The Department of Microbiology and Plant Pathology's weekly Plant Pathology 250 seminar series is presented this week by Dr. Martha Hawes from The University of Arizona.

Seminar Title: “Extracellular DNA traps in plant and animal defense: New insights into mechanisms of eukaryote immunity”

Abstract: Root tips of most plant species produce populations of metabolically active root border cells (insert) with specialized patterns of gene expression. In response to contact with free water, border cells disperse into suspension immediately, and renewed cell production in the root cap meristem is induced. Their function has been a mystery. Recent studies have revealed that border cells operate in a manner similar to that of mammalian neutrophils: Both cell types export a complex of extracellular DNA (exDNA) and antimicrobial proteins that neutralize threats by trapping pathogens in a host-microbe specific manner and thereby preventing invasion of host tissues. Extracellular DNases (exDNases) from animal pathogens degrade neutrophil extracellular traps (NETs) and thereby promote virulence and systemic spread of the microbes. In plants, adding DNase I to root tips inoculated with a pathogen eliminates border cell extracellular traps and abolishes root tip resistance to infection. Mutation of exDNase encoding genes in plant pathogenic bacteria and fungi results in reduced virulence and vascular movement in diverse plant tissues. The study of exDNA sequence specificity in plants and exDNase target activities in plant pathogens may yield new approaches to disease control.

Seminar Host: Dr. Emma Gachomo; emma.gachomo@ucr.edu