Integration of resistance QTL, expression QTL and co-expression modules reveals molecular responses of maize to the fungal pathogen Cercospora zeina
D. BERGER (1), N. Christie (2), A. Myburg (2) (1) Plant Science Department, Forestry and Agricultural Biotechnology Institute, University of Pretoria, South Africa; (2) Genetics Department, Forestry and Agricultural Biotechnology Institute, University of Pretoria, South Africa

Gray leaf spot (GLS) is a maize disease of global importance caused by the Dothidiomycete fungal pathogens Cercospora zeina or Cercospora zeae-maydis. Maize responses to GLS disease are quantitative with QTL for resistance previously identified from segregating populations. However, the genetic architecture of transcriptional responses to GLS in maize is under-explored. The aim of the study was to develop a systems genetics framework to link phenotypic QTL with global gene expression patterns. One hundred individuals from a sub-tropical maize population were challenged in the field with C. zeina, and RNA was extracted from infected leaf material for analysis using a well-annotated Agilent maize microarray. Transcriptome data was subjected to weighted gene co-expression network analysis (WGCNA) and expression QTL (eQTL) analysis using a pipeline constructed in Galaxy. Three co-expression modules correlated with resistance to GLS across the population. One of these modules was enriched for genes that had trans-eQTLs in an eQTL hotspot that coincided with a phenotypic QTL for GLS resistance on chromosome 4. This was corroborated by the fact that an eQTL for the co-expression module eigengene (“average” expression of module genes across the population) was mapped to the same position. Our work has provided evidence for a genetic basis for coordinated gene expression in maize in response to the pathogen C. zeina. Furthermore, we present an integrated bioinformatics framework which can be applied for similar studies of molecular plant-pathogen interactions.

Abstract Number: C6-4, P14-424
Session Type: Concurrent