Cytoprotective ribonuclease (RNase) required for resistance to abiotic stresses, acting as a positive regulator of mRNA decapping during stress (PubMed:25736060). Essential for the integrity and function of cytoplasmic messenger ribonucleoprotein (mRNP) complexes called stress granules (SGs) and processing bodies (PBs), sites of post-transcriptional gene regulation during stress (e.g. salt and heat) (PubMed:25736060). Involved in gibberellic acid (GA) biosynthesis and seed germination (PubMed:20396901). Essential for stress tolerance, probably by regulating mRNAs entering the secretory pathway (PubMed:20484005). Component of stress granules (SGs) that regulates growth under salt stress by modulating levels of GA20OX3 mRNA. Binds GA20OX3 mRNA (By similarity). May inhibit the degradation of mRNAs involved in stress adaptation (PubMed:26237081). Repressed by the specific inhibitor 3',5'-deoxythymidine bisphosphate (pdTp); this RNase activity inhibition impairs subcellular relocation upon abiotic stress and leads to reduced stress resistance. Accumulates heterogeneously in the cytosol, in patches around the nucleus and in the cell periphery, and relocates transiently to a diffuse pattern in response to salt stress (PubMed:20484005). Accumulates in cytoplasmic stress granules (SGs) and processing bodies (PBs) in response to abiotic stresses (e.g. salt and heat) (PubMed:25736060). Mostly expressed in seeds, and, to a lower extent, in leaves, flowers, roots and siliques (at protein level) (PubMed:20396901, PubMed:20484005). Accumulates strongly in the cap and elongation zone of the root apices (at protein level) (PubMed:20484005). In mature seeds, accumulates highly both in cotyledons and radicals. TNase-like domains are required for relocation to cytoplasmic foci upon abiotic stresses. Normal vegetative growth, flowering time and flower morphology, but delayed seed germination after vernalization (at 4 degrees Celsius); this phenotype is reversed by gibberellic acid (GA-3) but increased by paclobutrazol, a GA biosynthesis inhibitor. Reduced expression of enzyme involved in GA biosynthesis leading to reduced levels of GA-4 (e.g. GA20OX3) (PubMed:20396901). The double mutant tsn1 tsn2 exhibits severe alteration in germination, growth, and survival under high salinity stress. In normal conditions, moderate reduction in root growth due to cell elongation defect. Reduced levels of stress-regulated mRNAs encoding secreted proteins (PubMed:20484005). Abnormal stress granules (SGs) and processing bodies (PBs) assembly accompanied by reduced uncapped RNAs levels in heat-stressed double mutant tsn1 tsn2 (PubMed:25736060). The double mutant tsn1 tsn2 is also showing enriched uncapping and subsequent degradation of mRNAs involved in stress adaptation (PubMed:26237081).