Identification of germin isoforms in wheat callus

Abstract

Application of auxin causes cells of the wheat embryo to undergo dedifferentiation and form callus tissue. The synthesis of germin isoforms (G, G' and psiG) has been selectively associated with different phases of embryonic development and callus formation. G and G' germin isoforms are found to be associated with germination. psiG is an embryogenesis related germin isoform. It is clearly important to distinguish whether callus induction caused a precocious initiation of embryonic maturation-specific pseudogermin synthesis, or whether it effected a switch in the pattern of protein synthesis; eliciting accumulation of the normally germination-related germin proteins. To distinguish between these alternatives, it is necessary to identify the germin protein isoforms accumulated during callus formation. Following the electrophoretic separation of callus protein extracts, the position of germin isomers were detected by Western-blotting. The immunoreactive polypeptides accumulating in callus tissue were determined to be exclusively germin, rather than psiG.