The current study intends to evaluate the morpho-pathological variability among S. rolfsii isolates of wheat due to their ability to rapidly adapt and evolve, which will aid in the breeding of foot rot resistance. For this study, Ten isolates of Sclerotium rolfsii Sacc. collected from different wheat growing areas of Northern Karnataka were subjected for isolation from foot rot infected samples and these isolates showed variability with respect to cultural and morphological characters, toxin production and pathogenic ability. Isolates varied in mycelial characters like colony margin, mycelial growth and texture. With respect to sclerotial characters viz., variation in shape, colour, diameter, test weight, number of sclerotial bodies per cm2 and number of days taken to form sclerotial bodies were recorded. Oxalic acid production varied from 1.17 to 2.23 mg/ml. On the basis of pathogenicity, Pathotype-I consists of eight isolates, Pathotype II and III consists of only one isolate Sr DWR4 and Sr DWR1, respectively. Based on overall variability study, the S. rolfsii isolates were classified into two groups. Group I consist of four virulent isolates viz., Sr DWR2, Sr DWR5, Sr BGM2and Sr BGT2 and group II consists remaining six isolates which are less virulent. This study provides information on the genetic divergence and occurrence of pathogenic races and also it will be helpful for the development of effective disease management strategies.

Wheat, Sclerotium rolfsii, Isolates and Variability

Ten isolates of Sclerotium rolfsii Sacc. collected from different wheat growing areas of Northern Karnataka were subjected for isolation from foot rot infected samples and these isolates showed variability with respect to cultural and morphological characters, toxin production and pathogenic ability. Studies on variability within the population in a geographical region are important because these also document the changes occurring in the population. Variation in oxalic acid production in culture filtrate of S. rolfsii isolates is one of the impediments responsible for degrading the host tissue. So, it is necessary to study the variation in production of oxalic acid by different isolates and this information is use full in foot rot resistance breeding.

Sindhu M.M., P.V. Patil, Kiran B.M. and Supriya M.L. (2023). Morphological and Pathogenic Variability among Sclerotium rolfsii Sacc isolates, the Causal Agent of Wheat Foot Rot Disease. Biological Forum – An International Journal, 15(8): 01-05.