World Journal of Agricultural Sciences 6 (2): 195-200, 2010 ISSN 1817-3047 © IDOSI Publications, 2010 Corresponding Author: B.N. Chakraborty, Department of Botany, Immuno-Phytopathology Laboratory, University of North Bengal, Siliguri - 734 013, West Bengal, India E.mail: bncnbu@gmail.com 195 Evaluation of Phosphate Solubilizers from Soils of North Bengal and Their Diversity Analysis B.N. Chakraborty, U. Chakraborty, A. Saha, K. Sunar and P.L. Dey Immuno-Phytopathology Laboratory, Department of Botany, University of North Bengal, Siliguri - 734013, West Bengal, India Abstract: Four hundred isolates obtained from soil samples collected from forest, river basin, agricultural fields and rhizosphere of plantation crops of North Bengal were screened for phosphate solubilizing activity on Pikovskaya’s agar medium. Among the screened isolates, ninety showed phosphate solubilizing activity. Out of these, ten isolates belonging to Aspergillus niger, A. melleus and A. clavatus were selected for further studies. In vitro evaluation of phosphate solubilization by the different isolates using tricalcium phosphate (TCP) and rock phosphate (RP) revealed that the isolates could solubilize TCP better than RP. Selected isolates were mass multiplied using farm-yard manure (FYM) and were tested in vivo for their growth promoting activity in soybean. While all the isolates promoted growth, A. niger RSP-14 was found to be most effective. While the soil P content decreased due to the activity of the PSFs, root phosphate content showed an increase. These isolates were further analyzed for genetic variability. Genomic DNA from the fungal isolates were obtained and purified. UPGMA cluster analysis divided the ten isolates into two groups with the genetic similarity ranging from 0.35- 0.61. One group consisted of four isolates of A. niger and five isolates of A. melleus, while the other group had one isolate of A. clavatus. Key words: Phosphate solubilizing fungi Aspergillus niger A. melleus A. clavatus INTRODUCTION (polymorphisms) in the pattern of bands amplified from Fungi are important components of soil microbiota, genetic markers named Random Amplified Polymorphic typically constituting more of the soil biomass than DNA (RAPDs). Most of the published studies on genetic bacteria, depending on soil depth and nutrient conditions characterization, detection of genetic variations and gene [1]. A wide range of soil fungi are reported to solubilize mutations were concentrated on the variations in insoluble phosphorous. Strains of Aspergillus niger and chromosomes, isozyme polymorphism and biochemical Penicillium are the most common fungi capable of diversity. A single set of arbitrary-sequence 10 mers may phosphate solubilization. Many bacterial, fungal, yeast be used for fingerprinting any species. The many and actinomycetes species capable of solubilizing advantages of RAPD markers over RFLDs or isozyme sparingly soluble phosphorus in pure culture have been markers accelerated the adoption of RAPD technology for isolated and studied [2-5]. However, studies on genetic the construction of genetic maps, fingerprinting and diversity of these important group of phosphate population genetic studies. Current reviews of the solubilizing fungi (PSF) are limited. Williams, et al. [6] and applications of RAPD technology are available. The utility Welsh and McClelland [7] demonstrated the utility of of DNA markers as RAPD-DNA in detecting genetic single short oligonucleotide primers of arbitrary sequence variability among many phytopathogenic fungi have been for the amplification of DNA segments distributed recorded by various authors [8-10]. randomly throughout the genome. Also Welsh and The present study was undertaken to test selected McClelland showed that the pattern of amplified isolates of PSFs for their in vitro and in vivo activities and bonds could be used for genome fingerprinting and screen the random primers as effective molecular markers Williams, et al. [6] showed that the differences for genetic variability analysis among the isolates. genetically distinct individuals behaved as mendelian