TEMPORAL STATUS OF BT GENE EXPRESSION IN PAKISTANI COTTON

The present research study was conducted during 2009, 2012, 2013 and 2014 under National Cotton Varietal Trial (NCVT) for the expression profiling of Bt gene in local cotton genotypes/entries. Firstly, a total of 180 cotton lines (12, 75, 49 and 44 in years 2009, 2012, 2013 and 2014, respectively) were used to check the types of Bt gene(s) through immunostrip assay. Most of the entries were positive for the presence of Cry1Ac gene (Bollgard I) except CEMB-01 in 2009, DNH-105, BH-176 and CIM-573 (non Bt. Standard) in 2012, CIM-573 (non Bt. Standard) and CRIS-342 (non Bt. Standard) in 2013 and BH-185 and SLH-8 in 2014. Only a single entry (Kissan Early in 2012) was found positive for both Cry1Ac and Cry2Ab (Bollgard II). None of the entry gave positive result for Cry1F (Wide Strike event) through immunostrip assay. Later, expression level of Cry1Ac gene for all the entries were quantified through sandwich-ELISA. The expression level for twelve entries during 2009 was recorded in the range of 0.21-1.31 mu g/g of fresh weight leaf tissue. During 2012, the expression level for Cry1Ac was measured in the range of 0.05-0.86 mu g/g. All the positive entries for Cry1Acgave the expression level less than as recommended by EPA-USA (>1.5 mu g/g). In 2013 and 2014, the expression level for Cry1Ac was quantified in the range of 0.03-4.17 and 0.04-4.29 mu g/g, respectively. Data of four years revealed that considerable gradual improvement has been made in the levels of Bt toxin in local candidate cotton lines at breeder level. There is need to sustain the attained toxin levels under farmer field conditions.