Contrasting seasonal dynamics of dormancy, respiratory metabolism and cell cycle state in grapevine buds of a subtropical and Mediterranean climate

Grapevine (Vitis vinifera L.) is the most widely cultivated fruit crop worldwide, contributing substantially to rural economies. The production cycle and productivity depend on seasonal cues and can range from a strongly deciduous habit in cool-temperate climates to evergreen in subtropical and tropical climates. The influence of the different seasonal conditions on the dynamics of the perennating bud, including the degree of growth and metabolic quiescence, cell cycle status and internal tissue oxygen status between different climatic zones is largely unknown. This knowledge is important for adapting to changing climate conditions and for crop expansion to wider regions. This study investigated the growth and metabolic physiology of the perennating bud of commercially grown cv. Flame Seedless table grapes from Mediterranean and subtropical climate in Western Australia, from summer until late winter. Climate data were obtained, showing differences in minimum (night) temperature between the two climates, reflected by differences in calculated chilling units. Bud dormancy increased during autumn of both climates;however, the onset and depth of dormancy of buds from the subtropical region were attenuated relative to the Mediterranean condition. Stark contrasts were also observed in metabolism. The respiration of subtropical-grown buds increased over fivefold during late autumn and winter, while that of Mediterranean-grown buds increased less than twofold. This was also reflected in less desiccation of the subtropical-grown buds, and an apparently greater degree of hypoxia within the bud during late winter, prior to bud burst. Collectively, these data show pronounced differences in growth and metabolic physiology of commercially grown table grapes, which provide a foundation for investigating the influence of differing climate and seasonality on the growth and productivity of table grapes and how these may he managed through breeding and agronomy.