Utilisation of stored lipids during germination in dimorphic seeds of euhalophyte Suaeda salsa.

Utilisation of stored lipids plays an important role in germination of oil seeds. In the present study, key enzyme activity (lipase, isocitrate lyase and malate synthase) in lipid utilisation was determined during germination in dimorphic seeds of euhalophyte Suaeda salsa (L.) Pall. The results revealed that the percentage of germination were highest in intertidal brown seeds, followed by inland brown seeds and then inland black seeds moistened with 0 and 300 mM NaCl during early seed germination. The same trend was found in the activity of three enzymes and soluble sugar content when seeds were moistened with 0 and 300 mM NaCl for 3 h. Salinity reduced the activity of three enzymes in inland brown and black seeds in the initial 3 h, except that salinity had no adverse effect on isocitrate lyase activity of brown seeds. Salinity had no adverse effect on three enzymes in inland brown and black seeds in the initial 30 h, except that it decreased malate synthase activity of black seeds. Salinity had no effect on three enzymes in intertidal brown seeds in the initial 3 h and 30 h. In conclusion, high activity of these enzymes in brown seeds may play an important role in utilisation of stored lipids during their rapid seed germination. Suaeda salsa is an economically important euhalophyte because its seed oil is edible and rich in unsaturated fatty acids. Compared with black seeds, certain enzymes in the glyoxylate cycle in brown seeds play a more important role in the utilisation of stored lipids to provide soluble sugar during their rapid seed germination. This work provides new insights to aid understanding of the adaptation of dimorphic seeds to harsh saline environments. [ABSTRACT FROM AUTHOR]