Ergebnisse einer Diallelanalyse zur Vererbung der Resistenz gegenSynchytrium endobioticum (Schilb.) Perc., Pathotyp 1 (Dl) bei Kartoffeln (Solanum tuberosum L.)

Zusammenfassung Die Nachkommenschaften eines Diallels mit 10 Eltern, ohne reziproke Kreuzungen, wurden gegen Pathotyp 1 (Dl) des Kartoffelkrebses geprüft. Aufgrund der Aufspaltung in resistent und anf?llig lassen sich 5 genotypische Gruppen unterscheiden. Zwei Gruppen entsprechen in ihrer Resistenzvererbung dem einfaktoriellen Modell bei Autotetraploiden auf duplexer bzw. simplexer Basis. Der Nachweis von zwei weiteren Genotypen, die sich nicht einordnen lassen, l?\t eine h?here genetische Varianz erkennen, als nach dem autotetraploiden Modell theoretisht zu erwarten ist. Die M?glichkeit der Identifizierung weiterer Genotypen wird nicht ausgeschlossen.

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Summary The progeny of a diallel cross between 10 clones of table potatoes were tested for resistance toSynchytrium endobioticum Pathotype 1. Of the 10 parent clones, 9 were resistant, based on the characteristic defence necrosis, and one was very susceptible. In total 45 hybrid and 10 selfed progenies were tested with 60–100 genotypes in each case. The mean performance of each clone was assessed using the percentages of resistant genotypes for all 9 combinations with other clones, and the selfs. The 10 clones are arranged in Table 1 according to their rankings for this parameter. Five groups of genotypes (I–V) can be recognized; these are significantly different from one another. The mean values of the selfs for individual groups, and the combinations with the susceptible parent are also given. From these results it can be concluded that the clones in Groups I–III inherited resistance as if controlled by a single major dominant gene in the simplex or duplex condition in the autotetraploid. The susceptible parent gave a nulliplex-type. The corresponding test results given in Table 2 confirm these conclusions. According to Table 1, clones (4) and (9) do not fit into Groups I and III. They have another genotype. Since the parents used here cover only a small range of possible genotypes, no generally valid statements can be made about the number of groups and the frequency of the genotypes in the groups for all cultivars and clones ofSolanum tuberosum. Inheritance studies of wart resistance by other authors confirm the assumption that further genotype groups may be identified. Greater genetic variation can be expected than is theoretically possible in the single factor model of autotetraploidy.

     

Changes of the lipid catabolism in potato tubers from cultivars differing in susceptibility to autolysis during the storage

Summary The activities of lipolytic acyl-hydrolases (LAH) and lipoxygenases (LOX) were compared in stored tubers of potato cultivars resistant (Acresta, Eba, Pentland Envoy) and susceptible (Kastor, Pana, Tasso) to post-wounding autolysis. In most cultivars, LAH activities had reached a maximum by the end of December but in cv. Kastor activity continued to increase throughout the storage period. LOX activities increased during most of the storage period except in cv. Tasso. The level of the fatty acid hydroperoxides, assumed from determinations of the malonaldehyde level, also increased during storage. This work was supported by Project CPBP 05.02.2.10 financed by the Polish Academy of Science.     

More about the potato nematode,Heterodera rostochiensis Woll., in Peru

Thirteen resistant selections ofS. tuberosum hybrids bred in the U.S.A. and Europe and 44 diploid clones derived fromS. vernei, S. spegazzinii, S. neohawkesii, andS. sanctaerosae each with resistance to one or more pathotypes ofH. rostochiensis were tested for their resistance to three Peruvian populations of this nematode. Only one diploid clone ofS. sanctatrosae was found to be resistant to the three populations of nematodes, but several clones were resistant to one or another of the nematode populations. More clones were found to resist the nematode population collected near Cuzco than those populations collected near Huancayo or Otuzco. Morphometric measurements of body length, stylet length, and distance of median valve to excretory pore, of second stage larvae showed great variation and no clear difference among the three populations. The measurements obtained were closer to pathotype E from England than to any other recognized pathotypes.     

Genetics components of rice root architecture and carbon isotopic fractionation parameters: a tracer for breeding in a water-saving irrigation management

Journal of Crop Science and Biotechnology - Phenotyping is the major bottleneck in the effort to develop varieties of rice (Oryza sativa L.) suitable for growing under a water-saving irrigation...     

Resistance of Corynespora cassiicola from soybean to QoI and MBC fungicides in Brazil

Fungicide sprays on soybean in Brazil have contributed to the selection of less sensitive isolates of Corynespora cassiicola. We collected 59 isolates of C. cassiicola from three Brazilian states and two isolates from Paraguay. We investigated their EC₅₀ to quinone outside inhibitors (QoI) and methyl benzimidazole carbamate (MBC), any cross-resistance to compounds within QoI and MBC groups, and characterized the polymorphisms in their cytb and β-tubulin genes. Local associations of polymorphisms identified in each gene were statistically correlated with assays results. In total, 79% and 74% of the isolates were classified as resistant to QoI and MBC fungicides, respectively. There was positive cross-resistance to active ingredients within QoI and MBC groups. For QoI, all isolates presented heteroplasmy in G143A of cytb gene; the mutations F129L and G137R were not found. For MBC, 63% of isolates possessed E198A and 21% possessed F200Y mutations, associated with reduced control by MBC fungicides. Heteroplasmy was identified in two and one isolates from Brazil with E198A and F200Y mutations, respectively. The resistance factor for isolates with E198A (10.9) was statistically similar to the isolate with F200Y (8.8) mutation. Genic association analysis of the in vitro assays using discriminatory doses proved them to be accurate. Reduced sensitivity of C. cassiicola to QoI and MBC was also identified in isolates from Paraguay and resistance to QoI and MBC was widely present in C. cassiicola isolates from the main soybean-producing states in Brazil. Thus, integrated management measures should be adopted to manage soybean target spot in these countries.     

Trichoderma as a biological agent of Fusarium oxysporum species complex and Vigna unguiculata growth promoter

European Journal of Plant Pathology - This study aimed to evaluate the potential antagonistic role of Trichoderma in the control of Fusarium isolates belonging to the Fusarium oxysporum species...     

Mycoparasitic Trichoderma isolates as a biocontrol agent against Valsa ceratosperma,the causal agent of apple valsa canker

European Journal of Plant Pathology - Apple valsa canker, caused by the fungus Valsa ceratosperma, is one of the most destructive diseases of this crop. Conventional fungicide treatments are not...     

Evaluation of Cymbopogon flexuosus and Alpinia zerumbet essential oils as biopesticides against Callosobruchus maculatus

Journal of Plant Diseases and Protection - This study aimed to investigate the effects of the essential oils of Cymbopogon flexuosus and Alpinia zerumbet in the treatment of cowpea [Vigna...     

Population growth of stored product insects on wheat containing wheat bugs

Journal of Plant Diseases and Protection - In the present study we examined the effect of the presence of wheat bugs (Eurygaster spp. and Aelia spp.) on wheat on the mortality, progeny production...     

Enhancing the Reliability of Laboratory Phosphorus Filter Tests: Effect of Influent Properties and Interpretation of Effluent Parameters

The distribution of selected elements in individual fractions of organic matter from anthropogenically contaminated soils was investigated. The attention was paid especially at Hg. Furthermore, contents of S, Mg, Mn, Fe, Cu, Zn and Pb were also measured. The decomposition of organic matter to particular fractions was carried out by the resin DAX-8. Ten soil samples were collected, and the Advanced Mercury Analyzer (AMA-254) was used for the determination of the total Hg content. The two highest Hg values reached up to the concentration 10.5 mg kg^?1, and in the highest one, it was almost 29 mg kg^?1. In each extract, mercury was measured by inductively coupled plasma mass spectrometry (ICP-MS), for other elements, inductively coupled plasma optical emission spectrometry (ICP-OES) was applied. Results of the analysis show that the Hg content bound to the humic acids is inversely proportional to the content of Mg, Mn, Fe and Cu. However, this dependence was not confirmed by the samples with the mercury content above 10 mg kg^?1. In the case of fulvic acids, the relationship between Hg and S was observed and has again an inverse character.