Transpiration increases under high‐temperature stress: Potential mechanisms, trade‐offs and prospects for crop resilience in a warming world

Abstract

The frequency and intensity of high‐temperature stress events are expected to increase as climate change intensifies. Concomitantly, an increase in evaporative demand, driven in part by global warming, is also taking place worldwide. Despite this, studies examining high‐temperature stress impacts on plant productivity seldom consider this interaction to identify traits enhancing yield resilience towards climate change. Further, new evidence documents substantial increases in plant transpiration rate in response to high‐temperature stress even under arid environments, which raise a trade‐off between the need for latent cooling dictated by excessive temperatures and the need for water conservation dictated by increasing evaporative demand. However, the mechanisms behind those responses, and the potential to design the next generation of crops successfully navigating this trade‐off, remain poorly investigated. Here, we review potential mechanisms underlying reported increases in transpiration rate under high‐temperature stress, within the broader context of their impact on water conservation needed for crop drought tolerance. We outline three main contributors to this phenomenon, namely stomatal, cuticular and water viscosity‐based mechanisms, and we outline research directions aiming at designing new varieties optimized for specific temperature and evaporative demand regimes to enhance crop productivity under a warmer and dryer climate.

The OsERF115/AP2EREBP110 Transcription Factor Is Involved in the Multiple Stress Tolerance to Heat and Drought in Rice Plants

“…High-temperature increases transpiration rate and causes water deficit in diverse plants [53]. We found that OsERF115/AP2EREBP110-OE plants showed delayed visual symptoms of water deficit under the combined heat and drought stress conditions compared to WT plants (Figure 4a).…”

Responses of leaf respiration to heatwaves

“…Leaf R is significantly altered by the presence or absence of photosynthesis, particularly in cells that are photosynthetically active (N. G. Smith, Li, & Dukes, 2019). Water availability is especially important when considering extremely hot days and heatwaves, as drought and heat often occur concurrently due to the evaporative effects of heat on soils and the larger VPD between leaves and the surrounding air on hot days (Sadok, Lopez, & Smith, 2020; Teskey et al, 2014). With this in mind, we consider how dark to light transitions, and water limitations, would each impact the high temperature response of leaf R .…”

Scaling plant responses to high temperature from cell to ecosystem

“…Focusing on source‐sink dynamics, they emphasize the relevance of non‐foliar photosynthesis to supply carbon for highly energy intensive reproductive processes (Ferguson et al, 2021). Plant responses under heat are also strongly influenced by relative humidity, which can either enhance (dry air) or lower (moist air) evaporative demand, thus leading to the differential impact of heat stress on plants exposed to similar temperatures (Sadok, Lopez, & Smith, 2021). By examining stomatal‐, cuticular‐ and water viscosity‐based mechanisms, Sadok et al (2021) highlight the need to consider trade‐offs between temperature and evaporative demand while developing new crop varieties for future hotter and drier climates.…”

“…Plant responses under heat are also strongly influenced by relative humidity, which can either enhance (dry air) or lower (moist air) evaporative demand, thus leading to the differential impact of heat stress on plants exposed to similar temperatures(Sadok, Lopez, & Smith, 2021). By examining stomatal-, cuticular-and water viscosity-based mechanisms,Sadok et al (2021) highlight the need to consider trade-offs between temperature and evaporative demand while developing new crop varieties for future hotter and drier climates.The ability to maintain photosynthesis is critical for supplying carbohydrates to fuel metabolism and reproduction during heat stress, and this Special Issue compiles a suite of research papers investigating the response of CO 2 assimilation under warmer conditions Osei- Bonsu, McClain, Walker, Sharkey, and Kramer (2021). highlight the importance of photorespiration and alternative electron sinks in preventing photodamage to Photosystem II (PSII) in high temperature and high light conditions.…”