Mapping Of Resistance Genes To Small Brown Planthopper In Rice And Resistant Characteristics

The small brown planthopper (SBPH), Laodelphax striatellus Fallén (Homoptera: Delphacide), isa serious pest in rice. It not only causes direct damage by sucking plant sap but also transmits several viraldiseases such as Rice stripe virus (RSV) and Rice black-streaked dwarf virus (RBSDV), which often causemajor yield losses. In this study, we mapped a ressive gene resistant to SBPH by using SSR markers, andunderstood the resistant mechanism of rice after SBPH feeding through the cytohistological characteristics,physiologicaland biochemical index, as well as the expression of the resistance-related genes. The resultswere as follows:1. We mapped a ressive gene resistance to SBPH resistance on the12chromosome, flanked bySSR markers RM3331and RM5479in this exercise. The discovery and mapping of this gene will behelpful to explore the resistance mechanisms, clone the resistance gene and cultivate resistant rice varieties.2. Scanning electron microscopy showed that leaf thorns on the surface of rice were more andlonger of in resistant rice than that in susceptible rice. The results of transmission electronic microscopyshowed that the dysplasia chloroplast of susceptible rice contained a large number of starch grains, and thestructure of grana and thylakoid lamellae were blur. A lot of electron-dense materials accumulated in thecells and intercellular spaces, which may be phenolic compounds. These substances can strengthen the cellwall and provide an environment to defend the insects.3. We select three resistance rice cultivars and three susceptible rice varieties to determine thechanges of the activity of polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL) after SBPHfeeding at the different time. The results showed that the activities of these two enzymes changed afterSBPH feeding. The change range of enzymes activity in resistant rice varieties was significantly higher than that in the susceptible varieties. These two enzymes were related to the plant resistance, therefore, thechanges of the activity of PPO and PAL after SBPH feeding indicated that these two enzymes involved inresistant reaction.4.Real time-PCR technique was used to study the changes of the defense-related genes afterdifferent times of treatment(0,12,24,36,48,72h)in the resistant and susceptible rice. We use specificprimers to analyze the related genes in the major defense pathway of the resistant and susceptible rice. Theresults showed that transcript levels of the SA synthesis-related genes were higher in the resistant rice thanthat in susceptible rice after SBPH infestation, suggesting that it may activate an SA-dependent resistancepathway after SBPH feeding.