Mobilisation of carbohydrates during germination of spores ofOnoclea sensibilis L.

Abstract

SynopsisA high percentage of germination ofOnoclea sensibilisL. spores is initiated by a low fluence of red light while imbibed but unirradiated spores exhibit a very low percentage of germination.Onocleaspores contain lipid, protein and sucrose reserves. Sucrose is degraded and starch is synthesised during germination while lipid reserves are mobilised during early gametophytic development. The amount of protein remains constant during both developmental stages. There is very little detectable mobilisation of any of the reserves in the imbibed but ungerminating spores maintained in the dark for up to 18 days. Sucrose degradation and starch synthesis are not interrelated because photoenhanced sucrose degradation can occur without starch synthesis and photoinduction of starch synthesis can occur without sucrose degradation. Evidence is presented to suggest that the mode of action of light in enhancing starch synthesis is to increase the availability of a starch precursor rather than the activities of starch synthesising enzymes. Sucrose may be mobilised after irradiation because it becomes accessible to the sucrose degrading enzymes which are in abundance in the spores.