Graduate student University of California Riverside, California
Body of Abstract: The devastating, soil born plant-pathogenic fungus Macrophomina phaseolina (Mp) is spreading world wide in the wake of global warming, causing dramatic losses in agriculture. Many hosts of this broad-spectrum root pathogen are economically important crops. Prohibition of methyl bromide fumigation, an efficient solution to control Mp, increased the occurrence of crop diseases caused by this fungus. Alternative methods for Mp eradication are urgently needed, but host defenses against this detrimental pathogen are poorly understood. We are using interactions of Mp with the plant model species Arabidopsis thaliana (Arabidopsis) to gain a comprehensive understanding of host immunity against Mp. Testing over 100 natural A. thaliana accessions we found their tolerance against Mp to vary substantially. By RNA-seq in Col-0 we identified numerous genes showing strong transcriptional responses after Mp infection. Arabidopsis T-DNA mutants with compromised function of some of these genes show increased susceptibility against Mp. Use of Mp-responsive Arabidopsis promoters fused to the GUS reporter gene revealed that gene expression responses triggered by this pathogen in roots can be tissue-specific. We are planning to use fluorescence activated cell sorting (FACS) to study how different Arabidopsis root tissues cooperate in induced immunity against Mp.