The effect of silicon supply on photosynthesis and carbohydrate metabolism in two wheat (Triticum aestivum L.) cultivars contrasting in response to phosphorus nutrition.

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 CO2 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.

Combined Spraying of Boron and Zinc During Fruit Set and Premature Stage Improves Yield and Fruit Quality of European Hazelnut cv. Tonda di Giffoni.

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: B0+Zn0, B800+Zn400, and B1600+Zn800 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 B800+Zn400 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 B0+Zn0. Increased radical scavenging activity in B+Zn-treated kernels and leaves was not attributed to the accumulation of phenolics in P3 compared with B0+Zn0, 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.

Cluster roots of Embothrium coccineum modify their metabolism and show differential gene expression in response to phosphorus supply.

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.

Efecto de la suplementación del medio de incubación con extracto de Berberis microphylla (calafate) sobre la funcionalidad espermática en semen bovino descongelado / Effect of supplementation of incubation medium with Berberis microphylla (calafate) extract on sperm functionality in thawed bovine semen

RESUMEN: En el semen criopreservado, los procesos de congelación/descongelación y posterior manipulación, dañan las células espermáticas provocando disminución de la capacidad fecundante de los espermatozoides descongelados. Estos procesos han sido asociados con el estado de estrés oxidativo (EO) inducido por altos niveles de especies reactivas de oxígeno (EROS), causando daño a la función y estructura espermática. Los espermatozoides descongelados pueden ser protegidos de este daño, con la adición de antioxidantes (AO) al medio de incubación. El fruto de Calafate (Berberis microphylla G. Forst.) posee una alta capacidad antioxidante, lo que hace interesante investigar el efecto de sus componentes antioxidantes en estos procesos biotecnológicos especialmente postdescongelación. El objetivo de este estudio fue determinar el efecto de la suplementación de extracto liofilizado de fruto de Calafate (ELC), sobre la calidad espermática post-descongelación. Previamente se caracterizó el ELC, determinando la actividad antioxidante y metabolitos como fenoles y antocianinas; posteriormente, espermatozoides de bovino descongelados fueron incubados en un medio base suplementado con diferentes concentraciones de ELC. Post-incubación se evaluó la motilidad progresiva; la viabilidad e integridad de la membrana plasmática (SYBR14- PI) y acrosomal (FITC-PNA/PI) y la peroxidación lipídica (BODIPY) por citometría de flujo. La caracterización de ELC demostró que tanto la actividad antioxidante como los fenoles y antocianinas incrementan concomitante con el aumento de la concentración de ELC. La adición de ELC al medio de incubación, dependiendo de la concentración y tiempo de incubación, sería eficaz en proteger la motilidad, viabilidad e integridad de la membrana plasmática y disminuir la lipoperoxidación en los espermatozoides de bovino descongelados.

SUMMARY: In cryopreserved semen, the freezing/thawing process following of manipulation, damage the sperm cell, decreasing the fertilizing capacity of the thawed sperm; being one of the main factors of this damage the oxidative stress. The sperm once thawed can be protected from this damage, with the addition of antioxidants to the incubation medium. The Calafate fruit (Berberis microphylla G. Forst.) has a high antioxidant capacity, making it an interesting resource for investigating the effect of its antioxidant components on biotechnological processes. The objective of this study was to determine the effect of supplementation of Calafate fruit lyophilized extract (ELC) on sperm quality. The lyophilized extract of the Calafate fruit was characterized, determining the antioxidant activity and metabolites such as phenols and anthocyanins; subsequently, thawed bovine sperm were incubated in a medium supplemented with different concentrations of ELC. Post-incubation, progressive motility was evaluated. By flow cytometry, the viability and integrity of the plasma (SYBR14-PI), and acrosomal (FITC-PNA / PI), as well as lipid peroxidation (BODIPY), was determined. The characterization of Calafate fruits lyophilized extract indicated that antioxidant activity, phenols and anthocyanins increased concomitantly with the increase of dose extract used. The addition of ELC to the incubation medium, depending on the concentration and incubation time, would be effective to protect motility, viability and integrity of the plasma membrane and decreased lipid peroxidation in thawed bovine sperm.

Salinity impairs photosynthetic capacity and enhances carotenoid-related gene expression and biosynthesis in tomato (Solanum lycopersicum L. cv. Micro-Tom).

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, ß-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.

Manganese toxicity amelioration by phosphorus supply in contrasting Mn resistant genotypes of ryegrass.

We evaluated whether phosphorus (P) ameliorates manganese (Mn) excess harmful effects on photosynthetic performance, growth, oxidative stress, and antioxidants in ryegrass. Two perennial ryegrass genotypes, Banquet-II as Mn-resistant and One-50 as Mn-sensitive genotype, were growth under hydroponic conditions subjected to increased P (25, 50, 100, 200 and 400 µM), excess (750 µM) and sufficient Mn (2.4 µM) for 15 days. Growth rate, lipid peroxidation (LP), enzymatic and non-enzymatic antioxidants, photosynthetic parameters, and pigments were determined. Significant reduction of photosynthesis and growth in One-50 was observed under Mn-excess combined with low and adequate P, recovering under greater P-doses. The P concentration of both genotypes was enhanced towards increased P-supply, regardless of Mn treatments. Shoots Mn-concentration remained constant in both genotypes under Mn-excess, independently of P-levels; meanwhile, Banquet-II roots Mn-concentration increased 23% by P-supply. Furthermore, Banquet-II roots showed higher superoxide dismutase (SOD) activity than One-50, which increased towards the highest P dose under sufficient and excess of Mn. A high dose of phosphorus amendment alleviated Mn-toxicity in Mn-sensitive genotype (One-50). Besides, in the Mn-resistant genotype, enhanced plant performance is highlighted, explained by a high Mn-accumulation in roots and increased SOD activity, decreasing Mn translocation to shoots and therefore protecting the photosynthetic apparatus.

Metabolic diversity in tuber tissues of native Chiloé potatoes and commercial cultivars of Solanum tuberosum ssp. tuberosum L.

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.

Antimutagenic evaluation of traditional medicinal plants from South America Peumus boldus and Cryptocarya alba using Drosophila melanogaster.

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.

Criopreservación de espermatozoides de canino con extracto de hojas de arándano (Vaccinium corymbosum L. ) / Cryopreservation of canine spermatozoa with blueberry leaf extract (Vaccinium corymbosum L. )

La criopreservación espermática induce daño por estrés oxidativo en las células, lo que conlleva a un deterioro de la calidad del semen descongelado. Los espermatozoides pueden ser protegidos de este daño, por la adición de antioxidantes al medio de congelación. El objetivo de este estudio fue determinar el efecto de la adición de extracto de hojas de arándano (EHA) al medio de congelación, sobre la calidad de espermatozoides de canino criopreservados. Espermatozoides desprovistos del plasma seminal fueron congelados con diferentes concentraciones de EHA (0 %, control; 1 %, EHA1; 2 %, EHA2; 4 %, EHA4 y 6 %, EHA6) adicionadas al medio de congelación. Post descongelación se evalúo la motilidad progresiva; la viabilidad e integridad de la membrana plasmática (SYBR-14/PI) e integridad de la membrana acrosomal (FITC-PNA/PI) por citometría de flujo. La motilidad progresiva fue similar al control con las concentraciones de EHA1y EHA4 (P >0,05), mientras que con las concentraciones de EHA2 y EHA6 se observó una disminución significativa de este parámetro comparado con el control (P <0,01 y P <0,001 respectivamente). La adición de EHA1, EHA2 y EHA4 al medio de congelación no presentó diferencias significativas respecto al control sobre la viabilidad e integridad de la membrana plasmática (P >0,05); por el contrario, con la adición de EHA6 se observaron valores significativamente menores (P <0,001). Los valores de integridad de la membrana acrosomal, con las diferentes concentraciones de EHA no presentaron diferencias significativas respecto al control. En conclusión, los resultados obtenidos en este estudio revelaron que las concentraciones de EHA utilizadas no fueron eficaces en mejorar la calidad del semen canino descongelado.

During cryopreservation, oxidative stress damage leads to a deterioration of the quality of thawed semen, which could be reduced by the addition of antioxidants to freezing extender. This study was designed to determine the effect of the addition of blueberry leaf extract (EHA) to freezing extender, on quality of cryopreserved canine sperms. Sperm devoid from seminal plasma were frozen with different concentrations of EHA (0 %, control; 1 %, EHA1; 2 %, EHA2; 4 %, EHA4 y 6 %, EHA6) added to freezing extender. Post-thawing progressive motility was evaluated; the viability and plasma membrane integrity (SYBR-14/PI) and acrosomal membrane integrity (FITC-PNA/PI) were assessed by flow cytometry. Progressive motility was similar to the control with concentrations of EHA1 and EHA4 (P >0.05); at concentrations of EHA2 and EHA6 a significant decrease of this parameter compared to control (P <0.01and P <0.001, respectively) was observed. The addition of EHA1, EHA2 and EHA4 to the freezing extender showed no significant differences with respect to the control on viability and plasma membrane integrity (P >0.05); however with the addition of EHA6 values significantly lower (P <0.001) were exhibited. The concentrations of EHA used showed no significant differences with respect to the control on acrosome membrane integrity. In conclusion, the results of this study revealed that none of the concentrations of EHA used were effective in improving canine thawed semen quality.