Growth competence develops independently of cell division: uncoupling dormancy and cell cycle in grapevine buds
Abstract
Background and Aim: Winter chilling has long been considered the primary driver of bud dormancy release in woody perennials. However, the cellular mechanisms underlying dormancy transitions remain poorly understood. This study aimed to investigate the relationship between dormancy depth, cell cycle activity and cellular ultrastructure in grapevine buds across the dormancy cycle.
Methods: Bud dormancy progression in single-node explants of Vitis vinifera cv. ‘Cabernet Sauvignon’ was monitored from early autumn dormancy to the end of winter. Dormancy depth was quantified as the time to 50 % bud burst under forcing conditions. Cell cycle status was assessed using quantitative flow cytometry, while the cellular ultrastructure of the shoot apical meristem was examined by transmission electron microscopy.
Key Results: Dormancy depth declined dramatically from over 280 d in early autumn to ∼50 d in late autumn, despite negligible chilling exposure during this period. Following chilling exposure in winter, the depth of dormancy declined to ∼20 d. Strikingly, flow cytometry revealed that the majority of cells remained arrested in the G1 phase of mitosis throughout this period, regardless of dormancy depth, supported by ultrastructural analysis of the shoot apical meristem. Starch grains were abundant in both deeply dormant pre-winter buds (no chilling) and winter buds (with chilling), indicating that starch dynamics may be regulated independently of both dormancy status and chilling exposure. These findings demonstrate temporal uncoupling of dormancy release from cell cycle reactivation, challenging assumptions that dormancy release is directly linked to both chilling and cell cycle activation.
Conclusions: Our results establish that in grapevine the transition to growth competence occurs independently of detectable cell division and can precede significant winter chilling accumulation. This work provides new insights into the cellular basis of dormancy regulation in woody perennials and establishes a methodological framework for dissecting this relationship in other species.
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BibTeX
@article{hermawaty2026growth,
title = {{Growth competence develops independently of cell division: uncoupling dormancy and cell cycle in grapevine buds}},
author = {Dina Hermawaty and Peta L Clode and John A Considine and Santiago Signorelli and Michael J Considine},
journal = {Annals of Botany},
year = {2026},
month = jul,
doi = {10.1093/aob/mcag218},
url = {https://doi.org/10.1093/aob/mcag218},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Growth competence develops independently of cell division: uncoupling dormancy and cell cycle in grapevine buds
AU - Dina Hermawaty
AU - Peta L Clode
AU - John A Considine
AU - Santiago Signorelli
AU - Michael J Considine
PY - 2026
DA - 2026/07/18
JO - Annals of Botany
DO - 10.1093/aob/mcag218
UR - https://doi.org/10.1093/aob/mcag218
AB - Background and Aim: Winter chilling has long been considered the primary driver of bud dormancy release in woody perennials. However, the cellular mechanisms underlying dormancy transitions remain poorly understood. This study aimed to investigate the relationship between dormancy depth, cell cycle activity and cellular ultrastructure in grapevine buds across the dormancy cycle. Methods: Bud dormancy progression in single-node explants of Vitis vinifera cv. ‘Cabernet Sauvignon’ was monitored from early autumn dormancy to the end of winter. Dormancy depth was quantified as the time to 50 % bud burst under forcing conditions. Cell cycle status was assessed using quantitative flow cytometry, while the cellular ultrastructure of the shoot apical meristem was examined by transmission electron microscopy. Key Results: Dormancy depth declined dramatically from over 280 d in early autumn to ∼50 d in late autumn, despite negligible chilling exposure during this period. Following chilling exposure in winter, the depth of dormancy declined to ∼20 d. Strikingly, flow cytometry revealed that the majority of cells remained arrested in the G1 phase of mitosis throughout this period, regardless of dormancy depth, supported by ultrastructural analysis of the shoot apical meristem. Starch grains were abundant in both deeply dormant pre-winter buds (no chilling) and winter buds (with chilling), indicating that starch dynamics may be regulated independently of both dormancy status and chilling exposure. These findings demonstrate temporal uncoupling of dormancy release from cell cycle reactivation, challenging assumptions that dormancy release is directly linked to both chilling and cell cycle activation. Conclusions: Our results establish that in grapevine the transition to growth competence occurs independently of detectable cell division and can precede significant winter chilling accumulation. This work provides new insights into the cellular basis of dormancy regulation in woody perennials and establishes a methodological framework for dissecting this relationship in other species.
SN - 0305-7364
SN - 1095-8290
ER -