Morphological and molecular variability of Alternaria spp. causing leaf blight of cotton in India
S. a Ashtaputre: Department of Plant Pathology
<div><strong>Morphological and molecular variability of <em>Alternaria </em>spp. causing leaf blight of cotton in India</strong></p> <p><strong> S. A. Ashtaputre and V.R.Kulkarni</strong></p> <p>Department of Plant Pathology,</p> <p>University of Agricultural Sciences, Dharwad-580 005,Karnataka, India</p> <p>E mail: <a href="mailto:sudheendra67@gmail.com";>sudheendra67@gmail.com<;/a></p> <p>Variability with respect to morphological characters revealed that out of 25 isolates of <em>Alternaria</em> spp, 18 showed complete resemblance with <em>Alternaria</em> <em>macrospora </em>and remaining seven isolates resembled to <em>Alternaria</em> <em>alternata</em>. The conidial size varied from 42.43 x17.69 μm in Garag to 76.20x13.20 μm Tadakod isolates. As per structural figure description of <em>A. macrospora</em> by Ellis,18 isolates showed complete resemblance with <em>Alternaria</em> <em>macrospora</em> and remaining seven isolates resembles to <em>Alternaria</em> <em>alternata</em> morphologically. In molecular variability study, DNA sequences of twenty five isolates were compared using the bioinformatics tool of the National Centre for Bioinformatics (NCBI) blast programme. PCR amplification of <em>Alternaria</em> spp. with conserved primers ITS1 and ITS4 that yielded an approximately 560 bp rDNA amplicon product. Based on sequence comparison, the sequences of eighteen isolates were confirmed as <em>Alternaria macrospora</em> and seven as <em>Alternaria alternata </em>and accordingly phylogenetic trees were constructed. The present investigation revealed that there is greater morphological and molecular variability among the different isolates of <em>Alternaria</em> sp. It also showed that the genetic variation among the pathogen from different cotton growing areas of India.</div>
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