Functional analysis of AtPAP18 gene encoding a purple acid phosphatase in Arabidopsis thaliana

Phosphorus (P) is one of three essential macronutrients required for plants which is absorbed as phosphate ion (Pi) from the soil solution and plays an important role in plants growth and development. To cope with low Pi concentrations in soil, plants have a wide range of morphological and physiological adaptive responses including acid phosphatase secretion. In this study, the full-length cDNA encoding sequence of AtPAP18 was isolated from a cDNA pool of Arabidopsis and cloned in a plant expression vector to produce a series of overexpressed lines. Also, a homozygous knocked-out mutant was identified for disruption in AtPAP18 locus too. Our results indicated that the overexpression of AtPAP18 in Arabidopsis plants led to significant increases in total P contents and biomass production for plants grown in Pi-fed and starved conditions. Faster germination, remarkable decrease in fresh and dry weight of and the highest root–shoot ratio in the starved plants was the obvious symptoms of the knocked out plants in comparison to wild type or overexpressed ones. The results indicated that overexpression of the AtPAP18 gene offers an effective way to increase the utilization of soil insoluble Pi and reduce the consumption of the relevant chemical fertilizer.