CULTURAL, MORPHOLOGICAL AND BIOCHEMICAL VARIATIONS OF ALTERNARIA SOLANI CAUSING DISEASES ON SOLANACEOUS CROPS

Abstract

Alternaria solani is an economically important pathogen causing diseases on Solanaceae crops. Significant
morphological variations in length and breadth of conidia, numbers of horizontal, vertical and oblique septations
were observed in the test isolates. The conidia varied from 20.68-43.10 x 10.53-17.99μm in brinjal, 19.86-43.73
x 7.52-13.05μm in chilli, 21.5-33.21 x 8.03-17.85μm in potato and 30.31-75.47 x 7.26-27.42μm in tomato
isolates. Variability with respect to cultural characters showed that brinjal, tomato and potato isolates produce
cottony mycelia growth in all the tested media. Maximum growth was recorded on PDA for chilli and potato
(93.33mm and 95.00mm respectively), CDA for brinjal (85.33mm) and PCA for tomato (87.00mm). Isozyme
tested in PAGE showed that tomato produces three bands and potato, brinjal and chilli produces four bands each
for α- esterase. For β- esterase tomato and potato produces two bands each and chilli produces three bands. The
cluster analysis of morphological characters showed that brinjal, tomato and potato were in same cluster and in
isozyme studies potato, chilli and brinjal were in same and tomato in different cluster. Existence of variation
among different Alternaria isolates is evident from the results obtained.