A simple molecular approach for identifying a rare Acronychia (Rutaceae) provides new insights on its multiple hybrid origins

Hybridization plays an important role in the evolution of plant diversity. Nonetheless, it is often difficult to clearly ascertain hybrid origin by assessing morphological characters alone. Acronychia littoralis (Rutaceae) is a recently described rare tree from littoral rainforests in eastern Australia. Two forms have been tentatively distinguished on the basis of different leaf morphology however, because of the variability of the discriminatory characters across populations (and in some cases across single individuals), compiling data on the exact distribution of each form has been a difficult process. To further complicate matters, some of these distinguishing morphological characters are intermediate between those of closely related, sympatric species. As a result, simple molecular techniques were developed to assist the development of adequate conservation and management strategies for A. littoralis and to better understand its evolutionary history. Sequence data from the ITS2 region were obtained and haplotype specific primers that distinguished the two forms and the related taxa were developed. Sequence data suggest that the two forms of A. littoralis are each of hybrid origin but both involve different parental taxa. The findings provide a perspective on the evolutionary dynamics of the local rainforest flora and highlight the need for phylogenetic evaluation of rare taxa where there is taxonomic ambiguity.     

Do Collembola affect the competitive relationships among soil-borne plant pathogenic fungi?

The feeding preference of the collembolan Protaphorura armata in the presence of Fusarium culmorum and Gaeumannomyces graminis var. tritici, two soil-borne fungi pathogenic for winter cereals, was studied in a simplified experimental system including wheat seedlings. Analysis of gut content of all animals from microcosms containing inoculum of both fungi showed that F. culmorum was clearly preferred but that G. graminis var. tritici was also fed. At microscopic examination the majority of F. culmorum conidia present in the gut lacked cytoplasmic content, and only few conidial cells were intact. The feeding preference of P. armata favoured G. graminis var. tritici over F. culmorum in the competition for infection sites on wheat plants; in fact, the former resulted the prevalent cause of plant disease.

The viability of fungal propagules after passage through the gut of P. armata was also studied. No colonies of G. graminis var. tritici and only a few colonies of F. culmorum developed from faecal pellets set on agar medium. Fungal propagules dispersed by springtails were not sufficient to induce disease, as demonstrated by introducing animals, previously fed on fungal cultures separately, into microcosms containing a sterile substrate where wheat kernels were seeded.     

Allelic variation of the ACCase gene and response to ACCase-inhibiting herbicides in pinoxaden-resistant Lolium spp

BACKGROUND: The repeated use of acetyl‐coenzyme A carboxylase (ACCase) inhibiting herbicides to control grass weeds has selected for resistance in Lolium spp. populations in Italy. The efficacy of pinoxaden, a recently marketed phenylpyrazoline herbicide, is of concern where resistance to ACCase inhibitors has already been ascertained. ACCase mutations associated with pinoxaden resistance were investigated, and the cross‐resistance pattern to clodinafop, haloxyfop, sethoxydim, clethodim and pinoxaden was established on homo/heterozygous plants for four mutant ACCase alleles. RESULTS: Seven different mutant ACCase alleles (1781‐Leu, 1999‐Leu, 2041‐Asn, 2041‐Val, 2078‐Gly, 2088‐Arg and 2096‐Ala) and 13 combinations with two types of mutation were detected in the pinoxaden‐resistant plants. The 1781‐Leu allele appears to confer a dominant resistance to pinoxaden, clodinafop, haloxyfop, sethoxydim and clethodim at 60 g AI ha^?1. The 2041‐Asn and 2041‐Val alleles are associated with dominant or partially dominant resistance to FOPs, no substantial resistance to DIMs and a moderate resistance to pinoxaden. The 2088‐Arg allele endows a partially dominant resistance to clodinafop, sethoxydim and most likely to pinoxaden. In addition, non‐target‐site resistance mechanisms seem to be involved in pinoxaden resistance. CONCLUSION: Almost all the ACCase mutations selected in the field by other ACCase inhibitors are likely to confer resistance to pinoxaden. Although pinoxaden is sometimes able to control FOP‐resistant populations, it should not be considered as a sustainable ACCase resistance management tool. The presence of non‐ACCase‐based resistance mechanisms that could confer resistance to herbicides with different modes of action further complicates the resistance management strategies. Copyright © 2011 Society of Chemical Industry     

Synaptic pruning by microglia is necessary for normal brain development

Microglia are highly motile phagocytic cells that infiltrate and take up residence in the developing brain, where they are thought to provide a surveillance and scavenging function. However, although microglia have been shown to engulf and clear damaged cellular debris after brain insult, it remains less clear what role microglia play in the uninjured brain. Here, we show that microglia actively engulf synaptic material and play a major role in synaptic pruning during postnatal development in mice. These findings link microglia surveillance to synaptic maturation and suggest that deficits in microglia function may contribute to synaptic abnormalities seen in some neurodevelopmental disorders.     

Formation of Damascenone under both commercial and model fermentation conditions

The fermentations, at a commercial winery, of six different grape musts encompassing the varieties Riesling, Chardonnay, Sauvignon blanc, Shiraz, Grenache, and Pinot noir were monitored for damascenone concentration. In every case, the concentration of damascenone increased during fermentation from low or undetectable levels to concentrations of several parts per billion. Further increases in damascenone concentration were observed during barrel aging of three of these wines. Two ketones, megastigma-4,6,7-triene-3,9-dione (4) and 3-hydroxymegastigma-4,6,7-trien-9-one (5), were synthesized and subjected to fermentation conditions using two yeasts, AWRI 796, and AWRI 1537. In the case of the former compound, 4, synthesis confirmed the original, tentative assignment of the structure and confirmed 4 as a natural product, isolated from honey. Both compounds, under the action of both yeasts, produced appreciable amounts of damascenone (1), with ketone 5 and AWRI 796 yeast yielding the highest concentration of 1.     

Effect of soil moisture and transpiration on mineral content in leaves and berries of cabernet sauvignon grapevine

Leaf and berry transpiration ratio in grapevine (Vitis vinifera L.) was found to be affected by soil moisture. With the condition of diminished soil moisture, berry transpiration is higher prior to vèraison compared to conditions when the water content in the substrate is higher and berry transpiration decreases with an increase of leaf transpiration. Studies were conducted in 1993 and 1994 to investigate the link between soil moisture, traspiration, and accumulation of certain mineral elements in leaves and berries on plants of the Cabernet sauvignon cultivar grafted on Kober 5 BB rootstock. Leaf and berry transpiration and mineral accumulation were evaluated by gaseous exchange measurements, soil sampling and moisture analysis, and leaf and berry sampling and analysis of mineral content. Observations were repeated at about 15‐day intervals between full bloom and berry ripening. Transpiration per unit of surface area (mmol H₂O m^‐2 s^‐1) was always higher in leaves than in berries. Leaf transpiration varied from 5.62 mmol H₂O m^‐2 s^‐1 to 2.92 mmol H₂O m^‐2 s^‐1 in 1993 in the period between the 8th and 86th day after full bloom (DAFB), and from 6.49 mmol H₂O m^‐2 s^‐1 to 4.37 mmol H₂O m^‐2 s^‐1 in 1994 between the 12th and 94th DAFB. Berry transpiration ranged between 3.86 mmol H₂O m^‐2 s^‐1 and 1.04 mmol H₂O m^‐2 s^‐1 in 1993 and between 4.34 mmol H₂O m^‐2 s^‐1 and 0.5 mmol H₂O m^‐2 s^‐1 in 1994. Leaf transpiration was not correlated with the mineral element content in the leaves, whereas berry transpiration was directly correlated with the nitrogen (N), calcium (Ca), potassium (K), and phosphorus (P) content in berries. Leaf mineral composition was affected only for iron (Fe) content by the variation on soil moisture, whereas the berry N, P, K, and Ca contents were positively correlated with soil water content. The leaf and berry Ca content appeared to be greater with high soil moisture, i.e., in conditions which favor intense metabolism of the whole plant.     

Olive mill wastewater spreading and AMF inoculation effects in a low-input semi-arid Mediterranean crop succession

ABSTRACT

The study aimed to evaluate, in a marginal semi-arid Mediterranean agro-ecosystem (Sicily-Italy), the effects of arbuscular mycorrhizal fungi (AMF) inoculation and raw olive mill wastewater (OMW) (40 and 80 m³ ha^?1) on forage (durum wheat-snail medick intercropping) yield, and grain production of broad bean and chickpea. AMF inoculation significantly increased (+13.6%) forage dry biomass and durum wheat nitrogen (+22.8%) and phosphorus (+32.5%) uptake. AMF inoculation, significantly promoted broad bean phosphorus uptake (+11.5%) and root nodule number (+13.9%) in the absence of OMW. OMW spreading reduced weeds in the forage (?31.3%), root nodule number (?29.7%) and dry weight (?22.7%) in broad bean. OMW also significantly increased snail medick dry biomass (+19.3%) as compared to control treatments (0, 40 and 80 m³ H₂O ha^?1, average production 361 g m^?2), and broad bean grain yield with a production of 2.46 ± 0.12 and 1.94 ± 0.09 Mg ha^?1 with and without OMW, respectively. During the experiment AMF colonization was not affected by OMW volumes. The results obtained showed that in a marginal Mediterranean agro-ecosystem: 1) OMW, notwithstanding spreading volumes, is a valuable amendment to maximize legume yield while 2) AMF inoculation is a valuable practice to improve biomass production and N and P uptake in wheat.     

Response of rainbow trout gill (Na++K+)-ATPase and chloride cells to T3 and NaCl administration

With the aim of comparing the effects of oral T₃ and NaCl administration on trout hypoosmoregulatory mechanisms, three groups of rainbow trout (Oncorhynchus mykiss Walbaum) held in freshwater (FW) were fed a basal diet (C), the same diet containing 8.83 ppm of 3,5,3-triiodo-L-thyronine (T₃) (T) or 10% (w/w) NaCl (N) respectively for 30 d. They were then transferred to brackish water (BW) for 22 d and fed on diet C. Gill (Na⁺+K⁺)-ATPase activity and its dependence on ATP, Na⁺ and pH, number of gill chloride cells (CC), serum T₃ level as well as fish growth, condition factor (K) and mortality were evaluated. During the FW phase, as compared to C trout, T trout showed a two fold higher serum T₃ level, had unchanged gill (Na⁺+K⁺)-ATPase activity and increased CC number, whereas N trout showed higher gill (Na⁺+K⁺)-ATPase activity and CC number. At the end of the experiment the enzyme activity was in the order T>N>C groups and all groups showed similar CC number. Both treatments changed the enzyme activation kinetics by ATP and Na⁺. A transient increase in K value occurred in N group during the period of salt administration. In BW, T and N groups had higher and lower survival than C group respectively. Other parameters were unaffected by the treatments. This trial suggests that T₃ administration promotes the development of hypoosmoregulatory mechanisms of trout but it leaves the (Na⁺+K⁺)-ATPase activity unaltered till the transfer to a hyperosmotic environment.     

Multiple functions of buffer strips in farming areas

Buffer strips (BSs) are strips interposed between fields and streams that intercept and treat the waters leaving cropland, and so are a useful tool for reducing agricultural diffuse pollution in lowland areas. If properly vegetated and managed, they can also produce wood for burning, act as sinks for atmospheric CO₂ and enhance the landscape beauty.The paper presents an analysis of the different functions of BS and reviews the more important data from research programmes conducted over the last decade in Veneto Region (North-East Italy). Over a period of 3–5 years, in two experimental sites, young BS reduced total runoff by 33%, losses of N by 44% and P by 50% compared to no-BS. A mature BS was able to abate both NO₃–N and dissolved phosphorus concentrations by almost 100%, in most cases having exiting water that satisfied the limit for avoiding eutrophication. The BS also proved to be a useful barrier for herbicides, with concentrations abated by 60% and 90%, depending on the chemical and the time elapsed since application. Considering the CO₂ immobilized in the wood and soil together, the different BS monitored stored up to 80 t ha^?1 year^?1.The BS caused negligible disturbance to maize, soybean and sugarbeet yields. The hedgerows, particularly if composed of trees taller than 6 m, positively influenced the aesthetic value of the territory, improving its perceived naturalness and screening the man-made elements.Lastly, through a multi-objective analysis, opportunity costs were estimated to support the public decision-maker in determining the subsidies to be paid to encourage farmers to plant BS.