Interactive effect of sulphur and nitrogen on lipid accumulation, acetyl-CoA concentration and acetyl-CoA carboxylase activity in developing seeds of oilseed crops (Brassicacampestris L. and Erucasativa Mill.)

Field experiments were conducted to determine the interactive effect of sulphur (S) and nitrogen (N) on lipid accumulation, acetyl-CoA concentration and acetyl-CoA carboxylase activity in the developing seeds of oilseed crops viz. rapeseed (Brassica campestris L. cv. Pusa Gold) and taramira (Eruca sativa Mill.) differing in their lipid content. Two combinations of S and N (in kg/ha): 0S + 100N (−S+N) and 40S + 100N (+S+N) were used. The period between 10 to 40 days after flowering was observed as the active period of lipid accumulation in the seeds of both the genotypes. The accumulation of the lipid was preceded by a marked rise in acetyl-CoA carboxylase activity and acetyl-CoA concentration, which declined rapidly when lipid accumulation reached a plateau. Total sugar content decreased, while protein content increased during the active period of lipid accumulation in both the genotypes. The application of sulphur and nitrogen together significantly (P < 0.05) enhanced the lipid accumulation in both the genotypes at all the growth stages. The increase in the lipid content was 4-214% in rapeseed and 12-227% in taramira with +S+N treatment over −S+N treatment. The application of sulphur and nitrogen together (+S+N) also increased acetyl-CoA concentration, acetyl-CoA carboxylase activity, soluble protein, and sugar content in the developing seeds of both the genotypes. It is suggested that the increase in the lipid content with combined application of S and N may be associated with increased acetyl-CoA carboxylase activity through the enhancement of acetyl-CoA concentration. Further, the increased sugar content because of combined application of S and N provided enough carbon source and energy for lipid biosynthesis.