Assessment of the mycorrhizal community in the rhizosphere of maize (Zea mays L.) genotypes contrasting for phosphorus efficiency in the acid savannas of Brazil using denaturing gradient gel electrophoresis (DGGE)

Community structure of indigenous arbuscular mycorrhizal fungi (AMF) in the rhizosphere of tropical maize genotypes contrasting for phosphorus efficiency was evaluated using denaturing gradient gel electrophoresis (DGGE). Fragments of AMF ribosomal DNA (rDNA) were amplified using nested PCR with fungal universal primers and ITS (internal transcribed spacer) specific primers for Acaulosporaceae, Glomaceae and Gigasporaceae. ITS-Acaulosporaceae and Glomaceae-specific primers and DGGE were efficient in differentiating the composition of mycorrhizal communities. Maize genotypes had a greater influence on the rhizosphere mycorrhizal community than the level of P in the soil. DGGE profiles of maize roots revealed bands that were present only in P efficient genotypes (L3 and HT3060), suggesting that some mycorrhizal groups were stimulated by P efficient maize genotypes. Acaulospora longula, A. rugosa, A. scrobiculata, A. morrowiae and Glomus caledonium were found only in the rhizosphere of P efficient maize genotypes cultivated in low P soils. A greater number of mycorrhizal DGGE bands were found in soil samples from no-till maize than conventional tillage. Effective mycorrhizal colonization of crops may influence the maize yield under Brazilian savanna acid soils by modulating the capacity of different cultivars to tolerate P deficiency.