Genome Evolution in Plant Pathogens

Division of Plant Industry, Commonwealth Scientific and Industrial Research Organisation, Canberra, ACT 2614, Australia.
Science (Impact Factor: 33.61). 12/2010; 330(6010):1486-7. DOI: 10.1126/science.1200245
Source: PubMed


Pathogen genes that shut down specific host plant immune responses are highly divergent and have evolved rapidly to accommodate adaptation.

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Available from: Peter N Dodds
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    • "The biotrophs are entirely dependent upon living host and keep their host alive throughout their life cycle, the hemibiotrophs keep host alive for some period and then kill them, and the necrotrophs feed on host plants by killing them. The evolution of such lifestyles in fi lamentous pathogens was correlated with gain/loss of genes by comparative analysis (Dodds 2010 ) . Molecular plant pathologists have broadly classi fi ed plant disease resistance operating in natural habitats into two categories: the host resistance and the nonhost resistance (Heath 2000 ) . "
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    ABSTRACT: Alleviating the crop loss due to biotic stress is the primary aim of plant biologists to achieve sustainable evergreen revolution in order to feed rapidly growing population. In nature, continuous evolution of plants while interacting with pathogens has generated a complex immune system that consists of preformed barriers and induced responses. The induced responses are further subdivided based upon the recognition of microbe-associated molecular patterns and effectors produced by pathogens; however, overlap exists between the downstream signaling pathways. In last decade, great deal of information about molecular aspects of plant–pathogen interactions has been generated which can be utilized for improving crops through genetic manipulation. Plant breeding has helped in the isolation of species-specific resistance components (R genes) from many plants. The molecular breeding techniques have also helped in pyramiding several components to a single variety, especially QTLs responsible for plant resistance, high yield, and nutritional quality. The identification of nonhost components in model plants and incorporation of genetically modified crops in our cropping system have raised hopes that nonhost resistance can be utilized for generating broad-spectrum pathogen tolerance breaking the barriers of species level resistance. This chapter describes the recent molecular aspects of plant–pathogen interactions focusing on the nonhost resistance components. Additionally, strategies like specific regulation of induced defense responses, manipulation of susceptibility factors, and host-induced gene silencing (HIGS) are discussed. The development of GM crops using such strategies will help in generating higher yields against pathogen infestations
    Full-text · Chapter · Jan 2013
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    • "Biotrophic fungi spend at least part of their lifecycle in the host cell without causing symptoms of disease and represent important intracellular pathogens of humans, animals, and plants. In particular, such fungi cause devastating diseases of crops [1], but long standing questions concerning which metabolites the fungi make themselves, and what they obtain from the plant, are largely unanswered [2]–[4]. Determining the metabolites available to pathogens in host tissue could reveal new information regarding pathogen-host interactions that would point the way to novel mitigation strategies. "
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    ABSTRACT: Fungal diseases cause enormous crop losses, but defining the nutrient conditions encountered by the pathogen remains elusive. Here, we generated a mutant strain of the devastating rice pathogen Magnaporthe oryzae impaired for de novo methionine biosynthesis. The resulting methionine-requiring strain grew strongly on synthetic minimal media supplemented with methionine, aspartate or complex mixtures of partially digested proteins, but could not establish disease in rice leaves. Live-cell-imaging showed the mutant could produce normal appressoria and enter host cells but failed to develop, indicating the availability or accessibility of aspartate and methionine is limited in the plant. This is the first report to demonstrate the utility of combining biochemical genetics, plate growth tests and live-cell-imaging to indicate what nutrients might not be readily available to the fungal pathogen in rice host cells.
    Full-text · Article · Oct 2012 · PLoS ONE
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    • "There is evidence that supports a relationship between lytic enzyme production and the lifestyles of fungi and oomycetes. For instance, the genome of the oomycete Hyaloperonospora arabidopsidis has lost several of its hydrolytic enzymes compared with Phytophthora sp., which is likely its ancestor [75,76]. According to an analysis of the hydrolytic profiles of saprophytic/opportunistic and pathogenic fungi using diverse substrates, the species of phytopathogenic fungi are more active than the non-pathogenic fungi on six of eight tested substrates [74]. "
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    ABSTRACT: Microorganisms produce cell-wall-degrading enzymes as part of their strategies for plant invasion/nutrition. Among these, pectin lyases (PNLs) catalyze the depolymerization of esterified pectin by a β-elimination mechanism. PNLs are grouped together with pectate lyases (PL) in Family 1 of the polysaccharide lyases, as they share a conserved structure in a parallel β-helix. The best-characterized fungal pectin lyases are obtained from saprophytic/opportunistic fungi in the genera Aspergillus and Penicillium and from some pathogens such as Colletotrichum gloeosporioides.The organism used in the present study, Colletotrichum lindemuthianum, is a phytopathogenic fungus that can be subdivided into different physiological races with different capacities to infect its host, Phaseolus vulgaris. These include the non-pathogenic and pathogenic strains known as races 0 and 1472, respectively. Here we report the isolation and sequence analysis of the Clpnl2 gene, which encodes the pectin lyase 2 of C. lindemuthianum, and its expression in pathogenic and non-pathogenic races of C. lindemuthianum grown on different carbon sources. In addition, we performed a phylogenetic analysis of the deduced amino acid sequence of Clpnl2 based on reported sequences of PNLs from other sources and compared the three-dimensional structure of Clpnl2, as predicted by homology modeling, with those of other organisms. Both analyses revealed an early separation of bacterial pectin lyases from those found in fungi and oomycetes. Furthermore, two groups could be distinguished among the enzymes from fungi and oomycetes: one comprising enzymes from mostly saprophytic/opportunistic fungi and the other formed mainly by enzymes from pathogenic fungi and oomycetes. Clpnl2 was found in the latter group and was grouped together with the pectin lyase from C. gloeosporioides. The Clpnl2 gene of C. lindemuthianum shares the characteristic elements of genes coding for pectin lyases. A time-course analysis revealed significant differences between the two fungal races in terms of the expression of Clpnl2 encoding for pectin lyase 2. According to the results, pectin lyases from bacteria and fungi separated early during evolution. Likewise, the enzymes from fungi and oomycetes diverged in accordance with their differing lifestyles. It is possible that the diversity and nature of the assimilatory carbon substrates processed by these organisms played a determinant role in this phenomenon.
    Full-text · Article · Dec 2011 · BMC Microbiology
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