An ATP-synthesizing system in seeds.

Area of Science:

• Biochemistry
• Plant Physiology

Background:

• Adenosine triphosphate (ATP) is the primary energy currency in cells.
• Understanding ATP synthesis in seeds is crucial for comprehending germination and early plant development.

Purpose of the Study:

• To develop and characterize a semi-in vitro system for ATP synthesis using seed powder.
• To investigate the factors influencing ATP synthesis in seeds and its potential role during germination.

Main Methods:

• Development of a semi-in vitro system utilizing onion seed powder.
• Assay of ATP synthesis rates under varying substrate concentrations (AMP, PEP, orthophosphate), pH, and ionic conditions (K+, Mg2+, Li+, Na+, Ca2+).
• Comparison of in vitro ATP synthesis capacity with endogenous ATP levels during seed imbibition.

Main Results:

• The system requires AMP, phosphoenolpyruvate (PEP), and orthophosphate, with optimal activity at pH 6.4.
• ATP synthesis rate is dependent on seed powder concentration and exhibits linearity with time up to 40 minutes.
• The system is sensitive to specific cation concentrations, with optimal stimulation by low K+ and Mg2+.
• Maximal ATP synthesis rate in dry onion seeds is approximately 5 pmol min(-1) mg seed powder(-1).
• Activity increases significantly during imbibition, potentially providing 100 times more ATP than found in imbibed seeds during germination.
• The system is functional across ten different seed types.

Conclusions:

• A robust semi-in vitro system for seed ATP synthesis has been established.
• This system provides insights into the energy metabolism of seeds, particularly during germination.
• The findings suggest that seed-based ATP synthesis plays a vital role in providing energy for germination.