Inheritance of an insecticidal gene (cry1Ab) in genetically modified cotton

The present study was conducted to evaluate inheritance pattern of insecticidal gene (Cry1Ab) in F₁ and F₂ generations derived from six combinations of crosses made between two transgenic lines (CEMB-3 and CEMB-11) and two non transgenic lines (MNH-93 and CIM-482). PCR, southern blot, western dot blot assay and lab biotoxicity assay were used to confirm the gene integration and expression of insecticidal gene in successive generations. The insecticidal gene was stably integrated in the genome of all F₁ plants showing the dominant nature of introduced gene (cry1Ab). Furthermore, heterosis, heterobeltiosis, heritability and genetic advance studies of Bt gene were also conducted. Heterosis and heterobeltiosis were estimated for five characters i.e. cotton yield per plant, no. of bolls per plant, boll weight, ginning out turn % age and laboratory bioassay results. The heterosis and heterobeltiosis ranged from??15.19 to 107.07% and 18.58 to 98.79%, respectively for yield per plant; from ?20.34 to 81.36% and ?20.34 to 81.36%, respectively for number of bolls per plant; from -6.96 to 21.38% and ?9.30 to 9.99%, respectively for boll weight; from 13.02 to 26.44% and ?0.52 to 26.17%, respectively for ginning outturn; and from ?8.11 to 36.23% and ?5.56 to 23.68%, respectively for mortality % age of Heliothis larvae in laboratory bioassays. The Broad Sense Heritability and Genetic Advance for insect resistance in Bt versus non-Bt crosses were calculated. Both of these were high in four out of six hybrids. Our data recorded showed that these transgenic lines are an excellent source of germplasm to be used in conventional breeding programme.