GLUCOSINOLATE METABOLISM IN ZYGOTIC AND MICROSPORE-DERIVED EMBRYOS OF BRASSICA-NAPUS L

Microspore-derived embryos of Brassica napus L. cultured in vitro fail to accumulate detectable levels of glucosinolates until they are placed in a germination medium that supports true shoot and root formation. The resulting induction of glucosinolate accumulation is restricted initially to indole derivatives, but the pattern then becomes very similar to that observed in zygotic seedlings. The induction of glucosinolate accumulation in cultured microspore-derived embryos results specifically from reduction of the osmotic potential in the embryo environment. The failure of early-stage microspore-derived embryos to accumulate glucosinolates is not entirely due to a lack of biosynthetic capability, since labelled tryptophan is incorporated into indole glucosinolate derivatives in these embryos. Methionine, on the other hand, is not incorporated into alkenyl glucosinolates at this stage.