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Phoma Medicaginis: a Model Pathosystem for Medicago Truncatula

Dhulipala, Madhavi R.
The fungus Phoma medicaginis was transformed using Agrobacterium tumefaciens-mediated transformation and a collection of T-DNA tagged transformants generated and characterized. The interactions of P. medicaginis with the hosts, Medicago truncatula and M. sativa, were assayed and studied using fluorescent microscopy. Nine hundred eighty-two T-DNA tagged transformants of P. medicaginis were generated. T-DNA integration into the genome was confirmed and six of ten transformants were found to have single insertions. The genomic DNA flanking the T-DNA of a mutant transformant showed similarity to a serine/threonine protein kinase in the genome of Stagonospora nodorum. Detached leaves of Medicago spp. were inoculated with P. medicaginis and disease progress followed. Tested transformants were as virulent as wild types. Conidia of a GFP-tagged transformant germinated within 24 h and directly penetrated and infected epidermal and guard cells of leaves and penetrated through the stomata of cotyledons.