Modes of Gene Escape

Genetic material of G. hirsutum may escape from a test area by vegetative material, by seed, or by pollen. Propagation by vegetative material is not a common method of reproduction of cotton. Physical safeguards that inhibit the movement of vegetative material from the area should be adequate to prevent gene movement by this means. Movement of seed from the test area can likewise be inhibited by adequate physical safeguards.

Movement of genetic material by pollen is possible only to those plants with the proper chromosomal type. Movement to G. hirsutum and G. barbadense is possible if suitable insect pollinators are present and if there is a short distance from transgenic plants to recipient plants. Physical barriers, intermediate pollinator-attractive plants, and other temporal or biological impediments would reduce the potential for pollen movement.

Movement of genetic material to G. tomentosum is less well known. The plants are chromosoma-lly compatible with G. hirsutum, but there is some doubt about the possibility for pollination. The flowers of G. tomentosum seem to be pollinated by moths, not bees. And they are receptive at night, not in the day. Both these factors would seem to minimize the possibility of cross-pollination. However G. tomentosum may be losing its genetic identity from introgression hybridization of cultivated cottons by unknown means.

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