GLUCOSINOLATE CHANGES IN DEVELOPING PODS OF SINGLE AND DOUBLE LOW VARIETIES OF AUTUMN-SOWN OILSEED RAPE (BRASSICA-NAPUS)

Single and double low varieties of oilseed rape were grown in the 1987/88 and 1988/89 seasons to study changes in the concentrations of total and individual glucosinolates within pods during development. Total glucosinolate concentration in seeds of all varieties increased during development when expressed on a fresh weight basis. The levels of the major alkenyl glucosinolates present in the seed; 2-hydroxy-3-butenyl, 3-butenyl and 4-pentenyl had been reduced in the transition from single to double low varieties. The major indole glucosinolates in the seed, 4-hydroxy-3-indolylmethyl and 3-indolylmethyl were present in the same amounts in single and double low varieties but in the latter represented a greater proportion of the total seed glucosinolate content. A decline in the total glucosinolate concentration in the pod walls with time together with the analogous profile of individual glucosinolates in the seeds and pod walls suggests that the pod wall is a major site of seed glucosinolate synthesis. Other plant parts may also have an important role to play in provision of intact glucosinolates or precursors to the pod walls for glucosinolate biosynthesis.