Identification Of Resistant Rice Cultivars To Striped Stem Borer (SSB), Chilo Suppressalis (Walker), And Preliminary Excavation And Comfirmation Of Resistant Genes

Chilo suppressalis (Walker),commonly known as the striped stem borer, has greatly reduced rice production. The plant anti-insect genetic engineering technique is a safer, economic-friendly and more efficient control than other methods. To screen the valid insect-resistant genes for breeding insect-resistant rice,47 rice cultivars were grown containing 39 main rice cultivars which are largely grown in the northeast of China and 8 cultivars of weedy rice. The main research results are as follows:1. Identification of resistant rice cultivars to stirped stem borerTo determine the resistance level of different rice varieties toward C. suppressalis,47 rice cultivars were treated by artificial infestation. Field experiment indicated that there is 1,3, 13,15,12and 3 rice cultivars were determined as high resistant cultivar, resistant cultivars, moderate resistant cultivars, insect-enduring cultivars, susceptible cultivars and high susceptible cultivars, respectively. Results in the greenhouse revealed 1 resistant cultivar,1 middle cultivar,5 insect-enduring cultivars,5 susceptible cultivars and 3 high susceptible cultivars. Both field and greenhouse experiments showed 1688 and 1654 are resistant to striped stem borers.2. Analysis of transcriptome sequencing of rice induced by striped stem borer and screening of insect-resistant genesResistant cultivar 1688, moderate resistant cultivar 1654 and high susceptible cultivar 1665 were induced by striped stem borers and RNA-seq was conducted. According to statistic analysis,1688AI (Artificial Infestation, AI),1688CK,1665AI,1665CK,1654AI and 1654CK got 293284,48997360,49011744,48730342,49054738 and 48913978 clean reads, respectively. All the clean reads were annotated to 47 subclasses by GO analysis and there were 66360 differential expression genes annotated by Pathway analysis where 125 pathways in 1688,121 pathways in 1665 and 120 pathways in 1654. On the basis of these results,24 significant differences genes were selected with in five categories as candidate genes including proteinase inhibitor genes, lectin genes, chitinase genes, plant hormone signal transduction pathway and plant-pathogen interaction pathway.3. Confirmation of the expression level of candidate genes by RT-qPCRReal-time quantitative PCR (RT-qPCR) was conducted to determine the expression level of candidate genes. The expression of 24 candidate genes were analyzed in resistant cultivar1688, moderated resistant cultivar 1654 and high susceptible cultivar 1665, respectively. The results showed that there was a similar tendency of transcript amount of 21 candidate genes with the result of RNA-seq. The abudance of LTPL164 was most remarkably (86.52 fold) induced among the selected candidates in 1688. In addition, there were also 13 candidate genes up-regulated in 1688 (LTPL151, LTPL18, CHIT12, WRKY97, WRKY107, WRKY118, WRKY6, LOC_Os06g10790, LOC_Os07g04220, LOC_Os01g12160, LOC_Os02g34320, LOC_Os04g51070, LOC_Os11g32100) to various degrees.7 candidate genes were down-regulated in 1688 including CHIT6, LOC_Os07g03880, LOC_Os07g18230, LOC_Os03g15880, LOC_Os05g37690, LOC_Os09g26780 and LOC_Os03g56950.