FINE MAPPING OF DOMINANT RICE GALL MIDGE RESISTANCE GENE, Gm4 USING MICROSATELLITE MARKERS

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dc.contributor.advisorANURADHA, G
dc.contributor.authorVANI GUBBALA
dc.date.accessioned2016-08-27T15:06:16Z
dc.date.available2016-08-27T15:06:16Z
dc.date.issued2004
dc.description.abstractRice gall midge is one of the serious insect pests of rice. Chemical control of the pest is difficult and sometimes impossible and cultivation of varieties possessing one or more genes conferring resistance against gall midge is the economically feasible and ecologically viable strategy for its management. Many varieties possessing single gene conferred resistance have become gall midge susceptible due to emergence of virulent biotypes of the insect. Hence, many researchers have suggested pyramiding 2-3 gall midge resistance genes in a single genetic background for enhancing the durability of resistance. The dominant resistance gene, Gm4 originally identified from Ptb10 is an ideal candidate for deployment in gene pyramiding programmes. Gm4 was originally tagged with RAPD based marker F43 and mapped to Chromosome 8 of rice using RFLP markers by Nair et al. (1996) and Mohan et al. (1997) respectively. But none of these markers have been validated in alternative populations nor used in any gall midge resistance breeding programmes. The present study was designed to fine map Gm4 with help of rice microsatellite markers specific for Chromosome 8 of rice using the progeny tested F2 mapping population (consisting of 98 individuals) derived from the cross TN1/Abhaya. About 15-18 F3 seedlings derived from each F2 line were screened in a glasshouse using biotype 1 of gall midge to identify the genotype of each F2 line. Resistant F3 seedlings were observed to show presence of additional tiller and on dissection, they possessed necrotic brown discoloration in the meristematic region. Susceptible F3 seedlings showed gall formation and emergence of adult insect after 20th day of infestation. Twenty-six microsatellite markers located on Chr. 8 were screened for molecular polymorphism between the parental lines (TN1 and Abhaya) and six (RM547, RM25, RM337, RM152, RM256, RM32) were observed to be parental polymorphic. These six markers were analyzed in the F2 population for co-segregation with trait phenotype. Of the six markers, only two, RM547 and RM25 were observed to exhibit clear cosegregation with trait phenotype (resistance/susceptibility). Based on the cosegregation analysis, the linkage distance between the two markers and Gm4 was calculated to be 18.6 and 30.6 cM respectively with respect to RM547 and RM25. The other markers did not show any clear co-segregation pattern. A linkage map of Chr. 8 consisting of the five (excluding RM32) parental polymorphic microsatellite markers has been constructed with a total linkage distance of about 133.1cM. The two microsatellite markers RM547 and RM25 after further validation in a larger sized mapping population can be used for marker-assisted selection of the gene.en_US
dc.identifier.urihttp://krishikosh.egranth.ac.in/handle/1/74176
dc.language.isoenen_US
dc.publisherACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY RAJENDRANAGAR, HYDERABADen_US
dc.relation.ispartofseriesD7268;
dc.subAgricultural Biotechnology
dc.subjectFINE, MAPPING, DOMINANT, RICE, GALL, MIDGE, RESISTANCE, GENE, Gm4, MICROSATELLITE, MARKERS,en_US
dc.these.typeM.Sc
dc.titleFINE MAPPING OF DOMINANT RICE GALL MIDGE RESISTANCE GENE, Gm4 USING MICROSATELLITE MARKERSen_US
dc.typeThesisen_US
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