Abstract
In the reaction to non-adapted Blumeria graminis f. sp. hordei (Bg), Arabidopsis thaliana leaf epidermal cells deposit cell wall reinforcements called papillae or seal fungal haustoria in encasements, both of which involve intensive exocytosis. A plant syntaxin SYP121/PEN1 has been found to be of key importance for the timely formation of papillae, and the vesicle tethering complex exocyst subunit EXO70B2 has been found to contribute to their morphology. Here, we identify a specific role for the EXO70B2-containing exocyst complex in the papillae membrane domains important for the callose deposition and GFP-SYP121 delivery to the focal attack sites, as well as its contribution to encasement formation. The mRuby2-EXO70B2 co-localises with the exocyst core subunit SEC6 and GFP-SYP121 in the membrane domain of papillae, and both proteins have the capacity to directly interact. The exo70B2/syp121 double mutant has a reduced number of papillae and haustorial encasements in response to Bg, indicating an additive role of the exocyst in SYP121 coordinated non-host resistance. In summary, we report cooperation between the plant exocyst and a SNARE protein in penetration resistance against non-adapted fungal pathogens.
Highlight The exocyst complex containing EXO70B2 subunit has specific role in papilla and encasement formation, implemented in coordination with the pathway regulated by the SYP121 SNARE complex in defence.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
authors email addresses: jitka.ortmann{at}gmail.com, juro.seky{at}gmail.com, ikulich{at}gmail.com, jiri.santrucek{at}vscht.cz, dobrev{at}ueb.cas.cz, viktor{at}natur.cuni.cz, pecenkova{at}ueb.cas.cz
abbreviations
- Bg
- Blumeria graminis f. sp. hordei
- PAMP
- pathogen associated molecular patterns
- ROS
- reactive oxygen species
- EHM
- extra haustorial membrane
- Ep
- Erysiphe pisi
- PM
- plasma membrane
- SNARE
- soluble N-ethylmaleimide-sensitive factor Attachment protein REceptors
- SNAP
- soluble N-ethylmaleimide-sensitive factor adaptor protein
- VAMP
- vesicle-associated membrane protein
- MVB
- multivesicular bodies
- hpi
- hour post inoculation
- KO
- knockout line
- HSD
- honestly significant difference
- SA
- salicylic acid
- BD
- binding domain
- AD
- activation domain
- NA
- numeric aperture