Value-added products from forest biotechnology

The three major components of forest biotechnology addressed in this paper are asexual propagation, genomics and genetic engineering (GE). Forest biotechnology offers potential that cannot be realized from conventional breeding because of the long life of forest trees and because of the long time required to make genetic gains through tree improvement programs. Most of the biotechnology research in forest trees has concentrated on genetically variable traits that give a relative quick return on investment: growth, form, insect, disease and herbicide resistance, and wood properties. In the long run, other modified traits should have greater value than is obtained solely from timber management. At the tree or forest level, some of those traits will address carbon sequestration, bioenergy, bioremediation, biopulping and species restoration. At the gene level within a tree, the types of potential gains will include pharmaceuticals, resins, latexes, oils, flavonoids, and foodstuff, inclusive of increased fruit quantity and quality and the sugars and starches embedded in the cell walls. With the advent of nanotechnology, trees of the future will be dissected to form every wood product that is now commercially available and, in addition, a multitude of new products will appear.     

土壤中铜、铅、锌相对浓度比稳定性的研究

铜、铅、锌均与硫元素有较强的亲和力,从而使它们具有相似的地球化学性质,并在环境自然体中紧密共生.人们已经认识了铜和锌是人体必需的微量元素,而铅是有害的元素,它们的环境与生物地球化学行为,直接影响到人体的健康.因此,表生环境中的铜、铅、锌始终是研究的热点.     

Sensitivity of southern quebec lakes to acidic precipitation

Physico-chemical data from 258 Quebec lakes were collected during spring and summer 1980. These data are examined in order obtain a first general diagnosis of lake acidification in Quebec. The spatial variation of the mineralization of lakes is interpreted in relation to lithology and glacial deposits, allowing the identification of Shield areas particularly threatened by acid precipitation. A strong south-west to north-east gradient in sulphate concentration is observed and interpreted as a result of long range atmospheric transport of S and as an indication of increased sulphate levels in southern Quebec lakes. The frequency distribution of pH values and the relation between pH and sulphate are examined; the results obtained suggest that many Shield lakes are probably affected by acid precipitation. A comparison is made between spring and summer conditions; data obtained in spring show a substantial decrease in pH and alkalinity.     

Spring Precipitation as a Predictor for Peak Standing Crop of Mixed-Grass Prairie

Ranchers and range managers need a decision support tool that provides a reasonably accurate prediction of forage growth potential early in the season to help users make destocking decisions. Erroneous stocking rate decisions can have dire economic and environmental consequences, particularly when forage production is low. Predictions must be based on information that is easily obtained and relevant to the particular range. Our goal was to evaluate monthly precipitation in spring months as a potential predictor of forage production compared to annual and growing-season precipitation. We analyzed the relationships between grazed and ungrazed peak standing crop (PSC) and precipitation using nonlinear regression and a plateau model, Akaike’s information criterion for model selection, and data from three locations: Streeter, North Dakota; Miles City, Montana; and Cheyenne, Wyoming. The plateau model included a linear segment, representing precipitation limiting production, and a plateau, an estimate of average production when precipitation is no longer the limiting factor. Both the response and predictor variables were rescaled so variability in production from average production was related to variability in precipitation from the long-term average. We found that grazing did not affect the relationship between PSC and precipitation, nor were annual or growing-season precipitation good predictor variables. The best predictor variable was total precipitation in April and May for Montana, May and June for North Dakota, and April, May, and June for Wyoming, with r² ranging from 0.74 to 0.79 for precipitation less than long-term average. These results indicate that spring precipitation provides useful information for destocking decisions and can potentially be used to develop a decision support tool, and the results will guide our choice of possible predictor models for the tool.     

Diversity maintenance and use of Vicia faba L. genetic resources

The faba bean (Vicia faba L.) is an ancient crop that is represented in collections by cultivated forms only. Botanic and molecular data suggest that the wild ancestor of this species has not yet been discovered or has become extinct. This fact makes ex situ collections more crucial for the present and future breeding activities of this crop, especially when the modernization of agriculture reduces genetic diversity.     

An evaluation of thermo-assisted drying and decontamination for the elimination of porcine reproductive and respiratory syndrome virus from contaminated livestock transport vehicles

The purpose of this report is to validate a new protocol, the thermo-assisted drying and decontamination (TADD) system, for eliminating porcine reproductive and respiratory syndrome virus (PRRSV) from contaminated transport vehicles. Scale models of weaned pig trailers were used. The principle of TADD is to raise the interior temperature of trailers to 71 degrees C for 30 min to promote drying and degradation of PRRSV. Trailer interiors were artificially contaminated with 5 x 10(5) TCID50 of PRRSV strain MN 30-100, then treated with 1 of 4 treatments: 1) TADD; 2) air only (no supplemental heat); 3) overnight (8 h) drying; and 4) washing only. Following treatment, swabs were collected from the trailer interiors at 0, 10, 20, and 30 min post-treatment and from the overnight group after 8 h. Swabs were tested for PRRSV-RNA by polymerase chain reaction (PCR). As a measure of the presence of infectious PRRSV, sentinel pigs were housed in treated trailers for 2 h post-treatment and supernatants from swabs were injected IM into naive pigs (bioassay), the recipient pigs were then tested for PRRSV infection. All trailers were PRRSV positive by PCR immediately after washing, prior to treatment (pt). At 10 min pt, 7/10 swabs were positive from the TADD trailers; however, all swabs collected at 20 and 30 min pt were PRRSV negative by PCR, and trailer interiors were visibly dry. In contrast, 9/19, 6/10, and 6/10 swabs collected at 10, 20, and 30 min, respectively, from trailers treated with air only were positive and visibly wet. All swabs (10/10) collected from trailers treated with washing only were PRRSV positive by PCR and all swabs collected at 8 h of drying were PRRSV negative by PCR. All tests for the presence of infectious PRRSV were negative for trailers treated with TADD and overnight drying, while infectious PRRSV was detected in sentinel pigs and bioassay pigs in the other groups. Under the conditions of this study, the efficacy of the TADD system was equal to that of the overnight drying treatment, and it required a shorter period of time to complete its objective.     

Siderophore-mediated competition for iron and induced resistance in the suppression of fusarium wilt of carnation by fluorescent Pseudomonas spp

The mechanisms of suppression of fusarium wilt of carnation by two fluorescentPseudomonas strains were studied.Treatments of carnation roots withPseudomonas sp. WCS417r significantly reduced fusarium wilt caused byFusarium oxysporum f. sp.dianthi (Fod). Mutants of WCS417r defective in siderophore biosynthesis (sid^–) were less effective in disease suppression compared with their wild-type. Treatments of carnation roots withPseudomonas putida WCS358r tended to reduce fusarium wilt, whereas a sid^– mutant of WCS358 did not.Inhibition of conidial germination of Fod in vitro by purified siderophores (pseudobactins) of bothPseudomonas strains was based on competition for iron. The ferrated pseudobactins inhibited germination significantly less than the unferrated pseudobactins. Inhibition of mycelial growth of Fod by bothPseudomonas strains on agar plates was also based on competition for iron: with increasing iron content of the medium, inhibition of Fod by thePseudomonas strains decreased. The sid^– mutant of WCS358 did not inhibit Fod on agar plates, whereas the sid^– mutants of WCS417r still did. This suggests that inhibition of Fod by WCS358r in vitro was only based on siderophore-mediated competition for iron, whereas also a non-siderophore antifungal factor was involved in the inhibition of Fod by strain WCS417r.The ability of thePseudomonas strains to induce resistance against Fod in carnation grown in soil was studied by spatially separating the bacteria (on the roots) and the pathogen (in the stem). Both WCS417r and its sid^– mutant reduced disease incidence significantly in the moderately resistant carnation cultivar Pallas, WCS358r did not.It is concluded that the effective and consistent suppression of fusarium wilt of carnation by strain WCS417r involves multiple mechanisms: induced resistance, siderophore-mediated competition for iron and possibly antibiosis. The less effective suppression of fusarium wilt by WCS358r only depends on siderophore-mediated competition for iron.