Alternaria arborescens, IDENTIFIED AS A LEAF NECROSIS PATHOGEN OF Vigna radiata IN PAKISTAN
S. Shafique1, S. Shafique1,*, U. Attia1 and and M. Zameer2
1Department of Plant Pathology, Faculty of Agricultural Sciences, University of the Punjab, Lahore, Pakistan, 54590.
2Institute of Molecular Biology and Biotechnology, IMBB, University of the Lahore, Pakistan.
*Corresponding author’s email: shazia.iags@pu.edu.pk
ABSTRACT
Vigna radiata (mung bean) is a most cultivated legume crop having high nutritive and clinical value. A survey was accompanied to isolate leaf spot pathogen from mung bean plants. Infected leaf samples were collected and a novel pathogen, Alternaria arborescens was isolated and identified on morphological and molecular basis. Molecular identification was done using nucleotide sequence analysis of rDNA internal spacer sequence (ITS), partial glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and elongation factor (EF) regions. Morphological characters demonstrated grayish-black, woolly, concentric rings on Malt Extract Agar (MEA) plates. The conidiophores were well defined; septate with terminal and sub-terminal branches having tan to brown, short ovoid or ellipsoid, and 7-11 µm sized conidia with transverse septation. In molecular characterization, BLAST analysis of the rDNA-ITS region of the pathogen, A. arborescens exhibited maximum (99%) homology with other A. arborescens GenBank strains. Similarly, 100% homology was found with partial glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and translation elongation factor. Afterward, Koch’s pathogenicity aptitude of the identified pathogen was confirmed by the occurrence of the same disease symptomology and re-isolation of identical organisms from artificially inoculated leaves in the in vitro and in vivo trials. The study signifies the novel documentation of A. arborescens as a leaf spot pathogen of mung bean in Pakistan. The manifestation of this pathogen could result in a serious economic impact on mung bean or might be a possible pathogen of other pulse crops if not managed in time.
Keywords: Alternaria arborescens, Genetic characterization, Leaf spot disease, Morphology, Vigna radiata.
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