Characterization of the durable resistance to yellow rust in old winter wheat cultivars in the Netherlands

Summary Winter wheat cultivars released in the Netherlands before 1930 carried durable resistance to yellow rust. Cultivars released in the period between 1930 and 1950 often were durably resistant while recent cultivars infrequently showed durable resistance. This durable resistance was not difficult to transfer to new cultivars. Twenty nine older cultivars with durable resistance and eight recent non-durably resistant cultivars were tested in the seedling stage and in the adult plant stage against 12 West-European yellow rust races and against some non-European races in the seedling stage only. The adult plant tests were carried out in race nursery tests in the Flevopolder. Per race nursery all 37 cultivars, planted in hills of about 20 plants on both sides of the highly susceptible cv. Michigan Amber, were exposed to one race.The infection type of each cultivar-race combination was scored on 0 to 9 scale once in the seedling stage and twice in the adult plant stage. In the race nurseries the percentage leaf area affected was evaluated three times to be used to calculate the area under the disease progress curve (AUDPC). This AUDPC multiplied with the mean infection type in the field gave the susceptibility index (SI).The infection types were classified into resistant (R), intermediate (I) or susceptible (S) when the infection types were 0 to 3, 4 to 6 or 7 to 9, respectively. Four categories of resistance were discerned on the basis of the three infection type scores: 1) RRR, overall resistance; complete or near-complete resistant at all stages. 2) SRR, adult plant resistance, complete- or near-complete resistant at the adult plant stage only. 3) SRS and SSR, temperature sensitive resistance, the resistance changed from the one evaluation data to the other. 4) SSS and an SI lower than that of Michigan Amber, partial resistance.The frequencies of overall, adult plant and temperature sensitive resistance were 1.4, 52 and 54% in the older cultivars and 40, 62 and 22% in the recent ones, respectively. Among the older cultivars all had a fair to high level of partial resistance, the SI being on average only 20% of that of Michigan Amber, while most cultivars also seemed to carry temperature sensitive resistance. The partial resistance of the recent cultivars was of a much lower level with a mean SI compared to that of Michigan Amber of 61%. Partial resistance was highly correlated (r = –0.94) with the mean resistance scores from the Dutch Recommended Cultivars Lists. It was concluded that partial resistance and temperature sensitive resistance were the major components of the durable resistance in the older cultivars.     

小麦叶枯病病程的组织学研究

采用人工控制接种和发病条件，对硬粒小麦品种和与其亲和的从硬粒小麦上分离到的小麦叶枯病菌株以及软粒小麦品种和与其亲和的从软粒小麦上分离到的小麦叶枯菌株２个组合进行了病程的病理组织学研究。结果表明：接种后１２ｈ，分生孢子发芽并从气孔侵入气孔空腔，病害潜育期为８－１０ｄ；接种后１４ｄ，聚集在气孔空腔内的菌丝体开始以气孔空腔为模板形成分生孢子器并伴有个别分生孢子器完全形成和分生孢子成熟，病组织上病原大量释     

Dietary and animal-related factors associated with the rate of urinary oxalate and calcium excretion in dogs and cats

This paper reports the results of a cohort study and randomised clinical trial (RCT) in cross-over design. In the cohort study, the range of urinary oxalate (Uox) and calcium (Uca) excretion was determined within a sample of the Dutch population of dogs and cats, and dietary and animal-related factors associated with these urine parameters were identified. Spot urine samples were collected from privately owned dogs (n=141) and cats (n=50). The RCT determined the effect of a commercial raw meat diet versus a dry diet on Uox and Uca excretion rate in 23 dogs. In the cohort study, Uox excretion ranged from 21.1 to 170.6 mmol oxalate/mol creatinine in dogs and 27.5 to 161.6 in cats. Urinary calcium excretion ranged from 3.4 to 462.8 mmol calcium/mol creatinine in dogs and 10.1 to 128.0 in cats. In dogs, increased Uox and Uca excretion was associated with (1) the intake of a dry diet as the primary source of energy, (2) receiving no snacks and (3) breed. Increased Uox excretion was associated with males as well. In cats, urine collection in anaesthetised subjects was identified as a confounder. In the RCT, feeding the dry diet resulted in higher Uox (P<0.001) and Uca (P=0.021) excretion rates in dogs.     

A molecular diagnostic for tropical race 4 of the banana fusarium wilt pathogen

This study analysed genomic variation of the translation elongation factor 1α (TEF‐1α) and the intergenic spacer region (IGS) of the nuclear ribosomal operon of Fusarium oxysporum f. sp. cubense (Foc) isolates, from different banana production areas, representing strains within the known races, comprising 20 vegetative compatibility groups (VCG). Based on two single nucleotide polymorphisms present in the IGS region, a PCR‐based diagnostic tool was developed to specifically detect isolates from VCG 01213, also called tropical race 4 (TR4), which is currently a major concern in global banana production. Validation involved TR4 isolates, as well as Foc isolates from 19 other VCGs, other fungal plant pathogens and DNA samples from infected tissues of the Cavendish banana cultivar Grand Naine (AAA). Subsequently, a multiplex PCR was developed for fungal or plant samples that also discriminated Musa acuminata and M. balbisiana genotypes. It was concluded that this diagnostic procedure is currently the best option for the rapid and reliable detection and monitoring of TR4 to support eradication and quarantine strategies.     

The effects of different anesthetics on blood steroid concentrations in domestic tom-cats

Testosterone and androstenedione were measured in the plasma of mature tom-cats before, during and after anesthesia with thiopentone, ketamine, xylazine and alphaxolone/alphadolone. Samples were collected via an indwelling jugular catheter at 30 min intervals before anesthesia (5 samples) and during the recovery phase (8 samples), and at intervals of 15 min during anesthesia (7 samples). Thiopentone and ketamine anesthesia significantly depressed testosterone and androstenedione concentrations during and after anesthesia. Xylazine significantly increased testosterone concentrations during anesthesia but they returned to pre-anesthetic concentrations during recovery. Androstenedione concentrations were significantly depressed during the recovery phase from xylazine anesthesia. Alphaxolone/alphadolone anesthesia had no significant effect of testosterone concentrations but significantly increased and androstenedione concentrations during anesthesia and recovery. Testosterone and androstenedione concentrations in cats were significantly altered by these 4 commonly used anesthetics and this must be taken into account if hormone concentrations are measured while cats are anesthetised.     

Major Changes in Fusarium spp. in Wheat in the Netherlands

The re-emergence of fusarium head blight throughout the world and especially in Western Europe prompted a survey of the situation in the Netherlands. To allow for a high throughput screening of large numbers of samples, a diagnostic PCR method was developed to detect the most common species of Fusarium occurring on wheat. Seven primer pairs were tested for their ability to identify isolates of Fusarium avenaceum, F. culmorum, F. graminearum, F. poae, F. proliferatum and Microdochium nivale var. majus and M. nivale var. nivale. Each primer pair only generated a PCR product with the corresponding Fusarium species and all PCR fragments had different molecular sizes. This allowed the generation of these amplicons using a mixture of all seven primer pairs. The robustness of this multiplex PCR encouraged us to screen a large series of isolates collected in 2000 and 2001. In both years 40 fields were sampled leading to a collection of 209 isolates from 2000 and 145 isolates from 2001. The results of the multiplex PCR demonstrated that F. graminearum was the most abundant species in the Fusarium complex on wheat in both years. This is in sharp contrast to reports from the 1980s and early 1990s, which found F. culmorum as the predominant species. Primers derived from the tri7 and tri13 genes, which are implicated in the acetylation and oxygenation of the C-4 atom of the backbone of the trichothecene molecule, were used to discriminate between deoxynivalenol and nivalenol (NIV) producers. The populations of F. culmorum and F. graminearum both showed a slight increase in NIV-producers in 2001.