Elevated ozone concentration decreases whole‐plant hydraulic conductance and disturbs water use regulation in soybean plants

Abstract

Elevated tropospheric ozone (O ) concentration has been shown to affect many aspects of plant performance including detrimental effects on leaf photosynthesis and plant growth. However, it is not known whether such changes are accompanied by concomitant responses in plant hydraulic architecture and water relations, which would have great implications for plant growth and survival in face of unfavorable water conditions. A soybean (Glycine max (L.) Merr.) cultivar commonly used in Northeast China was exposed to non-filtered air (NF, averaged 24.0 nl l ) and elevated O concentrations (eO , 40 nl l supplied with NF air) in six open-top chambers for 50 days. The eO treatment resulted in a significant decrease in whole-plant hydraulic conductance that is mainly attributable to the reduced hydraulic conductance of the root system and the leaflets, while stem and leaf petiole hydraulic conductance showed no significant response to eO . Stomatal conductance of plants grown under eO was lower during mid-morning but significantly higher at midday, which resulted in substantially more negative daily minimum water potentials. Moreover, excised leaves from the eO treated plants showed significantly higher rates of water loss, suggesting a lower ability to withhold water when water supply is impeded. Our results indicate that, besides the direct detrimental effects of eO on photosynthetic carbon assimilation, its influences on hydraulic architecture and water relations may also negatively affect O -sensitive crops by deteriorating the detrimental effects of unfavorable water conditions.

Elevated Ozone Concentration Reduces Photosynthetic Carbon Gain but Does Not Alter Leaf Structural Traits, Nutrient Composition or Biomass in Switchgrass

“…Leaf minor vein density is an important determinant of leaf water and nutrient transport efficiency, which together are essential for hydraulic conductance and stomatal function. Previous work in other species reported that elevated O 3 decreases whole plant hydraulic conductance [65], but studies have not examined how elevated O 3 impacts the anatomical determinants of hydraulic conductance such as leaf minor vein density. Under temperature stress, leaf minor vein density and stomatal density increased in parallel supporting greater leaf hydraulic conductance [66].…”

Interactive effect of leaf age and ozone on mesophyll conductance in Siebold's beech

“…Ozone and the resultant reactive oxygen species (ROS) reach the cell membrane (Vainonen and Kangasjӓrvi 2015), which may affect G m through direct effects on aquaporins. In fact, O 3 may decrease leaf hydraulic conductance (Zhang et al 2018), which is related to vein architecture in association with aquaporins (Scoffoni and Sack 2017). This hypothesis needs to be tested in further studies.…”

Interactive effects of changing stratospheric ozone and climate on tropospheric composition and air quality, and the consequences for human and ecosystem health

“…In a study on the Chinese ornamental tree, Lonicera maackii, exposures to 160 µg O3 m -3 and water restriction increased the production of bioindicators of stress but decreased visible injury on leaves. 174 In soybeans (Glycine max), exposures to 80 µg O3 m -3 for 50 days caused a reduction in conductance of water in whole plants, 175 suggesting adverse interactions between exposure to O3 and water-stress.…”