TNO1 Is Involved in Salt Tolerance and Vacuolar Trafficking in Arabidopsis    

Abstract

The Arabidopsis (Arabidopsis thaliana) soluble N-ethylmaleimide-sensitive factor attachment protein receptor SYP41 is involved in vesicle fusion at the trans-Golgi network (TGN) and interacts with AtVPS45, SYP61, and VTI12. These proteins are involved in diverse cellular processes, including vacuole biogenesis and stress tolerance. A previously uncharacterized protein, named TNO1 (for TGN-localized SYP41-interacting protein), was identified by coimmunoprecipitation as a SYP41-interacting protein.TNO1 was found to localize to the TGN by immunofluorescence microscopy. A tno1 mutant showed increased sensitivity to high concentrations of NaCl, KCl, and LiCl and also to mannitol-induced osmotic stress. Localization of SYP61, which is involved in the salt stress response, was disrupted in the tno1 mutant. Vacuolar proteins were partially secreted to the apoplast in the tno1 mutant, suggesting that TNO1 is required for efficient protein trafficking to the vacuole. The tno1 mutant had delayed formation of the brefeldin A (BFA) compartment in cotyledons upon application of BFA, suggesting less efficient membrane fusion processes in the mutant. Unlike most TGN proteins, TNO1 does not relocate to the BFA compartment upon BFA treatment. These data demonstrate that TNO1 is involved in vacuolar trafficking and salt tolerance, potentially via roles in vesicle fusion and in maintaining TGN structure or identity.

The Arabidopsis Vacuolar Sorting Receptor1 Is Required for Osmotic Stress-Induced Abscisic Acid Biosynthesis

“…The osm1 mutant was sensitive to osmotic stress and soil drying and seemed to control stomatal response to ABA ). An Arabidopsis mutant in the SYP41-interacting protein Tonneau1 is also sensitive to salt and osmotic stress, possibly due to the mislocalization of SYP61 (Kim and Bassham, 2011). The antisense plants of Arabidopsis Vesicle-Associated Membrane Protein 7C showed improved salt tolerance through maintaining DpH and reducing vacuolar calcium release (Leshem et al, 2006).…”

Salt-Induced Remodeling of Spatially Restricted Clathrin-Independent Endocytic Pathways in Arabidopsis Root

“…Thus, both of these processes could be equally important in mediating the salt-response mechanisms regulated by VPS9a. Vacuolar trafficking plays a crucial role in salinity tolerance, as evidenced by multiple studies in which the alteration of expression levels of vacuolar trafficking regulators confers salt tolerance or sensitivity to plants (Mazel et al, 2004;Leshem et al, 2006;Kim and Bassham, 2011). Causal links between salinity-induced endocytic processes, vacuolar trafficking, and the formation of vacuolar compartments call for further investigation, as does the intriguing possibility that these processes may have survival value for plants under saline stress.…”

Grapevine and Arabidopsis cation-chloride cotransporters localise to the Golgi and trans-Golgi network and indirectly influence long-distance ion homeostasis and plant salt tolerance

“…Furthermore, both a phosphate transporter in Arabidopsis (AtPHT4;6) and a monosaccharide transporter from rice (OsGMST1) are Golgi localized, and reduced expression of either transporter reduces salt tolerance of plants (Cubero et al, 2009;Cao et al, 2011). Many vesicle trafficking-related proteins, such as RAB GTPases, and soluble N-ethyl-maleimide sensitive factor attachment protein receptors (SNARE) also localize to the Golgi and TGN, and knockout of these factors also results in altered salt sensitivity (Kim and Bassham, 2011;Asaoka et al, 2013). The role of endosomal-localized transporters in the control of shoot salt exclusion is unclear but might involve sensing cytoplasmic salt concentrations or regulating luminal pH or ion homeostasis, which is required for normal Golgi and TGN function.…”