Tuber yield and tuber traits of haploid-wild species F1 hybrids

Summary Haploid-wild species hybrids have been produced that incorporate desirable traits and genetic diversity from wild species into the cultivated potato. Nine wild species were represented in 210 hybrids which were evaluated in a yield trial with ten haploid parents and four cultivars. Haploid-wild species hybrids yielded up to 3.1 kg/hill, compared to 1.8 kg/hill for the haploids; the species parents did not tuberize. Some 2x hybrids outyielded three of the 4x cultivars. Tubers of most hybrids, especially those withSolanum berthaultii, S. canasense, S. chacoense, andS. tarijense as parents, were very smooth. Tuber set in many haploid-wild species hybrids was low. Extensive variability for dormancy and mass density (specific gravity) was also observed. Haploid-wild species hybrids which produce 2n pollen have been brought to the 4x level via 4x×2x crosses.

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Zusammenfassung Es wurden Haploid-Wildarten F₁-Hybriden erzeugt, um aus Wildarten in Zuchtkartoffeln wünschenswerte Merkmale und genetische Mannigfaltigkeit hineinzubringen. Vier Sorten, zehn Haploide und 210 Haploid-Wildarten F₁-Hybriden, einschliesslich der folgenden 2x-Wildarten, wurden in einen Ertragsversuch einbezogen:S. berthaultii (ber),S. boliviense (blv),S. canasense (can),S. chacoense (chc),S. infundibuliforme (ifd),S. microdontum (mcd),S. sanctae-rosae (sct),S. raphanifolium (rap), andS. tarijense (tar). Die Ertr?ge vieler Haploid-Wildarten Hybriden waren erstaunlich hoch, bis zu 3,1 kg/Hügel und gr?sser als bei jeweils beiden Eltern (Tabelle 1). Haploide ergaben bis zu 1,8 kg/Hügel, die Arten-Eltern bildeten keine Knollen. Die Abb. 1 veranschaulicht den Unterschied zwischen dem Ertrag einer Hybride und ihrer Eltern. Einige 2x-Hybriden übertrafen 4x-Sorten (Tabelle 2): Gr?ssere Pflanzweiten und eine lange Wachstumszeit m?gen den Hybriden einen Vorteil gegenüber den Sorten gegeben haben. Die Knollen der meisten Haploid-Wildarten Hybriden waren sehr weich, besonders diejenigen mit ber, can, che und tar als Eltern. Bei einigen Haploid-Wildarten Hybriden hatten alle Klone gleicher Abstammung eine lange Knollenkeimruhe, bei anderen waren einige Klone innerhalb der gleichen Abstammung mit langer, andere mit kurzer Keimruhe (Tabelle 3). Die Massendichte (spezifische Gewicht) variierte innerhalb der Haploid-Wildarten Hybriden von 1,050 für eine US-W2838 x tar Hybride und eine US-W457 x tar Hybride bis 1,110 für eine US-W2236 x tar Hybride; Haploide variieren von 1,058 bis 1,079 und Sorten von 1,051 bis 1,076. Die Erzeugung von Haploid-Wildarten Hybriden ist eine wirkungsvolle Methode, um nicht adaptiertes Wildarten-Erbgut in eine Form zu bringen, die Knollen ausbilden wird. Dies erlaubt die leichte Erhaltung wertvoller Genotypen und die Absch?tzung der Beitr?ge von Wildarten-Genotypen zum Ertrag und zu den Knollenmerkmalen. Auch erh?lt man damit ein hoch variables Material für genetische Untersuchungen. Haploid-Wildarten Hybriden, die 2n-Pollen erzeugen, wurden in 4x×2x Kreuzungen verwendet, um 4x-Hybriden herzustellen, die in Kartoffelzuchtprogrammen eingesetzt werden k?nnen.

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Résumé Des hybrides F₁ issus d'espèces haplo?des sauvages ont été produits dans le but d'introduire des caractères désirables et la diversité génétique dans les pommes de terre cultivées. Quatre variétés, dix haplo?des et 210 hybrides F₁ issus d'espèces haplo?des sauvages, incluant les espèces sauvages 2x, entraient dans l'essai de productivité:S. berthaultii (ber),S. boliviense (blv),S. canasense (can),S. chacoense (chc),S. infundibuliforme (ifd),S. microdontum (mcd),S. sanctae-rosae (sct),S. raphanifolium (rap) etS. tarijense (tar). La production de nombreux hybrides issus d'espèces haplo?des sauvages était notablement élevée, plus de 3.1 par pied, et plus forte que celle de leurs parents (tableau 1). Les haplo?des produisaient 1.8 kg/pied; les espèces parentales ne tubérisaient pas. La figure 1 illustre les différences observées entre le rendement de l'hybride et celui de ses parents. Quelques hybrides 2x surpassaient les variétés 4x (tableau 2). Un espacement important et une longue durée de végétation pourraient avoir donné un avantage aux hybrides sur les variétés. Les tubercules de la plupart des hybrides issus d'espèces haplo?des sauvages, notamment de ceux dont les parents étaient ber, can, chc et tar, étaient lisses. Quelques hybrides d'espèces haplo?des sauvages, tous apparentés, présentaient une longue dormance; pour d'autres la dormance était courte (tableau 3). Parmi les hybrides issus d'espèces haplo?des sauvages, la densité (le poids spécifique) variait de 1.050 pour US-W2838 x tar et US-W457 x tar à 1.100 pour US-W2236 x tar; les haplo?des s'échelonnaient de 1.058 à 1.079 et les variétés de 1.051 à 1.076. La production d'hybrides à partir d'espèces haplo?des sauvages est une méthode efficace pour introduire le caractère tubérifère chez des espèces sauvages qui ne le sont pas. Elle permet la maintenance facile de génotypes valables et l'évaluation de l'apport des génotypes d'espèces sauvages au rendement et aux caractéristiques des tubercules. Elle fournit aussi un matériel hautement variable pour les études génétiques. Des hybrides issus d'espèces haplo?des sauvages produisant du pollen 2n étaient utilisés dans les croisements 4x et 2x pour obtenir des hybrides 4x qui pourront contribuer aux programmes d'hybridation de la pomme de terre.

     

Airborne spread of foot-and-mouth disease – Model intercomparison

Foot-and-mouth disease virus (FMDV) spreads by direct contact between animals, by animal products (milk, meat and semen), by mechanical transfer on people or fomites and by the airborne route, with the relative importance of each mechanism depending on the particular outbreak characteristics. Atmospheric dispersion models have been developed to assess airborne spread of FMDV in a number of countries, including the UK, Denmark, Australia, New Zealand, USA and Canada. These models were compared at a Workshop hosted by the Institute for Animal Health/Met Office in 2008. Each modeller was provided with data relating to the 1967 outbreak of FMD in Hampshire, UK, and asked to predict the spread of FMDV by the airborne route.A number of key issues emerged from the Workshop and subsequent modelling work: (1) in general all models predicted similar directions for livestock at risk, with much of the remaining differences strongly related to differences in the meteorological data used; (2) determination of an accurate sequence of events on the infected premises is highly important, especially if the meteorological conditions vary substantially during the virus emission period; (3) differences in assumptions made about virus release, environmental fate and susceptibility to airborne infection can substantially modify the size and location of the downwind risk area. All of the atmospheric dispersion models compared at the Workshop can be used to assess windborne spread of FMDV and provide scientific advice to those responsible for making control and eradication decisions in the event of an outbreak of disease.     

Case–control study of Staphylococcus lugdunensis infection isolates from small companion animals

Background – Coagulase‐negative Staphylococcus lugdunensis has recently been shown to cause invasive infections of people, which are similar in pathogenic effect to those caused by Staphylococcus aureus. Little is known about the pathogenicity of S. lugdunensis in companion animals. Objectives – To compare potential risk factors for infection, body sites affected, and whether cases and controls had been treated with antimicrobial drugs based upon susceptibility test results. Animals – Thirty‐three cases of S. lugdunensis infection (25 dogs, six cats and two small mammals) were identified between January 2003 and August 2011. Two Staphylococcus pseudintermedius controls, which were identified by the microbiology laboratory immediately before and after each S. lugdunensis case, were host‐species matched to each case. Methods – A retrospective case–control analysis. Results – During the period evaluated, the prevalence of S. lugdunensis infection was 1.3 cases per 10,000 hospital admissions for dogs and 0.95 cases per 10,000 admissions for cats (P = 0.453). In univariate analyses, S. pseudintermedius isolation was significantly associated with skin infections (P < 0.0001), while S. lugdunensis isolation was associated with the respiratory tract (P = 0.03) and other deep tissues (P = 0.005). Cases were less likely than controls to have been treated based upon susceptibility test results (P = 0.02). A conditional logistic regression analysis showed isolation of S. lugdunensis to be associated with recent (≤ 30 days) steroid administration (odds ratio, 17.72; 95% confidence interval, 2.35–132.82; P = 0.005); and in‐patient status (odds ratio, 9.67; 95% confidence interval, 2.18–42.88; P = 0.003). Conclusions – These results suggest that S. lugdunensis may cause invasive infections in companion animals, which should be treated with antimicrobials based upon susceptibility tests when available.     

Effects of 2 different infusion rates of medetomidine on sedation score,cardiopulmonary parameters,and serum levels of medetomidine in healthy dogs

The effects of 2 different continuous rate infusions (CRIs) of medetomidine over an 8-hour period on sedation score, selected cardiopulmonary parameters, and serum levels of medetomidine were evaluated in 6 healthy, conscious dogs using a crossover study design. The treatment groups were: CONTROL = saline bolus followed by saline CRI; MED1 = 2 μg/kg body weight (BW) medetomidine loading dose followed by 1 μg/kg BW per hour CRI; and MED2 = 4 μg/kg BW medetomidine loading dose followed by 2 μg/kg BW per hour CRI. Sedation score (SS), heart rate (HR), respiratory rate (RR), temperature (TEMP), systolic arterial pressure (SAP), mean arterial pressure (MAP), and diastolic arterial pressure (DAP), arterial and mixed venous blood gas analyses, lactate, and plasma levels of medetomidine were evaluated at baseline, at various intervals during the infusion, and 2 h after terminating the infusion. Statistical analysis involved a repeated measures linear model. Both infusion rates of medetomidine-induced dose-dependent increases in SS and dose-dependent decreases in HR, SAP, MAP, and DAP were measured. Respiratory rate (RR), TEMP, central venous pH, central venous oxygen tension, and oxygen extraction ratio also decreased significantly in the MED2 group at certain time points. Arterial oxygen and carbon dioxide tensions were not significantly affected by either infusion rate. In healthy dogs, both infusion rates of medetomidine-induced clinically relevant sedative effects, accompanied by typical alpha₂ agonist-induced hemodynamic effects, which plateaued during the infusion and subsequently returned to baseline. While additional studies in unhealthy animals are required, the results presented here suggest that medetomidine infusions at the doses studied may be useful in canine patients requiring sedation for extended periods.     

Germplasm Release: Three Tetraploid Potato Clones with Resistance to Common Scab

Common scab caused by the soil-borne bacterium Streptomyces scabies is a serious disease for the potato industry. We have identified a strong source of resistance in the diploid wild relative Solanum chacoense. This resistance has been introgressed into tetraploid cultivated potato via unilateral sexual polyploidization. This paper describes three hybrid clones (M8, M16, M17) for use by potato breeding programs to enhance resistance to common scab. They were created by crossing a diploid clone (50% S. tuberosum, 50% S. chacoense) to tetraploid cultivars, producing hybrids with 75% cultivated and 25% wild germplasm. The clones are male and female fertile, and are adapted to temperate zone production environments.     

Transmission of Scab Resistance to Tetraploid Potato Via Unilateral Sexual Polyploidization

Resistance to common scab continues to be a high priority trait for potato breeders. We have identified a source of resistance in the diploid wild potato relative Solanum chacoense and have introgressed it into cultivated potato by crossing it to a dihaploid. A clone generated by crossing two full-sib hybrids is highly resistant and produces both 2n pollen and 2n eggs. This clone, named 4–48, is homozygous for a major QTL for scab resistance derived from S. chacoense. Clone 4–48 was reciprocally crossed to three round white cultivars Megachip, Pike, and White Pearl. Common scab resistance was transferred to tetraploid offspring, with transmission through the male parent generally more effective than through the female parent. The majority of progeny (70%) exhibited stability for resistance to common scab across environments. This germplasm will be useful for breeding new resistant cultivars.     

Characterization of spaC‐type Erysipelothrix sp. isolates causing systemic disease in ornamental fish

Since 2012, low‐to‐moderate mortality associated with an Erysipelothrix sp. bacterium has been reported in ornamental fish. Histological findings have included facial cellulitis, necrotizing dermatitis and myositis, and disseminated coelomitis with abundant intralesional Gram‐positive bacterial colonies. Sixteen Erysipelothrix sp. isolates identified phenotypically as E. rhusiopathiae were recovered from diseased cyprinid and characid fish. Similar clinical and histological changes were also observed in zebrafish, Danio rerio, challenged by intracoelomic injection. The Erysipelothrix sp. isolates from ornamental fish were compared phenotypically and genetically to E. rhusiopathiae and E. tonsillarum isolates recovered from aquatic and terrestrial animals from multiple facilities. Results demonstrated that isolates from diseased fish were largely clonal and divergent from E. rhusiopathiae and E. tonsillarum isolates from normal fish skin, marine mammals and terrestrial animals. All ornamental fish isolates were PCR positive for spaC, with marked genetic divergence (<92% similarity at gyrB, <60% similarity by rep‐PCR) between the ornamental fish isolates and other Erysipelothrix spp. isolates. This study supports previous work citing the genetic variability of Erysipelothrix spp. spa types and suggests isolates from diseased ornamental fish may represent a genetically distinct species.     

Effects of temperature on germination of sporangia,infection and protein secretion by Phytophthora kernoviae

Phytophthora kernoviae is a pathogen on a wide range of plants, but little is known of optimal infection conditions. Rhododendron ponticum leaves were inoculated with six different isolates of P. kernoviae sporangia and incubated at different temperatures from 10 to 28 °C. After 1 week, lesion development and pathogen recovery were only observed from all isolates at 15 and 20 °C and a few isolates at 10 °C. In an experiment with temperatures ranging from 20 to 25 °C, lesion development and pathogen recovery on R. ponticum, Magnolia stellata and Viburnum tinus occurred consistently at 20 and 21 °C, was limited at 22 °C, and did not occur at 23 °C and above. There was no difference in sporangia and zoospore germination at 20–25 °C. In a temperature fluctuation experiment, the necrotic area of inoculated R. ponticum leaves increased with longer incubation at 20 °C and decreased with longer incubation at 24 °C. Crude extracts of secreted proteins from P. kernoviae cultures grown at 20 and 24 °C were compared to determine any effects of temperature on pathogenicity. When spot tested on R. ponticum leaves, crude protein suspensions from cultures grown at 20 °C induced necrosis, while proteins from cultures grown at 24 °C did not. Proteomic analysis confirmed that a 10 kDa protein secreted at both 20 and 24 °C shared sequence homology to the conserved domains of known elicitins of other Phytophthora spp. The protein secreted at 20 °C that was responsible for necrosis has not been identified.     

Thyroid cystadenoma, colloid goiter, and hypothyroidism in an American black bear (Ursus americanus).

A 178-kg, 14-yr-old captive female American black bear (Ursus americanus) was examined because of lethargy, inappetance, obesity, and alopecia. Serum chemistry and complete blood count values were within normal limits. Based on serum levels for total thyroxine (T4), free T4 by equilibrium dialysis (fT4ED), and canine thyroid-stimulating hormone concentrations, using assays validated for domestic dogs, hypothyroidism was diagnosed presumptively, and therapy with levothyroxine sodium (0.022 mg/kg p.o. b.i.d.) was initiated. Haircoat, body weight, appetite, and activity level improved within 30 days. The levothyroxine dose was decreased twice (to 0.018 mg/kg p.o. b.i.d. and then to 0.011 mg/kg p.o. b.i.d.) during the course of treatment based on monitoring of serum T4 and fT4ED concentrations. After euthanasia for severe refractory lameness, postmortem examination revealed bilateral thyroid lobe enlargement and a fluid-filled cyst within the right lobe. Histologically, colloid goiter was present in both lobes, and a follicular cystadenoma had replaced one third of the cranial pole of the right lobe. The goiter and cystadenoma likely contributed to the hypothyroid condition in this bear and fT4ED was a more sensitive indicator of hypothyroidism than was T4. The recommended canine dosage of levothyroxine may be too high for the treatment of hypothyroidism in American black bears; 0.011 mg/kg p.o. b.i.d. may be a more appropriate dosage.