Cloned gene, insect toxicity

A major target in toxin gene analysis has been to identify protein regions that provide the toxicity or insect specificity of the 6-endotoxins. To date the conplete sequence of toxin genes from 4 B.t. strains have been reported (Table I). The structure of cloned genes and their regulatory elements have been well described in recent papers (, 28). 

Breeders have selected celery with relatively high amounts of psoralens because farmers prefer to grow insect resistant plants and consumers prefer to buy undamaged produce. Unfortunately, workers who harvest such celery sometimes develop a severe skin rash (NAS 2004), an unintended consequence of this conventional breeding. It is possible that if the gene encoding the toxic protein had been cloned and studied before being introduced into the new varieties, farm workers would have learned of the harmful effects before exposure. 

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