Expression of Bt protein in the backcross progenies of transgenic insect-resistant maize

The expression of Bt protein in three backcross progenies( HZ3152, HZ3342 and HC0142)of the transgenic insect-resistant maizes was quantified using Cry1Ab/Cry1 Ac Quanti Plate Kit. Samples were collected from different tissues at the same growth period or the same tissue from different growth periods. The results showed that the order of the Bt protein contents in different tissues of the backcross progenies was leaf immature seed filament seed husk. The Bt content showed an increasing trend from seedling to silking stage. The Bt protein content gradually declined after it reached the peak at silking stage. The expression levels of Cry1 Ac proteins HC0142, HZ3152, and HZ3342 were 4.16, 3.75, and 3.72 μg·g-1 at the seedling stage and 5.56, 4.58, and 4.79 μg·g-1 at the grain-filling stage), which were 68%, 69%, and 67% and 91%, 85%, and 87%,of the Bt protein contents at the silking stage(6.05, 5.36, and 5.50 μg·g-1), respectively. In general, Bt proteins declined in the later growth stage and the decrease was too small to influence the insect resistance. It showed that Bt gene can express stably in the maize backcross progenies. This paper provided useful information for the maize transgenic breeding.