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Professor Jayashankar Telangana State Agricultural University, Hyderabad (Telangana State)

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Subject: Agricultural Biotechnology × Thesis Type: M.Sc × Author: ANIL KUMAR, CH ×
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    ThesisItemOpen Access
    MOLECULAR TAGGING/ MAPPING OF GENE(S) ASSOCIATED WITH RESISTANCE TO BROWN PLANTHOPPER, Nilaparvata lugens (Stal) IN RICE, (Oryza sativa L.)
    (ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY, RAJENDRANAGAR, HYDERABAD., 2006) ANIL KUMAR, CH; SIVARAMAKRISHNAN, S
    The brown planthopper (Nilaparvata lugens Stal) (BPH) is an important insect pest posing serious threat to rice production in India and other rice growing countries. Genetic resistance to BPH has been well documented in rice germplasm collection. Several major genes and quantitative trait loci (QTLs) have been reported for BPH resistance in varieties as well as wild species of rice. In this study, an attempt was made to trace BPH resistance locus from IR71033-62-24, a derivative of Oryza sativa/O. minuta cross, using simple sequence repeat (SSR) markers. IR71033-62-24 showed moderate resistance to BPH in greenhouse screening experiments. A F3 segregating population (284 families) was produced by crossing IR71033-62-24 with a highly susceptible variety, Mahsuri (BFselection). The F3 families were phenotyped for BPH resistance using a standard seedbox screening test. Inheritance of BPH resistance in F3 population did not show Mendelian segregation. The frequency distribution of phenotypic values of F3 families indicated the quantitative nature of resistance in this population. The parents were surveyed with a set of 224 SSR primer pairs to assess the extent of DNA polymorphism. The parents showed about 50 per cent variation at DNA level suggesting the suitability of the segregating population for mapping studies. Phenotypic extremes (resistant or susceptible families) were identified based on phenotypic data of F3 families. DNA of corresponding F2 plants were pooled to make DNA bulks each for resistant and susceptible classes for bulked segregant analysis (BSA). The polymorphic SSR primers between parents were surveyed across DNA bulks to identify positive markers. Out of 119 polymorphic SSR markers screened, only 6 markers showed positive polymorphism in bulks as well as in individuals constituting the bulks viz., RM225, RM585 and RM204 (chromosome 6), RM346 and RM10 (chromosome 7) and RM264 (chromosome 8). A subset of 75 F2 individuals was screened using the positive markers to establish marker-trait association. Single marker analysis based on One-way ANOVA indicated that the SSR markers on chromosome 6 showed significant association with BPH resistance. The SSR marker RM585 showed the F-probability values of 0.0. The results indicated the possibility of a significant genetic locus on chromosome 6 for BPH resistance in this population.