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Host Plant Resistance (host + plant_resistance)
Selected AbstractsCombating plant diseases,the Darwin connectionPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 11 2009Derek W Hollomon Abstract Although Darwin knew of plant diseases, he did not study them as part of his analysis of natural selection. Effective plant disease control has only been developed after his death. This article explores the relevance of Darwin's ideas to three problem areas with respect to diseases caused by fungi: emergence of new diseases, loss of disease resistance bred into plants and development of fungicide resistance. Darwin's concept of change through natural or artificial selection relied on selection of many small changes, but subsequent genetic research has shown that change can also occur through large steps. Appearance of new diseases can involve gene duplication, transfer or recombination, but all evidence points to both host plant resistance and fungicide susceptibility being overcome through point mutations. Because the population size of diseases such as rusts and powdery and downy mildews is so large, all possible point mutations are likely to occur daily, even during moderate epidemics. Overcoming control measures therefore reflects the overall fitness of these mutants, and much resource effort is being directed towards assessment of their fitness, both in the presence and in the absence of selection. While recent developments in comparative genomics have caused some revision of Darwin's ideas, experience in managing plant disease control measures clearly demonstrates the relevance of concepts he introduced 150 years ago. It also reveals the remarkable speed and the practical impact of adaptation in wild microorganism populations to changes in their environment, and the difficulty of stopping or delaying such adaptation. Copyright © 2009 Society of Chemical Industry [source] Metabolomic analysis of host plant resistance to thrips in wild and cultivated tomatoes,PHYTOCHEMICAL ANALYSIS, Issue 1 2010Mohammad Mirnezhad Abstract Introduction , Western flower thrips (Frankliniella occidentalis) are among the most serious crop pests worldwide. Control of thrips mainly depends on pesticides, excessive use of which leads to human health risks and environmental contamination. As an alternative, we study host plant resistance to thrips. Objective , To apply nuclear magnetic resonance spectroscopy (NMR) metabolomics to study host plant resistance to thrips in wild and cultivated tomatoes. Methodology , Ten wild species and 10 cultivated tomato lines were compared. Five replicates of each species and lines were used for a thrips bioassay while another five replicates were used for the metabolomic analysis. The three most resistant and susceptible wild species, and cultivated lines, as identified by the thrips bioassay, were used for the metabolomics, performed by 1H NMR spectroscopy followed by principal component analysis. Results , Wild and cultivated tomatoes differed significantly in thrips resistance. Only wild tomatoes were thrips-resistant, among which Lycopersicon pennellii and L. hirsutum exhibited the lowest thrips damage. Their 1H NMR-based metabolomic profiles were significantly different from those of thrips-susceptible tomatoes. Thrips-resistant tomatoes contained acylsugars, which are known for their negative effect on herbivores. Conclusion , The identification of acylsugars as a resistance factor for thrips in tomato proves that NMR-based metabolomics an important tool to study plant defences, providing fundamental information for the development and realisation of herbivore resistance breeding programmes in agricultural crops. Copyright © 2009 John Wiley & Sons, Ltd. [source] Quantitative trait locus mapping of resistance in apple to Cydia pomonella and Lyonetia clerkella and of two selected fruit traitsANNALS OF APPLIED BIOLOGY, Issue 3 2009S. Stoeckli Abstract Apple, Malus×domestica, is the most important fruit grown within the temperate zonobiome. It is attacked by both fruit-damaging and leaf-damaging lepidopteran pest insects, which require regular control such as the carpophagous codling moth, Cydia pomonella, or frequent control such as the phyllophagous apple leaf miner, Lyonetia clerkella. As many environmentally friendly pest control tactics are only effective at low levels of infestation, host plant resistance is a promising future component of integrated pest management systems, but knowledge is still lacking on such genetically based approaches against lepidopteran pests. The aim of the study was to identify molecular markers linked to C. pomonella and L. clerkella resistance or susceptibility in commercial apple as well as markers linked to selected fruit traits. The number of C. pomonella -infested fruits and the number of L. clerkella mines were quantified as measures of apple resistance or susceptibility to the studied moth species. Herbivore surveys on 160 apple genotypes, representing a segregating F1 cross of the apple cultivars ,Fiesta' and ,Discovery', were carried out during two consecutive years and at two sites in Switzerland. Broad-sense heritability was 29.9% (C. pomonella), 18.2% (L. clerkella), 21.9% (fruit number) and 16.6% (fruit diameter). A subsequent analysis identified a quantitative trait locus (QTL) associated to C. pomonella susceptibility on the Discovery linkage group 10. The closest marker to this QTL was the random amplified polymorphic marker Z19-350. No significant QTL was identified for resistance to L. clerkella. A putative QTL associated to fruit number was identified on Fiesta linkage group 12. The presented QTL associated with C. pomonella susceptibility and the putative QTL linked to fruit number may facilitate marker-assisted breeding of resistant apple cultivars with cropping traits desirable for optimal fruit production. [source] | ||||||||||