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Previous compatible and incompatible lines had a tufted-seed expression. Fuzzy seededness occurred when n1 common in cultivars was introduced by le1 n1 recombination. The fuzzy-seed incompatible version had 2le1 Le2dav Ne2 requiring recombination of Le2dav ne2 if nectariless cultivars were developed. In the F2 population that fixed le1n1 was the heterozygous Le2dav Ne2 - / le2 - ne2 -. Selfing provided F3 segregating Ne2 - to ne2ne2 that were tested for presence of Le2dav ne2. Failing to detect the recombinant at the 5cM frequency our effort was repeated for F4, F 5, and F 6. But Le2dav ne2/ le2ne2 was not detected; suggesting the probability that recombination was larger than 0.4 and less than 2 cM. That there was genetic cause for nonrecovery could not be excluded. A fixed line of the F3 having 2 Le2dav-Ne2- was introduced into a tufted, compatible, pollen-sterile nectary-free stock for genetic studies. These F2 verified Ne2 Ms9 recombination greater than 6 cM and the persistence of Le2dav Ne2. Information also indicated that the event introducing n1 was exceptional. The resulting 2gl2le1 * n1 ne1 Ms8: 2 gl3 le2 * ne2 Ms9 also upgraded the background by furnishing segments that breeders had selected in the development of nectariless and glandless. For detecting the presence of Le2dav in pollen fertile plants using pollen of cultivars a simulation method was examined. It was highly correlated with emasculation and pollination by hand and in turn was similar to pollen vectoring by bees. Estimates of cross pollination in fields of Bt cultivars indicated a high level of ambient pollen. Simulation suggested either an advantage of application of pollen to tip of stigma or an efficacy of first pollination. One Le2dav ne2 ms9 / lew ne2 ms9 recombinant was indicated by embryonic lethality. Its pollen-sterile offspring with embryonic lethality were confirmed. |
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©National Cotton Council, Memphis TN |
Document last modified Monday, Jun 21 1999
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