Abiotic stress-inducible purple acid phosphatase from Solanum lycopersicum is targeted to peroxisome via non-canonical peroxisome targeting signal type 1

Abstract

Nutrient limitations combined with abiotic stress conditions, pose some of the most challenging scenarios regarding agricultural productivity. Phosphorus is an important macronutrient for plants. Though present in ample quantity in soil, the available phosphorous to plant is severely limited. Purple acid phosphatase (PAP) is a special class of acid phosphatase that plays a significant role in these phosphorous starvation situations. Primarily PAPs are secretory, however, a few intracellular PAPs have also been reported, which are primarily localized in various subcellular compartments. Here, we have identified a PAP from tomato, named Solanum lycopersicum PAP (SlPAP) 19, which was demonstrated to be localized in peroxisome and was also found to be induced by multiple abiotic stress conditions. It showed the highest upregulation by low-temperature stress followed by high-temperature and osmotic stress. The detailed in silico analysis revealed it to retain the traditional N-terminal transmembrane domain and the glycosylation domain, suggesting that the endoplasmic reticulum mediated peroxisome targeting pathway of PTS1 proteins could well be a novel peroxisomal import pathway. Intracellular PAPs have previously been demonstrated to possess additional peroxidase activity, which could be involved in reactive oxygen species (ROS) homeostasis under abiotic stress conditions. Being involved in supplying phosphorous macronutrient, upregulated by multiple abiotic stress conditions and intracellular localization, SlPAP19 could serve as a significant candidate for abiotic stress tolerance in plants.