Tethering factors mediate the initial contact between donor and acceptor membranes. Transport protein particle (TRAPP)III, a multisubunit tethering complex, controls both secretory pathway and autophagy in yeast. However, the roles of TRAPPIII is poorly understood in plants. We have isolated a recessive mutant displaying retarded root growth, defective root hair elongation, and compromised organization of quiescent center by introducing UAS tag in Arabidopsis thaliana and named defective quiescent center (dqc)-1. The tag localized in the 25th exon of At5g16280 encoding AtTRS85 specifying the TRAPPIII complex. Three additional T-DNA insertion mutants of dqc/attrs85 exhibited the defective gravitropic responses in addition to the weak dqc-1-like phenotypes. In dqc-2, the auxin-responsive DR5 expression in the columella was extended and an auxin efflux carrier PIN-FORMED1-GFP abnormally aggregated in the vacuole-like subcellular compartments. In the root epidermis of dqc-2, an early endosome (EE) marker was dispersed in the cytoplasm, a trans-Golgi network (TGN) marker localized in tonoplast, and a vacuole marker localized in the fragmented tonoplast. Furthermore, the endocytosis of FM4-64 in dqc-2 was compromised as evidenced by the decrease in the EE punctum formation, the rapid accumlation into the tonoplast, and the infrequent brefeldin A body formation. Together, DQC/AtTRS85 is essential for the integrity of TGN/EE and the vacuole fusion.
Bibliographical noteFunding Information:
This work was supported by a grant from the Basic Science Research Program through the National Research Foundation(Grant Number, 2018R1A6A1A03025607) funded by the Ministry of Education, Republic of Korea to M.M.L., the National Research Foundation of Korea (NRF-2018R1D1A1A09083240) to S. S., and research fund from Chosun University 2014 (K206888001) to S.S.
All Science Journal Classification (ASJC) codes
- Plant Science