Mendelian segregation pattern and expression studies of insecticidal gene (cry1Ac) in insect resistant cotton progeny

Tahira Hussain,Tayyab Husnain,Abdul Rao,Bushra Rashid,Samina Hassan,Ahmad Shahid,Bushra Munir,Allah Bakhsh

doi:10.9755/ejfa.v26i8.17794

Abstract

The progenies of transgenic lines Bt-14 and Bt-17 developed as an independent transformation event from a local cotton variety CIM-482 harboring two insecticidal genes (cry1Ac & cry2a) were evaluated to determine resistance against lepidopterans, mainly Helicoverpa armigera L. under field conditions. The standard molecular techniques, i.e. polymerase chain reaction (PCR), enzyme-linked immunosorbent assay (ELISA) and western dot blot were used to confirm gene presence and expression level of transformed Bt gene, and its transfer pattern to further progeny. PCR confirmed integration of insecticidal gene in most of the plants in transgenic progeny, while expression of Bt gene quantified by ELISA and western dot blot showed variation in cry1Ac expression levels but interestingly, it conferred full protection against targeted insect pests. The leaf bioassays were conducted to determine the effectiveness of Bt genes against Helicoverpa armigera by calculating the mortality percentage of larvae. Most of the transgenic lines showed 70-100% mortality % age of Helicoverpa armigera. The agronomic characteristics of the transgenic lines were also recorded along with non transgenic control variety CIM-482. Morphological, agronomic and fibre data of these transgenic lines was recorded and analyzed statistically. Our results show that these transgenic lines (especially Bt-17 line) are promising cotton germplasm to be used in an efficient breeding programme.

Highlights

Cotton (Gossypium hirsutum L.) is a soft, fluffy, staple fiber that grows in a boll around the seeds of the plant
Our results show that these transgenic lines are promising cotton germplasm to be used in an efficient breeding programme
Insect resistant Bt plants have emerged as potential alternative to the synthetic insecticides (Khan et al, 2011; Sohail et al, 2012)

Summary

Introduction

Cotton (Gossypium hirsutum L.) is a soft, fluffy, staple fiber that grows in a boll around the seeds of the plant. Conventional plant breeding methodologies have helped cotton breeders to improve crop, resistance to insect pests and diseases is not available in germplasm. The advent of genetic engineering technologies has helped plant reseachers to transfer genes from irrelevant origin into significantly important crop plants to induce insect resistance (Dhaliwal et al, 1998). The adoption of transgenic insect resistant cotton has resulted in the reduction of use of insecticides worldwide, Mexico (77%), China (65%), Argentina (47%), India (41%), and South Africa (33%) respectively (Qaim et al, 2009) which led to significant increase in farm yield. The production of transgenic plants with stable, highlevel transgene expression is important for the success of crop improvement programs based on genetic engineering (Meyer, 1998). To determine whether the introduced insecticidal gene (cry1Ac) is being stably inherited in fifth transgene progeny, Mendelian segregation pattern of (cry1Ac) has been studied

Material and Methods

Results and Discussion

Conclusion