Production of nonfood species is promoted to marginal, degraded lands abandoned by mainstream agriculture, where extremes of water availability (droughts and floods) have increased frequency and intensity and account for severe yield reduction. Arundo donax L., common name giant cane or giant reed, is a plant that grows spontaneously in different kinds of environments with limitation to low temperature and thus widespread in temperate and hot areas all over the world. Moreover, this perennial rhizomatous grass has been identified as a leading candidate crop for lignocellulosic feedstock in the Mediterranean environment, due to its high C3 photosynthetic capacity, positive energy balance and low agro-ecological management demand. In this study, the photosynthetic performance and growth response of A. donax to waterlogging and submergence stress following a time course, as well as their respective re-oxygenation were analyzed under reproducible and controlled environment conditions. Results of growth response showed that biomass production was strongly conditioned by the availability of oxygen. In fact, only waterlogged plants showed similar growth capacity to those under control conditions, while plants under submergence resulted in a dramatic reduction of this trait. The simultaneous measurements of both gas exchanges and chlorophyll fluorescence highlighted an alteration of both stomatal and non-stomatal photosynthetic behaviors during a short/medium period of oxygen deprivation and re-oxygenation. Photosynthetic CO2 uptake was strictly related to a combination of stomatal and mesophyll diffusional constrains, depending on the severity of the treatment and exposure time. Conditions of waterlogging and hypoxia revealed a slight growth plasticity of the species in response to prolonged stress conditions, followed by a fast recovery upon reoxygenation. Moreover, the rapid restoration of physiological functions after O2 deprivation testifies to the environmental plasticity of this species, although prolonged scarcity of O2 proved detrimental to A. donax by hampering growth and photosynthetic CO2 uptake.
Abstract The goal of this study was to define whether cuticular hydrocarbons ( CH s) could be used for taxonomic determination of putative species hidden in the A nastrepha fraterculus cryptic species complex, widespread from A rgentina to M exico. Recently, increasing evidence of phenotypic and genetic variability has resulted in the characterization of eight morphotypes within this complex. The CH profiles of six A . fraterculus populations from A rgentina, B razil, P eru, C olombia and M exico were analysed in this study by two‐dimensional gas chromatography coupled with mass spectrometry. In parallel, multiple factorial analyses were used to elucidate population structures. Vector populations segregated into four distinct groups. The analysis demonstrated that the studied populations from P eru, A rgentina and southern B razil ( V acaria) might be classified in accordance with the earlier division of the A . fraterculus complex into P eruvian, and B razilian‐1 cryptic species, using the specific CH profiles. Population from south‐eastern B razil ( P iracicaba) formed separated group. Mexican and A ndean ( C olombian) putative species had similar CH signatures, when compared to each other.
BACKGROUND. Orobanche ramosa L. (hemp broomrape) is one of the worst weeds affecting tobacco. It causes severe quanti-qualitative damage to production, and selective herbicides for control of this parasite are virtually non-existent. Thus the possibility of combating its development with an innovative stimulant designed to induce prior germination in the field may be of considerable interest. METHODS. Laboratory and field tests were conducted to test the effect of an experimental germination stimulant (Nijmengen 1 preparation ‐ BASF) on buried seed. Attention focused particularly on seedbank reduction following distribution of the stimulant prior to planting out the crop. RESULTS. Seedbank reduction was greatest in the upper 10 cm of soil (roughly 75% reduction), but became less marked with increasing seed burial depth. Seedbank reduction resulted in a smaller percentage of parasitized plants and a lesser emergence of spikes. Affected plants showed stunted growth and a lower macronutrient content in the various plant organs. CONCLUSIONS. The experimental stimulant was effective in achieving some reduction in the seedbank. However, the product is likely to be fully successful agronomically only if applied repeatedly over time, in order to enable it to take effect in the different soil horizons after a number of tillage operations.
A large expansion in renewable energy production is underway with an increasing focus on sustainable second-generation biofuels.Fast growing rhizomatous perennial grasses are leading candidates for lignocellulosic feedstock thanks to their positive energy balance, and low ecological/agro-management demands.Biomass accumulation is favored by the efficient use of available resources.The aim of this study was to identify which accumulation processes were most affected in the establishment year of a giant reed (Arundo donax L.) field crop grown under water and N deficiencies.The relative plasticity of growth of A. donax in response to various levels of resource availability was evaluated.A field scale experiment was carried out, and treatments were arranged as a randomized complete block, strip-plot design with irrigation treatments as the main plot factor and pre-planting N rate as the sub-plot factor.Biometric relationships between variables were assessed to understand how agro-management factors influence the above ground biomass of giant reed, as well as yield over time.Evidence is presented indicating that growth is strongly enhanced by water availability (+97% dry weight biomass).Changes in composition were not significant within or among fixed treatments, rather changes were observed over time.A high content of glucans and xylans were detected from early stage, and as the mobilization of minerals increased, lignin content significantly increased as well (from 12% to 36% w/w).These results suggest that an increase in the growth of A. donax in the establishment year is accomplished by a limited use of the water input.
Calcineurin (CN) inhibitors are effective clinical immunosuppressants but leave patients vulnerable to potentially fatal fungal infections. This study tested the hypothesis that CN inhibition interferes with antifungal immune defenses mediated by monocytes. We showed that NFAT is expressed by human monocytes, and is activated by exposure to fungal ligands. We confirmed that NFAT translocation potently activated target gene transcription using a human monocytic reporter cell line. Inhibition of CN-NFAT by cyclosporine A significantly reduced monocyte production of TNF-α, IL-10, and MCP-1 proteins in response to pattern recognition receptor ligands as well as to Aspergillus fumigatus conidia. Moreover, we revealed that human monocytes express the antifungal protein pentraxin-3 under control of NFAT. In conclusion, clinical CN inhibitors have the potential to interfere with the novel NFAT-dependent pentraxin-3 pathway as well as antifungal cytokine production in human monocytes, thereby impeding monocyte-mediated defenses against fungal infection in immune-suppressed patients.
Salinity stress impairs growth and physiological performance in tomato, which is one of the most economically important vegetables and is widely cultivated in arid and semi-arid areas of the world. Plant landraces, which are heterogeneous, local adaptations of domesticated species, offer a unique opportunity to valorize available germplasm, underpinning the productivity, resilience, and adaptive capacity of staple crops in vulnerable environments. Here, we investigated the response of fully mature tomato plants from a commercial variety, an ancestral wild relative, and a landrace under short-term salinity exposure, as well as their ability to recover upon cessation of stress. The heterogeneous panel evaluated in this study revealed different adaptative strategies to cope the stress. Our data highlighted the ability of the tomato clade to handle low and intermediate salinity stress for short-term exposure time, as well as its capacity to recover after the cessation of stress, although inter- and intraspecific variations in morphological and physiological responses to salinity were observed. Overall, the landrace and the wild type performed similarly to control conditions under low salinity, demonstrating an improved ability to maintain ionic balance. In contrast, the commercial genotype showed susceptibility and severe symptoms even under low salinity, with pronounced reductions in K+/Na+ ratio, PSII photochemical efficiency, and photosynthetic pigments. This research confirmed that improved salt tolerant genotypes can lead to substantial, positive impacts on horticultural production. While the salt tolerance mechanism of domesticated tomato was efficient under mild stress conditions, it failed at higher salinity levels.
