2010 Annual Report 1a.Objectives (from AD-416) The objective of this cooperative research project is to identify interspecific cotton progenies that have been converted from sterile triploids into fertile hexaploids, and to determine which chemical compounds and concentrations are most effective at producing such conversions. In addition, interspecific tetraploid breeding populations will be developed. 1b.Approach (from AD-416) Triploid progenies of Gossypium hirsutum/G. arboreum will be treated with amiprofosmethyl, colchicine, oryzalin, or trifluralin at four concentrations each. Cuttings of each triploid cross will be made and axillary buds treated with the dissolved compounds mixed in a lanolin paste. Controls will include no paste and water-lanolin. The number of self-fertile cuttings per treatment will be recorded. Chromosome counts will be conducted to confirm the ploidy of fertile plants. When tetraploid progeny of the interspecific hybrids are produced, random mated breeding populations will be developed to break up linkage blocks. 3.Progress Report The agreement was established in support of Objective 2 of the in-house project, the goal being to transfer resistance to reniform nematode into upland cotton from distant relatives of cotton. Transferring resistance is difficult, because upland cotton has four sets of chromosomes and the distant relatives of cotton that are resistant to reniform nematode only have two sets of chromosomes. Thus, plants resulting from crosses between the species have three sets of chromosomes and are sterile (unable to produce viable seeds). For the plants to be of use in breeding efforts, fertility must be restored by doubling the number of chromosomes the plants contain using chemical treatments. Previously, plants resulting from crosses between upland cotton and its distant relatives were treated with a variety of chemicals at several concentrations to double the number of chromosomes. After treatment, plants were evaluated to determine whether or not they were able to set bolls with viable seeds. During this reporting period, scientists at Texas A&M completed their evaluation of cuttings from these plants, where chromosome counts were used confirm whether or not the chromosome numbers were in fact successfully doubled. In total, 85 plants were evaluated. Of these, approximately 64% were confirmed to have six sets of chromosomes, indicating that the chemical treatments were successful in doubling the number of chromosomes in the plant. The remaining plants all had three sets of chromosomes, as was expected from a successful cross between cotton and one of its distant relatives. Research activities during this reporting period were monitored by the ADODR through email and telephone communications with the cooperator.