Bollgard Cotton Cultivars Differ in the Amount of Cry1Ac Protein Produced

Transgenic cotton plants expressing the Cry1AC Bt protein (Monsanto’s Bollgard) have been used successfully for more than ten years to manage lepidopteran pests. However, commercial cultivars of the Bollgard cotton differ in the amount of Bt protein produced. The plant mechanism for which this occurs is still unknown. Overall Cry1Ac levels among Bollgard cultivars have been correlated to survival levels in various lepidopteran pests that are intrinsically tolerant to this protein. In a paper published by the journal Transgenic Research, scientists from the US Department of Agriculture’s Agricultural Research Service (ARS) used quantitative real time polymerase chain reaction (qPCR) to determine the Cry1Ac protein levels in different Bollgard cotton cultivars.

The scientists found out that the difference in the production of the Cry1Ac proteins is accounted for by the difference in the production of cry1Ac mRNA from the transgene. The scientists noted that although post-translational effects or environmental factors could affect the levels of the Bt protein, genetic factors play a much bigger role in impacting the Cry1Ac levels among different Bollgard lines.

Differences in Bt protein expression in transgenic crops are normally detected using enzyme linked immunosorbent assay (ELISA). The ARS scientists demonstrated that qPCR based methods could be successfully employed for quantifying the expression levels of different Cry genes in plants without the expense of acquiring monoclonal antibodies.

The paper is available at http://dx.doi.org/10.1007/s11248-008-9198-z