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Research Project: Genetic Analysis of Complex Traits in Maize

Location: Plant Science Research

Title: Identification of a locus in maize controlling response to a host-specific toxin derived from Cochliobolus heterostrophus, causal agent of Southern Leaf Blight

Author
item XIAODONG, XIE - North Carolina State University
item OLUKOLU, BODE - North Carolina State University
item YANG, QIN - North Carolina State University
item Balint-Kurti, Peter

Submitted to: Molecular Plant-Microbe Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2018
Publication Date: 12/1/2018
Citation: Xiaodong, X., Olukolu, B., Yang, Q., Balint Kurti, P.J. 2018. Identification of a locus in maize controlling response to a host-specific toxin derived from Cochliobolus heterostrophus, causal agent of Southern Leaf Blight. Molecular Plant-Microbe Interactions. 131:2601-2612.

Interpretive Summary: We have shown that there is a toxin produced by Cochliobolus heterostrophus, a fungal pathogen of maize, that kills cells of some maize lines but not others. We have also shown that there is a gene in maize which is responsible for conferring susceptibility to this toxin. We have identified a specific gene that is likely to be the susceptibility gene. This gene encodes a protein that is important in the movement of membranes and vesicles within and between cells. We have also examined whether sensitivity to this toxin is responsible for susceptibility to southern leaf blight, the disease caused by C. heterostrophus. We have not been able to show definitively that this is the case.

Technical Abstract: Host-specific toxins (HSTs) produced by fungal plant pathogens, and their corresponding host susceptibility genes have been identified in several necrotrophic plant-pathogen interactions. In this study we identified a host-specific toxic activity from the culture filtrate (CF) of the fungus Cochliobolus heterostrophus, causal agent of the maize disease southern leaf blight (SLB). Two independent mapping populations, a 113-line recombinant inbred line population and a 258-line association population, were used to map sensitivity to the CF at the seedling stage. A major QTL on chromosome 4 was identified at the same locus using both populations. The precise mapping of the locus in the association mapping population allowed for the identification of a candidate gene, GRMZM2G140832 encoding a predicted Sec1-family transport protein Sly1, thought to be involved in intracellular membrane trafficking. By comparing CF-sensitivity of the parents of the RIL population with that of the F1 progeny, we determined that the sensitivity allele was dominant. No relationship was observed between CF-sensitivity in seedlings and SLB susceptibility in mature plants, however a significant correlation (-0.58) was observed between SLB susceptibility and CF sensitivity in seedlings.