Biology subjects

Kovaleski, A. P.

Publications and source records attributed to Kovaleski, A. P..

10 recordsLinked to original sources

bioRxiv2026

Warming Reduces Cold Hardiness of Boreal Plants but Damage Risk Varies by Species and Season

Winter warming is altering plant exposure to cold events, and its effects on seasonal cold hardiness dynamics remain poorly understood. Here we quantified the effect of whole-ecosystem warming (+0.00{degrees}C to +9.00{degrees}C) on bud cold hardiness of two overstory (Larix laricina and Picea mariana) and two understory (Chamaedaphne calyculata and Rhododendron groenlandicum) boreal peatland forest species across four dormant seasons. Warming reduced cold hardiness in fall and spring by delaying acclimation and advancing deacclimation, yet damage risk increased only in late winter and spring for three species. Warming also reduced snow cover, increasing temperature variability and cold damage for understory shrubs. Together, these results show that warming restructures rather than uniformly increasing cold hardiness risk, concentrating vulnerability at transitional seasons through species-specific dynamics and microclimate exposure.

plant biology↗

bioRxiv2025

Warming winters, changing springs: cold hardiness dynamics predict budbreak and associated low temperature threats on an intercontinental scale

Temperate woody perennial plants form buds that develop into leaves or flowers that emerge in the following growth season. To survive winter, dormant buds must attain cold hardiness, and timely lose it in spring to break bud while avoiding damage from low temperatures and late frosts. Here, we use a process-based model to predict bud cold hardiness of three grapevine varieties (V. vinifera Cabernet-Sauvignon and Riesling, and V. hybrid Concord) from historical temperature records of eight different locations in North America and Europe (n=329). Based on those predictions, and thresholds of cold hardiness at budbreak from literature, timing of budbreak was extracted. Despite the model being untrained to budbreak data, the cold hardiness model resulted in good predictions (RMSE=7.3d) that were further improved based on expected delays from cold damage (RMSE=7.2d). Both increasing and decreasing trends in freeze damage risk were predicted with increasing temperature, depending on the range of mean dormant season temperature (MDST; 1 Nov-30 Apr) in each location. Predictions in timing of spring phenology in relation to MDST also showed warming to advance (MDST<10{degrees}C) or delay (MDST>10{degrees}C) budbreak. Cold hardiness dynamics represents an advancement in phenological modeling that provides information for the entirety of the dormant season, as well as budbreak.

plant biology↗

bioRxiv2024

Integrating cold hardiness and deacclimation resistance demonstrates a conserved response to chilling accumulation in grapevines.

To survive the harsh conditions of winter, woody perennial species such as grapevine have adapted to use environmental cues to trigger physiological changes to induce dormancy, acquire cold hardiness, and measure the length of winter to properly time spring budbreak. Human induced climate change disrupts these cues by prolonging warm temperatures in fall, reducing the depth and consistency of midwinter, and triggering early budbreak through false spring events. We evaluated variation in dormant bud cold hardiness and chilling hour requirements of 31 different grapevine varieties over 3 years. Differential thermal analysis was used to track changes in cold hardiness and deacclimation resistance was assessed throughout the season to track dormancy progression. Results demonstrate wide variation in maximum deacclimation rate (1.03 - 2.87 {degrees}C/day) among varieties under forcing conditions. Absolute maximum rates of deacclimation show signatures of species-level responses to forcing temperatures. When integrated with variation in cold hardiness, these rates revealed a relationship between winter cold hardiness, changes in deacclimation rate and budbreak phenology. Standardizing rates among varieties as deacclimation potential demonstrated a conserved response to chilling exposure among varieties that alters our interpretation of the concept of high and low chill varieties and chilling requirement in grapevine.

plant biology↗

bioRxiv2024

Cold hardiness-informed budbreak reveals role of freezing temperatures and daily fluctuation in chill accumulation model

Fundamental questions in bud dormancy remain, including what temperatures fulfill dormancy requirements (i.e., chill accumulation). Recent studies demonstrate freezing temperatures promote chill accumulation and cold hardiness influences time to budbreak - the phenotype used for dormancy evaluations. Here we evaluated bud cold hardiness (CH) and budbreak responses of grapevines (Vitis hybrids) throughout chill accumulation under three treatments: constant (5{degrees}C), fluctuating (-3.5 to 6.5 {degrees}C daily), and field conditions (Madison, WI, USA). Chill treatments experiencing lower temperatures promoted greater gains in cold hardiness (CHfield>CHfluctuating>CHconstant). All treatments decreased observed time to budbreak with increased chill accumulation. However, perceived treatment effectiveness changed when time to budbreak was adjusted to remove cold acclimation effects. Among three classic chill models (North Carolina, Utah, and Dynamic), none were able to correctly describe adjusted time to budbreak responses to chill accumulation. Thus, a new model is proposed that expands the range of chill accumulation temperatures to include freezing temperatures and enhances chill accumulation under fluctuating temperature conditions. Most importantly, our analysis demonstrates adjustments for uneven acclimation change the perceived effectiveness of chill treatments. Therefore, future work in bud dormancy would benefit from simultaneously evaluating cold hardiness. HighlightA new chill accumulation model demonstrates how bud cold hardiness changes elicited by chill treatments affect the interpretation of thermal effectiveness in promoting dormancy progression and release.

plant biology↗

bioRxiv2023

Physiological and transcriptomic characterization of cold acclimation in endodormant grapevine under different temperature regimes

It is essential for the survival of grapevines in cool climate viticultural regions that vines properly acclimate in the late fall and early winter and develop freezing tolerance. Climate change-associated abnormities in temperature during the dormant season, including oscillations between extreme cold and prolonged warmth, impacts cold acclimation and threatens the sustainability of the grape and wine industry. We conducted two experiments in controlled environment to investigate the impacts of different temperature regimes on cold acclimation ability in endodormant grapevine buds through a combination of freezing tolerance based physiological and RNA-seq based transcriptomic monitoring. Results show that the freezing tolerance of buds was not altered from field levels when exposed to stable temperatures ranging from 2 {degrees}C to 22 {degrees}C but was enhanced when exposed to temperature cycling (7{+/-}5 {degrees}C). We also characterized the transcriptomic response of endodormant buds to high and low temperatures and the potential genetic control for the maintenance of endodormancy. Several pathways that were previously reported to be responsive or functional during cold acclimation, such as the ICE-CBF-COR cascade, were not observed to play a role in the enhancement of freezing tolerance or the sensing of different temperatures, indicating our current understanding of the genetic control of cold acclimation remains a challenge when generalizing across plant species and phenological stages.

plant biology↗

bioRxiv2023

NYUS.2: an Automated Machine Learning Prediction Model for the Large-scale Real-time Simulation of Grapevine Freezing Tolerance in North America

O_LIAccurate and real-time monitoring of grapevine freezing tolerance is crucial for the sustainability of the grape industry in cool climate viticultural regions. However, on-site data is limited. Current prediction models underperform under diverse climate conditions, which limits the large-scale deployment of these methods. C_LIO_LIWe combined grapevine freezing tolerance data from multiple regions in North America and generated a predictive model based on hourly temperature-derived features and cultivar features using AutoGluon, an automatic machine learning engine. Feature importance was quantified by AutoGluon and SHAP value. The final model was evaluated and compared with previous models for its performance under different climate conditions. C_LIO_LIThe final model achieved an overall 1.36 {degrees}C root-mean-square error during model testing and outperformed two previous models using three test cultivars at all testing regions. Two feature importance quantification methods identified five shared essential features. Detailed analysis of the features indicates that the model might have adequately extracted some biological mechanisms during training. C_LIO_LIThe final model, named NYUS.2, was deployed along with two previous models as an R shiny-based application in the 2022-2023 dormancy season, enabling large-scale and real-time simulation of grapevine freezing tolerance in North America for the first time. C_LI

plant biology↗

bioRxiv2022

Time to budbreak is not enough: cold hardiness evaluation is necessary in dormancy and spring phenology studies

Dormancy of buds is an important phase in the life cycle of perennial plants growing in environments where unsuitable growth conditions occur seasonally. In regions where low temperature defines these unsuitable conditions, the attainment of cold hardiness is also required to survive. The end of the dormant period culminates in budbreak and flower emergence, or spring phenology, one of the most appreciated and studied phenological events. Despite this, we have a limited physiological and molecular understanding of dormancy, which has negatively affected our ability to model budbreak. Here we highlight the importance of including cold hardiness in studies that typically only characterize time to budbreak. We show how different temperature treatments may lead to increases in cold hardiness, and by doing so also (inadvertently) increase time to budbreak. Therefore, erroneous interpretations of data may occur by not phenotyping cold hardiness. Changes in cold hardiness were very likely present in previous experiments to study dormancy, especially when those included below freezing temperature treatments. Separating the effects between chilling accumulation and cold acclimation in future studies will be essential for increasing our understanding of dormancy and spring phenology in plants.

plant biology↗

bioRxiv2022

Development of a new cold hardiness prediction model for grapevine using phased integration of acclimation and deacclimation responses

Cold injury limits distribution of perennial agricultural crops, though replacement of plants and other management practices may allow for some damage tolerance. However, winter damage to crops such as grapevines (Vitis spp.) can result in losses in yield the following year if buds are damaged, but over many years when vines must be replaced and reach maturity before fruiting. Despite risks, grapevines are cultivated at the edge of permissible climate and rely on cold hardiness monitoring programs to determine when cold damage mitigation and management practices are required. These monitoring programs represent a critical, but laborious process for tracking cold hardiness. To reduce the need for continuous monitoring, a model (WAUS.2) using cold hardiness data collected over many years from Washington state, USA, growers was published in 2014. Although the WAUS.2 model works well regionally, it underperforms in other regions. Therefore, the objective of this work was to develop a new model (NYUS.1) that incorporates recent knowledge of cold hardiness dynamics for better prediction outcomes. Cold hardiness data from V. labruscana Concord, and V. vinifera Cabernet Sauvignon and Riesling from Geneva, NY, USA were used. Data were separated in calibration (~2/3) and validation (~1/3) datasets. The proposed model uses three functions to describe acclimation, and two functions to describe deacclimation, with a total of nine optimized parameters. A shared chill response between acclimation and deacclimation provides a phased integration where acclimation responses decrease over the course of winter and are overcome by deacclimation. The NYUS.1 model outperforms the WAUS.2 model, reducing RMSE by up to 37% depending on cultivar. The NYUS.1 model also tends to be more conservative in its prediction, slightly underpredicting cold hardiness, as opposed to the overprediction from the WAUS.2 model. Some optimized parameters were shared between cultivars, suggesting conserved physiology was captured by the new model. Highlights- Multi-year cold hardiness data from three grapevine cultivars were used for modeling - Cold hardiness was modeled based on daily temperature and accumulated chill - Phased acclimation and deacclimation processes result in cold hardiness predictions - The new model was compared to the currently available model for grapevines - The model proposed here outperforms the currently available model

plant biology↗

bioRxiv2019

X-ray phase contrast imaging of Vitis spp. buds shows freezing pattern and correlation between volume and cold hardiness

Grapevine (Vitis spp.) buds must survive winter temperatures in order to resume growth when suitable conditions return in spring. They do so by developing cold hardiness through deep supercooling, but the mechanistic process of supercooling in buds remains largely unknown. Here we use synchrotron X-ray phase contrast imaging to study cold hardiness-related characteristics of V. amurensis, V. riparia, and V. vinifera buds: time-resolved 2D imaging was used to visualize freezing; and microtomography was used to evaluate morphological changes during deacclimation. Bud cold hardiness was determined (low temperature exotherms; LTEs) using needle thermocouples during 2D imaging as buds were cooled with a N2 gas cryostream. Resolution in 2D imaging did not allow for ice crystal identification, but freezing was assessed due to movement of tissues coinciding with LTE values. Freezing was observed to propagate from the center of the bud toward the outer bud scales. The freezing events observed lasted several minutes. Additionally, loss of supercooling ability appears to be correlated with increases in bud tissue volume during the process of deacclimation, but major increases in volume occur after most of the supercooling ability is lost, suggesting growth resumption processes are limited by deacclimation state.\n\nHighlightX-ray phase contrast imaging shows freezing occurs over several minutes and propagates from center toward tip of Vitis spp. buds. Incremental increase in bud volume correlates with cold deacclimation

plant biology↗

bioRxiv2018

Kinetics of winter deacclimation in response to temperature determines dormancy status and quantifies chilling requirement in grapevines (Vitis spp.)

2.Bud dormancy and cold hardiness are critical adaptations for surviving winter cold stress for temperate perennial plant species, with shifting temperature-based responses during the winter. The objective of this study was to uncover the relationship between dormancy transition (chilling requirement) and temperature on the loss of cold hardiness and budbreak. Dormant cuttings of Vitis vinifera, V. aestivalis, V. amurensis, and V. riparia were examined to determine the relationship between chilling requirement and temperature on rate of deacclimation (kdeacc). Differential thermal analysis was used to determine kdeacc using mean low temperature exotherms. Effect of chill was evaluated as the deacclimation potential ({psi}deacc), which was the change in kdeacc due to chill accumulation. Budbreak was also evaluated in fully chilled buds at different temperatures. Results indicate that {psi}deacc varies dependent on dormancy state, following a logarithmic response to chill accumulation. The effect of temperature on kdeacc was exponential at low and logarithmic at high temperatures. The combination of {psi}deacc and kdeacc resulted in good prediction of deacclimation. Budbreak phenology was also explained by differences in kdeacc. Deacclimation rates can be used as a quantitative determinant of dormancy transition and budbreak, and to refine models predicting effects of climate change.

plant biology↗