Phytopathological and molecular characterization of the partially mlo-virulent barley powdery mildew isolate HL-3
S. KUSCH (1) (1) RWTH Aachen University, Germany

Plants with loss-of-function mutation of specific Mildew Locus O (MLO) genes, coding for plant proteins with seven transmembrane domains, exhibit broad-spectrum resistance against powdery mildew. The lab-derived, artificially selected barley powdery mildew (Blumeria graminis f.sp. hordei, Bgh) isolate HL-3, however, is partially virulent on barley mlo plants. This implies that a mlo-virulent strain could possibly emerge in nature as well and thus pose a major threat for plant protection. My objectives are to quantitatively characterize the Bgh HL-3 infection on various host plants and to identify the fungal genes that are necessary to overcome mlo resistance. Compared to its development on wild type host plants, the growth of Bgh HL-3 on mlo mutant plants is delayed from 18 hours post inoculation (hpi) onwards, and microcolonies first appear 72 hpi. I found no indication of increased HL-3 virulence on the nonhost plants wheat and Arabidopsis. Next, I performed comparative transcriptome analysis using RNAseq of HL-3, and a Bgh isolate that is avirulent on barley mlo genotypes, to identify the causative genes for partial mlo virulence. Fungal samples were collected from barley mlo mutant and susceptible wild type plants. Identification and characterization of genes that may facilitate partial mlo virulence will help to understand the molecular mechanisms underlying mlo resistance, thus, ultimately increasing our understanding of plant immunity against biotrophic pathogens.

Abstract Number: P7-181
Session Type: Poster