Production of transgenic rice homozygous lines with enhanced resistance tothe rice brown planthopper

Mature seed-derived callus from an elite Chinese japonica rice (Oryza sativ a L.) cv. Eyi 105 was cotransformed with two plasmids. pWRG1515 and pRSSGNA 1, containing the selectable marker hygromycin phosphotransferase gene (hpt ), the reporter beta -glucuronidase gene (gusA) and the snowdrop (Galanthus nivalis) lectin gene (gna) via particle bombardment. After two rounds of s election on hygromycin-containing medium, resistant callus was transferred to hypromycin-containing regeneration medium for plant regeneration. Twenty -six independent transgenic rice plants were regenerated from 152 bombarded calli with a transformation frequency of 17%. Seventy-three percent of tra nsgenic plants contained all three genes, which was revealed by PCR/Southrm blot analysis. Thirteen out of 19 transgenic plants containing the gna gen e expressed GNA (68%) at Various levels with the highest expression being a pproximately 0.5% of total soluble protein. Genetic analysis confirmed Mend elian segregation of transgenes in progeny. From R2 generations with their R1 parent plants showing 3:1 Mendelian segregation patterns, we identified three independent homozygous lines containing and expressing all three tran sgenes. Insect bioassay and feeding tests showed that these homozygous line s had significant inhibition to the rice brown planthopper (Nilaparvata lug ens, BPH) by decreasing BPH survival and overall fecundity, retarding BPH d evelopment and reducing BPH feeding. This is the first report that homozygo us transgenic rice lines expressing GNA, developed by genetic transformatio n and through genetic analysis-based selection. conferred enhanced resistan ce to BPH, one of the most damaging insect pests in rice.