SCREENING TIMOTHY GENOTYPES FOR NITRATE REDUCTASE-ACTIVITY USING AN ELISA TECHNIQUE

Timothy (Phleum pratense L.) is the most cultivated forage crop in Eas tern Canada. Like most perennial grasses, ample amounts of nitrogen ar e needed to obtain adequate yields. A selection program to reduce the nitrogen requirements of timothy and improve its nitrogen use efficien cy could be undertaken if a suitable method were developed to screen l arge plant populations and identify genotypes with high nitrate reduct ase (NaR) activity. An enzyme-linked immunosorbent assay (ELISA) using anti-barley (Hordeum vulgare L.) NaR immunoglobulin has been develope d. It has been used to evaluate genetic variability for NaR activity i n two timothy cultivars. Using the ELISA procedure, no significant dif ferences in NaR activity were detected between the two cultivars. Howe ver, significant differences were observed between randomly selected g enotypes within one of the two cultivars. The ELISA procedure repeated ly and accurately detected very small amounts of NaR activity. This pr ocedure could enable the screening of large populations of timothy or other forage grasses for selection of genotypes with high NaR activity . The presence of genetic variability for NaR activity in timothy coul d be exploited in a selection program.