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Plant pathogenicMagnaporthales inAustralia, withparticular referenceto Pyricularia oryzaeon wild andcultivated rice Wanporn Khemmuk2017 год

Plant pathogenic Magnaporthales in Australia, with particular reference to Pyricularia oryzae on wild and cultivated rice
dissertation

Полный текстСтраница публикацииПубликация в OpenAlex
Аннотация: The Magnaporthales is an order of fungi that contains plant pathogens and saprobes.This order consists of three families, Pyriculariaceae, Magnaporthaceae and Ophioceraceae, which are phylogenetically, morphologically and ecologically distinct.To date, about 200 species have been described in Magnaporthales, of which approximately 50% are plant pathogens.Some species are important pathogens of grasses and cereals such as the rice blast fungus Pyricularia oryzae (syn.Magnaporthe oryzae) and the take-all pathogen of cereals Gaeumannomyces graminis.The study of classification and identification of Magnaporthales in Australia and pathogenicity of Pyricularia oryzae are reported in this thesis.The genus Pyricularia comprises species that cause blast diseases on various hosts, especially grasses (Poaceae) that include crops such as rice, wheat, barley and grasses.This study used morphology, phylogenetic concordance, ecology and pathogenicity, to study Pyricularia and allied genera in the Magnaporthales.The fungi associated with blast diseases on eleven monocot hosts in Australia were identified by morphological characters and DNA sequence analysis in Chapter 2. Three species of Pyricularia, namely, Pyricularia angulata, Pyricularia pennisetigena and Pyricularia oryzae, were confirmed as present in Australia.Another species, Pyricularia rabaulensis was found to belong to a recently established genus Barretomyces.A formal transfer of this fungus to Barretomyces has been proposed.In Chapter 3, the phylogenetic relationships of some other Australian Magnaporthe-like fungi were investigated based on morphology and DNA sequence analysis of multiple genes.The root pathogenic fungi of Cynodon dactylon and Agrostis stolonifera as well as holotype specimens of Magnaporthe garrettii and Magnaporthe griffinii were examined.Two novel genera, Budhanggurabania and Wongia, were described as well as a new species, Magnaporthiopsis agrostidis.Rice (Oryza sativa L., Poaceae) is the most important cereal crop globally and a primary source of starch for more than half the world's population.The major constrain to rice production worldwide is rice blast disease, which is caused by the fungus Pyricularia oryzae Cavara (syn.Magnaporthe oryzae Hebert).Rice blast disease is a problem in over 85 countries in all continents where rice is cultivated in both paddy and upland situations.Unpredictable epidemics can cause significant economic losses.Foliar disease surveys of wild and cultivated rice in northern Queensland were completed in 2014 and 2015.The results presented in Chapter 4 show that a total of 109 fungal isolates was recovered and classified into seven genera, viz.Bipolaris, Colletotrichum, Curvularia, Nigrospora, Phoma, Pestalotiopsis and Pyricularia.Isolates from three genera, Pyricularia, Bipolaris and Curvularia were identified to species level by multigenes analysis because of their potential to cause important diseases on rice.The rice blast pathogen, Pyricularia oryzae, brown spot pathogen, Bipolaris oryzae and a large diversity of Curvularia species were recovered.To remove uncertainty about the identity of the host plants from which the fungi were isolated, a DNA barcoding strategy was developed using regions of the chloroplast genome.In Chapter 5, pathogenicity and cross infectivity of Pyricularia species are investigated.Four Australian isolates of Pyricularia oryzae, two isolates from domesticated rice and two isolates from wild rice, were tested onto nine commercial rice cultivars namely, Doongara, langi, Kyeema, Illabong, Sherpa, Reiziq, Koshi, Opus and Quest.The results showed that infection occurred on all rice varieties with Quest the most susceptible and Sherpa the least susceptible.The host ranges of four Australian isolates of Pyricularia oryzae from rice and one isolate from barley, were tested on barley, oats, rice and wheat.None of the isolates infected wheat, and one isolate from rice infected oats.Isolates of Pyricularia oryzae from Setaria italica and Pennisetum clandestinum were shown to cause blast disease on their original hosts and barley but did not infect rice and wheat.The research described in this thesis presents the identification and classification of plant pathogenic fungi in order Magnaporthales in Australia.Three species of Pyricularia were identified in this study based on a phylogenetic species concept as well as two novel species of root pathogens in family Magnaporthaceae.Phylogenetic analysis placed two Australian root pathogen species, Magnaporthe garrettii and Magnaporthe griffinii, in the new genus, Wongia, Diaporthomycetidae.Conidial morphology is a primary character to distinguish genera.The Magnaporthales is a diverse order and more novel species certaintly await discovery.Future researches that might provide better understanding of Pyricularia oryzae and other closely related fungi in the Magnaporthales are discussed in Chapter 6.
Год издания: 2017
Авторы: Wanporn Khemmuk
Ключевые слова: Plant Pathogens and Fungal Diseases, Plant Disease Resistance and Genetics, Mycotoxins in Agriculture and Food
Другие ссылки: doi.org (HTML)
Queensland Department of Agriculture and Fisheries archive of scientific and research publications (Queensland Department of Agriculture and Fisheries) (PDF)
Queensland Department of Agriculture and Fisheries archive of scientific and research publications (Queensland Department of Agriculture and Fisheries) (HTML)