Is dormancy breaking of potato tubers the reverse of tuber initiation?

Abstract

SummaryTuber formation is a well orchestrated physiological event that involves many metabolic changes. Dormancy gradually develops in potato tubers from the moment cell division in the stolon tip has stopped and the tuber starts to develop. Dormancy breakage may be the reverse of dormancy initiation suggesting that there may be similarities between tuber induction and dormancy development.Based on a literature review it is concluded that, when comparing tuber induction and the breaking of dormancy, hormonal activities are only partly reversed, whereas carbohydrates and enzyme activities might be reversed.For more definite conclusions more research should be done to assess precisely the moment of dormancy breaking. Moreover. measurements on events associated with tuber induction and dormancy breaking should be carried out using the same techniques and the same material.Molecular genetic analyses may provide well-defined markers for the timing of breaking of dormancy.

Regulation of potato tuber sprouting

“…Since tuber dormancy is established during tuber formation, it is not surprising that factors influencing tuberisation such as day length, temperature, nutrient and water supply also affect dormancy and sprouting (summarised in Jackson 1999; Claassens and Vreugdenhil 2000;Suttle 2007). Early work reported that potatoes cultivated under short days have a shorter dormancy period than those grown under long-day conditions (Emilsson 1949; reviewed by Claassens and Vreugdenhil 2000). Besides day length, temperature has a strong impact on tuber development.…”

“…Other post-harvest conditions such as humidity and the composition of the atmosphere also impair dormancy (see Wiltshire and Cobb 1996;Claassens and Vreugdenhil 2000;Suttle 2007). …”

“…Coincident with tuber development, meristematic activity in the stolon apex and the nodes ceases completely and the tuber enters a period of dormancy (Burton 1989;Xu et al 1998;Claassens and Vreugdenhil 2000). Thus, inception of dormancy largely parallels tuber enlargement (Fernie and Willmitzer 2001).…”

Expression of an Escherichia coli phosphoglucomutase in potato (Solanum tuberosum L.) results in minor changes in tuber metabolism and a considerable delay in tuber sprouting

“…Asterisk denotes values significantly different from the wild type control lower in the phosphoglucomutase overexpressing lines. Whilst a major role in the breaking of dormancy is clearly played by hormones with evidence being presented for the involvement of gibberellins (Carrera et al 2000), abscisic acid (Claassens and Vreugdenhil 2000), cytokinins (Galis et al 1995) and ethylene (Claassens and Vreugdenhil 2000), evidence is beginning to accumulate for a parallel role of carbohydrate metabolism. The most compelling, albeit surprising, result was observed when analysing transgenic plants ectopically expressing a bacterial pyrophosophatase.…”

The effect of the time and mode of application of gibberellic acid on the growth and yield of potato plants derived from true potato seed

“…The fact that single applications of GA 3 increase vegetative growth without essentially affecting yield indicates that the inhibitory effects of GA 3 on tuberisation relate to temporary changes in enzymes involved in carbohydrate metabolism. 17 On the other hand, the reduction in mean tuber yield following repeated applications of GA 3 (Table 6) apparently relates not only to a reduction in photosynthesis resulting from the lower chlorophyll content of leaves (Table 5) but also to the increased utilisation of sugars for vegetative growth at the expense of starch accumulation in the tubers, 8 thus increasing the dry matter content of the shoots but decreasing that of the tubers. 18 However, other mechanisms may also be involved, since GA 3 application has also been reported to inhibit adenosine-5-diphosphoglucose pyrophosphorylase (AGP-ase) activity in developing tubers, with a concomitant reduction in starch accumulation.…”