| Rice (Oryza sativa L.) as an important food crop is attacked by a large number of insects. Among these insect pests, rice planthopper is one of the most serious pests of rice. The three major planthoppers attacking rice are the brown planthopper, the small brown planthopper and the white-backed planthopper. These insects feed on rice phloem sap, affecting the growth of rice plants and resulting in "hopperburn" in the case of BPH and WBPH, resulting in yield losses and reduction of the grain quality. More seriously, these rice planthoppers also act as vectors of major viral diseases. BPH transmits viral diseases such as grassy stunt virus and rugged stunt virus. SBPH transmits viral diseases such as rice stripe virus (RSV) and rice black-streaked dwarf virus (RBSDV). WBPH can transmit southern black streaked dwarf disease. In recent years, the increasing damage caused by rice planthopper resulted in severe yield losses in rice. This is a serious threat to rice production in China and other rice grown countries and the global food security. Nowadays, the control for rice planthopper and viral diseases transmitted by rice planthopper mainly depends on chemical pesticides. While repeated over-application of pesticides increases the cost of agricultural production, causes environmental pollution, kills predators, and destroys the ecological balance and so on. The most economical and effective way to control insects and diseases is developing new resistant cultivars. However, due to rice planthopper showing strong adaptability to resistance gene, rice planthopper can soon overcome the resistance after the usage of new resistant cultivars. Therefore, it is necessary to continuly explore new resistance genes from diverse sources. This lays the foundation for pyramiding multiple resistance genes and developing durable resistance cultivars.In previous screening for planthopper resistance resources, a rice variety IR54751-2-44-15-24-2 provided by IRRI display high resistance against BPH, SBPH, and WBPH. In order to investigate the genetic basis of this variety resistance to rice planthopper, explore the relationship of the three rice planthopper resistance and provide new resistance genes for developing rice planthopper resistant varieties, we constructed a F2 population derived from the cross between IR54751-2-44-15-24-2 and susceptible japonica 02428 in this study, and used 116 SSR and InDel markers uniformly distributed on 12 rice chromosomes to construct the genetic linkage map. Furtherly, we evaluated the resistance of F2:3 families against three types of rice planthopper and conducted the rice planthopper resistance quantitative trait loci (QTL) analysis. The major results are as follows:1. One major QTL conferring BPH resistance was detected on the short arm of chromosome 4 between markers RM7575 and RM6659, with a LOD score of 14.35, explaining 78.1% of the phenotypic variance.2. Two QTLs, qSBPH6 and qSBPH10 conferring SBPH were detected in this population. qSBPH6 is located on the short arm of chromosome 6 between markers 16-1 and RM3805, with a LOD score of 4.53, explaining 29.9% of the phenotypic variance. SBPH10 is mapped on the long arm of chromosome 10 between markers 110-5 and 110-7, with a LOD score of 2.37, explaining 13.1% of the phenotypic variance.3. A minor QTL controlling WBPH resistance was detected, located on chromosome 12 between markers 112-5 and 112-7, with a LOD score of 2.53, explaining 13.4% of the phenotypic variance.The four rice planthopper resistance genes detected in this study are all from the resistant parent IR54751-1-44-15-24-2. Comparative analysis of the resistance genes against three types of rice planthopper showed that the resistance of IR54751-1-44-15-24-2 to BPH, SBPH and WBPH are cotrolled by different resistance genes. The new resistant genes identified in this study provides the foundation for cloning of rice planthopper resistance gene and developing resistant varieties to control rice planthopper and viral diseases transmited by rice planthopper. |
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