Inheritance and segregation of exogenous genes in transgenic cotton

Three transgenic cotton varieties (lines) were chosen for the study of inhe ritance and segregation of foreign Bt (Bacillus thuringiensis toxin) and tf dA genes in cotton. The transformed cotton varieties CCRI 30 and NewCott 33 B expressing the Bt cryIA gene, and cotton line TFD expressing the tfdA gen e were crossed with CCRI 19, CCRI 12 and Lumian 6. The results confirm inhe ritance and segregation of (i) the exogenous Bt gene in transgenic CCRI 30 and NewCott 33B, governing resistance to bollworm, and (ii) the exogenous t fdA gene in transgenic TED, governing resistance to the herbicide 2,4-D. Bo th resistance characters were governed by a single dominant nuclear gene, a nd were not affected by cytoplasm. Our data support the conclusion that for eign traits encoded by single genes are inherited and expressed in Mendelia n fashion in cotton. Our results also indicate that a practical backcross b reeding program could be used to develop cotton cultivars combining one or more resistance traits from foreign and native gene sources.