Lore, Jagjeet SinghKamboj, Ishwinder2023-04-222023-04-222021Kamboj, Ishwinder (2021) Biology of Ustilaginoidea virens (Cooke.) Takahashi and mapping QTL for resistance to false smut in rice (Oryza sativa L.) (Unpublished Ph.D. Dissertation). Punjab Agricultural University, Ludhiana, Punjab, India.https://krishikosh.egranth.ac.in/handle/1/5810196554The false smut of rice is caused by fungus Ustilaginoidea virens (Villosciclava virens). The disease causes 0.2-49% yield losses besides qualitative losses. The knowledge of disease cycle about the pathogen and the availability of resistant sources for false smut is lacking. The present study was conducted with various treatments for seed-borne, soil-borne and air-borne nature of primary inoculum in pot experiment. The disease incidence and percent infected panicles was more in case of plants with uncovered panicles (10-36%) than covered panicles (0-9%), in infected soil (9-33%) than in sterilized soil (8-13%) and in case of plants raised from infected seed (0-10%) than from healthy seed (0%). The percent infection was the highest in case of air-borne experiment in plants with uncovered panicles than in plants grown in infected soil whereas the plants raised from infected seeds reported only 5% infection. In another experiment, screening of 212 rice accessions against false smut disease under field conditions resulted in selection of 27 resistant lines. These lines were further screened under artificial conditions against the disease along with susceptible checks (GSR123 and PR116) resulted in selection of 19 resistant lines. Out of 19, the lines CANAROXA and IAC 47 with good agronomic trait were used as donors for preparing crosses with PR126 and PR116, respectively. Out of 78 SSR markers, the markers which show polymorphism in PR116  IAC 47 includes RM16493, RM18457, RM25149 and RM28404 on chromosome 4, 5, 10 and 12, respectively. On the other hand, the polymorphic markers in case of PR126  CANAROXA includes RM104, RM289, RM7434, RM8243, RM264, RM25149, RM10 and RM26643 on chromosome 1, 5, 6, 8, 10 and 11, respectively. These polymorphic markers were used to identify genetic diversity in the mapping population. However, the identified polymorphic markers in this study fail to depict the association between the marker and false smut resistance gene due to lack of definite pattern of markers at loci. Further analysis in next generation will help us to uncover the association between the marker and the false smut resistance gene.EnglishThesis