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Stomatal movements are involved in elevated CO2‐mitigated high temperature stress in tomato

Zhang, Huan, Pan, Caizhe, Gu, Shaohan, Ma, Qiaomei, Zhang, Yiqing, Li, Xin, Shi, Kai
Physiologia plantarum 2019 v.165 no.3 pp. 569-583
agroecosystems, carbon dioxide, carbon dioxide enrichment, climate, climate change, heat, heat stress, heat tolerance, hydrogen peroxide, plant growth, respiratory burst, seedlings, stomatal movement, temperature, tomatoes, water use efficiency
Climate changes such as heat waves often affect plant growth and pose a growing threat to natural and agricultural ecosystems. Elevated atmospheric CO₂ can mitigate the negative effects of heat stress, but the underlying mechanisms remain largely unclear. We examined the interactive effects of elevated CO₂ (eCO₂) and temperature on the generation of the hydrogen peroxide (H₂O₂) and stomatal movement characteristics associated with heat tolerance in tomato seedlings grown under two CO₂ concentrations (400 and 800 µmol mol⁻¹) and two temperatures (25 and 42°C). eCO₂ ameliorated the negative effects of heat stress, which was accompanied by greater amounts of RESPIRATORY BURST OXIDASE 1 (RBOH1) transcripts, apoplastic H₂O₂ accumulation and decreased stomatal aperture. Silencing RBOH1 and SLOW-TYPE ANION CHANNEL, impeded eCO₂‐induced stomatal closure and compromised the eCO₂‐enhanced water use efficiency as well as the heat tolerance. Our findings suggest that RBOH1‐dependent H₂O₂ accumulation was involved in the eCO₂‐induced stomatal closure, which participate in maintaining balance between water retention and heat loss under eCO₂ concentrations. This phenomenon may be a contributor to eCO₂‐induced heat tolerance in tomato, which will be critical for understanding how plants respond to both future climate extremes and changes in CO₂.