Use of zoospores of Polymyxa betae in screening beet seedlings for resistance to beet necrotic yellow vein virus

A system to culture viruliferousPolymyxa betae and to produce zoospores is described. The zoo spores were used for inoculation of beet seedlings, grown in nutrient solution, in tests for resistance to beet necrotic yellow vein virus (BNYVV). On most occasions in a time course experiment, and with various zoospore cultures, the partially resistant cultivar Rima and the accession Holly-1–4 had virus concentrations similar to the susceptible cultivar Regina, but the virus concentration inBeta vulgaris ssp.maritima accession WB42 was significantly lower (P<0.05). ‘Regina’ could be distinguished from various resistant accessions by a significantly higher virus concentration (P<0.05) shortly after inoculation, or after transplanting the seedlings from the nutrient solution into sand. Results of screening for resistance to BNYVV, using zoospores for inoculation, did not correspond with results of a test in which infested soil was used.Tests in which seedlings are grown in nutrient solution and inoculated with zoospores are suitable for the detection of accessions with a high level of resistance to BNYVV. To obtain virus infection in all plants, the optimal density of the zoospore suspension should first be determined and plants should be assayed shortly after inoculation.     

Influence of threonine intake on whole-body protein deposition and threonine utilization in growing pigs fed purified diets.

The relationship between available threonine (Thr) intake and whole-body protein deposition (PD) was established using the serial slaughter method in 36 individually housed growing gilts between 39 and 77 kg live BW. Pigs were prescreened for their maximum PD (PDmax), based on a N balance starting at 25 kg BW while they consumed semi-ad libitum a nonlimiting diet. Pigs were fed combinations of a casein and cornstarch-based diet that was confirmed to be first-limiting in Thr and a protein-free diet starting at approximately 30 kg BW. Casein-bound Thr was provided at 60, 70, 80, 90, 100, or 120% of estimated Thr requirements for PDmax. Energy intake was kept constant across treatments and exceeded requirements for PDmax. Pigs were fed three equal meals per day; feeding levels were adjusted weekly based on BW. Pigs were killed at either 39 kg BW (n = 2 per treatment) or 77 kg BW (n = 4 per treatment) for determining chemical body composition. Composition of 39-kg BW pigs was not different across treatments (P > 0.10); therefore, an overall mean initial body composition was used to estimate body protein content at the initial BW. Across treatments, mean daily ME intake was 25.3 (SE 0.08) MJ/d and did not differ (P > 0.10) among treatments. Average daily true ileal digestible Thr intake varied between 5.33 and 9.66 g/d, representing means for pigs on the lowest and the highest Thr intakes, respectively. Mean PD was 93, 102, 118, 124, 139, and 133 (SE 4.2) g/d for pigs on the six respective treatments. Dietary Thr intake did not influence (P > 0.10) Thr content of body protein at the final BW or the partitioning of body protein between carcass, viscera, and blood. The efficiency of Thr utilization for PD was lowest (P < 0.05) at the highest Thr intake level and highest (P < 0.05) at the lowest Thr intake level. It was similar (P > 0.10) at the four intermediate Thr intake levels, in which the relationship between true ileal digestible Thr intake and PD was linear. Based on these four treatments, calculated Thr disappearance, which is closely associated with inevitable Thr catabolism, was 23.5 (SE 0.55)% of available Thr intake. This value is consistent with an efficiency of using available Thr intake above maintenance Thr requirements (54 mg/kg BW0.75) for Thr retention with PD of 73.4 (SE 1.11)%. Based on N balances conducted at approximately 40 and 75 kg BW, the marginal efficiency of Thr utilization was not influenced by BW.     

The ecology and conservation of Kunzea sinclairii (Myrtaceae), a naturally rare plant of rhyolitic rock outcrops

Kunzea sinclairii is a local endemic on Great Barrier Island, northeastern New Zealand. While variously ranked as vulnerable and endangered in the past, we show that this species is naturally uncommon and under no threat of extinction. Previous assessments of its conservation status have been based on inadequate knowledge of its ecology. K. sinclairii is a rupestral species whose optimum habitat is low shrubland on rhyolitic rock outcrops and cliffs. Because of past logging and burning of forest adjacent to the habitat to which it is adapted, K. sinclairii expanded its range. However, in regeneration back to forest, K. sinclairii is being excluded as it is overtopped by other species. This has led to the impression that it is declining. Similarly, a suggestion that K. sinclairii could be threatened by hybridisation with the more abundant closely related K.ericoides is not supported as the hybrids are confined to the disturbed sites created by logging and fire. This case study highlights the importance of having a good understanding of the ecology of uncommon plant species before making decisions on their conservation. Natural rarity does not itself necessarily equate with increased extinction risk and these taxa should not be classified as threatened.     

Die Beziehungen zwischen Lebensraum und Lebensäußerungen von Insekten

Ohne Zusammenfassung Mit 3 Abbildungen     

Establishment of a standard operating procedure for predicting the time of calving in cattle

Precise calving monitoring is essential for minimizing the effects of dystocia in cows and calves. We conducted two studies in healthy cows that compared seven clinical signs (broad pelvic ligaments relaxation, vaginal secretion, udder hyperplasia, udder edema, teat filling, tail relaxation, and vulva edema) alone and in combination in order to predict the time of parturition. The relaxation of the broad pelvic ligaments combined with teat filling gave the best values for predicting either calving or no calving within 12 h. For the proposed parturition score (PS), a threshold of 4 PS points was identified below which calving within the next 12 h could be ruled out with a probability of 99.3% in cows (95.5% in heifers). Above this threshold, intermitted calving monitoring every 3 h and a progesterone rapid blood test (PRBT) would be recommended. By combining the PS and PRBT (if PS ≥ 4), the prediction of calving within the next 12 h improved from 14.9% to 53.1%, and the probability of ruling out calving was 96.8%. The PRBT was compared to the results of an enzyme immunoassay (sensitivity, 90.2%; specificity, 74.9%). The standard operating procedure developed in this study that combines the PS and PRBT will enable veterinarians to rule out or predict calving within a 12 h period in cows with high accuracy under field conditions.     

Monogenic control of resistance in the tomato to the tobacco flea beetle: Probable repellance by foliage volatiles

Summary In comparisons made under typical summer conditions in the field at Davis, California, the foliage of the anthocyanin-deficient mutant af proved to be much more susceptible to attack by Epitrix hirtipennis (Melsheimer) than that of the isogenic normal line, normal cultivars, or any other tested mutant. Since a relatively uniform level of damage was observed in leaves of various ages that contacted the soil, the interaction is probably of a preference rather than antibiotic nature. A comparison with nine other anthocyaninless mutants proved that anthocyanin deficiency is not responsible for susceptibility. The severe reduction of glandular hairs and consequent lack of foliage aroma—hitherto unsuspected pleiotropic effects of af—probably account for the high susceptibility of this mutant. The evolutionary significance of the distinct foliage aromas characteristic of each tomato species is discussed.     

The crossing of common wheat (Triticum aestivum L.) with cultivated rye (Secale cereale L.). I. crossability,pollen grain germination and pollen tube growth

Summary The crossing of common wheat (Triticum aestivum L.) with rye (Secale cereale L.), and especially the action of the crossability genes of wheat, was studied using the readily crossable wheat cv Chinese Spring (genotype kr ₁ kr ₁ kr ₂ kr ₂ >), the poorly crossable wheat cv Hope (genotype Kr ₁ Kr ₁ Kr ₂ Kr ₂ ), as well as the disomic substitution line of chromosome 5B of Hope into Chinese Spring (CS/Hope 5B, genotype Kr ₁ Kr ₁ kr ₂ kr ₂ ). By comparing crossability and actual fertilization, the poor crossability with rye of both cv Hope and the CS/Hope 5B substitution line was shown to result from absence of fertilization. Studies of pollen grain germination and pollen tube growth showed that the dominant alleles of the crossability genes manifested themselves through retardation and eventually inhibition of pollen tube growth at the style base and in the ovary wall. In Hope the growth of all pollen tubes was inhibited, whereas in CS/Hope 5B rarely fertilization was achieved. The recessive alleles of the crossability genes do not seem to have an influence on the growth of rye pollen tubes in wheat pistils.     

Resistance to Polymyxa betae in Beta Species of the Section Procumbentes, in Hybrids with B. vulgaris and in Monosomic Chromosome Additions of B. procumbens in B. vulgaris

Plant regeneration from callus cultures of Allium trifoliatum subsp. hirsutum fertile accession F-370, was studied as a means for clonal multiplication and germplasm storage of Allium spp. Callus was induced on in votro-cultured basal leaf explants. Best proliferation was obtained on modified BDS medium supplemented with (mg/1): 0.75 picloram, 2.0 benzyl adenine, and 900 casein hydrolysate. Shoot and root organogenesis were obtained in 3 to 5 month old subcultured calli, on BDS or MS medium supplemented with (mg/1): either 0.03 picloram or no auxin, 2 BA or 2-isopentenyladenine, and 900 casein hydrolysate. Direct bulb formation, without shoot elongation, occurred on BDS medium with 10 mg/1 IBA. Under these conditions, callus formation and organogenesis were not obtained with A. trifoliatum subsp. hirsutum var. sterile, a male-sterile genotype. Most regenerants were phenotypically normal, but some abnormal shoots were also observed, i.e. shoots with vitrified or extremely broad leaves. Isozyme polymorphism analysis of seven proteins in the latter regenerants, and in several callus cultures, revealed significant deviation from the original pattern in esterase, 6-phosphogluconate dehydrogenase and superoxide dismutase. No such deviations were detected in normal regenerated plants.