Functional analysis of Ustilago hordei effector UhAVR1 during compatible and incompatible interactions with its barley host
A. MONTENEGRO ALONSO (1), G. Bakkeren (2) (1) The University of British Columbia, Canada; (2) Agriculture and Agri-Food Canada, Canada

Genome analysis of the barley pathogen Ustilago hordei, revealed 333 candidate secreted effectors which are hypothesized to aid infection by suppressing host defenses. We recently identified effector UhAVR1, an avirulence gene product that is expressed upon infection of barley seedlings causing incompatibility on cultivar Hannchen (Ruh1) and compatibility on cultivar Odessa. In order to understand UhAVR1 functions, identify its target in barley and delineate defense triggering, transcriptome analyses were conducted in barley seedlings, comparing susceptible and resistant interactions by inoculating wild type and an UhAVR1 deletion mutant. Fungal penetration and growth were followed by microscopy, and the expression of a diagnostic defence gene, PR1.1b, was studied. Samples were collected from 24 to 120 hrs post inoculation (hpi) with teliospores. In the incompatible interaction, defense initiation was strong at 24 hpi and PR1.1b levels stayed high when using wild type spores but were reduced in the mutant at 48 hpi indicating recognition of UhAVR1 by the plant. At that time point during the compatible interaction, PR1.1b levels were reduced, indicating defense suppression, though the mutant incited also a reduction. At 96 hpi however, this mutant triggered a higher expression compared to wild type infection, suggesting that UhAVR1 plays a role at that infection stage. These materials are used for global transcriptome analyses using RNAseq to detail these responses.

Abstract Number: P10-338
Session Type: Poster