Genetic improvement of Bacillus thuringiensis against the cotton bollworm, Earias vitella (Fab.) (Lepidoptera: Noctuidae), to improve the cotton yield in Pakistan

Abstract

In the present study, CryIAc (Crystal protein) gene was cloned under Cry3A promoter, which is known to express vegetatively as a sporulation independent promoter, transformed into acrystalliferous strain of Bacillus thuringiensis. Its potential was evaluated as a strain to be used for formulation development against the spotted cotton bollworm Earias vitella (Fab.) (Lepidoptera: Noctuidae), the major pest of cotton, the important cash crop in Pakistan. The crystal protein produced in a new strain, i.e., Bt1, had comparable potency as of crystal protein produced during sporulation. The new strain Bt1 had the maximum expression of Cry1Ac protein during the vegetative stage, i.e., in the first 24 h, thereby reducing the growth period until crystal protein production, from 72 to 24 h. In addition, crystal protein produced during vegetative stage under Cry3A promoter remained encapsulated within the cells, which could protect them from UV degradation and was independent of sporulation; therefore; it did not produce spores and thus is not a source to spread Bt spores in the environment. It can, therefore, be called as an environmentally friendly pesticide to control cotton pest especially bollworms and ultimately improve the yield of cotton.

Effect of Urea Spray on Boll Shell Insecticidal Protein Content in Bt Cotton

“…Previous research has reported the factors influencing the expression of Bt insecticidal protein and its corresponding mechanism ( Chen et al, 2005 , 2017 ; Wang et al, 2020 ). Some studies have suggested that tannins produced by cotton plants could bind to insecticidal proteins, which changed the structure of insecticidal protein and inactivated it ( Ma et al, 2012 ); others have suggested that the decreased expression of insecticidal proteins was caused by inactivation of insecticidal protein by methylation promoter of Bt gene ( Yunus et al, 2019 ; Patricia et al, 2020 ); it has also been suggested that changes in the ability of protein synthesis and decomposition can alter the expression of insecticidal proteins ( Chen et al, 2004 , 2005 ; Dong and Li, 2007 ). Chen et al (2017) showed that elevated nitrogen metabolism was beneficial for square development and insect resistance.…”

Genetically Modified Plants Based on Bacillus Genes and Commercial Bacillus-Based Biopesticides for Sustainable Agriculture

“…Transgenic crop cultivation expressing the insecticidal cry gene derived from B. thuringiensis, the most successful bioinsecticide, is now a common practice worldwide [62]. These transgenic plants include cotton, cauliflower, tomato, corn, chilli, and eggplants, products famous for their resistance against insects [63]. Two toxins, Cry1Ac and Cry2Ab, have been commercialized for the cotton crop with the name of Bollgard II, protecting against lepidopteran pests [64].…”