Enhancement of acid phosphatase activity in Capsicum annuum L. plants in response to phosphate deficiency

Abstract

This study examined acid phosphatase activity in the extracts of Capsicum annuum L. cv. Sweet Banana seedlings grown axenically on water-agar medium or plants grown in a hydroponic system with or without phosphate. Initially, no elevated phosphatase activity was detected in the root surface, in root surface extractions or cell-free tissue extracts from plants that were not showing morphological symptoms of stress. Then elevated specific phosphatase activity was evident in all organ tissue extracts of the plants that showed signs of growth inhibition. The increase in specific activity in the cell free extracts of different organs appeared to be primarily the result of increased activity of the dominant isozyme present in all these extracts, instead of due to de novo synthesis of new isozymes. These and other experiments indicate the lack of phosphate starvation-inducible (psi) excreted phosphatase in Capsicum annuum L. cv. Sweet Banana. Some limitations with the use of XP, 5-bromo-4-chloro-indolyl phosphate p-toluidine, particularly when incorporated into growth media and buffer with or without phosphate for the study of phosphate starvation-inducible excreted phosphatase activity were noted.