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Item type:Publication, Physiological responses of maca (Lepidium meyenii Walp.) plants to UV radiation in its high-altitude mountain ecosystem(Nature Research, 2020-12-01)Ultraviolet (UV) radiation is a small fraction of the solar spectrum, which acts as a key environmental modulator of plant function affecting metabolic regulation and growth. Plant species endemic to the Andes are well adapted to the harsh features of high-altitude climate, including high UV radiation. Maca (Lepidium meyenii Walpers) is a member of Brassicaceae family native to the central Andes of Peru, which grows between 3500 and 4500 m of altitude, where only highland grasses and few hardy bushes can survive. Even though maca has been the focus of recent researches, mainly due to its nutraceutical properties, knowledge regarding its adaptation mechanisms to these particular natural environmental conditions is scarce. In this study, we manipulated solar UV radiation by using UV-transmitting (Control) or blocking (UV-block) filters under field conditions (4138 m above the sea level) in order to understand the impact of UV on morphological and physiological parameters of maca crops over a complete growing season. Compared to the UV-blocking filter, under control condition a significant increase of hypocotyl weight was observed during the vegetative phase together with a marked leaf turnover. Although parameters conferring photosynthetic performance were not altered by UV, carbohydrate allocation between above and underground organs was affected. Control condition did not influence the content of secondary metabolites such as glucosinolates and phenolic compounds in hypocotyls, while some differences were observed in the rosettes. These differences were mainly related to leaf turnover and the protection of new young leaves in control plants. Altogether, the data suggest that maca plants respond to strong UV radiation at high altitudes by a coordinated remobilization and relocation of metabolites between source and sink organs via a possible UV signaling pathway. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Glucosinolate catabolism during postharvest drying determines the ratio of bioactive macamides to deaminated benzenoids in Lepidium meyenii (maca) root flour(Elsevier, 2020-11-01)Postharvest processing of maca (Lepidium meyenii Walp., Brassicaceae), a traditional high-altitude Andean root crop, involves slow field drying prior to milling into flour. The progressive tissue dehydration and release of hydrolytic enzymes and substrates from cellular compartments results in the slow accumulation of free monosaccharides, fatty acids and amino acids. A more complex, and faster, kinetic profile is that of glucosinolate breakdown. A number of reactive transient and stable accumulation products are generated during drying, some of which have noteworthy bioactive properties. Among these are macamides, inhibitors of endocannabinoid neurotransmitter degradation in mammalian nervous systems. They result from the condensation of benzyl amine, a glucosinolate hydrolysis product, with free fatty acids released from lipid hydrolysis. Recent research has focused on developing drying processes under controlled conditions that can modulate the biochemistry of glucosinolate hydrolysis to optimize the content of bioactive compounds in the root flour. Low temperature (35 °C) oven-drying of shredded maca roots under controlled air flow generates benzyl amine as primary accumulation product, accounting for up to 94% of hydrolyzed glucosinolate in the flour. Kinetic evidence suggests that both deaminated benzenoids and macamides are allocated from the benzylamine pool through amine oxidase activity or condensation with free fatty acids, accounting for the remaining hydrolyzed glucosinolate (<5%). These activities determine the allocation to either one of these pathways. Later stages of dehydration result in shifts in the molar ratios of deaminated benzenoids, the accumulation of benzoic acid esters and benzyl alcohol. We propose that these are the result of changes in the rates of the reductive and oxidative half-reactions of endogenous aldehyde dehydrogenases. It is the ratio of benzylamine deamination to amide formation that determines the eventual yields of macamides in relation to benzenoids and their esters in maca flour. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Bioengineering potato plants to produce benzylglucosinolate for improved broad-spectrum pest and disease resistance(Springer Science and Business Media Deutschland GmbH, 2021-10-01)In traditional, small-scale agriculture in the Andes, potatoes are frequently co-cultivated with the Andean edible tuber Tropaeolum tuberosum, commonly known as mashua, which is believed to exert a pest and disease protective role due to its content of the phenylalanine-derived benzylglucosinolate (BGLS). We bioengineered the production of BGLS in potato by consecutive generation of stable transgenic events with two polycistronic constructs encoding for expression of six BGLS biosynthetic genes from Arabidopsis thaliana. First, we integrated a polycistronic construct coding for the last three genes of the pathway (SUR1, UGT74B1 and SOT16) into potato driven by the cauliflower mosaic virus 35S promoter. After identifying the single-insertion transgenic event with the highest transgene expression, we stacked a second polycistronic construct coding for the first three genes in the pathway (CYP79A2, CYP83B1 and GGP1) driven by the leaf-specific promoter of the rubisco small subunit from chrysanthemum. We obtained transgenic events producing as high as 5.18 pmol BGLS/mg fresh weight compared to the non-transgenic potato plant producing undetectable levels of BGLS. Preliminary bioassays suggest a possible activity against Phytophthora infestans, causing the late blight disease and Premnotrypes suturicallus, referred to as the Andean potato weevil. However, we observed altered leaf morphology, abnormally thick and curlier leaves, reduced growth and tuber production in five out of ten selected transgenic events, which indicates that the expression of BGLS biosynthetic genes has an undesirable impact on the potato. Optimization of the expression of the BGLS biosynthetic pathway in potato is required to avoid alterations of plant development. Graphical [Figure not available: see fulltext.] - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Variation of non-structural carbohydrates across the fast-slow continuum in Amazon forest canopy trees(Wiley, 2021-11-20)Tropical tree species span a range of life‐history strategies within a fast–slow continuum. The position of a species within this continuum is thought to reflect a negative relationship between growth and storage, with fast‐growing species allocating more carbon to growth and slow‐growing species investing more in storage. For tropical species, the relationship between storage and life‐history strategies has been largely studied on seedlings and less so in adult trees. We evaluated how stored non‐structural carbohydrates (NSC) vary across adult trees spanning the fast–slow continuum in the Peruvian Amazon by: (a) analysing whole‐tree NSC in two species of contrasting growth and (b) investigating the relationships with key life‐history traits across a broader set of species. Our results are consistent with a growth–storage trade‐off. The analysis of whole‐tree NSC revealed that the slow‐growing Eschweilera coriacea stored about 2.7 times as much NSC as the fast‐growing Bixa arborea due to markedly higher storage in woody stems and roots. B. arborea also had higher seasonality in NSC, reflecting its strong seasonality in stem growth. Across a range of species, stem starch was negatively related to species growth rate and positively related to wood density. Given the role of NSC in mediating plants' response to stress, our results suggest that slow‐growing species with greater storage reserves may be more resilient to drought than fast‐growing species. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Non-structural carbohydrates mediate seasonal water stress across Amazon forests(Nature Research, 2021-12-01)Non-structural carbohydrates (NSC) are major substrates for plant metabolism and have been implicated in mediating drought-induced tree mortality. Despite their significance, NSC dynamics in tropical forests remain little studied. We present leaf and branch NSC data for 82 Amazon canopy tree species in six sites spanning a broad precipitation gradient. During the wet season, total NSC (NSCT) concentrations in both organs were remarkably similar across communities. However, NSCT and its soluble sugar (SS) and starch components varied much more across sites during the dry season. Notably, the proportion of leaf NSCT in the form of SS (SS:NSCT) increased greatly in the dry season in almost all species in the driest sites, implying an important role of SS in mediating water stress in these sites. This adjustment of leaf NSC balance was not observed in tree species less-adapted to water deficit, even under exceptionally dry conditions. Thus, leaf carbon metabolism may help to explain floristic sorting across water availability gradients in Amazonia and enable better prediction of forest responses to future climate change. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Aboveground biomass in secondary montane forests in Peru: slow carbon recovery in agroforestry legacies(Elsevier, 2021-08-01)Andean tropical montane forests (TMF) are hotspots of biodiversity that provide fundamental hydrological services as well as carbon sequestration and storage. Agroforestry systems occupy large areas in the Andes but climatic pressures, market volatility and diseases may result inagroforest abandonment, promoting secondary succession. Secondary forests are well-adapted and efficient carbon sinks whose conservation is vital to mitigate and adapt to climate change and to support biodiversity. Little is known, however, about how secondary TMF recover their aboveground biomass (AGB) and composition after abandonment. We established a 1.5 ha plot at 1780 masl on a 30-year old abandoned agroforest and compared it against two control forest plots at similar elevations. Agroforestry legacies influenced AGB leading to far lower stocks (42.3 ± 5.4–59.6 ± 7.9 Mg ha−1 using allometric equations) than those expected after 30 years (106 ± 33 Mg ha−1) based on IPCC standard growth rates for secondary montane forests. This suggests a regional overestimation of mitigation potentials when using IPCC standards. Satellite-derived AGB largely overestimated our plot values (179 ± 27.3 Mg ha−1). Secondary growth rates (1.41–2.0 Mg ha−1 yr−1 for DBH ≥ 10 cm) indicate recovery times of ca. 69 to 97 years to reach average control AGB values (137 ± 12.3 Mg ha−1). This is 26 years above the average residence time of montane forests at our elevation (71 ± 1.91 years) suggesting a non-recovery or far slower recovery to control AGB values. Three variables appear to define this outcome compared to the control plots: lower DBH (15.8 ± 5.9 cm vs 19.8 ± 11.0 cm), lower basal area (12.67 ± 0.7 vs 28.03 ± 1.5 m2 ha−1) and higher abundance of lighter-wood tree genera (0.46 ± 0.10 vs 0.57 ± 0.11 gr cm3) such as Inga, a common shade-tree in Andean agroforests. With 3.2 million hectares committed to restoration, Peru needs to target currently neglected TMF recovery schemes to support biodiversity, water and carbon storage and fulfill its international commitments. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Detektion und Visualisierung der Pflanzen-Pathogen-Response durch Nah-Infrarot-fluoreszente Polyphenolsensoren(Wiley, 2021-10-06)Pflanzen nutzen Sekundärmetabolite, wie Polyphenole, zur chemischen Verteidigung gegenüber Pathogenen und Herbivoren. Trotz ihrer wichtigen Rolle bei der Reaktion von Pflanzen auf Pathogene bleibt die Detektion von Polyphenolen in komplexen Pflanzengeweben eine Herausforderung. Hier berichten wir vom Aufbau molekularer Sensoren zur Visualisierung pflanzlicher Polyphenole, basierend auf Nah‐Infrarot (NIR)‐fluoreszenten Kohlenstoff‐Nanoröhren (SWCNTs). Dabei identifizierten wir Oberflächenmodifikationen mit Polyethylenglycol‐Phospholipiden, die (6,5)‐SWCNTs sensitiv (Kd=90 nM) gegenüber pflanzlichen Polyphenolen machen und die Emission (ca. 1000 nm) quenchen und bathochrom (bis zu 20 nm) verschieben. Diese Sensoren detektieren Unterschiede im Gesamtphenolgehalt nach Herbivor‐ oder Pathogenstimulus im Nutzpflanzensystem und in Blattextrakten. Ferner erlauben sie die Bildgebung der Pathogen‐induzierten Polyphenolausschüttung (24 h). Dieser Ansatz ermöglicht die In‐situ‐Visualisierung und Charakterisierung der chemischen Pflanzenverteidigung in Echtzeit und ebnet den Weg zur Phänotyp‐basierten Optimierung der Polyphenolsekretion. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Detection and imaging of the plant pathogen response by near-infrared fluorescent polyphenol sensors(Wiley, 2021-10-06)Plants use secondary metabolites such as polyphenols for chemical defense against pathogens and herbivores. Despite their importance in plant pathogen interactions and tolerance to diseases, it remains challenging to detect polyphenols in complex plant tissues. Here, we create molecular sensors for plant polyphenol imaging that are based on near‐infrared (NIR) fluorescent single‐wall carbon nanotubes (SWCNTs). We identified polyethylene glycol–phospholipids that render (6,5)‐SWCNTs sensitive (Kd=90 nM) to plant polyphenols (tannins, flavonoids, …), which red‐shift (up to 20 nm) and quench their emission (ca. 1000 nm). These sensors report changes in total polyphenol level after herbivore or pathogen challenge in crop plant systems (Soybean Glycine max) and leaf tissue extracts (Tococa spp.). We furthermore demonstrate remote chemical imaging of pathogen‐induced polyphenol release from roots of soybean seedlings over the time course of 24 h. This approach allows in situ visualization and understanding of the chemical plant defense in real time and paves the way for plant phenotyping for optimized polyphenol secretion. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Patterns and drivers of evapotranspiration in South American wetlands(Universidad Científica del Sur, 2021-04-14) - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Combination of single-point standard addition calibration and natural internal standardization for quantification of terpenes in Pisco samples(Academic Press Inc., 2021-07-01)Combination of single-point standard addition calibration and natural internal standardization was investigated as a practical strategy for the quantification of terpenes in Pisco samples using HS-SPME-GC-MS. All GC-MS data were acquired under simultaneous Full Scan and SIM modes using two quantification strategies identified as “reference strategy” and “simplified strategy”. Linearity was first confirmed for linalool oxide, linalool and α-terpineol in a non-aromatic Pisco sample. The simplified strategy consisted of standard multicomponent addition of these same three terpenes to aromatic Pisco samples evaluating functionality of naturally present esters acting as candidate internal standards. The reference strategy consisted in the individual addition of every terpene standard to samples, using other naturally present terpenes as internal standards. Uncertainty budgets were presented for both calibration strategies. Relative combined standard uncertainties were between 6.6% and 10% for the reference strategy and between 1.9% and 33% for the simplified strategy using isoamyl acetate as natural internal standard and obtaining zeta-score values smaller than 2. Combination of single-point standard addition and use of a natural internal standard for HS-SPME-GC-MS measurements appears to be a potentially useful and reliable approach for measurements of terpenes in Pisco, and possibly in other measurements fields still in development.
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