Towards unravelling the exserohilum turcicum-sorghum pathosystem through inoculation trials and transcriptome data
B. LANGENHOVEN (1), M. Craven (2), S. Murray (3), A. Nieuwoudt (4), M. Human (4) (1) University of Pretoria, South Africa; (2) Agricultural Research Centre-Grain Crops Institute, South Africa; (3) University of Cape Town, South Africa; (4) University of Pretoria, South Africa

Exserohilum turcicum (Pass.) is the causal agent of northern leaf blight disease (NLB), which is an economically important foliar disease that occurs worldwide. This destructive fungal pathogen is able to infect maize, sorghum, and other related grass species. Even though E. turcicum has a broad host range, reports have indicated that isolates of E. turcicum may be specific to the crop from which it was isolated. One such haplotype that was isolated from sorghum was shown to specifically infect sorghum, as it was not virulent on maize. The main aim of this study was therefore to assess the virulence of an E. turcicum sorghum isolate on multiple maize and sorghum lines. The haplotype of the E. turcicum sorghum isolate was verified with twelve E. turcicum specific simple sequence repeat markers, and was compared with previously haplotyped E. turcicum isolates from maize and sorghum using principle coordinate analysis (PCoA). PCoA indicated that the sorghum E. turcicum isolate grouped separately from the major maize E. turcicum isolates. Four sorghum and eight commercial maize cultivars that vary in susceptibility to NLB as well as a differential maize set were used in an inoculation trial to determine if the E. turcicum haplotype isolated form sorghum is virulent on sorghum and/or maize seedlings. It was shown through disease scoring that the sorghum E. turcicum isolate was virulent on sorghum seedlings, and little to no susceptible responses were observed on maize lines. Work is currently ongoing to assess whether a selection of genetically distinct E. turcicum isolates from sorghum and maize can cross infect host plants. The information gathered by this study will shed light on the E. turcicum-sorghum interaction, which will in turn lead to improved management strategies for this economically important disease.

Abstract Number: P17-553
Session Type: Poster