Heterosis in Bt Cotton Hybrids Analyzed

In two separate experiments conducted by Chinese researchers, hybrids derived from Bt cotton parents showed increased heterosis in many characters. This means that hybrids from Bt transgenic cotton parents maybe valuable for commercial utilization.

The experiments, conducted in Shandong Cotton Research Center in China, utilized four commercial Bt cotton varieties as male parents and five commercial varieties as female parents. The mid-parent heterosis observed in the Bt cotton hybrids was 21.3% in lint yield. There are also considerable heterosis detected in boll numbers, boll size and Bt protein content. The researchers believe that the enhanced endotoxin expression in terms of Bt protein concentration in Bt hybrids is due to over-expression of heterozygous transgenes - Bt genes that are in different chromosomes of the hybrids.

The heterosis in other characters was also explained to be influenced by the increased leaf area and the improved flow capacity of photosynthates at late stage of growth and development of the hybrids.

The abstract, with link to the full paper can be accessed at http://www.blackwell-synergy.com/doi/abs/10.1111/j.1439-0523.2007.01321.x.