Genetic Analysis And Gene Mapping Of Rice Blast Resistance Gene In Super Japonica Rice (Oryza Sativa L.sp.Japonica)

Rice is one of the most important crops in the world which is infected by all kinds of diseases and insects in the whole growth duration. Rice blast caused by Pyricularia grisea is one of the most serious diseases to rice yield decrease. Utilization of genetic resistance is the most effective and environment friendly strategy for the disease control. However, breeding for stable resistance to blast is extremely difficult. Although some cultivars with durable resistance has been recognized, the resistance of most cultivars is still short-lived. SN606 is the super-rice cultivar cultivated by Shenyang Agricultural University Rice Research Institute. Recently it has been growing extensively in north of China, and the cultivar expresses a high resistance to the north rice blast races. Inheritance analysis and molecular mapping of rice blast resistance gene were performed in this study. All the results were showed as follows:1. In order to effectively use its broad spectrum resistance, two rice varieties, blast resistant SN606 and blast susceptible LTH, have been crossed. The race ZA41 of Magnaporthe grisea (hebert) barr have been used to inoculate the two parents, F₁, F₂ population in the conservatory. The results showed that the segregation ratio of resistance and susceptible to ZA41 was 632:196 in F₂ population. Theχ² test showed that the genetic mechanism of resistance to ZA41 blast race was controlled by single dominant blast-resistance gene.2. SRAP is a novel molecular marker based on PCR, which can amplify ORF differentially. So it takes advantage of lots of research fields such as gene mapping, gene cloning and construction of genetic map. This research constructed stability reacting system of SRAP for rice, for 15μL sestem, 25ng DNA, 200 mmol.L^-1 dNTP, 1 U T aq DNA polymerse, 0.3μmol.L^-1 primer, 2.5 m mol.L^-1 Mg²⁺.3. The results revealed that two SRAP primers were linked with the blast resistance gene to ZA41 in SN606. The possible linkage distance was 2.8 and 7.7cM with molecular marker m5e1-500 and m2e5-600.4. Rice blast resistance gene is anchored with 84 pairs of primers of SSR and preliminarily mapped in chromosome 8 of rice. It linked with RM25 by 9.8 cM.5. Sequencing the one fragment linked to the resistance gene and compared with the RGP and NCBI data-bases, the result proved the gene maped on chromosome 8, which was consistent with the SSR result, so proved that anchoring chromosome can utilize the sequence of SRAP segment.In all, the blast resistance in SN606 was controlled by single dominant blast-resistance gene. One SSRmarker and two SRAP markers linked to the resistance gene were selected. The resistance gene was mapped on chromosome 8. The stability reacting system of SRAP for rice was constructed. It will be useful in gene cloning and mapping.