Submitted to: Potato Association of America Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 3/31/2003
Publication Date: 8/4/2003
Citation: SUTTLE, J.C. REGULATION OF TUBER DORMANCY. 87th ANNUAL MEETING OF THE POTATO ASSOCIATION OF AMERICA. 2003. P. 26. ABSTRACT NO. S3.
Technical Abstract: At harvest and for an indeterminate time thereafter, potato tubers are dormant and will not sprout. The length of dormancy is dependent on both tuber genotype and environmental conditions during tuber development and storage. Uncontrolled postharvest sprouting results in numerous physiological changes that adversely affect tuber quality and market value. Improvements in postharvest sprout control technology is hindered by ignorance of the biological bases of tuber dormancy. Tuber dormancy is characterized by low rates of many metabolic processes and by the near-complete absence of bud or eye meristematic activity. Non-dividing cells in tuber bud meristems are arrested in the G-1 phase of the cell cycle prior to DNA replication. The resumption of cell division at the end of dormancy is accompanied by numerous changes in chromatin composition, gene expression and increased DNA synthesis. Although widely believed to play a role in tuber dormancy, the exact roles of endogenous plant hormones in tuber dormancy control are only now being experimentally verified. The sustained synthesis and action of abscisic acid (ABA) are required for both the initiation and maintenance of tuber dormancy. In addition, ethylene action is required during the earliest stages of dormancy inception. Although both ABA levels and ethylene production decline during storage, these declines are not essential for dormancy termination. Increases in both cytokinins and gibberellins occur as dormancy weakens and sprouting commences. Recent evidence suggests that only the increase in cytokinin content is required for the termination of tuber dormancy; while the increase in gibberellin content is important in subsequent sprout growth. Manipulation of plant hormone systems offers unique possibilities for postharvest sprout control. For example, treatment of dormant tubers with stable cytokinin analogs rapidly terminates tuber dormancy and may be of use in the seed industry. Conversely, manipulation of ABA and other dormancy-inducing hormones may offer novel methods to prevent postharvest sprouting.