Variability in temperature-independent transpiration responses to evaporative demand correlate with nighttime water use and its circadian control across diverse wheat populations

Bishal G. Tamang, Rémy Schoppach, Daniel Monnens, Brian J. Steffenson, James A. Anderson, Walid Sadok

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

Main conclusion: Nocturnal transpiration, through its circadian control, plays a role in modulating daytime transpiration response to increasing evaporative demand, to potentially enable drought tolerance in wheat. Limiting plant transpiration rate (TR) in response to increasing vapor pressure deficit (VPD) has been suggested to enable drought tolerance through water conservation. However, there is very little information on the extent of diversity of TR response curves to “true” VPD (i.e., independent from temperature). Furthermore, new evidence indicate that water-saving could operate by modulating nocturnal TR (TRN), and that this response might be coupled to daytime gas exchange. Based on 3 years of experimental data on a diverse group of 77 genotypes from 25 countries and 5 continents, a first goal of this study was to characterize the functional diversity in daytime TR responses to VPD and TRN in wheat. A second objective was to test the hypothesis that these traits could be coupled through the circadian clock. Using a new gravimetric phenotyping platform that allowed for independent temperature and VPD control, we identified three and fourfold variation in daytime and nighttime responses, respectively. In addition, TRN was found to be positively correlated with slopes of daytime TR responses to VPD, and we identified pre-dawn variation in TRN that likely mediated this relationship. Furthermore, pre-dawn increase in TRN positively correlated with the year of release among drought-tolerant Australian cultivars and with the VPD threshold at which they initiated water-saving. Overall, the study indicates a substantial diversity in TR responses to VPD that could be leveraged to enhance fitness under water-limited environments, and that TRN and its circadian control may play an important role in the expression of water-saving.

Original languageEnglish (US)
Pages (from-to)115-127
Number of pages13
JournalPlanta
Volume250
Issue number1
DOIs
StatePublished - Jul 1 2019

Keywords

  • Canopy conductance
  • Circadian clock
  • Drought tolerance
  • Gravimetric phenotyping
  • Nocturnal transpiration
  • Stomata conductance
  • Vapor pressure deficit
  • Wheat

PubMed: MeSH publication types

  • Journal Article

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