2012 Annual Report
Identify, characterize, and move genes for resistance to Meloidogyne spp. into cotton and peanut germplasm and cultivars. Utilization, mechanisms, and interactions of classical and contemporary methods in integrated nematode management. Enhance native and introduced antagonists of nematodes in cotton and peanut cropping systems.
Considerable progress was made in identifying and improving resistance to nematodes in cotton and peanut, and developing integrated strategies for management of plant-parasitic nematodes.
DNA markers associated with nematode resistance genes will make selection of resistant plants faster and more accurate. In cotton, a simple sequence marker CIR316 linked to root-knot nematode resistance was found. In subsequent research, we more precisely defined the location of one resistance gene to a 3.6 cM region flanked by two DNA markers. There are two genes involved in nematode resistance in cotton. We have separated these genes into separate plants and will begin to study the individual effects of the two genes. In peanut, a genetic marker (197/909) linked with resistance to root-knot nematodes was identified. A peanut cultivar (Tifguard), which has a high level of resistance to both the tomato spotted wilt virus (TSWV) and root-knot nematodes, was developed and publicly released. This cultivar will enable growers to eliminate the use of nematicides, thus saving up to $100 per acre. We created a cotton germplasm line with a high level of resistance to root-knot nematodes, but which has yield and fiber quality similar to modern cotton varieties. This germplasm will be a valuable resource for cotton breeders in developing cultivars with resistance to root-knot nematodes.
We showed that tropical spiderwort, an invasive weed, supported significant levels of reproduction by two wide-spread species of root-knot nematodes, the reniform nematode, and a major peanut disease (southern stem rot). Therefore, controlling tropical spiderwort is critical when managing nematodes and diseases with crop rotation. Cereal rye produces compounds that are toxic to nematodes; however, incorporating rye as a green manure did not suppress populations of root-knot nematodes or improve cotton yield. In cotton, we showed that root-knot nematodes can affect fiber quality by reducing fiber length, and the detrimental effects of nematode parasitism and drought stress are typically additive rather than synergistic. Therefore, nematodes must be managed to prevent loss of fiber quality, and irrigation does not compensate for nematode-induced yield loss. We showed that abundance of the nematode-parasitic bacterium Pasteuria penetrans was greater when peanut was rotated with another host (eggplant) for root-knot nematodes than when peanut was rotated with a nonhost. Our research indicated that root-knot nematodes could become resistant to this parasitic bacterium and that this could pose a problem for commercial products containing Pasteuria penetrans. We showed that use of the fumigant nematicide 1,3-dichloropropene in cotton reduced natural biological suppression of plant-parasitic nematodes (in part due to predatory nematodes), but that this negative effect did not persist into the next spring.
Aryal, S.K., Davis, R.F., Stevenson, K.L., Timper, P., Ji, P. 2011. Influence of infection of cotton by Rotylenchulus reniformis and Meloidogyne incognita on the production of enzymes involved in systemic acquired resistance. Journal of Nematology. 43(3-4):152-159.
Aryal, S.K., Davis, R.F., Stevenson, K.L., Timper, P., Ji, P. 2011. Induction of systemic acquired resistance by Rotylenchulus reniformis and Meloidogyne incognita in cotton following separate and concomitant inoculations. Journal of Nematology. 43(3-4):160-165.
Timper, P., Davis, R.F., Jagdale, G., Herbert, J. 2012. Resiliency of a nematode community and suppressive service to tillage and nematicide application. Applied Soil Ecology. 59:48-59.
Ortiz, B.V., Perry, C., Sullivan, D., Lu, P., Kemerait, R., Davis, R.F., Smith, A., Vellidis, G., Nichols, R. 2012. Variable rate application of nematicides on cotton fields: A promising site-specific management strategy. Journal of Nematology. 44(1):31-39.
Holbrook Jr, C.C., Dong, W., Timper, P., Culbreath, A.K., Kvien, C.K. 2012. Registration of peanut germplasm line TifGP-2, a nematode susceptible sister line of 'Tifguard'. Journal of Plant Registrations. 6:208-211.