Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/8/2005
Publication Date: 9/16/2005
Citation: Gilbert, R.A., Gallo-Meagher, M., Comstock, J.C., Miller, J.D., Jain, M., Abouzid, A. 2005. Agronomic evaluation of sugarcane lines transformed for resistance to sugarcane mosaic virus strain E. Crop Science. 45:2060-2067 Interpretive Summary: Transgenic plants of sugarcane with inserts of an untranslatable form of the coat protein gene of sugarcane mosaic virus strain E displayed variability in cane yield and tons sugar per hectare as well as their reaction of sugarcane mosaic. The large variability with a large portion of the individual sugarcane plants having lower yields than source plants clearly indicate that it is necessary to test and eliminate all undesirable transgenic plants prior to selecting a plant for commercial use. The undesirable variability detected in this study indicates that the development of transgenic sugarcane plants may be slow.
Technical Abstract: Genetic transformation of sugarcane (Saccharum spp.) holds promise for increasing yields and disease resistance. However, the tissue culture and transformation process may also produce undesirable field characteristics in transgenic sugarcane not readily identifiable in the laboratory. The primary objective of this study was to evaluate variability in agronomic characteristics and field disease resistance of sugarcane transformed for resistance to sugarcane mosaic virus (SCMV) strain E. One hundred sugarcane plants derived from cultivars CP 84-1198 and CP 80-1827, consisting of four independent virus resistant (VR) lines, were evaluated in two field experiments. Transgenics derived from CP 84-1198 had significantly greater tons of sucrose per hectare (TSH) and significantly lower SCMV disease incidence than those from CP 80-1827 in the plant-cane, first-ratoon and second-ratoon crops. Plants from the VR18 line had significantly greater economic indices than all other lines in plant cane, and lower SCMV disease incidence in all three crops. Phenotypic variation was high in Experiment 1, with tons of cane per hectare (TCH) ranging from 26 - 211 and TSH from 3.2 - 28.9 in the plant-cane crop. Agronomic trait variation decreased with increased selection pressure in Experiment 2, with TCH ranging from 70 - 149 and TSH from 8.5 - 19.0 in plant cane. Based on five crop-years of data, six VR18 plants with greater yields and disease resistance than the non-transformed parental control were identified. The large variability in yield characteristics and disease resistance encountered in this study demonstrates the necessity of thorough field evaluation of transgenic sugarcane while selecting genetically stable and agronomically acceptable material for commercial use.