2009 Annual Report
Efforts to incorporate useful levels of resistance to reniform nematode into upland cotton continue. Breeding efforts to transfer moderate levels of resistance from less-adapted day-neutral Texas race stock lines into commercially desirable lines resulted in several promising lines. Seeds of these lines are being increased to allow evaluation in replicated tests next year. Work to transfer genes for resistance to reniform nematode into upland cotton from its distant relatives resulted in development of resistant germplasm with associated molecular markers, as described in the Accomplishments section of this report. In addition, resistance from the related species Gossypium arboreum was transferred into upland cotton. Genetic studies and marker development for this source of resistance are underway. Progeny from additional crosses are being evaluated and distant relatives of cotton are being screened to identify novel sources of resistance for future work.
Work to evaluate the impact of resistant cotton lines on nematode population development continues. A multi-year experiment evaluating the impact of selected day-neutral Texas race stock lines on reniform nematode population levels in the soil is in its third year. Due to variability in nematode densities in plots in the previous two years, a fourth year of the test will likely be required. A separate study evaluating the ability of selected nematode sub-populations to reproduce on the cotton lines is likely to be delayed for at least one year because sufficient progress has not been made in selecting reniform nematode sub-populations that reproduce on each of the moderately-resistant cotton lines in the study.
Research to identify chemical methods that can minimize losses to reniform nematode continues. Field trials are in progress to determine the effectiveness of newly registered and experimental nematicide seed treatment combinations such as Aeris and Avicta as compared to Temik, which has been used for many years. Results collected to date suggest that Temik is more effective at controlling reniform nematode than the newer products, with higher rates being more effective but sometimes causing toxicity symptoms on plants.
Some research is being done in cooperation with scientists at other institutions: Mississippi State University (Specific Cooperative Agreement, subordinate project 6402-22000-005-01S), Pasteuria Bioscience (Specific Cooperative Agreement, subordinate project 6402-22000-005-04S), and Texas A&M University (Nonfunded Cooperative Agreement, subordinate project 6402-22000-005-03N). Separate reports summarize work completed under these agreements.
Stetina, S.R., Sciumbato, G.L., Young, L.D., Blessitt, J.A. 2009. Cotton Cultivars Evaluated for Tolerance to Reniform Nematode. Plant Health Progress. doi:10.1094/PHP-2009-0312-01-RS
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.
Robinson, A.F., Westphal, A., Overstreet, C., Padgett, G., Greenberg, S.M., Stetina, S.R., Wheeler, T.A. 2008. Detection of suppressiveness against Rotylenchulus reniformis in soil from cotton (Gossypium hirsutum) fields in Texas and Louisiana. Journal of Nematology. 40(1):35-38.
Kantartzi, S.K., Ulloa, M., Sacks, E., Stewart, J.McD. 2009. Assessing genetic diversity in Gossypium arboreum L. cultivars using genomic and EST-derived microsatellites. Genetica 136: 141-147.