Introgressed genomic regions and gene silencing-related genes associated with Rice tungro bacilliform virus resistance derived from rice cultivar Utri Merah
2018
Matres, J.K.
Rice tungro disease (RTD) is an important viral disease of rice caused by mixed infection of Rice tungro spherical virus (RTS) and Rice tungro bacilliform virus (RTBV). UtriMerah, an Indonesian rice cultivar is resistant to RTSV and RTBV. A locus associated with RTBV resistance had been previously mapped to a 200-kb region in chromosome 4. Based on the genomic location and functional relevance, OsAGO2 and OsAGO3 were selected as the candidate genes for RTBV resistance. Investigation of accessions closely related to UtriMerah (resistant) and those closely related to Taichung Native 1 (TNI, susceptible) showed within-cluster correlation for RTBV resistance. To identify RTBV resistance gene, association between single nucleotide polymorphisms (SNPs) in candidate genes and RTBV level was examined in 95 rice accessions related to UtriMerah or to TNI. Results showed that two OsAGO2 SNPs located at 31,238,604 Mb (promoter) and 31,240,651 Mb (coding region) appear to be associated with RTBV resistance. This suggests that RNA silencing might be involved in antiviral defense against RTBV. An expression analysis of selected RNA silencing-related genes revealed significant changes in expression of these genes in TNI and TWI6 as a response to RTBV infection. More importantly, expression level of OsAGO2 is significantly higher in TW16 than in TNI. These results imply that OsAGO2 might be the gene for RTBV resistance.
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