Oilseed rape has been modi®ed extensively by conventional breeding for the production of varieties useful for human consumption (blended vegetable oil and margarine) and industrial processes (rubber additives and high-temperature lubricants).

The effects of the fungicides, flutriafol, triadimenol and an experimental compound (2,2‐dimethyl‐3‐(2‐chlorobenzyl)‐4‐(1,2,4‐triazol‐1‐yl)‐butan‐3‐ol), on conidial viability and lipid composition, have been examined in strains of barley and wheat powdery mildew (Erysiphe graminis DC.) sensitive or resistant to DMI fungicides. In the absence of fungicides, these strains had the same sterol composition, regardless of their sensitivity to DMIs. Following treatment with the compounds, conidia contained eburicol and obtusifoliol, indicating inhibition of the 14α‐demethylase. There was also an accumulation of episterol, suggesting that introduction of the 5,6‐double bond was also inhibited. The changes in sterol composition induced by the fungicides were small. The fatty acid composition of sensitive and resistant strains was also determined. Triadimenol treatment caused an increase in the saturation of C22 and C24 acids in all strains examined, but changes were not correlated with the biological effects of the fungicide. No single mechanism of resistance emerged from the study.

Glyphosate and glufosinate-ammonium herbicide tolerance traits were combined into both winter and spring lines of Brassica napus L. This allowed the study of possible interactions between these transgenes in two genetic backgrounds when treated with a variety of herbicides. Selective herbicides that are commonly used within Brassica crops showed no adverse effects on the transgenic plants or their null controls. Lines containing both glyphosate and glufosinate transgenes remained tolerant to their respective herbicides, regardless of the presence of the second tolerance transgene. Lines containing only a single transgene retained tolerance to the encoded trait and did not show cross-tolerance to the second. Null lines were killed by either herbicide. All plant lines, regardless of their transgene content, were found to be equally susceptible to three herbicides (paraquat, metsulfuronmethyl and mecoprop), commonly used to remove volunteer B napus from succeeding crops and set-a-side land.

No abstract

No abstract