Integration of pre- and postharvest treatments for the control of black spot caused by Alternaria alternata in stored persimmon fruit

In Israel, black spot caused by Alternaria alternata is the main postharvest factor that impairs the quality and reduces the storability of persimmon fruit (Diospyros kaki cv. Triumph). The fungus infects the fruit in the orchard and remains quiescent until harvest. After harvest, the pathogen slowly colonizes the fruit during storage at 0 °C, which elicits black spot symptom development 2–3 months after storage entry. A commercial postharvest dip treatment in chlorine at 500 mg L^?1, released from sodium troclosene tablets, effectively controlled black spot in fruit stored for up to 2 months. However, decay incidence increased as the length of storage was extended beyond 2.5 months. The long incubation period that precedes black spot symptom development after harvest enabled the development of a series of integrative approaches for application at the pre- and postharvest stages, in combination with the commercial chlorine dip treatment, to improve the control of black spot disease. Preharvest treatments included treatment with the cytokinin-like N₁-(2-chloro-4-pyridyl)-N₃-phenylurea (CPPU) 30 d after fruit set, or a single spray with the curative fungicide polyoxin B 14 d before harvest, and when one of these was applied in combination with the postharvest chlorine dip treatment, the black spot infected area was reduced by 3 and 60%, respectively, compared with the chlorine dip alone. At the postharvest stage, fogging during storage, or post-storage on-line spraying with sodium troclosene, when applied in combination with the postharvest chlorine dip, improved the percentage of marketable fruit by 2 or 10%, respectively, compared with the chlorine dip alone. The results indicate that postharvest pathogens that show a slow colonization pattern might enable the integration of pre- and postharvest disease control methods to improve quality and reduce postharvest disease development.     

采前与采后处理结合控制柿子贮藏过程中链格孢菌(Alternaria alternata)引起的黑斑病的研究

由链格孢菌引起的黑斑病是导致以色列柿子(Diospyros kaki cv.Triumph)贮藏过程中果实品质下降、贮期缩短的主要因素。其病原真菌在采收前的果园中即开始侵染果实,但一直处于休眠状态。采收后,在0℃贮藏环境中病原菌开始繁殖,当贮藏2～3个月后,柿果表面出现黑斑症状。商业上采用二氯异氰尿酸钠片剂溶解后生成500 mg.L-1的氯水浸果,可在2个月的贮期内有效控制黑斑病的发生。然而,当贮期超过2个半月后,柿子果实的腐烂率则不断增加。在柿子采后出现黑斑症状之前病原真菌较长的潜伏期内,采前与采后阶段可采取一系列的综合技术措施,并与商业氯水浸果处理相结合来提高对贮藏柿果黑斑病的防控效果。采前处理包括柿子坐果30 d后,以1-(2-氯-4-吡啶)-3-苯基脲(CPPU)处理或采收前14 d以治疗性杀菌剂多抗霉素(polyoxin B)进行喷果处理。试验结果表明,与采后单独使用氯水浸果处理相比,将CPPU或polyoxin B处理与采后商业处理相结合,可使柿果黑斑浸染面积分别减小3%和60%;采收后贮藏期间二氯异氰尿酸钠喷雾处理或采后立即用二氯异氰尿酸钠喷果处理与采后商业氯水处理相结合比单独使用氯水处理可分别提高柿子好果率2%和10%。研究结果表明,对于具有较长潜伏侵染方式的采后病原菌来说,可应用采前和采后处理相结合的方法来提高果实的贮藏品质及减轻采后病害的发生。     

Low Water Tensions in Defined Growth Stages of Processing Tomato Plants and their Effects on Yield and Quality

In drip irrigation experiments where water was applied daily it was found that low water tensions could be maintained in the soil to a range of 10 to 20 centibars and that these conditions had a considerable influence on yield and quality of processing tomatoes, Lycopersicon esculentum cv VF 317. The response of the plant in different growth stages to low soil water tensions was studied. Irrigation during the period of fruit set and fruit development was found to increase yield levels by 53 t ha^-1 compared with non-irrigated plants. Irrigation applied only during the period of fruit development had a favourable influence on yield as well as on the efficiency of water utilization. However, irrigation at this stage had an unfavourable influence on fruit quality characteristics, namely, total soluble solids, acidity, viscosity and vitamin C. The effects of irrigation on fruit set and fruit development are discussed.     

Detailed insight into genetic diversity of the Old Kladruber horse substructure in comparison to the Lipizzan breed

The aim of the present study was to analyse the genetic subdivision of the Old Kladruber horse population compared to the historically close Lipizzan breed and to estimate genetic relatedness between them. A set of 13 microsatellites was used for genotyping a total of 270 Old Kladruber horses representing grey and black colour varieties and 418 Lipizzan horses from Slovak and Slovenian studs. The proportion of obtained heterozygosity indicates no major loss of genetic diversity within them. At the individual level across analysed populations, the formation of clusters in respect to breed’s origin and particular studs was observed. The Wright’s F_ST and genetic distances indicated genetic segregation of both colour varieties at the intraspecific level of the Kladruber breed. Moreover, the membership probability outputs showed that the frequencies of alleles varied across the three main regions represented by both Old Kladruber varieties and Lipizzan, depending on breeding history and strategy of studs.     

Expression of an Antifungal Peptide in Saccharomyces: A New Approach for Biological Control of the Postharvest Disease Caused by Colletotrichum coccodes

ABSTRACT A cecropin A-based peptide inhibited germination of Colletotrichum coccodes at 50 muM. The DNA sequence encoding the peptide was cloned in pRS413, using the Saccharomyces cerevisiae invertase leader sequence for secretion of the peptide, and expressed in yeast. Yeast transformants inhibited the growth of germinated C. coccodes spores and inhibited decay development caused by C. coccodes in tomato fruits. Expression of the antifungal peptide in yeast therefore represents a new approach for the biological control of postharvest diseases.     

Parasites in pet reptiles

Exotic reptiles originating from the wild can be carriers of many different pathogens and some of them can infect humans. Reptiles imported into Slovenia from 2000 to 2005, specimens of native species taken from the wild and captive bred species were investigated. A total of 949 reptiles (55 snakes, 331 lizards and 563 turtles), belonging to 68 different species, were examined for the presence of endoparasites and ectoparasites. Twelve different groups (Nematoda (5), Trematoda (1), Acanthocephala (1), Pentastomida (1) and Protozoa (4)) of endoparasites were determined in 26 (47.3%) of 55 examined snakes. In snakes two different species of ectoparasites were also found. Among the tested lizards eighteen different groups (Nematoda (8), Cestoda (1), Trematoda (1), Acanthocephala (1), Pentastomida (1) and Protozoa (6)) of endoparasites in 252 (76.1%) of 331 examined animals were found. One Trombiculid ectoparasite was determined. In 563 of examined turtles eight different groups (Nematoda (4), Cestoda (1), Trematoda (1) and Protozoa (2)) of endoparasites were determined in 498 (88.5%) animals. In examined turtles three different species of ectoparasites were seen. The established prevalence of various parasites in reptiles used as pet animals indicates the need for examination on specific pathogens prior to introduction to owners.     

Multilocus sequence analysis for Mycoplasma synoviae molecular genotyping

1. The aim of this study was to identify molecular techniques which enable clear discrimination between Mycoplasma synoviae isolates for improved epidemiology.

2. Multilocus sequence analysis (MLSA) of 6 M. synoviae loci was conducted for genotyping of isolates with previously determined 5?-vlhA sequences.

3. Sequencing of three polymorphic genes (5?-vlhA, cysP and nanH) enables good discrimination between isolates with different genotypes. Such a genotyping scheme revealed 10 distinct genotypes, which were confirmed by sequencing of an additional three loci of the M. synoviae genome. Epidemiologically linked strains formed clusters with the same genotypes which clearly differed between clusters.

4. MLSA used in this study is a promising tool for epidemiology of M. synoviae isolates, but it should be evaluated by further investigations using a much higher number of M. synoviae strains.

     

A Bayesian networks approach for predicting protein-protein interactions from genomic data

We have developed an approach using Bayesian networks to predict protein-protein interactions genome-wide in yeast. Our method naturally weights and combines into reliable predictions genomic features only weakly associated with interaction (e.g., messenger RNAcoexpression, coessentiality, and colocalization). In addition to de novo predictions, it can integrate often noisy, experimental interaction data sets. We observe that at given levels of sensitivity, our predictions are more accurate than the existing high-throughput experimental data sets. We validate our predictions with TAP (tandem affinity purification) tagging experiments. Our analysis, which gives a comprehensive view of yeast interactions, is available at genecensus.org/intint.