EVALUATION OF SELECTED CULTURE MEDIA FOR GROWTH AND SPORULATION OF Alternaria ISOLATE CAUSING GREY BLIGHT DISEASE OF MUSTARD AND ITS MOLECULAR CHARACTERIZATION

Abstract

Mustard (Brassica spp.) is the most important oilseed crop in Bangladesh and Grey blight disease caused by Alternaria sp. is a major constraint causing severe yield loss every year. For the reason to study cultural, morphological and molecular characterization of the pathogen is very important. The experiment was conducted in the Molecular biology and plant virology laboratory, Department of plant pathology, Sher-e-Bangla Agricultural University, Dhaka-1207. For molecular characterization of the pathogen fungal DNA was extracted from the pure culture of Alternaria isolate and PCR amplification was done using the ITS primer which was designed to amplify at 700 bp. To study the growth and sporulation of Alternaria, 11 media were selected viz. T 1 = Dehydrated Potato Dextrose Agar (D-PDA) media, T 2 = Potato Dextrose Agar (PDA) media, T 3 = Corn Meal Agar (CoMA) media, T 4 = Potato Sucrose Agar (PSA) media, T 5 = Potato Glucose Agar (PGA) media , T 6 = Mustard Potato Dextrose Agar (MPDA) media, T 7 = Mustard Potato Sucrose Agar (MPSA) media, T 8 = Mustard Potato Glucose Agar (MPGA) media, T 9 = Cabbage Potato Dextrose Agar (CPDA) media, T 10 = Cabbage Potato Sucrose Agar (CPSA) media and T 11 = Cabbage Potato Glucose Agar (CPGA) media. From the study of the cultural and morphological characteristics, it was found that the highest radial mycelial growth was observed in CoMA media but spread very thinly. The best media selected for radial mycelial growth was D-PDA media from this study. In case of sporulation, MPGA media gave the highest spore concentration. From the molecular characterization study, the nucleotide sequence of Alternaria isolate had showed 99% similarities with the existing nucleotide sequences and closely related to Alternaria brassicicola that globally found in GenBank database.