The response of marigold (Tagetes erecta Linn.) to ozone: impacts on plant growth and leaf physiology

Abstract

Progressively increasing ozone (O) concentrations pose a potential threat to the value of marigold (Tagetes erecta Linn.), a plant widely used in urban landscaping. The response of marigold to elevated O has been reported earlier, but the mechanisms underlying the O effect have not been clearly elucidated. In the present study, we exposed marigold "Moonsong Deep Orange" plants to elevated O, including ambient non-filtered air (NF) plus 60 ppb (NF+60) and 120 ppb (NF+120) O, to assess visible injury and the possible physiological consequences of this pollutant. Yellow lesions appeared after 4 days under NF+120 treatment and 12 days under NF+60 treatment, with 85.6% and 36.8% of the leaves being injured at harvest time, respectively. Compared with NF, NF+60 inhibited leaf photosynthesis, stem-diameter growth, and biomass production significantly, while the parameters were decreased more by NF+120. Although the stomatal conductance decreased under elevated O exposure, the O flux into leaves increased by 28.0-104.8% under NF+60 treatment and 57.5-145.6% under NF+120 treatment. The total ascorbic acid (ASA) content increased due to elevated O exposure, while the reduced ASA content did not, resulting in a decreased ratio of reduced to total ASA. A lower level of jasmonic acid (JA) was observed under elevated O exposure. In conclusion, the impacts of elevated O on marigold plants may be ascribed to increased O flux into leaves and reduced protective capacity of leaves to convert oxidized to reduced ASA and synthesize endogenous JA.

The Combined Effect of Elevated O3 Levels and TYLCV Infection Increases the Fitness of Bemisia tabaci Mediterranean on Tomato Plants

“…O 3 is by far the most phytotoxic air pollutant and is a strong oxidant (Overmyer et al 2009). After entering the plant stomata, O 3 is broken down in the apoplast to form reactive oxygen species (ROS), which in turn trigger an active oxidative burst within the plant, affecting substances such as carbohydrates and proteins and altering lipid oxidation (Yang et al 2017, Zhang et al 2017, Cui et al 2018). O 3 reacts primarily with the plasma membrane, causing alterations in lipoxygenase activities and increasing the production of linoleic acid, a precursor of JA biosynthesis (Rao et al 2000, Wasternack and Hause 2013).…”

Leaf Functional Traits Vary in Urban Environments: Influences of Leaf Age, Land-Use Type, and Urban–Rural Gradient

“…Stomatal density was determined using scanning electron microscopy in accordance with the methods of Yang et al (2017). Three fresh needles wiped with a wet towel were placed immediately in a plastic bottle with a fixative solution (70%, v/v, ethanol:glacial acetic acid:formalin; 90:5:5) to maintain the integrity of cellular structure.…”