Identifying allelopathic compounds emitted by Pittosporum undulatum in Eucalypt forests

Changing climatic conditions played a major role in plants evolution and could modify the composition, structure and functionality of native plant communities, favoring invasive species. Studies conducted in south-eastern Australia have reported Pittosporum undulatum, a native tree, to be an aggressive invader of Eucalyptus forests. We tested the hypothesis that its negative impact on floristic diversity is due to the release of allelopathic compounds inhibiting the germination and growth of other plants. Thus, we compared the germination of Pittosporum undulatum, Eucalyptus ovata and lettuce on different substrates. Seeds were watered with leachates made from fresh P. undulatum leaves, litter collected from underneath P. undulatum or Eucalyptus trees, or distilled water.P. undulatum seeds germinated more slowly than the other two species, however showed faster growth rates. E. ovata mortality rates seedlings were very high immediately after germination. While there were no significant treatment effects on germination rates, there were differences in morphology. The root system, in lettuce and E. ovata, was short and damaged when watered with fresh P. undulatum leaves extract.Additionally, we investigated the possible emission of specific Biogenic Volatile Organic Compounds (BVOCs) which could have ecological functions or increase P. undulatum stress resistance. Using Solid Phase Microextraction (SPME) fibers, BVOCs were collected and analysed using Gas chromatography-mass spectrometry (GC-MS) to compare the emissions in eucalypt forests with and without P. undulatum. The main difference between the two sites was the higher D-limonene and α-pinene aerial concentration in P. undulatum infested sites.Our results suggest that the high invasiveness of P. undulatum is mainly related to morphological and physiological characteristics rather than to allelopathic compounds emitted by this species. Additionally, the greater emission of D-limonene and α-pinene from P. undulatum compared to eucalypts could increase the resistance to abiotic stresses, such as drought or ozone

Isoprene Responses and Functions in Plants Challenged by Environmental Pressures Associated to Climate Change

The functional reasons for isoprene emission are still a matter of hot debate. It was hypothesized that isoprene biosynthesis evolved as an ancestral mechanism in plants adapted to high water availability, to cope with transient and recurrent oxidative stresses during their water-to-land transition. There is a tight association between isoprene emission and species hygrophily, suggesting that isoprene emission may be a favorable trait to cope with occasional exposure to stresses in mesic environments. The suite of morpho-anatomical traits does not allow a conservative water use in hygrophilic mesophytes challenged by the environmental pressures imposed or exacerbated by drought and heat stress. There is evidence that in stressed plants the biosynthesis of isoprene is uncoupled from photosynthesis. Because the biosynthesis of isoprene is costly, the great investment of carbon and energy into isoprene must have relevant functional reasons. Isoprene is effective in preserving the integrity of thylakoid membranes, not only through direct interaction with their lipid acyl chains, but also by up-regulating proteins associated with photosynthetic complexes and enhancing the biosynthesis of relevant membrane components, such as mono- and di-galactosyl-diacyl glycerols and unsaturated fatty acids. Isoprene may additionally protect photosynthetic membranes by scavenging reactive oxygen species. Here we explore the mode of actions and the potential significance of isoprene in the response of hygrophilic plants when challenged by severe stress conditions associated to rapid climate change in temperate climates, with special emphasis to the concomitant effect of drought and heat. We suggest that isoprene emission may be not a good estimate for its biosynthesis and concentration in severely droughted leaves, being the internal concentration of isoprene the important trait for stress protection

UV radiation promotes flavonoid biosynthesis, while negatively affecting the biosynthesis and de-epoxidation of xanthophylls: consequence for photoprotection?

There is evidence that UV radiation may detrimentally affect the biosynthesis of carotenoids, particularly de-epoxided xanthophylls, while strongly promoting phenylpropanoid, particularly flavonoid biosynthesis in a range of taxa. Here we tested the hypothesis that mesophyll flavonoids might protect chloroplasts from UV-induced photo-oxidative damage, by partially compensating for the UV-induced depression of xanthophyll biosynthesis. To test this hypothesis we grew two members of the Oleaceae family, Ligustrum vulgare L. and Phillyrea latifolia L., under either partial shading or fully exposed to sunlight, in the presence or in the absence of UV radiation. The examined species, which display very similar flavonoid composition, largely differ in their ability to limit the transmission of UV and visible light through the leaf and, hence, in the accumulation of flavonoids in mesophyll cells. We conducted measurements of photosynthesis, chlorophyll a fluorescence kinetics, the concentrations of individual carotenoids and phenylpropanoids at the level of whole-leaf, as well as the content of epidermal flavonoids. We also performed multispectral fluorescence micro-imaging to unveil the intra-cellular distribution of flavonoids in mesophyll cells. UV radiation decreased the concentration of carotenoids, particularly of xanthophylls, while greatly promoting the accumulation of flavonoids in palisade parenchyma cells. These effects were much greater in L. vulgare than in P. latifolia. UV radiation significantly inhibited the de-epoxidation of xanthophyll cycle pigments, while enhancing the concentration of luteolin, and particularly of quercetin glycosides. Flavonoids accumulated in the vacuole and the chloroplasts in palisade cells proximal to the adaxial epidermis. We hypothesize that flavonoids might complement the photo-protective functions of xanthophylls in the chloroplasts of mesophyll cells exposed to the greatest doses of UV radiation. However, UV radiation might result in adaxial mesophyll cells being less effective in dissipating the excess of radiant energy, e.g., by decreasing their capacity of thermal dissipation of excess visible light in the chloroplast

Dissecting Adaptation Mechanisms to Contrasting Solar Irradiance in the Mediterranean Shrub Cistus incanus

Molecular mechanisms that are the base of the strategies adopted by Mediterranean plants to cope with the challenges imposed by limited or excessive solar radiation during the summer season have received limited attention. In our study, conducted on C. incanus plants growing in the shade or in full sunlight, we performed measurements of relevant physiological traits, such as leaf water potential, gas exchange and PSII photochemistry, RNA-Seq with de-novo assembly, and the analysis of differentially expressed genes. We also identified and quantified photosynthetic pigments, abscisic acid, and flavonoids. Here, we show major mechanisms regulating light perception and signaling which, in turn, sustain the shade avoidance syndrome displayed by the ‘sun loving’ C. incanus. We offer clear evidence of the detrimental effects of excessive light on both the assembly and the stability of PSII, and the activation of a suite of both repair and effective antioxidant mechanisms in sun-adapted leaves. For instance, our study supports the view of major antioxidant functions of zeaxanthin in sunny plants concomitantly challenged by severe drought stress. Finally, our study confirms the multiple functions served by flavonoids, both flavonols and flavanols, in the adaptive mechanisms of plants to the environmental pressures associated to Mediterranean climate

Regulation of secondary metabolism in Vitis vinifera by an extract of A.nosodum effects of physiology and grape quality

Heat and drought are major abiotic stresses that impact on many Vitis vinifera physiological processes and berry development, especially as global climate change is speeding up the expected frequency and severity of both stress factors. Nevertheless, seaweed extracts might represent a strategy to confer to treated plants the capability to be more prone to counteract short-term periods of severe stresses. In this paper, we report the effects of foliar treatments with an Ascophyllum nodosum extract on physiological and biochemical parameters of grapevine. In our study performed in the 2016 season in open field in Tuscany, we assessed differences in leaf gas exchanges, chlorophyll fluorescence and midday stem water potential between treated and untreated vines. In addition, the in-depth analysis of anthocyanins and flavonols in berries presented within the work adds significantly to our knowledge of the influence of seaweed extract on the phenylpropanoid pathway. Moreover, our work witness the treatment-promoting greater tolerance to stress in vines, and support previous studies that hypothesize an influence of treatments with algae extracts on qualitative characteristics in V.vinifera

Ethyl acetate extract from Cistus x incanus L. leaves enriched in myricetin and quercetin derivatives, inhibits inflammatory mediators and activates Nrf2/HO-1 pathway in LPS-stimulated RAW 264.7 macrophages.

Abstract Cistus x incanus L. is a Mediterranean evergreen shrub used in folk medicine for the treatment of inflammatory disorders but the underlying mechanisms are not fully understood. We therefore investigated the anti-inflammatory effects of an ethyl acetate fraction (EAF) from C. x incanus L. leaves on lipopolysaccharide (LPS) activated RAW 264.7 macrophages. HPLC analysis revealed myricetin and quercetin derivatives to be the major compounds in EAF; EAF up to 1 µM of total phenolic content, was not cytotoxic and inhibited the mRNA expression of interleukin-6 (IL-6) and cyclooxygenase-2 (COX-2) (p < 0.05) and the production of prostaglandins E2 (PGE2) (p < 0.05). Meanwhile, EAF triggered the mRNA expression of interleukin-10 (IL-10) and elicited the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2), as well as the expression of its main target gene, heme oxygenase-1 (HO-1) (p < 0.05). These data indicate that EAF attenuates experimental inflammation via the inhibition of proinflammatory mediators and at least in part, by the activation of Nrf2/HO-1 pathway. These effects are likely due to myricetin and quercetin derivatives but the role of other, less abundant components cannot be excluded. Further studies to confirm the relevance of our findings in animal models and to highlight the relative contribution of each component to the anti-inflammatory activity of EAF should be conducted

Respuesta a la multiplicación agámica de clones selectos de Lippia integrifolia" "incayuyo"

Lippia integrifolia (Griseb.) Hieron. "incayuyo" es un arbusto aromático, subleñoso que crece en el noroeste y centro de Argentina. Se emplea tradicionalmente la decocción de sus hojas y flores para afecciones del tracto digestivo (Bonzani et al., 2003; Barboza et al., 2006). Se ha comprobado su actividad colerética, antiespasmódica (Gorzalczany et al., 2008), biocida en ensayos in vitro sobre Trypanosoma cruci (Sülsen et al., 2006), antibacteriana mediante extractos clorofórmicos, sobre bacterias de interés médico como Pseudomonas aeruginosa (Coronel et al., 2003), larvicida sobre larvas de mosquitos de Culex quinquefasciatus (Bonino, 2009), además se identificaron las propiedades antiadherentes de extractos acuosos de ?incayuyo? contra el principal inductor de la gastritis, la bacteria Helicobacter pylori (Marcial et al., 2014) Se lo emplea en bebidas aperitivas y yerbas compuestas (Juliani et al., 2007). La especie puede propagarse tanto por vía asexual o agámica como por vía sexual.Fil: Leiva, Romina Dolores. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; ArgentinaFil: Ojeda, M. S.. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; ArgentinaFil: Brunetti, Paula Cecilia. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Metabolic plasticity in the hygrophyte Moringa oleifera exposed to water stress

Over the past decades, introduction of many fast-growing hygrophilic, and economically valuable plants into xeric environments has occurred. However, production and even survival of these species may be threatened by harsh climatic conditions unless an effective physiological and metabolic plasticity is available. Moringa oleifera Lam., a multipurpose tree originating from humid sub-tropical regions of India, is widely cultivated in many arid countries because of its multiple uses. We tested whether M. oleifera can adjust primary and secondary metabolism to efficiently cope with increasing water stress. It is shown that M. oleifera possesses an effective isohydric behavior. Water stress induced a quick and strong stomatal closure, driven by abscisic acid (ABA) accumulation, and leading to photosynthesis inhibition with consequent negative effects on biomass production. However, photochemistry was not impaired and maximal fluorescence and saturating photosynthesis remained unaffected in stressed leaves. We report for the first time that M. oleifera produces isoprene, and show that isoprene emission increased three-fold during stress progression. It is proposed that higher isoprene biosynthesis helps leaves cope with water stress through its antioxidant or membrane stabilizing action, and also indicates a general MEP (methylerythritol 4-phosphate) pathway activation that further helps protect photosynthesis under water stress. Increased concentrations of antioxidant flavonoids were also observed in water stressed leaves, and probably cooperate in limiting irreversible effects of the stress in M. oleifera leaves. The observed metabolic and phenotypic plasticity may facilitate the establishment of M. oleifera in xeric environments, sustaining the economic and environmental value of this plant

Estimación del tamaño muestral para estudios de variabilidad morfológica in situde Lippia integrifolia (Verbenaceae) en el Parque Nacional Talampaya, La Rioja (Argentina)

Lippia integrifolia “incayuyo” is an aromatic and medicinal shrub of economic importance, distributed from Bolivia to northwestern and central Argentina. It has shown a wide variation between individuals of the same species, which could be the result of interaction with the environment and / or be genetically determined. On the basis of this variability, characterization studies are needed for further agronomic evaluations, plant breeding, selection, conservation and reproduction of specimen with desirable characteristics. The aim of this study is to determine, using two estimation methods, the minimum number of individuals to be assessed that represents in situ morphological variability of a population of L. integrifolia. From a preliminary sampling conducted in the Parque Nacional Talampaya, in which 11 morphometric characters were registered in L. integrifolia, a parametric and a nonparametric estimation of the Minimum Sample Size was performed. Based on the morphometric characters evaluated here it is recommended a minimum sample size in between 35-40 individuals, determined by the characters that showed greater variability, with which the morphological variability of the species would be guaranteedLippia integrifolia“incayuyo” es un arbusto aromático y medicinal de interés económico cuya distribución abarca desde Bolivia hasta el noroeste y centro de Argentina. Presenta una amplia variabilidad intraespecífica, la cual podría ser el resultado de la interacción con el ambiente y/o estar determinada genéticamente. Debido a esta variabilidad, estudios de caracterización son necesarios para posteriores evaluaciones agronómicas, mejoramiento genético, selección,reproducción y conservación de ejemplares con características deseables. El objetivo de este trabajo es determinar, utilizando dos métodos de estimación, el número de individuos mínimo a relevar in situque representen la variabilidad morfológica de una población de L. integrifolia. A partir de un muestreo preliminar realizado en el Parque Nacional Talampaya en el que se registraron 11 caracteres morfométricos en L. integrifolia, se realizó una estimación paramétrica y una no paramétrica del Tamaño Muestral Mínimo. Sobre la base de los caracteres morfométricos aquí evaluados se recomienda un tamaño de muestra mínimo de entre 35 a 40 ejemplares, determinado por los caracteres que mostraron mayor variabilidad, con el cual se garantizaría poder captar la variabilidad morfológica de la especie

Evaluation of the agronomic performance and taxonomic characterization of four clones of oregano (Origanum sp.)

The objectives of this study were to evaluate four clones of oregano grown in major production areas andcarry out the taxonomic identification of these clones. Four clones of oregano named as "Mendocino","Compacto", "Cordobés" and "Criollo" were field evaluated in two locations: La Consulta (Mendoza) andCapilla de los Remedios (Córdoba). The following traits were measured: plant height (taken as the length ofthe longest branch in cm), fresh weight (kg ha-1) and dry weight (kg ha-1) and the water (%) and fiber contentwere estimated. The fiber content was estimated as the ratio dry weight / fresh weight). The botanicalidentification of the tested clones was conducted using the identification keys proposed by Ietswaart, Xifredaand Rouquaud & Videla. Significant differences between environments and between clones were observed forall analyzed traits. From the botanical identification it was determined that the clone "Medocino" correspondsto the hybrid Origanum x majoricum, the clone "Compacto" belongs to the species Origanum vulgare sspvulgare and clones "Criollo" and "Cordobés" both belong to the species Origanum vulgare ssp hirtum. Thedifferences observed between clones in terms of their agronomic performance were consistent with the resultsof the taxonomic identification of the clones.Fil: Torres, Lorena Elizabeth. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; ArgentinaFil: Chaves, Ana Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Córdoba. Facultad de Cs.agropecuarias. Departamento de Fundamentación Biologica; ArgentinaFil: Barboza, Gloria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Brunetti, Paula Cecilia. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; ArgentinaFil: Bustos, J. A.. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; ArgentinaFil: Massuh, Yamile. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Ocaño, S.. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; ArgentinaFil: Castillo, N.. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; ArgentinaFil: Ojeda, M. S.. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; Argentin