Studies on Symptomatology, Morphological and Molecular Characterisiation of Erysiphe cichoracearum Causing Powdery Mildew of Okra

Abstract

Okra (Abelmoschus esculentus (L.) Moench) is a globally important annual vegetable belongs to family malvaceae, it is most broadly distributed vegetable all over the world. Among the fungal diseases affecting okra crop, powdery mildew caused by Erysiphe cichoracearum DC. is the most important disease causing considerable yield losses. The disease was characterized by the appearance of small white powdery specks on upper surface of the lower leaves which enlarged and coalesced forming bigger patches. Later on the disease spread to the upper leaves, coalescing of the white powdery specks and enlargement in their size ultimately resulted in complete coating of white fungal mass on the leaves. The morphological studies of the pathogen in the laboratory revealed, that the mycelium is septate, ectophytic, hyaline and adjacent to the mycelium, basal septum of the conidiophores was seen. The conidiophores were erect, on which conidia were produced either singly or in short chains. The conidia were found cylindrical or barrel in shape, hyaline, non-septate and measured 75.23 µm x 40.65 µm. Molecular characterisation of the native isolate resulted in the DNA amplicon at the region 531 bp. Further, DNA sequence was obtained for ITS Rdna and was deposited in NCBI gene bank. Accession number ‘MW774352’ was obtained and it was confirmed that the causal pathogen of okra powdery mildew of Raichur region is Erysiphe cichoracearum.