Indian J. Plant Genet. Resour. 24(1): 40–42 (2011) M Vignesh, DK Yadava, V Sujata, Anil K Yadava, T Mohapatra, KV Prabhu 40 *Author for Correspondence: E-mail: dkygenet@gmail.com Characterization of an Indian Mustard (Brassica juncea) Indigenous Germplasm Line Bio-YSR for White Rust Resistance M Vignesh 1 , DK Yadava 1∗ , V Sujata 1 , AK Yadava 1 , T Mohapatra 2 and KV Prabhu 1 1 Division of Genetics, Indian Agricultural Research Institute, New Delhi–110 012 2 NRC on Plant Biotechnology, Indian Agricultural Research Institute, New Delhi–110 012 (Received: 9 November 2010; Accepted: 3 December 2010) White rust, caused by Albugo candida is one of the major diseases of Indian mustard in India, causing heavy yield losses ranging from 17 to 34%. The breakdown of resistance is the prime concern to search for new genes to develop a durable resistance against white rust in mustard. A stable donor Bio-YSR (INGR No. 04099) has been developed indigenously, which need genetical characterization. Bio-YSR, the resistant donor germplasm line was crossed with popular, widely grown and high yielding susceptible cultivars Varuna and Bio-902 (Pusa Jai Kisan), to study the mode of inheritance of white rust resistance gene. The F 1 plants of these crosses were resistant indicating the dominant nature of the resistance. The segregation pattern in F 2 of the crosses fits well in 3 resistant (R): 1 susceptible (S) ratio indicating Bio-YSR carries a single dominant gene. This monogenic dominant nature was confirmed from the results of backcross populations as well. Hence, the major gene governing white rust resistance in the indigenous germplasm line Bio-YSR, will be of immense use in breeding for durable resistance by the way of diversification of resistant sources and gene pyramiding. Key Words: Indian mustard, Indigenous germplasm, Inheritance, Resistance, White rust Introduction White rust, caused by Albugo candida, is a common disease of many economically important cruciferous vegetables and oilseed crops. It is most wide-spread and highly destructive to Brassica juncea, reported to cause 17–34 % yield losses (Kolte, 1985). The Indian genotypes are highly susceptible to white rust (Li et al., 2008) and an appreciable loss in seed yield has been reported to the extent of 50% under late sown conditions (Saharan et al., 1984). Amongst the four oleiferous Brassica spp. grown in India, B. juncea is the predominant one and occupies more than 80% of the total area under rapeseed- mustard. Though, B. juncea is hardy in comparison to other oilseed Brassicas, yet it is highly susceptible to white rust. This disease is recurring every season with different degrees of intensity at different stages of crop growth, causing significant reduction in yield. The disease is characterized by the formation of white pustules on the cotyledons, leaves, stems and inflorescence. Systemically infected inflorescence becomes hypertrophied, causing the characteristic staghead galls (Verma and Petrie, 1980). It has been estimated that combined infection of leaf and inflorescence causes yield losses to the extent of 62.7%, the loss being more severe (89.8%) as a result of staghead formation in the susceptible cultivars (Lakra and Saharan, 1989). The most cost-effective way of protecting mustard plants from white rust is through introgression of genetic resistance. Identification of different sources of resistance to white rust is an important prerequisite in managing this disease by means of effective and durable genetic resistance. Genetic analysis of available white rust resistance has elucidated a digenic mode of inheritance with duplicate gene action in B. napus (Fan et al., 1983; Verma and Bhowmik, 1989) and monogenic dominant resistance in B. juncea (Tiwari et al., 1988; Bansal et al., 1999; Sachan et al., 2000; Chauhan and Sharma, 2001) as well as in B. rapa, B. carinata and B. nigra (Delwiche and Williams, 1974; 1981). The earlier studies were based on the exotic sources of white rust resistance. A stable donor Bio-YSR has been developed indigenously, and the genetics of this resistance source has not been studied. In comparison to the different exotic sources taken for genetic studies and used in white rust resistance breeding programme, Bio-YSR is agronomically superior and also stable under Indian conditions (Katiyar and Chopra, 1990). Dynamic changes in race composition of the pathogen have often resulted in short-lived efficiency of host resistance in the improved varieties which necessitates identification and characterization of new sources of white rust resistance. Hence, the present study was undertaken to investigate the nature and inheritance of white rust