INTRODUCTION OF NEW TRAITS INTO COTTON THROUGH GENETIC-ENGINEERING - INSECT RESISTANCE AS EXAMPLE

The main goal of gene transfer into cotton is the development of insec t-resistant varieties. The stakes are important since cotton protectio n against insects uses almost 24% of the world's chemical insecticides market, which is not without consequences on the environment. The fir st approach was to introduce and express in the cotton genome genes fr om the bacterium Bacillus thuringiensis (B.t.) which produces entomopa thogenic toxins. The development of an efficient Agrobacterium tumefac iens mediated transformation system was the first step. The expression of B.t. genes was studied and synthetic genes more adapted to a plant genome have been constructed. Studies on their expression in cotton i s underway. The second focus was to develop strategies that would mini mize the risks of inducing insect resistance. The main approach is to associate several genes coding for entomopathogenic proteins with diff erent modes of action. Genes encoding protease inhibitors were chosen. One possibility is to associate a B.t. gene and a gene encoding a pro tease inhibitor. Several protease inhibitors were tested in artificial diets on major pests of cotton. The corresponding genes have been int roduced into the cotton genome. These various orientations of the rese arch program will be presented.