Conversion of SO²⁻₄‐S and Changes in Glucosinolate Content in Leaves of Rape Seedlings Transplanted

Abstract

The conversion of SO2‐4 ‐S and changes in content of S in various constituents in leaves of rape seedlings transplanted were investigated by using (NH4)235SO4 as a tracer to exploit formation and accumulation of glucosinolates in oilseed rape. Seedlings grown under sandy culture absorbed 35SO2‐4 which was added to the cultural solution and incorporated into amino acids, glucosinolates and proteins rapidly. Distribution of extractable 35S with 70 % methanol in glucosinolates in leaves declined with time from labelling, while those in amino acids rised correspondingly. Per cents of 35S incorporated into bound form in total 35S increased linearly and those of 35S into glucosinolates and amino acids decreased with time within five days from labelling. After that the relative amounts of 3SS in three constituents was basically constant. Content on dry weight basis of labelled glucosinolates and amino acids expressed as μmol S/g.d.w. increased linearly with time from labelling with absorption of 35SO2‐4from soil by the seedlings under soil culture. Compared with seedlings grown under sandy culture, more 35S was incorporated into glucosinolates in leaves of seedlings grown under soil culture.