Development of transgenic rice pure lines with enhanced resistance to ricebrown planthopper

Mature seed-derived callus from an elite Chinese japonica rice cv. Ewan 5 w as cotransformed with two plasmids, pWRG1515 and pRSSGNA1, containing the s electable marker hygromycin phosphotransferase gone (hpt), the reporter bet a -glucuronidase gene (gusA) and the snowdrop (Galanthus nivalis) lectin ge ne (gna) via particle bombardment. Thirty-five independent transgenic rice plants were regenerated from 177 bombarded calluses. Eighty-three percent o f the transgenic plants contained all three genes, as revealed by Southern blot analysis. Western blot analysis revealed that 23 out of 29 gna-contain ing transgenic plants expressed Galanthus nivalis agglutinin (GNA) (79%) at various levels with the highest expression being approximately 0.5% of tot al soluble protein. Genetic analysis confirmed Mendelian segregation of all three transgenes (gna, hpt and gusA) in the R2 progeny. Amongst the R2 gen eration, two independent homozygous lines were identified that expressed al l three transgenes. Insect bioassay and feeding tests showed that these hom ozygous lines had significant inhibition to lice brown planthopper (Nilapar vata lugens, BPH) by decreasing the survival, overall fecundity of BPH, ret arding development, and decreasing the feeding of BPH. These BPH-resistant lines have been incorporated into a rice insect resistance breeding program . This is the first report that homozygous transgenic rice lines expressing GNA, developed by genetic transformation and through genetic analysis-base d selection, conferred enhanced resistance to BPH.