US EPA

6981380 

Journal Article 

Nitrogen fertility effects on Bt delta-endotoxin and nitrogen concentrations of maize during-early growth 

Bruns, HA; Abel, CA; , 

2003 

Yes 

Agronomy Journal
ISSN: 0002-1962
EISSN: 1435-0645 

AMER SOC AGRONOMY 

MADISON 

207-211 

WOS:000182261000023 

Nitrogen deficiencies interfere with protein synthesis and growth in general in maize (Zea mays L). Transgenic maize hybrids with the Bacillus thuringiensis Berliner (Bt) gene produce proteins that are solubilized and become insecticidal in the highly alkaline midgut of certain lepidopteran insects. The effect N fertility has on Bt delta-endotoxin and how whole-plant N concentrations relate to Bt delta-endotoxin levels has yet to be documented in early-growth maize. Two Bt maize hybrids ('Pioneer 33V08(,1). with Bt event MON-810 and 'Dekalb 626Bt(,1) with Ill event DBT 418) were grown in pots in duplicate greenhouse experiments with N fertility rates of 0, 1 12, 224, and 336 kg ha(-1) N as NH4NO3. Fertilizer was blended into a-potting mixture of a 2:1:1 ratio of peat moss/sand/soil at planting. Plants were harvested at growth stage V5 and assayed for Bt delta-endotoxin using a commercial quantification plate kit. Whole-plant N concentrations were determined by semimicro-Kjeldahl. Whole-plant N concentrations were 25.8, 33.1, 35.1, and 37.7 mg g(-1), and Bt delta-endotoxin concentrations were 350, 367, 486, and 534 mug kg(-1) at N fertility levels of 0, 112, 224, and 336 kg ha(-1), respectively. Increased available N likely increases Bt delta-endotoxin-synthesizing proteins and thus increases the Bt delta-endo-toxin concentration. The response of the two Bt hybrids to increased N fertility was similar. Adequate levels of N fertility during early growth appear essential for Bt delta-endotoxin production by the plant and may affect the ability of maize plants to resist insect predation.