Our Research

Our group seeks to understand fundamental principles that govern the development, stress response, and evolution of plants. We use a broad range of approaches including molecular biology, classical morphology, and experimental physiology. We aim to extend basic knowledge of plant biology, while also developing applications of these learned biological principles to advance sustainable agriculture and forest conservation.


Plant biophysics

The exchange of water for CO2 to synthesize sugars in plant leaves is the most fundamental process of terrestrial life. Traits related to plant structure, biochemistry, and physiology evolved to optimize this exchange within each environment. We seek to understand the fundamental physical limits to plant form and function to explain patterns of adaptation and acclimation. Exploring these limits takes lab members to the High Sierra treeline, the tops of the tallest conifers, and the Arctic Circle.


Study of plant water relations

Water is essential to life. Our focus is to understand intra- and intercellular transport processes in plants from the perspective of fluid dynamics, chemistry, and biology. We are currently investigating hydration through leaf surfaces (absorption of fog and rain) across many plant species, and its importance to plant stress recovery and the summer condition of both orchard and forest trees.


Study of plant non-structural carbohydrates

Carbohydrate metabolism constitutes the major physiological activity allowing plant function. Non-structural carbohydrates (NSCs) constitute a dynamic pool of plant energy resources that fluctuate in response to environmental conditions and plant phenological status. We aim to understand physiological and biological activity of plant NSC management, across spatial and temporal scales from cells to whole organisms and from seconds to years.


Biologically inspired agricultural innovation - Carbohydrate Observatory

Translation of basic knowledge to applied technologies can be a game-changer. We use a citizen science approach to involve stakeholders in our research of carbohydrate management by trees to both accelerate research discoveries and provide an interface between researchers and orchard managers. Together we are building a new tool to determine orchard’s health and physiological activity to facilitate and guide agricultural practices to conserve water, reduce nitrogen input, and better predict yield potential and harvest dates.

We will collect the leaves when they mature, so check back for results. For more information contact Alana Chin: arochin@ucdavis.edu

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Z-Lab NEWS



06/10/2019 -- Lab - 8 people - are going to Alaska behind Polar Circle to determine if trees are sleeping when there is no night



02/16/2017 -- We have decided on the meeting this year. It is Ecological Society of America in Portland, OR - meet us there



Liquid handler arrived !!! Be first to get naming rigths. It made its firtst plate on 01/16/2017. It is fast, but not faster than Aude



Chill removal from almond buds biophysical bases of predicting bud break time - research program developed and run by Dr. Aude Tixier was presented at Almond Conference in Sacramento 2017



Acclimation of Pistacia integerrima trees to frost in semi-arid environments depends on autumn's drought - accepted in Planta (O. Sperling, F. Secchi, J Godfrey, and M.A. Zwieniecki)



Special lab meeting in PES 2004 - Thursday (17th of November) at 3:00 pm - Kaare Jensen will discuss his research on phloem and leaves



Lab meeting - Friday PES 3001 4:30pm Friday 18 of November - Jessica will be presenting her progress in almond resurection project



We are getting new liquid handler to increase precision starch analysis



Paula's paper got accepted in Tree Physiology - 11/14/16



People of the Lab

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Recent Lab Alumni



Carbohydrate Observatory

The Carbohydrate Observatory uses a citizen science approach, the citizens being almond, pistachio and walnut growers who send us monthly wood and bark samples from their orchards to be analyzed for sugars and starch. The results are made available through a website that each grower has access to. Growers then track the carbohydrate levels of their nut trees throughout the year while pairing this information with pheneological events such as dormancy, pollination, bud break, flowering, fruiting, harvest, and leaf drop. The goal is to have a better biological understanding of the role carbohydrates and use this massive data set as a tool to predict yield and understand environmental stresses such as lack of chilling hours and drought.


Our goals are to:


1) Understand how annual patterns of starch and soluble sugars (NSC – nonstructural carbohydrates) concentration in orchard trees differ throughout the Central Valley, which will aid in the improvement of spring/fall management practices and our understanding of chilling requirements.
2) To develop a novel tool that uses NSC levels as a predictor of yield for the following year and to understand variable crop yields.
3) Create an easy interactive NSC data sharing online platform.



To learn more about Carbohydrate Observatory visit its page

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Bloom time prediction tool for tree crops

Trees in seasonal climates gauge winter progression to assure vital and productive blooming. However, how dormant plants asses environmental conditions remains obscure. We postulated that it involves the energetic reserves required for bloom, and therefore studied winter carbohydrate metabolism in deciduous trees.
We quantified non-structural carbohydrates throughout winter in almond, peach, and pistachio trees in California and Israel and characterized winter metabolism. We constructed a carbohydrate-temperature (C–T) model that projects changes in starch and soluble carbohydrate concentrations by temperature mediated kinetics. Then, we tested the C–T model projections of bloom times by 20 years of temperature and phenology records from California.
The C–T model attributes winter carbohydrate regulation in dormant trees to continuous updates of metabolic pathways. The model projects a surge in starch synthesis at the end of winter, and critically low concentrations of soluble carbohydrates, that trigger bloom. This is supported by field measurements of starch accumulation at the end of winter (˜50 mg g−1 DW in almonds) that preceded bloom by ˜10 days.
The C–T model provides a physiological framework for bloom forecasts in deciduous orchards. It integrates contrasting notions of chill and heat and elucidates why abnormal winter temperatures may compromise bloom in deciduous orchards.



link to bloom time prediction tool for almonds



Recent Publications and Press

Full bibliography

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Grant Support


Big thanks to benefactors and in-kind contributions


If you would like to contribute to Carbohydrate Observatory Z-Lab research effort please contact Maciej Zwieniecki at mzwienie@ucdavis.edu (gifts to UC Davis may be tax deductible)



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Contact Us

Maciej Zwieniecki
Department of Plant Sciences
PES #2316, One Shields Avenue
UC Davis , Davis, CA 95616
Phone 530-752-9880