Morpho-cultural, pathological and molecular variability in Phloeospora maculans causing leaf spot of mulberry (Morus species) in India

AbstractBackground:Leaf spot disease (LSD) of mulberry caused byPhloeospora maculansis a major threat to the silk industry of Jammu and Kashmir, India, therefore, it was necessary to study the population structure of the pathogen for successful management of the disease.Methods and ResultsTo understand the diversity in thePhloeospora maculans, a combination of conventional (morphological, cultural and pathological) and molecular (ISSR markers) approaches were employed to discern the variability in 27 isolates collected from Srinagar, Bandipora, and Baramulla districts of Jammu and Kashmir, India. The studies revealed a high level of variability in the pathogen. Based on the morpho-cultural and pathological studies, the pathogen isolates were grouped into different categories based on colony growth, texture, margin and colour besides changes in colour of medium, incubation period, leaf area infected, etc.A high level of polymorphism was observed in different isolates ofP. maculansusing ISSR markers, which indicated that these markers are suitable for studying the genetic diversity in this pathogen. All the isolates (27) ofP. maculanswere clustered into two groups or populations as indicated by mean delta K value. Analysis of molecular variance revealed the low genetic variation among the populations (1.08%) and a high level of genetic variation within the populations (98.91%). Fstvalue was found to be 0.01 indicating smaller amount of genetic differentiation between the populations against calculated P-value of 0.29ConclusionA high level of diversity based on morphological, cultural, pathological and molecular levels was observed inPhloeospora maculanscollected from various districts of Kashmir valley, which indicates that the study of population structure is necessary for successful management of the disease.