Functional Assessment of an Overexpressed Arabidopsis Purple Acid Phosphatase Gene (AtPAP26) in Tobacco Plants

BACKGROUND: Overexpression of known genes encoding key phosphate (Pi)-metabolizing enzymes, such as acid phosphatases (APases), is presumed to help plants with Pi availability and absorption as they are mostly exposed to suboptimal environmental conditions for this vital element. OBJECTIVES: In this study, the overexpression effect of AtPAP26, one of the main contributors in retrieving Pi from intracellular and extracellular compounds, was evaluated from various viewes in tobacco plant. MATERIALS AND METHODS: As a heterologous expression system, the encoding cDNA sequence of AtPAP26 was transferred into tobacco plants. RESULTS: A high growth rate of the transgenic lines was observed which could be due to an increased APase activity, leading to the high total phosphorus as well as the free Pi content of the transgenic plants. Interestingly, a significant increased activity of the other APases was also noticed, indicating a networking among them. These were accompanied by less branched and short primary roots and a decreased lateral root numbers grown in Pi-starvation condition compared to the wild type seedlings. Besides, a delayed germination and dwarf phenotype indicates the possible reduction in gibberellic acid biosynthesis in the transgenic lines. CONCLUSIONS: Such transgenic plants are of interest not only for increased yield but also for the reduced need for chemical fertilizers and removal of excessive Pi accumulation in soils as a consequence of fertilizers’ or poultry wastes’ over-usage.