Rice Genetics IV - IRRI books - International Rice Research Institute

Table 2. Summary of screening for rice ragged stunt virus (RRSV) resistance in transgenic ricecontaining RRSV pathogen-derived resistance (PDR) genes.Resistance aPDR gene Promoter Sense/ No. ofantisense lines tested Low Medium HighRRSV S5 rolC Sense 4 0 3 1Antisense 4 0 1 1*RRSV S7 rolC Sense 5 1 0 0Antisense 5 0 0 0Ubi1(I) Sense 1 0 0 0Antisense 3 2 0 0Act1 Sense 1 0 0 0Antisense 2 0 1 0RTBV Sense 5 1 2 0Antisense 3 1 1 0CaMV 35S Sense 30 11 2 0Antisense 20 2 1 1RRSV S8 Ubi1(I) Antisense 1 0 1 0RRSV S9 rolC Sense 5 2 1 1Antisense 12 4 6 2*Ubi1(I) Sense 4 1 1 1Antisense 4 0 0 1RRSV S9DI rolC Sense 5 2 0 0Antisense 5 2 0 0RRSV S9 Act1 Sense 23 5 0 4Antisense 17 7 3 2RRSV S9M Act1 Sense 4 0 2 0RRSV S9D Act1 Sense 25 4 3 7RRSV S10 CaMV 35S Antisense 1 0 1 0aResistance reconfirmed in T 2 /T 3 generation. All transgenic lines were of cv. Taipei 309 except the linescontaining RRSV S5, which were of cv. Chinsurah Boro II background. All were produced by biolisticsexcept CaMV 35S-RRSV S7 transgenic lines, which were produced by Agrobacterium-mediated transformation.The 10–14-d-old T 1 progeny seedlings were inoculated with viruliferous insects (Nilaparvatalugens) for 2 d and seedlings were then disinfected. Observations on symptom development and/orreverse transcriptase-polymerase chain reaction (RT-PCR) analysis were performed after 25–40 d. Percentageinfection (RT-PCR and/or symptom positive) in nontransgenic control plants was taken as abenchmark to score resistance in transgenic plants as low (50–75% of that of control plants), medium(25–50%), and high (0–25%).Transgenes derived from the RDV S8 or RRSV S9 genes have been placed underthe control of the CaMV 35S promoter and transferred into rice, but no resistance wasobserved (Matsumura and Tabayashi 1995).TenuivirusesRice stripe virus (RSV), rice grassy stunt virus (RGSV), and rice hoja blanca virus(RHBV) are tenuiviruses with some unusual properties. They are similar to reovirusesin having the dsRNA genome, genome segments with panhandle structures,replicase associated with virus particles, and the capacity to replicate in their insectvectors as well as in their plant hosts. However, they differ from reoviruses in thatthey form filamentous virus particles, package both single (negative)-stranded anddouble-stranded forms of their four genome segments, and express their genes using414 Upadhyaya et al