Nos résultats confirment qu’il existe une corrélation directe entre le degré de stress hydrique et la teneur en proline dans les plantules. En conséquence, les concentrations en proline pourraient être utilisées comme marqueurs biochimiques du niveau de stress hydrique chez le noyer. Introducción. El estrés causado por la sequía es el factor principal que influye el crecimiento, el desarrollo y la producción de nogales. En Irán, cerca de 33 Mha de tierras están afectadas por la salinización y por la sequía. Es importante para estas regiones semi-áridas encontrar recursos genéticos que toleran la sequía en diferentes estadios de crecimiento. Nuestro objetivo fue comprender mejor los mecanismos de adaptación que permiten los diferentes genotipos de nogales sobrevivir en condiciones de estrés hídrico. También pretendimos aportar, mediante el empleo de los recursos genéticos existentes, algunas indicaciones útiles para una mejora de estos árboles con respecto a la tolerancia de la sequía. Material y métodos. Con el fin de estudiar los mecanismos de ciertos genotipos de nogales persas implicados en la tolerancia de la sequía, se indujo un estrés hídrico mediante el empleo del polietilenglicol-6000 para producir potenciales hídricos de 0 Mpa (testigo), –0.10 MPa, –0.50 MPa, –0.75 MPa, –1.00 MPa, –1.50 MPa y –2.00 MPa. El nivel de acumulación de prolina y de los azúcares solubles en cuatro genotipos de nogales (‘Panegine20’, ‘Lara’, ‘Serr’ y ‘Chandler’) se determinó tras su exposición a diferentes niveles de potenciales hídricos. Resultados. Para los cuatro genotipos estudiados, los valores de germinación de las semillas se redujeron considerablemente por los bajos potenciales hídricos. Las siembras de los genotipos tolerantes ('Panegine20' y 'Chandler') expuestos al estrés hídrico, en relación con los genotipos sensibles, presentaron las cantidades más grandes de azúcares solubles en las raíces y en las ramas, pero una cantidad menor de almidón en sus tejidos. Los resultados en cuestión sugieren la importancia de los azúcares solubles y solutos, que confieren a estos genotipos la resistencia a la sequía. Los niveles de prolina libre aumentaron igualmente en respuesta a la sequía. Fueron más elevados en los genotipos tolerantes a la sequía que en aquellos que eran más sensibles (‘Lara’ y ‘Serr'). El contenido en prolina aumentó considerablemente más en las ramas que en las raíces. No obstante, las fluctuaciones de azúcar soluble y del almidón fueron más elevadas en las raíces. Conclusión. Nuestros resultados confirman que existe una correlación directa entre el grado de estrés hídrico y el contenido en prolina en las plántulas. Por consecuente, las concentraciones de prolina podrían emplearse como marcadores bioquímicos del nivel de estrés hídrico en el nogal.

In many plants, free proline accumulates in response to the imposition of a wide range of biotic and abiotic stresses. Controversy has surrounded the extent to which this shift in nitrogen metabolism benefits plants under adverse environmental conditions. Most attempts to account for the phenomenon have focused on the ability of proline to mediate osmotic adjustment, stabilise subcellular structures and scavenge free radicals. However, often the cytoplasmic pool of free proline even after the imposition of stress is insufficient size to account for pronounced biophysical effects. Alternatively, selective preservation of this stress-induced response may relate to endpoints other than simply augmenting the cellular pool of free proline. Proline accumulation may reduce stress-induced cellular acidification or prime oxidative respiration to provide energy needed for recovery. High levels of proline synthesis during stress may maintain NAD(P)+/NAD(P)H ratios at values compatible with metabolism under normal conditions. Consideration of the cofactor preference of plant Δ1-pyrroline-5-carboxylate (P5C) reductase as well as the in vivo concentrations of the two pyridine nucleotide cofactors and their respective redox ratios suggests that even a small increase in proline biosynthesis might have a large impact on the level of reduction of the cellular NADP pool. The increased NADP+/NADPH ratio mediated by proline biosynthesis is likely to enhance activity of the oxidative pentose phosphate pathway. This would provide precursors to support the demand for increased secondary metabolite production during stress as well as nucleotide synthesis accompanying the accelerated rate of cell division upon relief from stress, when oxidation of proline is likely to provide an important energy source for ADP phosphorylation. Thus, the extreme sensitivity of the metabolic processes of proline synthesis and degradation themselves may be of benefit by regulating metabolic processes adversely affected by stress. This viewpoint is supported by consideration of other physiological phenomena not directly related to stress responses, but in which proline metabolism may also play a regulatory role. A mechanism is proposed whereby the interconversions of proline and P5C in different cell types and the associated transfer of redox potential between tissues may constitute a form of metabolic signalling within higher plants. Stress-related alterations in proline metabolism may impinge on systems of redox control of plant gene expression.[PUBLICATION ABSTRACT]

Theobroma cacao L. is a crop of major importance for their potential applications in pharmacy and agriculture. It contains metabolites that are of great interest for its natural biological functions in plant response to different types of stress, both biotic and abiotic. The presence, type and concentration of both primary and secondary metabolites may vary depending on the genotype analyzed and these compounds can accumulate in the architecture associated structures such as leaf trichomes. The aim of this study was to characterize 26 clones of the germplasm bank of Padrón, INIA-Miranda, Miranda State, Venezuela and study the relationship between biochemical indicators assessed and the number of trichomes. The content of phenolic compounds, soluble protein, free proline, total carbohydrates, lignins, the number of trichomes and the relationship between all traits was determined. The results showed that in the two dimensional space explained 46.68% of the variability, five homogeneous groups were defined: 10 clones were associated with the maximum gradient of proline, total carbohydrate and lignin content. Nine clones were associated with high content of phenols and a group of seven clones with the highest number of trichomes on leaves. It was found that the number of trichomes was not related to the concentration of phenolic compounds. The clones of Forastero cocoa type showed higher concentration of total phenols and carbohydrates, meanwhile the Trinitario type presented higher concentration of proteins and prolina.

Calcium serves as an important second messenger in many adaptational and developmental processes of plants. The CDPK-related kinases (CRKs) are a type of serine-threonine kinases belonging to the CDPK-SnRK superfamily. In this study, a T-DNA insertion mutant of AtCRK1 (crk1-1) was employed to explore the possible function of AtCRK1 in salt tolerance. Our results indicated that crk1-1 transformants had a decreased tolerance to salt stress during seed germination compared with both wild-type plants and the complemented transgenic lines, in which the full-length genomic AtCRK1 clone with a 2.3 kb promoter was inserted into crk1-1 to drive CRK1 expression under the control of the CRK1 promoter. Furthermore, a higher malondialdehyde (MDA) level and lower free proline content were measured in crk1-1 plants. The qRT-PCR analyses revealed that the transcription of several stress-related genes was decreased in crk1-1 plants. These results indicate that AtCRK1 is involved in the tolerance to salt stress by changing both MDA and proline levels in Arabidopsis, and may act as a positive regulator in the induction of stress-response gene transcription.

Temperate plants develop a greater ability to withstand freezing in response to a period of low but nonfreezing temperatures through a complex, adaptive process of cold acclimation. Very little is known about the signaling processes by which plants perceive the low temperature stimulus and transduce it into the nucleus to activate genes needed for increased freezing tolerance. To help understand the signaling processes, we have isolated mutants of Arabidopsis that are constitutively freezing-tolerant in the absence of cold acclimation. Freezing tolerance of wild-type Arabidopsis was increased from -5.5 degrees C to -12.6 degrees C by cold acclimation whereas the freezing tolerance of 26 mutant lines ranged from -6.8 degrees C to -10.6 degrees C in the absence of acclimation. Plants with mutations at the eskimol (esk1) locus accumulated high levels of proline, a compatible osmolyte, but did not exhibit constitutively increased expression of several cold-regulated genes involved in freezing tolerance. RNA gel blot analysis suggested that proline accumulation in esk1 plants was mediated by regulation of transcript levels of genes involved in proline synthesis and degradation. The characterization of esk1 mutants and results from other mutants suggest that distinct signaling pathways activate different aspects of cold acclimation and that activation of one pathway can result in considerable freezing tolerance without activation of other pathways