Plant growth promotion under phosphate deficiency and improved phosphate acquisition by new fungal strain, Penicillium olsonii TLL1

Microbiomes in soil ecosystem play a significant role in solubilizing insoluble inorganic and organic phosphate sources with low availability and mobility in the soil. They transfer the phosphate ion to plants, thereby promoting plant growth. In this study, we isolated an unidentified fungal strain, POT1 ( Penicillium olsonii TLL1), and confirmed its ability to promote root growth, especially under phosphate deficiency as well as solubilizing activity for insoluble phosphates such as AlPO 4 , FePO 4 ·4H 2 O, Ca 3 (PO 4 ) 2 and hydroxy apatite. Indeed, in vermiculite containing low and insoluble phosphate, POT1 promoted the growth of Arabidopsis and leafy vegetable. We also tested the growth of crops in Singapore local soil containing highly insoluble phosphate and confirmed an improved crop growth for Bok Choy and Rice with POT1. Furthermore, we demonstrated that plant growth promotion and phosphate solubilizing activity of POT1 were more effective than those of four different Penicillium strains such as P. bilaiae , P. chrysogenum , P. janthinellum and P. simplicissimum under phosphate limiting conditions. Our findings uncover a new fungal strain and provide a better understanding of symbiotic plant–fungal interactions and suggest the potential use of POT1 as a biofertilizer to improve phosphate uptake and use efficiency in phosphate-limiting conditions.