Sypium hirsutum ) production. Genetic resistance could drastically advantage US growers. Moreover, the removal of chemical compounds in the market for nematode control is accentuating the have to have for genetic resistance to cotton nematodes. Years ago, screening of cotton germplasm collections revealed no higher resistance to reniform nematodes amongst 52-chromosome Gossypium species, but revealed really higher resistance within the 26-chromosome cotton relative G. longicalyx, a spindly African relative (2n=52). Very good resistance levels have been noted for other 26-chromosome species, as well. Revolutionary breeding and collaborative efforts helped us circumvent ploidy and genomic barriers to introgression on the African species’ resistance. We subsequently utilised breeding materials to localize and map the introgressed gene (Renlon) to chromosome-11, and to establish a technique for marker-assisted choice that contributed substantially to the development LONREN-1 and LONREN-2, two extremely resistant lines that have been jointly “released” towards the public. Subsequent field-tests, nonetheless, revealed that the LONREN lines suffer from variable levels of “stunting”, and that stunting was quite extreme in some areas. Different tests suggest that the severity of stunting is connected with nematode population density, and that LONREN lines are hypersensitive for the nematode combined with other soil pathogens. Various lines of evidence also indicate that genes linked towards the introgressed gene (Renlon) influence resistance to other pathogens, and other people have an effect on field and fiber efficiency. Genetic dissection and characterization of this region is desirable for scientific and sensible reasons. Towards these ends, we have mounted a map-based approach for high-resolution recombination, mapping, and minimization from the alien segments flanking the resistance gene. Our hypotheses with regards to the “stunting” and approaches to analyze it will likely be discussed, like our breeding techniques, efforts to create new sequence-based markers inside the flanking region and the strategies to recover informative recombinants.Meeting Abstracts 493 GOSSYPIUM ACCESSIONS RESISTANT TO ROTYLENCHULUS RENIFORMIS Vary IN SENSITIVITY Towards the HERBICIDE FLUOMETURON. Stetina1, Salliana R. and W.T. Molin2. 1USDA ARS, Crop Genetics Investigation Unit, PO Box 345, MK-0457 Stoneville, MS 38776, 2USDA ARS Crop Production Systems Analysis Unit, PO Box 350, Stoneville, MS 38776. Reniform nematode (Rotylenchulus reniformis) resistance is becoming transferred to Upland cotton (Gossypium hirsutum) from its distant relatives. Anecdotal observations of fluometuron damage to LONREN lines with resistance from G. longicalyx raised concerns about introducing herbicide sensitivity from other resistance sources. The study objective was to evaluate fourteen sources of reniform nematode resistance for their reaction to fluometuron within a replicated greenhouse trial: G. herbaceum accessions A1-017 and A1-024; G. arboreum accessions A2-083, A2-100, A2-190, and A2-194; G. barbadense accessions Pima PHY 800, GB 713 and TX 110; G. hirsutum accessions T19, T1347, and T1348; and three G. hirsutum lines with resistance introgressed from G. barbadense (FR-05) or G. longicalyx (LONREN-1 and LONREN-2). The manage was G. hirsutum cultivar Deltapine 161 B2RF. Six seeds of each and every line have been planted on leading of a mixture of sandy loam soil and sand (three:1 by volume) in ten cm square pots. Fluometuron added to 100 cm3 added soil mix (1:1, sandy loam:sand) at prices of 0, 0.34, 0.67, 1.