Sun Xiaofen

Transgenic rice homozygous lines expressing GNA showed enhanced resistance to rice brown planthopper

Mature seed-derived calli from two elite Chinese japonica rice (Oryza sativa L.) cultivars Eyi 105 and Ewan 5 were co-transformed with two plasmids, pWRG1515 and pRSSGNA1, containing the selectable marker hygromycin phosphotransferase gene (hpt), the reporter β-glucuronidase gene (gusA) and the snowdrop (Galanthus nivalis) lectin gene (gna) via particle bombardment. 61 independent transgenic rice plants were regenerated from 329 bombarded calli. 79% transgenic plants contained all the three genes, revealed by PCR/Southern blot analysis. Western blot analysis revealed that 36 out of 48 gna-containing transgenic plants expressed GNA (75%) at various levels with the highest expression being approximately 0.5% of total soluble protein. Genetic analysis confirmed Mendelian segregation of transgenes in progeny. From the R2 generations whose R1 parent plants showing 3:1 Mendelian segregation patterns, we identified five independent homozygous lines containing and expressing all the three transgenes. Insect bioassay and feeding tests showed that these homozygous lines had significant inhibition to rice brown planthopper (Nilaparvata lugens, BPH) by decreasing BPH survival and overall fecundity, retarding BPH development and declining BPH feeding. These BPH-resistant lines have been incorporated into 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-based selection, conferred enhanced resistance to BPH, one of the most damaging insect pests in rice.