Identify of rice resistance to blast (magnaporthe grise) with SSR markers

The broad-spectrum blast resistance gene Pi-1, from the donor line Lac23, was introduced into a line Nyou69-1, which possessed great resilience but high susceptibility to rice blast. The F8 individuals used in this study consisted 297 plants derived from a successively self-crossed with the material (a cross between Nyou69-1 and Lac23). SSR markers near Pi-1 gene at the end of the 11th chromosome of rice were used to detect the polymorphism in Nyou69-1 and Lac23. Five pairs of core primers showed polymorphism between Nyou69-1 and Lac23 were selected. Detect the F8 individuals with these primers, compare the lab result with the field trial, verify the accuracy of SSR marker to identify the rice blast resistance in field individuals. The result showed that there was an apparent change in the phenomena of a gene recombination between markers and the Pi-1 caused by the great self-cross. In the lab trial, RM6293 got the highest accuracy rate among the 5 pairs of core primers, which was the most efficient single primers. Its result contained 22 individuals (53.66% in the positive bands) getting the property of resistance to blast(the standard according to the result of field trial). Evaluating the different combinations of primers from the core primers indicated that RM6094/RM2136 was very efficient in identifying those F8 cultivars. 28 cultivars of F8 colony, representing 10 materials with the grade I rice blast resistance, 12 materials with the grade III rice blast resistance, 6 materials with the grade V rice blast resistance, showed the positive strip in the testing. 14 materials with grade I, 30 materials with grade III and 19 materials with grade V have rice blast resistance in the field trial. Its accuracy rate reaches 73.68%. The result shows the elevation of the accuracy rate depend on the quantity of the primer combination. The more primers form the combination, the higher accuracy rate it represent. Select three primers from the five core primers arbitrarily as a combination to detect the rice blast resistance, no fake positive materials have been detected. what is more, most of the materials selected by the three primers combination are grade I of the rice blast resistance, only 1 material is grade III of the rice blast resistance and no one is grade V of the rice blast resistance. The evidence proves that materials with high blast resistance were selected by the core primer combination efficiently. Some of the rice blast resistance materials be selected as the negative in the lab trial is insufficient through this research.