SummaryStrigolactones are plant hormones that regulate both above-and belowground plant architecture. Strigolactones were initially identified as rhizosphere signaling molecules. In the present work, the tomato (Solanum lycopersicum) CAROTENOID CLEAVAGE DIOXYGENASE 8 (SlCCD8) was cloned and its role in rhizosphere signaling and plant physiology assessed by generating knock-down lines.Transgenic SlCCD8 plants were generated by RNAi-mediated silencing. Lines with different levels of strigolactone reduction -confirmed by UPLC-MS/MS -were selected and their phenotypes investigated.Lines exhibiting reduced SlCCD8 levels displayed increased shoot branching, reduced plant height, increased number of nodes and excessive adventitious root development. In addition, these lines exhibited reproductive phenotypes such as smaller flowers, fruits, as well as fewer and smaller seeds per fruit. Furthermore, we show that strigolactone loading to the xylem sap is possibly restricted to orobanchol.Infestation by Phelipanche ramosa was reduced by 90% in lines with a relatively mild reduction in strigolactone biosynthesis and secretion while arbuscular mycorrhizal symbiosis, apical dominance and fruit yield were only mildly affected. This demonstrates that reduction of strigolactone biosynthesis could be a suitable tool in parasitic weed management. Furthermore, our results suggest that strigolactones are involved in even more physiological processes than so far assumed.
To better manage invasive populations, it is vital to understand the environmental drivers underlying spatial variation in demographic performance of invasive individuals and populations. The invasive common ragweed, Ambrosia artemisiifolia, has severe adverse effects on agriculture and human health, due to its vast production of seeds and allergenic pollen. Here, we identify the scale and nature of environmental factors driving individual performance of A. artemisiifolia, and assess their relative importance. We studied 39 populations across the European continent, covering different climatic and habitat conditions. We found that plant size is the most important determinant in variation of per-capita seed and pollen production. Using plant volume as a measure of individual performance, we found that the local environment (i.e. the site) is far more influential for plant volume (explaining 25% of all spatial Published in "Biological Invasions doi: 10.1007/s10530-017-1640-9, 2018" which should be cited to refer to this work. variation) than geographic position (regional level; 8%) or the neighbouring vegetation (at the plot level; 4%). An overall model including environmental factors at all scales performed better (27%), including the weather (bigger plants in warm and wet conditions), soil type (smaller plants on soils with more sand), and highlighting the negative effects of altitude, neighbouring vegetation and bare soil. Pollen and seed densities varied more than 200-fold between sites, with highest estimates in Croatia, Romania and Hungary. Pollen densities were highest on arable fields, while highest seed densities were found along infrastructure, both significantly higher than on ruderal sites. We discuss implications of these findings for the spatial scale of management interventions against A. artemisiifolia.
The genetic relationship between 195 Mangalica and 79 non-Mangalica pigs was studied using mitochondrial D-loop SNP genotyping. Altogether, 35 polymorphic sites and 27 haplotypes were identified. Of the haplotypes, eight and 16 are Mangalica and non-Mangalica specific, respectively, while three contain both Mangalica and non-Mangalica individuals. Genetic distance values and phylogenetic analysis indicate that Mangalica individuals are very closely related, and five haplotypes represent approximately 92% of the Mangalica pigs involved in the study, thus determining the major maternal lineages. In contrast to previous microsatellite studies, individuals of Mangalica could not be distinguished as three separate breeds using mtDNA genotyping. Comparing modern and archaeological mtDNA sequences revealed that present day Mangalica is related to pigs that lived in the Carpathian basin where postulated ancestors of Mangalica also lived. This is the first DNA-based genetic evidence to support the described breeding history of Mangalica.
Transient spark (TS), a DC-driven self-pulsing discharge generating a highly reactive atmospheric pressure air plasma, was employed as a rich source of NOx. In dry air, TS generates high concentrations of NO and NO2, increasing approximately linearly with increasing input energy density (Ed), reaching 1200 and 180 ppm of NO and NO2, at Ed = 400 J/L, respectively. In humid air, the concentration of NO2 decreased down to 120 ppm in favor of HNO2 that reached approximately 100 ppm at Ed = 400 J/L. The advantage of TS is its capability of simultaneous generation of the plasma and the formation of microdroplets by the electrospray (ES) of water directly inside the discharge zone. The TS discharge can thus efficiently generate plasma-activated water (PAW) with high concentration of H2O2−(aq), NO2−(aq) and NO3−(aq), because water microdroplets significantly increase the plasma-liquid interaction interface. This enables a fast transfer of species such as NO, NO2, HNO2 from the gas into water. In this study, we compare TS with water ES in a one stage system and TS operated in dry or humid air followed by water ES in a two-stage system, and show that gaseous HNO2, rather than NO or NO2, plays a major role in the formation of NO2−(aq) in PAW that reached the concentration up to 2.7 mM.
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