Morphology, molecular identification and phylogenetic analysis based on internal transcribed spacer (ITS) of the ribosomal nuclear DNA (rDNA) sequence of a pathogenic fungal isolate Aspergillus niger LKO1

Abstract

Aspergillus niger is the causal organism of “black mold” disease of fruits and vegetables. The objective of the present investigation was to characterize the pathogen morphologically in vitro and to confirm its molecular identity and phylogenetic position by the sequence of ITS region of rDNA. A. niger LKO1 was isolated from soil and cultured in PDB and PDA media. The characteristic of growth was monitored and the reproductive structures were analyzed. After 3 days of growth, the diameter of each colony was 1.5 cm, after which the colony was extended its diameter 1 cm per day and subsequently black conidiophores were formed with black pigmented spore heads carrying numerous conidia. Fungus was also characterized using molecular methods based on ITS-PCR (GenBank accession number MK696283). The amplified sequence was compared with the available sequences in the NCBI GenBank. The sequence showed 100% similarity with other isolates of A. niger. The isolation, morphological characterization and sequencing of ITS region of rDNA will help in further research on the management of this plant pathogen and its commercial utilization.