Isogenic analysis of glufosinate-ammonium tolerant and susceptible summer rape lines

Abstract

The development of transgenic Brassica napus L., tolerant to non-selective broad-spectrum herbicides, such as glyphosate and glufosinate-ammonium, could provide canola growers with an efficient method of weed control. The objective of this study was to determine whether the phosphinothricin-acetyl transferase (pat) gene which imparts tolerance to glufosinate-ammonium, affects the growth, development, productivity, and seed quality of B. napus canola. Nineteen glufosinate-ammonium tolerant and susceptible isogenic pairs of the B. napus cv. Westar, derived from independent transformation events, were evaluated in two field trials in each of 2 yr in Saskatchewan. Tolerant lines of six isogenic pairs were similar in their agronomic performance and seed quality to their susceptible counterparts indicating that glufosinate-ammonium tolerant B. napus can be developed that is not negatively affected in yield and quality by the presence of the pat gene. Several tolerant lines exhibited delayed flowering and maturity, lower biomass and seed yields, and lower oil and protein contents indicating positional effects of the pat gene on performance. Tolerant lines carrying two inserts of the pat gene were more negatively affected in their growth and development than single insert tolerant lines. The results of this study indicate that it would be beneficial to generate a number of different transformants and select elite transgenic lines which are not affected in their performance by the presence of the pat gene for use in cultivar development. Key words: Brassica napus, glufosinate-ammonium tolerance, isogenic analysis