TSA1 is a crucial factor in ER body formation and facilitates the ER body formation by jasmonic acid

Abstract

The endoplasmic reticulum body (ER body) which is derived from the endoplasmic reticulum (ER) is found in Brassicale. Recent studies have shed light on the biogenesis and physiological function of ER body in plants. Until now, biogenesis and formation of ER body are not well understood. Therefore, we examined the physiological role of TSK-associating protein 1 (TSA1) which is close homolog of NAI2 that is factor of ER body formation and investigated the relationship between ER body formation and TSA1. TSA1 is lumen protein of ER body and N-glycosylated in ER lumen. TSA1 was highly induced by the plant defense hormone, methyl jasmonic acid (MeJA). The ectopic expression of TSA1:GFP induce the ER body formation in leaf tissue of Nicotiana benthamiana (N. benthamiana) and the transgenic plant harboring TSA1:GFP induce the ER body formation in root of Arabidopsis thaliana (A. thaliana). TSA1 and NAI2 formed a heterocomplex and induced the ER body in an additive manner in N. benthamiana. The plant hormone of MeJA induce the ER body in knockout mutant plant of tsa1 and nai2, but not double knockout plant of tsa1/nai2. In addition, constitutive ER body formation was altered in young seedlings of nai2 plants but not tsa1 plants. Therefore, we suggested that TSA1 plays a critical role in MeJA-induced ER body formation in plants.