Degradation Dynamics Of Cry1Ab Insecticidal Protein Expressing In Transgenic Bacillus Thuringiensis Corn Plants Under Different Conditions And Its Accumulation In Soil

The levels of Cry1Ab protein expression and degradation dynamics in two transgenic Bt corn pollen on plant axillaes, seedling debris and different tissues of corn plants in harvest of events MON810 and Bt11 were quantified and evaluated by using enzyme -linked immunosorbent assay (ELISA), The degradation dynamics of Cry1Ab insecticidal protein within transgenic Bacillus thuringiensis corn different tissues in harvest, different length stalks in cornfield and Wheatfield, soils and roots, broken stalks in laboratory of events MON810 and Bt11 were investigated and compared. The results as follows:1. The Cry1Ab insecticidal protein in seedling debris of events MON810 and Bt11 decreased to 99.81% and 100% of the initial amount at 50d, the speed of degradation were significantly different within the same time between the two events.2. The degradation of Cry1Ab toxin in Bt corn pollen on plant axillaes of events MON810 and Bt11 were gradual and rapidly. The speed of degradation was significantly different between the two events, The Cry1Ab insecticidal protein within transgenic Bacillus thuringiensis corn pollen on plant axillaes of events MON810 and Bt11 could degrade completely in 15 d andl8 d, respectively, which could not cumulate in cornfield.3. The content of Cry1Ab insecticidal protein in different plant tissues of events MON810 and Bt11 were significantly different at harvest.. The Cry1Ab toxin was highest expressed in stalks of MON810 and in leaves of Bt11. There are also significantly different in space within the same tissue in same event.4. Degradation of Cry1Ab toxin in stalks and leaves buried under the soil where the corn had been grown was slower than that under the soil where winter wheat was growing, significantly faster than that kept in surface of soil where the corn had been grown.5. The residues of Cry1Ab insecticidal protein in stalks of events MON810 and Bt11 were significantly different in different sampling times, different length treatments of stalks and different conditions. Degradation of Bt toxin in cut or smashed stalks buried under the soil where the winter wheat was growing is the fastest, and then in sequence are that buried under the soil and the whole stalk kept in the surface where the com had been grown.6. The residues and degradation of Cry1Ab insecticidal protein in root debris of events MON810 and Bt11 and released from root exudates of rhizosphere soil where the events MON810 and Bt11 grown were significantly different. The initial amount of Bt toxin in MON810 root debris and released from root exudates of rhizosphere soil where MON810 planted were significantly higher than that of Bt11. The Bt toxin in the roots of Bt11 was degraded completely in 210 d, Degradation of the Cry1Ab toxin in MON810 corn roots were very slow in the first 150 d, and then increased. The residue of Bt toxin in MON810 roots was 12.67% after 8 months. No residue of Bt toxin in Bt11 roots was detected after 7 months. It takes 210 d and 240 d for completely degradation of the Bt toxin released from root exudates in rhizosphere soil where Bt11 and MON810 had been grown, respectively.7. Degradation dynamics of Cry1Ab insecticidal protein expressing in transgenic Bacillus thuringiensis corn stalks of events MON810 and Bt11 under different conditions in environment chambers were investigated and compared. Results showed that the Bt toxin degradation was faster in sterile water than that in tap water at initial stage, the toxin degradation was slower in sterile water than in tap water at late stage. The speed of degradation was not significantly different in nonsterile soil+ sterile water than that in sterile soil+sterile water. The degradation of Cry1Ab insecticidal protein in stalks of events MON810 and Bt11 were that nonsterile soil+water was faster than in tap water at the first 7 day of the experiment, but the other sampling time was contrary.