Temperature responses of photosynthesis and leaf hydraulic conductance in rice and wheat

Abstract

Studies on the temperature (T) responses of photosynthesis and leaf hydraulic conductance (K leaf ) are important to plant gas exchange. In this study, the temperature responses of photosynthesis and K leaf were studied in Shanyou 63 (Oryza sativa) andYannong 19 (Triticum aestivum). Leaf water potential (Ψ leaf ) was insensitive to T in Shanyou 63, while it significantly decreased with T in Yannong 19. The differential Ψ leaf − T relationship partially accounted for the differing g m -T relationships, where g m was less sensitive to T in Yannong 19 than in Shanyou 63. With different g m -Tand Ψ leaf -T relationships, the temperature responses of photosynthetic limitations were surprisingly similar between the two lines, and the photosynthetic rate was highly correlated with g m . With the increasing T, K leaf increased in Shanyou 63 while it decreased in Yannong 19. The different K leaf -T relationships were related to different Ψ leaf -T relationships. When excluding the effects of water viscosity and Ψ leaf , K leaf was insensitive to T in both lines. g m and K leaf were generally not coordinated across different temperatures. This study highlights the importance of Ψ leaf on leaf carbon and water exchanges, and the mechanisms for the g m -T and K leaf -T relationships were discussed. K E Y W O R D Sleaf hydraulic conductance, leaf water potential, mesophyll conductance, photosynthetic limitations, temperature

Mesophyll conductance: walls, membranes and spatial complexity

“…Normalized temperature responses of mesophyll conductance, g m . Multiple responses are shown for rice (a) and wheat (b) (Scafaro et al ., 2011; von Caemmerer & Evans, 2015; Li et al ., 2020; Yang et al ., 2020), a diverse range of C 3 species (c) (von Caemmerer & Evans, 2015) and C 4 species (d) (Ubierna et al ., 2017). For each response, g m values were normalized relative to the value measured at 25°C.…”

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

“…In liquids such as water, this friction decreases with increasing temperature, due the increase of thermal energy of water molecules enabling them to overcome the attraction of other molecules from adjacent layers of flow (Kestin, Sokolov, & Wakeham, 1978; Seeton, 2006; Figure 2). Changes in water viscosity have been invoked to partially explain temperature‐mediated increases in leaf transpiration rate (Fredeen & Sage, 1999; Matzner & Comstock, 2001; Sack & Holbrook, 2006; Yang, Zhang, Huang, Peng, & Li, 2020). For instance, Fredeen and Sage (1999) found that decreases in water viscosity explained half of the increase in leaf transpiration rate in white spruce resulting from increases temperature from 10 to 35°C, and a similar finding was established by Yang et al (2020) on rice and wheat in the 15 to 40°C range.…”

Mechanisms of the Morphological Plasticity Induced by Phytohormones and the Environment in Plants

“…Recent advances in omics technologies and gene transformation have allowed genetic analyses to investigate the molecular mechanisms of plant development, ecology, and evolution [3,170]. Recent works also have made great breakthroughs in the fields of environmental signals sensing [171][172][173], phytohormone interactive networks [29], and plant stress combinations [174,175]. Until now, the molecular mechanisms underlying leaf development have been extensively elucidated [114,176].…”