How Sweet Cherry Flower Buds Avoid Freezing by Supercooling

Greg Howard
23rd August, 2024

How Sweet Cherry Flower Buds Avoid Freezing by Supercooling

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at the University of British Columbia (Okanagan) studied how sweet cherry flower buds avoid freezing through supercooling
  • They found that barriers to ice formation are unique to each part of the bud that will develop into flowers or leaves
  • The study showed that as buds transition from winter to spring, the development of water-conducting tissue allows ice to form, reducing supercooling ability
Surviving low temperatures is a significant challenge for many plant species, particularly during winter. One of the mechanisms plants use to cope with freezing temperatures is supercooling, which allows them to avoid ice formation within their tissues. However, the exact mechanisms behind supercooling are not entirely understood. A recent study conducted by researchers at the University of British Columbia (Okanagan) investigated the properties that promote supercooling in overwintering sweet cherry (Prunus avium) flower buds[1]. The study used differential thermal analysis (DTA) to observe where ice forms within the bud structure and to identify changes during the overwintering period that correlate with the gain and loss of supercooling capacity. The researchers found that barriers to ice propagation are likely unique to each primordium, the part of the bud that will develop into flowers or leaves. These barriers were inferred from exotherms—heat released during freezing—produced from buds subjected to DTA. Interestingly, multiple primordia could freeze simultaneously, but ice was primarily accommodated between the bud scales and within the bud axis. This study's findings align with earlier research on peach flower buds, which also highlighted the importance of bud structural features in preventing ice propagation[2]. In peach buds, supercooling was dependent on the viability of the bud axis tissue, and wounding the buds prevented supercooling, indicating the significance of the bud's structural integrity. Similarly, the sweet cherry study found that disturbing tissues around the primordia interfered with typical supercooling patterns, producing more erratic and numerous exotherms during DTA. Another critical observation from the sweet cherry study was the correlation between vascular differentiation in primordia and the loss of supercooling in the spring. As the buds transitioned from winter to spring, the development of xylem (water-conducting tissue) in the primordia provided a pathway for ice propagation, compromising the buds' ability to supercool. This finding is consistent with earlier studies that emphasized the role of vascular tissue continuity in ice propagation[2][3]. The research also noted that the full expression of supercooling in sweet cherry buds was not dependent on the presence of bud scales, which contrasts with findings in Picea abies (Norway spruce) where bud scales played a crucial role in preventing ice penetration[3]. This difference highlights the species-specific nature of supercooling mechanisms. Furthermore, the study's use of water-soluble dye uptake throughout the overwintering period provided insights into the anatomical changes associated with supercooling. The dye uptake experiments revealed that the region directly below the primordia acted as a barrier to ice propagation in winter, protecting the flower from freezing damage. This protective mechanism is lost in the spring as xylem differentiation occurs, allowing ice to propagate and compromising supercooling. The findings from this study contribute to a broader understanding of how plants manage freezing stress, which is a critical factor in their ecological distribution and productivity[4]. By elucidating the anatomical and physiological changes that facilitate supercooling, this research provides valuable insights that could inform agricultural practices, such as selecting frost-resistant cultivars and optimizing management practices to mitigate frost risk. Overall, the study conducted by the University of British Columbia (Okanagan) sheds light on the complex interplay of anatomical and physiological factors that enable supercooling in sweet cherry flower buds. These findings, when integrated with earlier research on other species, enhance our understanding of plant survival strategies in freezing temperatures and offer potential applications in agriculture and horticulture.

AgricultureBiochemPlant Science

References

Main Study

1) Investigating properties of sweet cherry (Prunus avium) flower buds that help promote freezing avoidance by supercooling.

Published 21st August, 2024

https://doi.org/10.1111/plb.13697

Related Studies

2) Properties of peach flower buds which facilitate supercooling.

Journal: Plant physiology, Issue: Vol 70, Issue 5, Nov 1982

3) Complex bud architecture and cell-specific chemical patterns enable supercooling of Picea abies bud primordia.

https://doi.org/10.1111/pce.13078

4) Effects of environmental factors and management practices on microclimate, winter physiology, and frost resistance in trees.

https://doi.org/10.3389/fpls.2015.00259


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