Evaluation of soybean for resistance to soybean rust in Vietnam

Soybean rust, caused by Phakopsora pachyrhizi Sydow, is a severe foliar disease of soybean [Glycine max (L.) Merr.] that occurs throughout most soybean producing regions of the world. The objective of this research was to evaluate selected soybean genotypes for resistance to soybean rust in Vietnam. Five field experiments in Vietnam were completed from 2006 to 2009. The area-under-the-disease-progress-curve (AUDPC) was calculated for each soybean genotype based on four disease assessments taken during the reproductive growth stages. AUDPC units among soybean genotypes in each experiment differed (P < 0.05). Over the five experiments, the resistant check DT 2000 was most often the genotype with the lowest AUDPC units while the sources of rust resistance (Rpp1-5) did not always have low AUDPC units in each experiment, although PI 230970 (Rpp2) appeared to be more stable. A few genotypes with non-characterized genes for resistance, such as PI 398998, PI 437323, and PI 549017, had the lowest AUDPC units in at least one of the experiments. These genetic resources may be useful for host plant resistance studies and breeding soybeans for rust resistance in Vietnam and other locations like Brazil and the United States that have more recently been inundated with soybean rust. A significant (P < 0.001) experiment × genotype interaction was found when the AUDPC data of 14 soybean genotypes tested in Experiments 1, 2, and 3 were combined and analyzed. This result indicates the potential importance of changing fungal races and/or biotypes that occur in the rust population.     

接种茄病镰刀菌(Fusarium solani f.sp.glycines)对不同基因型大豆植株和须根的影响

摘要：茄病镰刀菌（Fusarium solani f．sp．glydne）是一种土生细菌,通过侵染大豆根系引发猝死综合症。利用温室盆栽试验和须根培养试验研究了接种茄孢镰刀菌对13个不同基因型大豆的影响。结果表明：接种后所有盆栽大豆主根都有明显深褐色的侵染病斑;移植后21d测定了盆栽植株叶部发病程度,Peking表现最为严重,然后依次为Spencer,Ripley,P3981,Williams82,Essex,Forrest,Iroquois,PI520733,Hartwig,PI567650B,Jack,和PI567374。叶部发病程度与冠高（r=-0．422,P=0．0018）、冠重（r=-0．857,P〈0．0001）和根重（r=-0．732,P〈0．0001）呈显著负相关。主根病斑长度与叶部发病程度没有相关性,表明大豆对病原菌的抗性不能仅通过根系得到充分控制。对培养的大豆须根接种茄病镰刀菌菌丝体10d后,不同基因型大豆的菌落直径的变化范围为17—40mm,差异显著（P=0．05）,其中Spencer和Peking须根上的菌落直径显著（P=0．05）大于PI567374和PI520733。对Spencer和PI567374的须根接种10灿茄病镰刀菌常量成分悬浮液,10d后菌落直径分别为50和38mm,差异显著（P=0．05）。通常,不同基因型大豆间茄病镰刀菌在培养须根上的生长与整株的症状间有一定的相关性,但不总是这样,这是因为即使根系对毒素产生抗性来减少叶部病害症状,但并不是所有的大豆都表现出明显的根系抗性。     

Developing bioelectrical impedance analysis methods for age‐0 brook trout

Year class strength of many fishes often is determined by survival through the first winter. Increased fat reserves improve survival and overall cohort success. Bioelectrical impedance analysis (BIA) methods are established for estimating proximate composition of adult brook trout, Salvelinus fontinalis (Mitchill), but none have been developed for early life stages. Small‐fish BIA would provide information about age‐0 percent dry weight, a proxy for fat reserves, allowing for better prediction of cohort success. The objective of this study was to develop BIA methods that provide reliable estimates of percent dry weight for age‐0 brook trout. BIA measurements were taken at seven anatomical locations from 48 to 115 mm fish. A model developed using BIA measures taken by subdermal needle electrodes precisely predicted percent dry weight (best model, RMSE = 1.03, R² = 0.86). Although lacking support, as determined by information theoretical analysis, BIA measured with non‐invasive external rod electrodes also precisely predicted percent dry weight (RMSE = 1.09, R² = 0.85). Models developed using two electrode locations performed better than models developed with only one location. For small brook trout, a dorsal to ventral pre‐dorsal fin electrode location should be used in conjunction with a dorsal total length location when measuring BIA to predict percent dry weight.     

The influence of the injection site on the bioavailability of ampicillin and amoxycillin in beagles

Influence of the injection site on bioavailability in dogs was investigated for injections with ampicillin anhydrate or amoxycillin trihydrate suspensions. Firstly, pharmacokinetic parameters were calculated after IV administration of the sodium salts. Then the dogs were injected in the neck (SC), in the lateral thorax region (SC), in the back (IM) and in the thigh (IM), respectively. The most obvious depot effect was seen after subcutaneous injection of ampicillin in the thorax region, though bioavailability seemed to be low. No differences were seen between the injection sites with amoxycillin. For ampicillin SC injection in the neck seems most favourable; for amoxycillin SC injection may be preferred because it is less burdening. Serum concentrations with amoxycillin were higher and persisted longer than with ampicillin. Further investigation is necessary to determine whether this also counts for tissues or focus of infection.     

Movement of <Emphasis Type="Italic">Phakopsora pachyrhizi</Emphasis> (soybean rust) spores by non-conventional means

Soybean, caused by the rust fungus Phakopsora pachyrhizi, is the most important foliar pathogen infecting soybean. Historically, the disease was important only in the Eastern Hemisphere, but since 1994 the disease has been reported in many countries in Africa and the Americas. In the U.S.A., soybean rust has been perceived as a threat to soybean production and monitoring of the disease occurs throughout the country where soybean is grown. The objectives of this study were to show conclusive evidence that soybean rust spores can be transported by non-conventional means such as clothing. The implication may affect how researchers approach monitoring this disease in research and sentinel plots.     

Molecular detection of Fusarium solani f. sp. glycines in soybean roots and soil

A polymerase chain reaction (PCR)-based method was developed to detect DNA of Fusarium solani f. sp. glycines , the cause of soybean sudden death syndrome. Two pairs of primers, Fsg1/Fsg2 designed from the mitochondrial small subunit ribosomal RNA gene, and FsgEF1/FsgEF2 designed from the translation elongation factor 1-α gene, produced PCR products of 438 and 237 bp, respectively. Primer specificity was tested with DNA from 82 F. solani f. sp. glycines , 55 F. solani non-SDS isolates, 43 isolates of 17 soybean fungal pathogens and the oomycete Phytophthora sojae , and soybean. The sensitivity of primer Fsg1/Fsg2 was 10 pg while that of FsgEF1/FsgEF2 was 1 ng when using F. solani f. sp. glycines total genomic DNA or down to 10³ macroconidia g⁻¹ soil. Nested PCR increased the sensitivity of the PCR assay 1000-fold to 10 fg using primers Fsg1/Fsg2, and 1 pg using primers FsgEF1/FsgEF2. F. solani f. sp. glycines DNA was detected in field-grown soybean roots and soil by PCR using either single pairs of primers or the combination of two pairs of primers. The occurrence of F. solani f. sp. glycines was determined using nested PCR for 47 soil samples collected from soybean fields in 20 counties of Illinois in 1999. F. solani f. sp. glycines was detected in soil samples from all five Illinois Agricultural Statistic Districts including 100, 89, 50, 92 and 50% of the samples from East, Central, North-east and West Districts, respectively.     

Testing the protective effectiveness of vaccines against infection with Pseudomonas aeruginosa in mink (Lutreola vison)

Infections by Pseudomonas aeruginosa have caused losses on mink farms in recent years, particularly with a clinical manifestation of haemorrhagic pneumonia. This paper includes the first results of the practical use of the Czechoslovak soluble monovaccine of polyvalent action in the treatment of mink infected by Pseudomonas aeruginosa. The action of the vaccine is based on the protective effect of Original Endotoxin Protein (OEP), antigen common to all species of the genus Pseudomonas. After due testing, the vaccine was given to mink. Doses of 50, 200 and 500 micrograms, and in another series 50 and 200 micrograms of the vaccine were tested in subcutaneous administration at 0.2 ml volume in a 7-day interval. No adverse side-effects and reactions were observed in the animals. A protective action was demonstrated, resulting in a higher number of reared mink in comparison with the control groups. After vaccination, titres ranging from 2 to 160 were determined by the indirect haemagglutination method and from 320 to 164,000 by the RIA method. In 1984 the vaccine was used for practical treatment on a mink farm with the stock exposed to Pseudomonas aeruginosa infection (5551 mink were treated). In the vaccinated group losses amounted to 3.1% whereas in the control group the mortality level was above 17%. Vaccination was demonstrated to have a favourable effect and the vaccine was then preventively used on the same farm in the subsequent year; the treatment of 29,350 mink had the required protective effect.     

Kinetics and kinematics of the equine hind limb: in vivo tendon loads and force plate measurements in ponies

Loads on the suspensory ligament, deep digital flexor tendon, superficial digital flexor tendon, and long digital extensor tendon of the equine hind limb were determined in ponies by use of implanted strain gauges consisting of silicone rubber tubes filled with mercury. Recordings were made simultaneously with force plate measurements and high-speed film recordings while the ponies were walking. The relationship between strain gauge signals and tendon loads was obtained from tension-strain tests performed after death of the ponies. The suspensory ligament and the 2 digital flexor tendons were loaded during the stance phase, and the extensor tendon was loaded mainly during the swing phase. The loading pattern of the suspensory ligament, with peak loads of 4.6 N/kg of body weight, correlated well with the vertical component of the ground reaction force. Maximal loading of the deep digital flexor tendon was observed during the second half of the stance phase, with peak values of 6.7 N/kg. The superficial digital flexor tendon was loaded maximally at the beginning of the stance phase, with a peak load of 4.1 N/kg, and the long digital extensor tendon was loaded maximally during the swing phase, with a peak load of 0.3 N/kg. Recordings made from this procedure for calibration of the strain gauge signals to tendon load and tendon strain, in combination with the force plate measurements, enabled verification of the results by torque analysis of the lower portion of the hind limb, using the vector of the ground reaction force, limb conformation, and limb geometric configuration. Torque analysis of the lower extremity indicated that the determined tendon loads were in agreement with the recorded ground reaction forces.