Autoria: OLIVEIRA-PAIVA, C. A.; SCHAFFERT, R. E.; SÁ, N. M. H. de; GOMES, E. A.; MARRIEL, I. E.; MUZZI, M. R. S.; RAPOSEIRAS, R.; LANA, U. G. de P.; GUIMARAES, C. T.; ALVES, V. M. C.

Resumo: The maize improvement program at the Embrapa Maize and Sorghum in Brazil has developed a series of maize tines and hybrids differing in phosphorus acquisition efficiency. Bacterial and arbuscular endomycorrhizal (AM) fungi have an important function in soil nutrient acquisition and mobilization, especially phosphorus (P). Soil and roo~ samples were taken from the root zone of maize cultivars during flowering growing red latosol with low P availability. The root zone soil of P efficient and inefficient maize hybrids and inbred lines were studied. Mycorrhizal and bacterial DNA was extracted from the rhizosphere soi! using BIO 101 Kit protocols. The mycorrhizal rDNA fragments were amplified based on nested PCR using fungal universal primers and the ITS/Glomaceae specific primers. Sixteen S rDNA fragments were amplified to study bacterial populations. PCR products were loaded in a 6% polyacrylarnide gel with denaturing gradients between 45% and 70% of urea-formamide gels (DGGE) and run for 16h in a BIO-RAD Dcode System, VA, USA. A routine silver staining protocol was used for detection of DNA and the gels were photographed with a digital camera. The mycorrhizal and bacterial-DGGE profiles obtained suggest population differences in the microbial cornrnunities in the rhizosphere of P efficient and P inefficient maize genotypes grown under P stress. The profiles showed bands that were present in P efficient tines on1y, indicating that some mycorrhizal groups are favored with efficient maize genotypes. The results suggest a greater genetic bacterial population diversity in the rhizosphere soil of genotypes under P stress, indicating that certain microbial populations may be favored with P stress.This study demonstrated the potential of using DGGE fingerprints based upon 16S rDNA fragments amplified via nested PCR to characterize the bacterial cornrnunity in the rhizosphere of maize cultivars. The results demonstrate that the ITS/Glomaceae specific primers used in the present study, and DGGE, can be used to differentiate the diversity and dynarnics of complex natural mycorrhizal cornrnunities; however more studies will be necessary to discriminate phylogenerically closely related organisms in the rDNA sequences. Additional research is currently being conducted with other primers looking to improve the methodology and identify possible differences.

Ano de publicação: 2005

Tipo de publicação: Artigo em anais e proceedings

Unidade: Embrapa Milho e Sorgo

Palavras-chave: Phosphorus efficiency, Rhizosphere microorganisms