Changes in Growth Regulator and Carbohydrate Levels in Roots and Shoot Tips of Cornus sericea during Cold Storage and Emergence from Dormancy

Abstract

<jats:p><jats:italic>Cornus sericea</jats:italic> L. rooted cuttings were held in cold storage for 60 days and then transferred to a growth chamber in hydroponic culture. Roots and shoot tips were sampled during storage and through resumption of vegetative growth. Samples were analyzed for abscisic acid (ABA), indole-3-acetic acid (IAA), zeatin, zeatin riboside, glucose, fructose, sucrose, and starch. Budbreak was associated with increasing levels of the cytokinins and IAA, and decreasing levels of sucrose and starch in the shoot tips. Regeneration of new roots was preceded by an increase in the cytokinins and IAA, and a decrease in ABA in roots. Root sucrose increased nearly two times 1 week after budbreak and starch content generally decreased throughout the experiment. The results agree, in general, with previous reports indicating decreasing levels of ABA and increasing levels of cytokinins to be associated with root regeneration and budbreak. They also indicate that, of the four carbohydrates studied, sucrose levels changed most dramatically during the root regeneration and budbreak processes.</jats:p>

Hormonal Control of Dormancy

“…IAA levels remained low in dormant buds, tubers, seeds, and micropropagated strawberry shoots and increased during bud break and sprouting (Nagar, 1995;Sukhova et al, 1993;Cappiello and Kling, 1994;Borkowska and Michalczuk, 2000) which may suggest that auxins are also involved in other than apical dominance types of dormancy.…”