PhPT4 Is a Mycorrhizal-Phosphate Transporter Suppressed by Lysophosphatidylcholine in Petunia Roots

An important characteristic of arbuscular mycorrhizal (AM) symbiosis is the transfer of phosphate from AM fungi to plants. This transfer is facilitated by mycorrhiza-inducible phosphate transporter proteins. Lysophosphatidylcholine (LPC) stimulates mycorrhiza-inducible phosphate transporter gene expression. This study aims to detect the pattern of five Petunia hybrida phosphate transporter (PhPT1-5) genes associated with AM development and their response to LPC in petunia roots. Using the method of real-time reverse transcription-polymerase chain reaction (RT-PCR), we explored the transcriptional changes of PhPT1-5 genes. Our results reveal that the PhPT4 transcript level is enhanced by 8,320-fold at 40 days after inoculation in mycorrhizal roots compared with uninoculated roots. However, PhPT4 is depressed by LPC, which acts as a mycorrhiza signal in several mycorrhizal plants. Our results suggest that PhPT4 is a mycorrhiza-specific phosphate transporter and LPC is not always a universal signal in AM fungi-plant symbiosis.