Arabidopsis GOLD36/MVP1/ERMO3 Is Required for Powdery Mildew Penetration Resistance and Proper Targeting of the PEN3 Transporter.

The Arabidopsis PENETRATION 3 (PEN3) ATP binding cassette (ABC) transporter contributes to penetration resistance against nonadapted powdery mildew fungi and is targeted to papillae deposited at sites of interaction with the fungus. Timely recruitment of PEN3 and other components of penetration resistance to the host-pathogen interface is important for successful defense against this biotrophic pathogen. A forward genetic screen was previously carried out to identify Arabidopsis mutants that mistarget the PEN3 transporter or fail to accumulate PEN3 at sites of attempted powdery mildew penetration. This study focuses on PEN3 mistargeting in the aberrant localization of PEN3 4 ( alp4 ) mutant and identification of the causal gene. In the alp4 mutant, PEN3 accumulates within the endomembrane system in an apparently abnormal endoplasmic reticulum and is not exported into papillae at powdery mildew penetration sites. This targeting defect compromises defenses at the host-pathogen interface, resulting in increased penetration success by a nonadapted powdery mildew. Genetic mapping identified alp4 as an allele of GOLGI DEFECTS 36 ( GOLD36 ), a gene encoding a GDSL-lipase/esterase family protein that is involved in maintaining normal morphology and organization of multiple endomembrane compartments. Genetic complementation confirmed that mutation in GOLD36 is responsible for the PEN3 targeting and powdery mildew penetration resistance defects in alp4 . These results reinforce the importance of endomembrane trafficking in resistance to haustorium-forming phytopathogens such as powdery mildew fungi.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.