Blast disease of wheat has emerged as a new and serious field disease affecting wheat production in South America. The causal agent of wheat blast, Magnaporthe oryzae, infects cultivated crops including rice, wheat and barley, while M grisea is adapted to infect wild grass species. Durable disease resistance of crops against fungal pathogens may be achieved through non-host resistance; which is defined as resistance of a plant species to a non-adapted pathogen. Cellular defence responses and transcriptional changes of wheat cv. Renan, infected with adapted and non-adapted isolates of Magnaporthe spp., were investigated. Appositions formed beneath attempted penetration sites appeared to prevent colonisation by the nonadapted M grisea isolate, but were breached by the adapted M oryzae isolates. Microarray analysis indicated that wheat undergoes extensive transcriptome reprogramming following inoculation with both adapted and non-adapted isolates of Magnaporthe spp. A distinct set of transcripts were induced exclusively in response to the non-adapted M grisea isolate, while others were induced in response to both adapted and non-adapted isolates. Defence-related transcripts induced in common by adapted and non-adapted isolates were differentially regulated in response to M oryzae and M grisea isolates over time. Establishment of a virus induced gene silencing (VIGS) system in wheat cv. Renan enabled functional analysis of differentially expressed transcripts. Silencing the gene WIRT increased cell-to-cell spread of M oryzae hyphae, but not penetration efficiency, suggesting a postpenetration resistance role for this gene. Another gene, TaNIN was induced at early time points in response to both adapted and non-adapted Magnaporthe isolates. A partial sequence of this gene was cloned and shown to be the first nodule inception (NM-like gene characterised in wheat. This study provides an insight into the development of Magnaporthe spp. on wheat, together with functional characterisation of transcripts differentially expressed during adapted and nonadapted Magnaporthe spp. -wheat interactions.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:522402 |
| Date | January 2009 |
| Creators | Tufan, Hale Ann |
| Publisher | University of East Anglia |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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