Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 3/1/2006
Publication Date: 3/15/2006
Citation: Rajasekaran, K., Ulloa, M., Hutmacher, R., Cary, J.W., Cleveland, T.E. 2006. Disease resistance in transgenic cottons. In: Proceedings of the National Cotton Council Beltwide Cotton Conference, January 4-6, 2006, San Antonio, Texas. p. 895-903. Interpretive Summary:
Technical Abstract: Transgenic Upland cottons (Gossypium hirsutum L.) expressing the antifungal peptide D4E1 were evaluated for tolerance to Fusarium wilt caused by Fusarium oxysporum f.sp. vasinfectum (FOV) race 1 in a sandy soil field, also infected with root-knot nematodes (Meloidogyne incognita). A transgenic line expressing the uidA (GUS) marker gene only and the original non-transgenic parent cultivar used for transformation were used as controls. The transgenic lines included in this study were shown to be effective against fungal pathogens in vitro and in planta in laboratory and greenhouse studies. Commercial Acala (G. hirsutum) and Pima (G. barbadense) cultivars were also planted alongside for comparison. Entries were planted in a Randomized Complete Block design with four replications on 10 m long plots and evaluated for plant survival, foliage symptoms, vascular root staining due to FOV in the presence of root-knot nematode and agronomic traits. No significant differences were observed in all of the above evaluated traits between transgenic and control cottons, except for plant survival. Transgenic lines NO-373 and NO-358 showed a higher number of plant survival and stand during the season. Lack of significant differences in this field trial is partly due to the fact that the evaluation of hirsutum lines for FOV tolerance is much more complex possibly due to the following reasons - Upland cultivars may have higher levels of resistance, and exhibit a far less genetic variation for resistance among them rendering investigation of FOV symptoms difficult using the disease severity scales as used in this study. On the other hand, resistance for FOV in Pima cottons seems to be more complete at the host plant level. Further large scale evaluations of the transgenic cottons using well defined disease severity scales are needed to assess the full potential regarding tolerance to plant pathogens including FOV.