Ammonia Accumulation as an Index of GlufosinateTolerant Soybean Cell Lines

Selection of soybean (Glycine max L. cv. SJ 4) cell lines tolerant to glufosinate was attempted using cell suspension cultures induced from hypocotyls of young seedlings. The cell suspension was cultured on MS basic medium supplemented with B5 vitamins, 0.3% sucrose, and 10 mg/L NAA. Using a stepwise selection with increasing concentration of herbicide, a soybean line tolerant to 10-7 M glufosinate was obtained through direct selection of diploid cells in the suspension culture. It is referred to as 10-7 M glufosinate-tolerant soybean cell line. Determination of ammonia concentration in the herbicide-treated cells indicated that the normal (nontolerant) cells accumulated up to 15-fold more ammonia than the tolerant cells. This information suggested that lower ammonia accumulation in the tolerant cells can be used as an indicator to select for glufosinate-tolerant soybean cell lines.