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Non-structural carbohydrate dynamics associated with antecedent stem water potential and air temperature in a dominant desert shrub |
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| Authors: | Jessica S Guo Linnea Gear Kevin R Hultine George W Koch Kiona Ogle |
| Institution: | 1. Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA;2. Department of Chemistry and Biochemistry, Northern Arizona University, Flagstaff, Arizona, USA;3. Department of Research, Conservation, and Collections, Desert Botanical Garden, Phoenix, Arizona, USA;4. Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA;5. Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, Arizona, USA |
| Abstract: | Non-structural carbohydrates (NSCs) are necessary for plant growth and affected by plant water status, but the temporal dynamics of water stress impacts on NSC are not well understood. We evaluated how seasonal NSC concentrations varied with plant water status (predawn xylem water potential, Ψ) and air temperature (T) in the evergreen desert shrub Larrea tridentata. Aboveground sugar and starch concentrations were measured weekly or monthly for ~1.5 years on 6–12 shrubs simultaneously instrumented with automated stem psychrometers; leaf photosynthesis (Anet) was measured monthly for 1 year. Leaf sugar increased during the dry, premonsoon period, associated with lower Ψ (greater water stress) and high T. Leaf sugar accumulation coincided with declines in leaf starch and stem sugar, suggesting the prioritization of leaf sugar during low photosynthetic uptake. Leaf starch was strongly correlated with Anet and peaked during the spring and monsoon seasons, while stem starch remained relatively constant except for depletion during the monsoon. Recent photosynthate appeared sufficient to support spring growth, while monsoon growth required the remobilization of stem starch reserves. The coordinated responses of different NSC fractions to water status, photosynthesis, and growth demands suggest that NSCs serve multiple functions under extreme environmental conditions, including severe drought. |
| Keywords: | antecedent conditions carbon–water relations creosote bush plant water potential starch sugar |