Salt stress is a detrimental factor for plant growth and development. Components in the intracellular trafficking system, as well as components of the ubiquitin-proteasome system, have been shown to involve in salt stress response. However, the mechanism of the combined process including ubiquitination and intracellular trafficking in salt response is not clear.

Through screening a Ac-Ds Arabidopsis insertion lines in RING finger genes library, scientists in Dr. XIE Qi’s group of the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences identified a mutant strf1-1 with an increased tolerance to salt.

In vitro, biochemistry analysis showed that STRF1 (Salt Tolerance RING Finger 1) was an active E3 ligase and subcellular localization assays indicated that STRF1 localized mainly at the plasma membrane and at the intracellular endosomes, especially the Golgi and PVC (Pre-vacuolar compartment). strf1-1 loss of function mutant seedlings exhibited accelerated endocytosis and reduced membrane trafficking in roots which were demonstrated by the FM4-64 and BFA (Brefeldin A) staining respectively, and had an increased expression of RAB7 gene involved in the membrane trafficking system.

Furthermore, the genetic evidence that rab7/amiR-STRF1 seedlings possessed the similar sensitivity phenotype of rab7 mutant to salt stress also confirmed the relationship of STRF1 and RAB7. This work clarified that how a membrane-localized E3 ligase STRF1 regulates salt tolerance by modulating intracellular membrane trafficking.

This work entitled “The RING finger E3 ligase STRF1 is involved in membrane trafficking and modulates salt stress response in Arabidopsis thaliana” has been published on Plant Journal (DOI:10.1111/tpj.12797) with Dr. TIAN Miaomiao and Ph.D candidate LOU Lijuan as the co-first authors.

This research was supported by 973 Program Grant from the National Basic Research Program of China and the State Key Laboratory of Plant Genomics.