Response of Tobacco Budworm Larvae to Cotton Seedlings Carrying Various Combinations of Gland-determining Alleles1
- F. D. Wilson2
Five- and 6-day-old larvae of the tobacco budworm, Heliothis virescens. (F.), discriminated among seedlings cotton, Gossypium hirsutum L., carrying the 4 true-breeding combinations of the gland-determining alleles Gl2 and Gl3. Seedling damage was least, and larval numbers were lowest on dimeric glanded, Gl2Gl2Gl3Gl3, intermediate on the 2 monomerics Gl2Gl2gl3gl3 and gl2gl2Gl3Gl3, and highest on glandless, gl2gl2gl3gl3, when readings were made 24 and 48 hours after infestation. Howevers, eedling damage was less at the second reading and numbers of larvae left on the seedlings were less at both readings in Gl2Gl2gl3gl3 than in the other monomeric line. Larval response was correlated both with the number of pigment glands in the cotyledonary petioles of the seedling, and with percent gossypol in seed meats of the genotypes studied. Results suggest that this bioassay technique may be useful in selecting seedlings with varying levels of gossypol. In fact, it may be possible to select seedlings by counting glands, without resorting to a bioassay. However, the effects of varied genetic background on gland number have not been studied. Also, the relationship of seedling resistance to mature-plant resistance is not known. Several applications of this bioassay technique are discussed in relation to a number of other breeding, entomological, and genetic problems.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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