Genetic resistance could considerably benefit US growers. Furthermore, the removal of chemical compounds in the marketplace for nematode manage is accentuating the have to have for genetic resistance to cotton nematodes. Years ago, screening of cotton germplasm collections buy CP-690550 citrate revealed no high resistance to reniform nematodes among 52-chromosome Gossypium species, but revealed quite high resistance in the 26-chromosome cotton relative G. longicalyx, a spindly African relative (2n=52). Great resistance levels were noted for other 26-chromosome species, too. Innovative breeding and collaborative efforts helped us circumvent ploidy and genomic barriers to introgression with the African species’ resistance. We subsequently made use of breeding components to localize and map the introgressed gene (Renlon) to chromosome-11, and to establish a program for marker-assisted choice that contributed drastically to the development LONREN-1 and LONREN-2, two highly resistant lines that were jointly “released” towards the public. Subsequent field-tests, having said that, revealed that the LONREN lines endure from variable levels of “stunting”, and that stunting was really severe in some locations. Different tests suggest that the severity of stunting is associated with nematode population density, and that LONREN lines are hypersensitive towards the nematode combined with other soil pathogens. A number of lines of proof also indicate that genes linked to the introgressed gene (Renlon) have an effect on resistance to other pathogens, and other individuals impact field and fiber overall performance. Genetic dissection and characterization of this area is desirable for scientific and practical causes. Towards these ends, we have mounted a map-based method for high-resolution recombination, mapping, and minimization of the alien segments flanking the resistance gene. Our hypotheses relating to the “stunting” and approaches to analyze it will be discussed, including our breeding strategies, efforts to develop new sequence-based markers in the flanking area and also the techniques to recover informative recombinants.Meeting Abstracts 493 GOSSYPIUM ACCESSIONS RESISTANT TO ROTYLENCHULUS RENIFORMIS Differ IN SENSITIVITY Towards the HERBICIDE FLUOMETURON. Stetina1, Salliana R. and W.T. Molin2. 1USDA ARS, Crop Genetics Analysis Unit, PO Box 345, Stoneville, MS 38776, 2USDA ARS Crop Production Systems Research 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 issues about introducing herbicide sensitivity from other resistance sources. The analysis objective was to evaluate fourteen sources of reniform nematode resistance for their reaction to fluometuron in 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 were planted on best of a mixture of sandy loam soil and sand (three:1 by volume) in ten cm square pots. Fluometuron added to one hundred cm3 extra soil mix (1:1, sandy loam:sand) at rates of 0, 0.34, 0.67, 1.