Interactive effects of substrates and ectomycorrhizal colonization on growth of a poplar clone

A balsam poplar clone (Populus trichocarpa cv. Weser 6) was inoculated by two ectomycorrhizal strains (Laccaria bicolor MW 158 and Paxillus involutus 1444) in Kick‐Brauckmann‐pots. The substrates were two arable sandy soils (Cambisols) with different organic matter content and nutrient supply. One soil (WIL) was rich in organic matter (C_org = 1.6%) and total nitrogen (N_t = 0.14%), whereas the other soil (RIE) had low contents of C_org (0.8%) and N_t (0.08%). Leaf nutrient concentrations, shoot lengths, root and shoot biomass production and nitrogen accumulation in the biomass were determined to discover possible inoculation effects. Mycorrhization indices (% colonized fine roots) of 36% with Laccaria bicolor and 40% with Paxillus involutus were observed on the C_org rich soil (WIL) in contrast to 16% and 14% on the C_org poor soil (RIE), respectively. Inoculation of poplar on the soil WIL increased shoot length, biomass production, shoot:root ratio and total N uptake of the cuttings, whereas on the soil RIE only the shoot:root ratio increased and the N nutrition was improved. We conclude that interactions between soil and fungus should be tested when choosing ectomycorrhizal strains for inoculation.     

Long-term separate and combined effects of environmental hypercapnia and hyperoxia in Atlantic salmon (Salmo salar L.) smolts

Atlantic salmon (Salmo salar L.) parr (mean start weight 50 g) were reared in freshwater (FW) and exposed to three levels of oxygen saturation measured in effluent water; control group (93% O₂, LO₂), medium (111% O₂, MO₂) and high (123% O₂, HO₂). Further three groups were exposed to similar water oxygen levels in combination with elevated carbon dioxide levels (17–18 mg L^– 1 CO₂), named LO₂–CO₂, MO₂–CO₂ and HO₂–CO₂, respectively. The experiment was run in duplicate tanks for 42 days, and the fish were subsequently transferred to the same seawater (SW) regime for 45 days for an assessment of post-smolt growth. As a consequence of the CO₂ addition, tank pH levels in the FW period were reduced from 6.7 to 5.9 for the hypercapnia groups compared to for the normcapnia groups. Water temperature in FW ranged between 6.4 and 9.0 °C. Citrate was added to the water to complex labile aluminium.In the CO₂ groups observed ventilation frequencies were significantly increased compared to the control (p < 0.05). This difference declined towards the end of the FW period, suggesting acclimation to elevated CO₂. The degree of oxygenation appeared to contribute to the acclimation as the lowest mean ventilation frequency on day 36 was found in the HO₂–CO₂ group and the highest in the LO₂–CO₂ group. Lower plasma chloride and sodium levels were observed in the CO₂ groups relative to the respective oxygenation groups during the FW period, while plasma chloride and sodium levels were normalised to equal levels for all groups after 44 days in SW. No significant differences were found among treatments for blood concentrations of red blood cells, haemoglobin, potassium and glucose during the experiment.By termination of the FW period, the HO₂ group had significantly higher body weight than all other groups (p < 0.05), with specific growth rate significantly higher than the CO₂ groups (p < 0.05). Further, the condition factor was significantly lower in all the CO₂ groups at the end of the FW period compared to the control and normcapnia groups (p < 0.05). Although variable among replicates, occurrence of nephrocalcinosis was 10 times higher in the hypercapnia groups than in the control and normcapnia groups. Mortality was negligible (< 2.0%) during the trial, and most of the mortality occurred following SW transfer.     

Fimbriae in Escherichia coli isolated from the small intestine of piglets

Ninety E. coli strains, isolated from piglets which had died from neonatal diarrhea, were tested for the presence of K88, K99, 987P and type 1 fimbriae. Two or more types of fimbriae were demonstrated in 14 of the strains, a single fimbria! type in 44 strains while in 32 strains no fimbriae were detected. Of the 14 E. coli strains with more than 1 type of fimbriae, 12;, 10, 8 and 4 strains showed K88, K99, 987P and type 1, respectively.Twelve E. coli strains were isolated from piglets which had died in the neonatal period without showing signs of neonatal diarrhea at necropsy. One strain showed 987P and 3 strains showed type 1 fimbriae, while the remaining 8 strains were unfimbriated.Sixteen fimbriated E. coli strains were subcultured in order to examine the stability of fimbrial expression in the strains. The K88 and the type 1 fimbriae were regularly expressed, while the K99 and 987P were inconsistently demonstrated.     

Radial agenesis and ulnar hypoplasia in two caprine kids

Two of three caprine triplets caused dystocia due to malformed forelimbs. This malformity was caused by radial agenesis and ulnar hypoplasia. Other congenital anomalies were also present. The influence of diet versus genetics could not be ascertained. Bilateral ulnar fractures in one kid revealed histologically rounded fracture ends with prominent periosteal new bone formation.     

Antioxidant and 15-lipoxygenase inhibitory activity of rotenoids, isoflavones and phenolic glycosides from Sarcolobus globosus

From Sarcolobus globosus, two rotenoids (villosinol and 6-oxo-6a,12a-dehydrodeguelin), one isoflavone (genistin) and four phenolic glycosides (vanillic acid 4-O-beta-d-glucoside, glucosyringic acid, tachioside and isotachioside) were identified for the first time from this species. Extracts and compounds from S. globosus were evaluated for their DPPH radical scavenging and 15-lipoxygenase (15-LO) inhibitory activities. All tested rotenoids were found to inhibit 15-LO, while they lacked DPPH radical scavenging effect.     

A New Method to Produce 4× Triticales and their Application in Studying the Development of a New Polyploid Plant

F₁ hybrids of triticale × rye derived from commercial varieties were backcrossed to the respective triticale parent. Selfing of the backcross generation yielded a large number of 4× triticales containing a genetically balanced wheat genome. This indicates that the 28-chromosome F₁ plants with the genomic constitution of ABRR produced functional 14-chromosome gametes in high frequency each with a complete wheat and rye genome. The cytological mechanism leading to the formation of tetraploid triticales is described. The chromosomal constitution of the wheat genome in the progenies of 30 back cross plants was analysed by the C-banding technique. One offspring possessed a complete B genome of wheat. The production of tetraploid triticale through backcrossing in comparison to selfing the ABRR hybrid is largely independent of the genotype; it leads to new tetraploids in just three generations and it reduces the chance of translocations between the homoeologous wheat chromosomes. The possibility of studying the effect of different mixtures of chromosomes of the A and B genomes of wheat on the phenotype of the tetraploid triticale is discussed.     

Taxonomy of Mexican landraces of maize,Zea mays,based on their resistance to European corn borer,Ostrinia nubilalis

Summary The resistance to the European corn borer, Ostrinia nubilalis (Hubner), of thirty-seven indigenous landraces of Mexican maize was examined. The relationship of resistance and existing taxonomy of maize according to Wellhausen et al., (1952), was subjected to numerical analyses. Variables examined were: seedling DIM-BOA content, the extent of leaf feeding damage by early instar larvae both in the field and in the laboratory, the extent of plant breakage and stalk tunneling by late instar larvae, plant height, and the extent of fungal damage by Gibberella zeae and Ustilago maydis. Significant differences in resistance among the major taxonomic groupings were reflected in the existing taxonomy of maize (Wellhausen et al., 1952). The most resistant landrace grouping was Wellhausen et al.'s Prehistoric Mestizos. Eighty-five percent of a series of modern inbred lines, pools, and Argentine landraces were found to have affinities with one of the more susceptible groupings, the Ancient Indigenous Races, based upon analysis of the resistance data.     

Resistance gene analogs associated with Fusarium head blight resistance in wheat

Fusarium head blight (FHB) is one of the most destructive diseases in wheat. Identification of resistance gene analogs (RGAs) may provide candidate genes for cloning of FHB resistance genes and molecular markers for marker-assisted improvement of wheat FHB resistance. To identify potential RGAs associated with FHB resistance in wheat, 18 primer pairs of RGAs were screened between two parents (Ning7840 and Clark) and seven informative RGA primer combinations were analyzed in their recombinant inbred lines (RILs). Five PCR products amplified from three primer combinations showed significant association with FHB resistance, and their sequences are similar to the gene families of RGAs. Three of them (RGA14-310, RGA16-462, RGA18-356) were putatively assigned to chromosome 1AL and explained 12.73%, 5.57% and 5.9% of the phenotypic variation for FHB response in the F₇ population, and 10.37%, 3.37% and 4.53% in F₁₀ population, respectively; suggesting that these RGAs may play a role in enhancing FHB resistance in wheat. Analysis of nucleotide sequence motifs demonstrated that all the RGA markers contain a heat shock factor that initiates the production of heat shock proteins. A sequence tagged site (STS) marker (FHBSTS1A-160) was successfully converted from RGA18-356, and validated in fourteen other cultivars. Significant interaction between the quantitative trait locus (QTL) on 1AL and the QTL on 3BS was detected. The marker FHBSTS1A-160 in combination with markers linked to the major QTL on 3BS could be used in marker-assisted selection (MAS) for enhanced FHB resistance in wheat.     

Organic acids in root exudates from Picea abies seedlings influenced by mycorrhiza and aluminum

Organic acid anions exuded from roots of Picea abies (Norway spruce) seedlings grown on glass beads in the presence and absence of mycorrhiza (Laccaria bicolor) and aluminum (Al) at pH 3.9 were measured. We wanted to test if the roots exuded more organic acid anions when exposed to Al and if mycorrhization influenced the exudation. Oxalate was exuded in far higher amounts than any other organic acid anion, with a maximum rate of 1.7 nmol (mg root DW)^–1 d^–1. Mycorrhizal roots exuded significantly more oxalate than nonmycorrhizal roots. The presence of Al did not enhance oxalate exudation. We conclude that the oxalate exuded constitutively by Picea abies/Laccaria bicolor may lead to rhizosphere oxalate concentrations that are relevant for Al resistance.