Identification of New Source of Resistance to Powdery Mildew of Indian Mustard and Studying Its Inheritance
J. Nanjundan, C. Manjunatha, J. Radhamani, Ajay Thakur, Rashmi Yadav, Arun Kumar, Mohan Lal Meena, Rishi Tyagi, Devender Kumar Yadava, Dhiraj Singh
Abstract
Powdery mildew of Indian mustard (Brassica juncea), caused by Erysiphe cruciferarum, is emerging as major problem in India. All the Indian mustard cultivars presently grown in India are highly susceptible to powdery mildew and so far no resistance source has been reported. In this study, with an aim to identify resistant source, 1,020 Indian mustard accessions were evaluated against E. cruciferarum PMN isolate, at Wellington, The Nilgiris, Tamil Nadu, India under natural hot spot conditions. The study identified one accession (RDV 29) with complete resistance against E. cruciferarum PMN isolate for the first time, which was consistent in five independent evaluations. Genetic analysis of F 1 , F 2 and backcross populations obtained from the cross RSEJ 775 (highly susceptible) RDV 29 (highly resistant) for two season revealed that the resistance is governed by two genes with semi-dominant and gene dosage effect. Further, a new disease rating system using six scales (0, 1, 2, 3, 4, and 5) has also been proposed in this study to score powdery mildew based on progress of fungal growth in different plant parts of the F 2 population.