Dormancy and sprouting

Abstract

This chapter reviews the internal factors that accompany and possibly regulate dormancy progression and early sprout growth. The existence of dormancy in primitive Archaean phyla suggests that dormancy was a very early adaptation to environmental extremes. Plant dormancy has been further subdivided into three distinct (but often overlapping) types: endodormancy, paradormancy, and ecodormancy. In endodormancy, a meristem is arrested by physiological factors arising from within the affected structure; in paradormancy, a meristem is arrested by external physiological factors; and in ecodormancy, a meristem is arrested by external environmental factors. During their life-cycle, potato tubers can exhibit all three types of dormancy. Tuber dormancy is unlike that of other plant meristems in that there are no specific environmental cues required for dormancy exit. Much has been learned about the effects of tuber dormancy status on gene expression, protein levels, enzyme activities, and hormone content. In this scenario, dormancy exit would occur as a result of a progressive decline in one or more inhibitory factor(s) or the gradual accumulation of growth-promoting factor(s). The application of molecular genetics and biotechnology to dormancy research will undoubtedly reveal new insights into dormancy-control mechanisms. Regardless of the approaches taken, new information concerning the internal processes controlling potato tuber sprouting will result in improved storage technologies, enhanced market and nutritional value, and reduced post-harvest losses due to physiological and pathogen-induced deterioration. © 2007 Elsevier B.V. All rights reserved.