Stability of Gene Expression and Agronomic Performance of a Transgenic Herbicide-Resistant Sugarcane Line in South Africa

Abstract

Sugarcane (Saccharum hybrid) cultivar NCo310 was transformed with the pat gene, which confers resistance to the herbicide Buster (glufosinate ammonium; Bayer CropScience, Monheim am Rhein, Germany). The effect of the expression of this gene on the agronomic performance of a successful transgenic line, 22.2, was investigated. Field testing showed that the pat gene was stably expressed during three rounds of vegetative propagation. Morphological and agronomic characters such as stalk height, diameter, population, fiber, disease resistance, and yield, measured in the first ratoon, were not significantly different in the transgenic line and its untransformed counterpart. Of four weed treatments applied to transformed and untransformed plots, there were two scenarios in which significantly higher yields were observed: (i) untransformed cane treated using the conventional (non‐Buster) herbicide protocol, widely used for weed control in the South African sugar industry, and (ii) transformed cane treated with a conventional preemergence cocktail, followed by two 5‐L ha−1 Buster applications. However, the most economical weed control treatment is dependent on the cost of the herbicide to which resistance has been engineered. Buster currently costs (in South African Rand) ZAR150 (≈US $14.01) L−1 For Buster treatments to be cost effective for commercial growers, the price would have to be considerably lower. However, since hand‐hoeing is deleterious to the cane, small‐scale growers currently controlling weeds manually would find herbicide use an advantage. If they were to adopt transgenic sugarcane, Buster costs would need to be reduced only slightly for them to increase their returns.

Herbicide-tolerant sugarcane (Saccharum officinarum L.) plants: an unconventional method of weed removal

“…Similarly, herbicide-resistant sugarcane was successfully developed by Zambrano et al (2003) and Manickavasagam et al (2004). The stability of gene expression and agronomic performance of a transgenic herbicide-resistant sugarcane was evaluated by Leibbrandt et al (2003). From this study, it was concluded that a glyphosate-tolerant transgene is functional in transgenic sugarcane plants at a level that can tolerate the glyphosate application at a dosage that all the weeds and control plants were unable to survive.…”

Genetic Engineering of Saccharum

“…(Falco et al 2000 ) • bar , CaMV 35S , Agrobacterium , Phosphinothricin (5 mg/l), No fi eld trial, Co 92061 and Co 671 (Manickavasagam et al 2004 ) • pat , Maize Ubi-1 , Biolistic, Glufosinate ammonium, No fi eld trial, NCo 310 (Leibbrandt and Snyman 2003 ) Biotic stress tolerance Insect • Sugarcane stem borer: -cry1A(b) , CaMV 35S / nos , Electroporation, GUS, Field trial, Ja60-5 (Arencibia et al 1997(Arencibia et al , 1999 , maize phopshoenolpyruvate carboxylase promoter and pith promoter, Biolistic, Neomycin, Field trial, SP80-1842 and SP80-3280 (Braga et al 2003 ) -cry1A(c) , Maize Ubi-1 / nos , Biolistic, Geneticin (50 mg/l), No fi eld trial, YT79-177 and ROC16 (Weng et al 2006 ) • Sugarcane canegrub, gna or pinII , Maize Ubi-1 / nos , Biolistic, Geneticin, No fi eld trial, Q117 (Nutt et al 1999 Metabolic engineering for other economically important traits such as enhancing sucrose content and using transgenic sugarcane to produce novel and value-added products represent a more recent era of genetic improvement (Table 11.2 ).…”

Sugarcane Transformation

“…These include the Bt endotoxin gene (17), herbicide resistance (25,28) and SCMV resistance (23). Despite these successes, intellectual property restrictions may limit commercial application of transgenic sugarcane.…”