The crop in which the Bt gene has been used for genetic transformation and has caused controversy in India is cotton. The Bt gene is a gene derived from the bacterium Bacillus thuringiensis, which produces a protein toxic to certain pests, including the bollworm, a major pest in cotton production. By introducing the Bt gene into cotton plants, they become resistant to bollworm infestations, reducing the need for chemical pesticides and increasing crop yields.

This controversy in India arose primarily due to concerns about the potential impact of Bt cotton on the environment and farmers. Critics argue that Bt cotton has led to the emergence of new pests and increased pesticide use, as well as causing loss of diversity in cotton varieties. Supporters, on the other hand, highlight the benefits of reduced pesticide use and increased yields.

It is interesting to note that Bt cotton has been widely adopted by farmers in India since its introduction in 2002, making India one of the largest producers of Bt cotton in the world. However, the controversy surrounding its use remains a topic of debate and discussion.