ATP synthesis and utilization in the early stage of seed germination in relation to seed dormancy and quality

Abstract

In addition to the possible activities of the well‐known biochemical cycles, the ATP‐synthesizing system in dry seeds consists of a pathway which oxidizes malate and provides phosphoenolpyruvate (PEP). This system seems to be regulated primarily by the malate dehydrogenase (EC 1.1.1.37) activity, which together with the PEP carboxylase (EC 4.1.1.38) provides PEP and NADH. This latter compound may play a role as the “sparker” for the whole cycle. Breaking seed dormancy does not seem to be related to the rate of ATP synthesis per se but to facilitate enzyme‐substrate interaction, probably caused by intracellular compartment‐fusion. The compartmentation process is probably a result of the seed ripening and maturation functions. The ATP accumulated at the early stage of seed germination is a result of ATP synthesis and ATP utilization. Thus, ATP accumulation may result from a high rate of synthesis (high quality seeds) or from a low utilization ability (low‐quality seeds). Also, since 95% of the synthesized ATP is utilized concomitantly with its synthesis, the accumulated amount is relatively insignificant and does not indicate seed quality. This conclusion is also supported by many experimental results in which no such correlation was found.