PJB-2022-366
MORPHOLOGICAL AND MOLECULAR CITATIONS OF ASPERGILLUS FUMIGATUS ASSOCIATED WITH LEAF NECROSIS OF HELIANTHUS ANNUUS L. IN PAKISTAN &am
SHAZIA SHAFIQUE
Abstract
Sunflower (Helianthus annuus L.) is an annual edible oil produce rich in minerals, vitamins, and nutrients. Sunflower is susceptible to many fungal diseases including rusts, rotting, sclerotinia stalk, downy mildew, and leaf spots. The harshness of such diseases results in low yields. However, disease management requires correct identification of the causal agent. In the present study, sunflower leaf spot symptoms were observed in Jallo Park, Botanical Garden; University of the Punjab, Canal road, and fields of Johar town, Lahore. The infected leaves were sampled from fields for pathogen isolation, purification, and identification morphologically as well as genetically by nucleotide sequencing of rDNA using four primers i.e., Internal spacer region (ITS), Glyceraldehyde-3-phosphate-dehydrogenase (GAPDH), β-Tubulin (Bt2) and Osteomodulin (OMD). The pathogen exhibited a green colony on MEA. Conidiophores were cylindrical, with conical terminal vesicles. Conidial heads were uni-seriate and conidia were smooth-walled, globose, green, and their size was 2-4 µm. On the Base of morphological analysis, the fungus was labeled as Aspergillus fumigatus (Fresenius, B. 1863). BLAST results executed with all primers revealed 99-100% homology of the pathogen with A. fumigatus strains in Genbank. To confirm the pathogenicity, Koch’s pathogenicity test was performed by inoculating fungal suspension on pots and plate assays. The emergence of similar symptoms of disease and re-isolation of the identical pathogen verified Koch’s postulates. The study signifies the first report of A. fumigatus as pathogen inducing leaf spot of sunflower in Pakistan and explicates the need for the management of the pathogen.
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