Expression of P Transporter Genes and the Functional Diversity of Phosphate Uptake in Maize Roots Associated with Arbuscular Mycorrhizal Fungi.

A greenhouse experiment was conducted to investigate the relationship between the expression of P transporter genes and the functional diversity of phosphate uptake in maize roots colonized by different arbuscular mycorrhizal (AM) fungi. Maize roots associated with no AM fungi, Glomus mosseae, Glomus intraradices, Gigaspora gigantean, Glomus deserticola and a mixture of these 4 species were established under two phosphate levels: Hoagland’s nutrient solution with no P and 1 mM P. Plant materials were harvest after 9 weeks. Root length colonized by AM fungi, biomass of shoots, and shoot P content were measured. Expressions of two root P transporter genes, ZEAma: Pht1;3 and ZEAma: Pht1;6 (AM specific induced), were quantified by real-time PCR. The extent of root colonization by AM fungi, shoot biomass and shoot P content were significantly different among the AM treatments. Glomus mosseae, Glomus intraradices and the mixed species inoculation had greater AM colonization, shoot biomass and shoot P content compared to maize inoculated with Gigaspora gigantean or Glomus deserticola. The addition of P significantly decreased AM colonization of maize roots, but increased shoot biomass and shoot P content. Colonization by AM fungi decreased expression of the plant P transporter gene ZEAma: Pht1;3 in maize root, but increased the expression of the AM inducible plant P transporter ZEAma: Pht1;6. Glomus mosseae, Glomus intraradices and the mixed species inoculation showed greater up-regulation of ZEAma: Pht1;6 and down-regulation of ZEAma: Pht1;3 while providing increased benefit to plant growth. The results of this study indicate that maize shows functional diversity in P uptake or growth when colonized with different AMF may due to the different abilities of AMF to regulate P transporter genes in root.