Transformation and evaluation of Broad-Spectrum insect and weedicide resistant genes in Gossypium arboreum (Desi Cotton)

Abstract

<i>Gossypium arboreum</i> (Desi Cotton) holds a special place in cotton industry because of its inherent ability to withstand drought, salinity, and remarkable resistance to sucking pests and cotton leaf curl virus. However, it suffers yield losses due to weeds and bollworm infestation. Genetic modification of <i>G. arboreum</i> variety FBD-1 was attempted in the current study to combat insect and weedicide resistance by incorporating <i>cry1Ac, cry2A</i> and <i>cp4-EPSPS</i> genes under control of 35S promoter in two different cassettes using kanamycin and GUS as markers through <i>Agrobacterium</i>-mediated shoot apex cut method of cotton transformation. The efficiency of transformation was found to be 1.57%. Amplification of 1700 bp for <i>cry1Ac</i>, 167 bp for <i>cry2A</i> and 111 bp for <i>cp4-EPSPS</i> confirmed the presence of transgenes in cotton plants. The maximum mRNA expression of <i>cry1Ac</i> and <i>cp4-EPSPS</i> was observed in transgenic cotton line L3 while minimum in transgenic cotton line L1. The maximum protein concentrations of Cry1Ac, Cry2A and Cp4-EPSPS of 3.534 µg g^-1, 2.534 µg g^-1 and 3.58 µg-g^-1 respectively were observed for transgenic cotton line L3 as compared to control cotton line. On leaf-feed-based insect bioassay, almost 99% mortality was observed for <i>Helicoverpa armigera</i> on the transgenic cotton plant (L3). It completely survived the 1900 ml hectare^-1 glyphosate spray assay as compared to non-transgenic cotton plants. The necrotic spots appeared on the third day, leading to the complete death of control plants on the fifth day of assay. The successful multiple gene-stacking in <i>G. arboreum</i> FBD-1 variety could be further used for qualitative improvement of cotton fiber through plant breeding techniques.