Identification of Phytophthora blight resistant mutants through induced mutagenesis in sesame (Sesamum indicum L.)

Sesame (Sesamum indicum L.) is one of the oldest cultivated plants in the world and is also known as ‘queen’ of oilseed crops. The production of sesame is not consistent compared to other oilseed crops as it is susceptible to waterlogging and low temperature conditions and constant devastating effects of various diseases. Phytophthora blight caused by Phytophthora nicotianae is an economically important oomycete pathogen affecting sesame plant growth and yield to great extent. This disease is predominant in all sesame growing areas. Mutant varieties resistant to Phytophthora blight in sesame have been developed in the Republic of Korea and Sri Lanka. In the present study, 416 gamma-rays induced M3 mutants were raised at Palampur, 164 mutants at Kangra and 314 at Akrot in India. The mutants were screened for Phytophthora blight resistance both under natural field as well as laboratory conditions through ‘detached leaf technique’ at Palampur. Out of these, 186 and 62 M4 mutants were screened again under natural field conditions at Palampur and Kangra, respectively during rainy season of 2016. Based on the screening for 2 years through ‘detached leaf technique’ as well as under natural field conditions, twelve mutants having moderate to high resistance against Phytophthora blight could be isolated. One mutant P97-1 (300 Gy) exhibited highly resistant reaction against Phytophthora blight during both seasons. The isolated mutant can further be utilized in hybridization programme for the introgression of Phytophthora blight resistance in sesame.