Expression of cry1Fain Bahiagrass Enhances Resistance to Fall Armyworm

Bahiagrass (Paspalum notatumvar. saurae) is the predominant forage grass in Florida and in other subtropical regions. To improve pest resistance against fall armyworm [Spodoptera frugiperda(J. E. Smith)], an optimized cry1Fagene encoding a δ‐endotoxin from Bacillus thuringiensiswas synthesized, subcloned under the transcriptional control of the constitutive ubi1promoter, and introduced into the bahiagrass cultivar Tifton 9 by particle bombardment. Three transgenic bahiagrass lines were generated using minimal transgene expression cassettes without vector backbone. Southern blot analyses showed independent cry1Fatransgene integration patterns for the three lines. Transcripts of cry1Fawere detected in all three transgenic lines by reverse transcriptase polymerase chain reaction. Cry1Fa protein was detected in two lines by immuno‐chromatography and quantitative Cry1Fa enzyme linked immunosorbent assay (ELISA). The Cry1Fa ELISA also indicated stable cry1Fatransgene expression in vegetative progeny plants of both lines. Cry1Faexpression levels correlated well to resistance levels determined by insect bioassays. An average mortality rate of 83% was observed when neonate larvae of fall armyworm were fed with transgenic leaves of the highest cry1Faexpressing line. These results indicate that minimal expression cassette technology supports stable and high level expression of cry1Fain bahiagrass which can control fall armyworm, a devastating pest of forage grasses.