The researchers learned that the astonishing diversity of cadherin in pink
bollworm from India is caused by alternative splicing, a novel mechanism of resistance that allows a single DNA sequence to code for many variants of a protein.
«We wanted to see if field - resistant pink
bollworm from India harbored these same changes in the cadherin gene,» Fabrick said.
He said that by collaborating with Indian scientists, «we discovered that the same cadherin gene is associated with the resistance in India, but the mutations are different and much more numerous than the ones we found in lab - selected pink
bollworm from Arizona.»
Not exact matches
«Perhaps the most compelling evidence that refuges work comes
from the pink
bollworm, which evolved resistance rapidly to Bt cotton in India, but not in the U.S.,» Tabashnik said.
A concerning finding among the Brazilian hybrids was that one was 51 per cent earworm but included a known resistance gene
from the
bollworm.
Scientists
from the UA and the U.S. Department of Agriculture worked closely with cotton growers in Arizona to develop and implement resistance management strategies such as providing «refuges» of standard cotton plants that do not produce Bt proteins and releasing sterile pink
bollworm moths.
Since then, scientists have used the technique to eradicate the screwworm fly, which causes lesions on livestock,
from North and Central America; the tsetse fly, which brings sleeping sickness,
from Zanzibar; and the pink
bollworm, a pest of cotton,
from California.
The protein produced
from the gene kills the cotton
bollworm and the native budworm.
In addition to Fabrick and Tabashnik, the following authors collaborated on the study: Jeyakumar Ponnuraj
from the National Institute of Plant Health Management in Hyderabad, India, who studied pink
bollworm resistance as a visiting scholar in Tabashnik's lab; Amar Singh and Raj Tanwar of the National Centre for Integrated Pest Management at the Indian Agricultural Research Institute in New Delhi; and Gopalan Unnithan, Alex Yelich, Xianchun Li and Yves Carrière
from the UA Department of Entomology.
By sequencing the DNA of resistant pink
bollworm collected
from the field in India — which grows the most Bt cotton of any country in the world — the team found that the insects produce remarkably diverse disrupted variants of cadherin.