Biology subjects

Sekeres, J.

Publications and source records attributed to Sekeres, J..

2 recordsLinked to original sources

bioRxiv2021

The EXO70B2 exocyst subunit contributes to papillae and encasement formation in anti-fungal defence in Arabidopsis

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. HighlightThe 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.

cell biology↗

bioRxiv2019

Functional analysis of phospholipase Dδ family in tobacco pollen tubes

Phosphatidic acid (PA), important signalling and metabolic phospholipid, is predominantly localized in the subapical plasma membrane (PM) of growing pollen tubes. PA can be produced from structural phospholipids by phospholipase D (PLD) but the isoforms responsible for production of plasma membrane PA were not identified yet and their functional roles remain unknown. Following genome-wide bioinformatic analysis of PLD family in tobacco, we focused on the pollen-overrepresented PLD{delta} class. Combining live-cell imaging, gene overexpression or knock-down, lipid-binding and structural bioinformatics, we characterized 5 NtPLD{delta} isoforms. Distinct PLD{delta} isoforms preferentially localize to the cytoplasm or subapical PM. Using fluorescence recovery after photobleaching, domain deletion and swapping analyses we show that membrane-bound PLD{delta}s are tightly bound to PM, primarily via the central catalytic domain. Knock-down, overexpression and in vivo PA level analyses revealed isofom PLD{delta}3 as the most important member of the PLD{delta} subfamily active in pollen tubes. PA promotes binding of PLD{delta}3 to the PM, thus creating a positive feedback loop, where PA accumulation leads to the formation of massive PM invaginations. Tightly controlled production of PA generated by PLD{delta}3 at the PM is important for maintaining the balance between various membrane trafficking processes, that are crucial for plant cell tip growth.

plant biology↗