Expression of NtPT5 Is Correlated with the Degree of Colonization in Tobacco Roots Inoculated with Glomus etunicatum

An important characteristic of arbuscular mycorrhizal (AM) symbiosis is the transfer of phosphate (Pi) from AM fungi to plants, and this transfer is facilitated by plasma membrane-spanning phosphate transporter (PT) proteins. Five Nicotiana tabacum PT genes (NtPT), members of Pht1 family, express in the root. However, the ways these genes contribute to the development of AM is unclear. In this study, transcription analysis was performed to study the expression levels of NtPT1-5 genes in tobacco roots. To investigate the expression pattern of these five genes during the development of AM from no inoculation to high colonization, we screened for differentiating transcriptional responses of non-mycorrhizal roots and AM roots by real-time PCR. Our results indicate that only NtPT5 was mycorrhiza-specific phosphate transporter during arbuscular mycorrhizal symbiosis in tobacco roots, and the induction was tightly correlated with the degree of root colonization by Glomus etunicatum. In addition, based on an alignment and analysis of the evolution of Pht1 family members in six solanaceous plants, we developed the evolutionary pattern of the Pht1 gene family members in six solanaceous plants.