| 摘要 |
<p>The present invention relates to fine mapping and potential application of dna markers linked to a gall midge resistance gene, gm7 for marker-aided selection in rice. Towards this, the present invention discloses a combination of novel sequence characterized amplified region (SCAR) primers for use in assay with the DNA of Rice plants in question. A cross between the gall midge resistant parent, RP2333 carrying the Gm7 gene and susceptible parent Shyamala, is developed and a F5 progeny is raised. A polymorphic band is identified from the F5 progeny, using AFLP that cosegregates with the susceptible phenotype. This band is eluted from the gel and cloned. The cloned AFLP fragment is sequenced and primers are developed for selectively amplifying DNA of susceptible phenotypes, thus differentiating them from the resistant phenotypes. This Gm7 gene linked marker is mapped onto chromosome 4 of rice and is also shown to be linked to Gm2 gene and the blight resistance gene, Xal through fine mapping using Yeast Artificial Chromosomes (YACS) and cosmids. This marker is present in a single copy in the susceptible parent, Shyamala. Primers developed from this marker are able to differentiate between the resistant and susceptible phenotypes in different crosses carrying different gall midge resistance genes. A number of screenings of resistant and susceptible varieties of rice with these primers show consistent polymorphism between them. The use of primers for PCR amplification of DNAs from F3 progenies derived from crosses between three different parental lines and the primers also differentiates the resistant phenotypes from the susceptible one. The primers of the present invention therefore have a great use in marker assisted selection as they show polymorphism between resistant and susceptible plants and therefore between plants with or without gall midge resistance genes.</p> |
