|Bell, Alois - Al|
|Meredith Jr, William|
|Stetina, Salliana - Sally|
Submitted to: World Cotton Research Conference Proceedings
Publication Type: Review Article
Publication Acceptance Date: 7/30/2007
Publication Date: 8/1/2008
Citation: Robinson, A.F., Augudelo, P., Avila, C.A., Bell, A.A., Callahan, F.E., Cook, C.G., Dighe, N.D., Gutierrez, O.A., Hayes, R.W., Jenkins, J.N., Johnson, J.T., Kantety, R., Lawrence, G.W., Lawrence, K.S., Mangineni, L., Mccarty, J.C., Menz, M.A., Meredith, W.A., Nichols, R.L., Robbins, R.T., Sacks, E., Scheffler, B., Sciumbato, G.L., Smith, C.W., Starr, J.L., Stelly, D.M., Stetina, S.R., Stewart, J.M., Thaxton, P.M., Wallace, T.P., Weaver, D.B., Wubben, M.J., Young, L.D. 2008. Development of reniform nematode resistance in Upland cotton. In: Proceedings of the World Cotton Research Conference-4, September 10-14, 2007, Lubbock, Texas. 2008 CDROM.
Interpretive Summary: There are many kinds of microscopic worms called nematodes that feed on the roots of cotton and other crops, debilitating the plants and markedly decreasing yields. The direct losses to U.S. cotton farmers caused by nematodes each year are estimated by the National Cotton Council to exceed $300,000,000. The reniform nematode is one of the most important nematodes on cotton in the U.S. All varieties of cotton available to farmers are susceptible to this nematode but there are wild species of cotton that have been found to be resistant when they are grown in greenhouse pots containing the nematode. It is theoretically possible to make genetic crosses between resistant wild species and agronomic cotton to develop resistant varieties for farmers. This review discusses progress being made toward the development of cotton breeding lines that are resistant to the reniform nematode at three Agricultural Research Service Laboratories and several universities, by transferring genes from such plants into cotton. Most projects are also concurrently developing molecular markers for resistance genes, which will enable cotton seed companies to use these resistant but not fully agronomic breeding lines, in order to rapidly and cost effectively develop highly agronomic resistant varieties for sale to farmers. Simultaneous development of varieties with resistance from different types of wild plants is expected to provide cotton farmers with a broad arsenal of tools for combating nematodes, should nematodes in some fields acquire the ability to reproduce on and damage one or more of the types of resistant varieties being developed.
Technical Abstract: The purpose of this review is to assess development of resistance to the reniform nematode (Rotylenchulus reniformis) in Upland Cotton (Gossypium hirsutum). Cotton cultivars with reniform nematode resistance are needed. The development of resistant cultivars appears possible but presents a significant research challenge, primarily for two reasons. First, the best sources of resistance occur within diploid species that are genetically incompatible with Upland Cotton. Second, without molecular markers, reniform nematode resistance can only be detected by lengthy nematode reproduction assays. Thus, it is absolutely essential to discover a molecular marker for each resistance source to provide seed companies with a tool for monitoring inheritance of resistance as they proceed through the cultivar development process. Simultaneous introgression of resistance from sources within several species is the wisest approach, because incomplete expression or incorporation of closely linked deleterious genes is possible in all cases, and in each case an investment of many years is required before success can be gauged by field testing of elite resistant breeding lines at multiple sites. Currently, researchers at more than a dozen USDA laboratories and state supported universities in the United States have projects targeted at the introgression of reniform nematode resistance into agronomic Upland Cotton, from primitive tetraploid accessions of Gossypium hirsutum and G. barbadense, and diploid G. arboreum, and G. longicalyx. This task will take many years to complete. However, significant progress has been made toward developing cultivars carrying resistance from each source, and the first resistant cultivars could appear within three years, with committed follow through by commercial planting seed companies.