Expression of a maize Myb transcription factor driven by a putative silk-specific promoter significantly enhances resistance to Helicoverpa zea in transgenic maize.
Hi II maize (Zea mays) plants were engineered to express maize p1 cDNA, a Myb transcription factor, controlled by a putative silk specific promoter, for secondary metabolite production and corn earworm resistance. Transgene expression did not enhance silk color, but about half of the transformed plant silks displayed browning when cut, which indicated the presence of p1-produced secondary metabolites. Levels of maysin, a secondary metabolite with insect toxicity, were highest in newly emerged browning silks. The insect resistance of transgenic silks was also highest at emergence, regardless of maysin levels, which suggests that other unidentified p1-induced molecules likely contributed to larval mortality. Mean survivor weights of corn earworm larvae fed mature browning transgenic silks were significantly lower than weights of those fed mature nonbrowning transgenic silks. Some transgenic pericarps browned with drying and contained similar molecules found in pericarps expressing a dominant p1 allele, suggesting that the promoter may not be silk-specific.
Johnson
Eric T
ET
Crop Bioprotection Research Unit, and New Crops and Processing Technology Research, National Center for Agricultural Utilization Research, Agricultural Research Service, U.S. Department of Agriculture, Peoria, Illinois 61604, USA. johnet@ncaur.usda.gov
Berhow
Mark A
MA
Dowd
Patrick F
PF
D000818:Animals; D015870:Gene Expression; D009036:Moths; D010935:Plant Diseases / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics*; D030821:Plants, Genetically Modified / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012639:Seeds / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics*; D003313:Zea mays / Q000235:genetics*
D010940:Plant Proteins; D014157:Transcription Factors