title: Molecular genetic identification of yeast strains isolated from egyptian soils for solubilization of inorganic phosphates and growth promotion of corn plants.
abstract: Forty yeast strains isolated from soils taken from different locations in Egypt were tested for their P-solubilizing activities on the basis of analyzing the clear zone around colonies growing on a tricalcium phosphate medium after incubation for 5 days at 25degreesC, denoted as the solubilization index (SI). Nine isolates that exhibited P-solubilization potential with an SI ranging from 1.19 to 2.76 were genetically characterized as five yeasts belonging to the genus Saccharomyces cerevisiae and four non-Saccharomyces, based on a PCR analysis of the ITS1-26S region amplied by SC1/SC2 species-specific primers. The highest Psolubilization efficiency was demonstrated by isolate PSY- 4, which was identified as Saccharomyces cerevisiae by a sequence analysis of the variable D1/D2 domain of the 26S rDNA. The effects of single and mixed inoculations with yeast PSY-4 and Bacillus polymyxa on the P-uptake and growth of corn were tested in a greenhouse experiment using different levels of a phosphorus chemical fertilizer (50, 100, and 200 kg/ha super phosphate 15.5% P2O5). The results showed that inoculating the corn with yeast PSY-4 or B. polymyxa caused significant increases in the shoot and root dry weights and P-uptake in the shoots and roots. The P-fertilization level also had a significant influence on the shoot and root dry weights and P-uptake in the shoots and roots when increasing the P-level from 50 up to 200 kg/ha. Dual inoculation with yeast strain PSY-4 and B. polymyxa at a P-fertilization level of 200 kg/ha gave higher values for the shoot and root dry weights and P-uptake in the shoots and roots, yet these increases were nonsignificant when compared with dual inoculation with yeast strain PSY-4 and B. polymyxa at a P-fertilization level of 100 kg/ha. The best increases were obtained from dual inoculation with yeast strain PSY-4 and B. polymyxa at a P-fertilization level of 100 kg/ha, which induced the following percentage increases in the shoot and root dry weights, and P-uptake in the shoots and roots; 16.22%, 46.92%, 10.09%, and 31.07%, respectively, when compared with the uninoculated control (fertilized with 100 kg/ha).
authors.affiliation: Genetics Department, Faculty of Agriculture, Assiut University, Assiut, Egypt. hesham_egypt5@yahoo.com
authors.forename: Abd El-Latif
authors.initials: Ael-L
authors.lastname: Hesham
authors.forename: Hashem
authors.initials: H
authors.lastname: Mohamed
mesh_terms: D001407:Bacillus / Q000378:metabolism; D004271:DNA, Fungal / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D004534:Egypt; D008969:Molecular Sequence Data; D010710:Phosphates / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism; D010802:Phylogeny; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism / Q000382:microbiology; D012988:Soil Microbiology; D015003:Yeasts / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D003313:Zea mays / Q000254:growth & development* / Q000378:metabolism / Q000382:microbiology
chemical_list: D004271:DNA, Fungal; D004275:DNA, Ribosomal; D010710:Phosphates; D010758:Phosphorus