The first cases of herbicide resistance were reported around 1970. Since then resistance of monoand dicotyledonous weeds to herbicides has become an increasing problem world-wide. In March 2006 the International Survey of Herbicide-Resistant Weeds recorded 305 herbicide-resistant biotypes with 182 weed species – 109 dicotyledonous and 73 monocotyledonous weeds [1]. The relatively steady increas...

Amaranthus tuberculatus is a troublesome weed in corn and soybean production systems in Midwestern USA, due in part to its ability to evolve multiple resistance to key herbicides including 4-hydroxyphenylpyruvate dioxygenase (HPPD). Here we have investigated the mechanism of resistance to mesotrione, an important chemical for managing broadleaf weeds in corn, in a multiple herbicide resistant p...

The genetic basis for susceptibility or nonsusceptibility of plants to viruses is understood poorly. Two selectable tobacco etch virus (TEV) strains were developed for identification of Arabidopsis thaliana mutants with either gain-of-susceptibility or loss-of-susceptibility phenotypes. These strains conferred a conditional-survival phenotype to Arabidopsis based on systemic expression of herbi...

Results are presented from a three gene population genetics and dynamics model of herbicide resistance in annual ryegrass. The models predictions are compared with those of other one and two gene resistance models to validate the modelling approach which will ultimately be used to develop a five-gene herbicide resistance model. The importance of initial gene frequencies for resistance in unsele...

37 Introduction 38 Materials and methods 40 Results 45 Discussion 56 Literature cited 60 IV. SUMMARY AND CONCLUSION 63

We studied the effects of different media for callus induction and differentiation, and pre-culture period of immature wheat embryo culture on biolistic transformation efficiency for including antifreeze gene KN2 and bar conferring resistance to the herbicide bialaphos. The percentage of plantlets generated from induction and differentiation media without Cu2+ was lower than those cultured on d...