Effects of methyl jasmonate on plant growth and leaf properties

Abstract

Exogenous application of methyl jasmonate (MeJA) can induce anatomical and chemical changes that are components of defence responses in plants. Particularly, MeJA is well‐known to increase leaf trichome density to protect against insect herbivory, but surprisingly little is known about the effects of MeJA on other leaf properties and plant growth. Using sunflower (Helianthus annuus), tomato (Solanum lycopersicum), and soybean (Glycine max) treated with 0.0, 0.1, 0.5, 1.0, and 2.5 mM MeJA, we examined changes in leaf trichome density, stomatal density, cuticle thickness, cuticle composition, plant height, and biomass production. For all three plant species, MeJA (especially at the higher concentrations) caused significant decreases in plant height (up to 39%) and biomass (up to 79%). MeJA caused substantial increases in leaf trichome density (being 1.3–3.5‐times higher) in all three species, with the magnitude of these effects increasing with MeJA concentration. However, we also observed that MeJA resulted in significant changes in cuticle composition and thickness, and stomatal density, although the magnitude of these changes was smaller relative to changes in trichome density. Specifically, high concentrations of MeJA increased the relative content of phenolic compounds and cutin in leaf cuticle while decreasing the relative content of polysaccharide. The changes in stomatal density varied with plant species and MeJA concentration. Also, MeJA increased cuticle thickness in tomato but decreased that in sunflower and soybean. Thus, studies investigating MeJA should also consider the importance of changes in other leaf properties and plant growth.

Leaf metabolic signatures induced by real and simulated herbivory in black mustard (Brassica nigra)

“…MeJA caused visual changes in B. nigra that were in agreement with foliar phenotypes previously observed in other systems (Ananieva et al 2007; Ding et al 2018; Li et al 2018). The resulting changes in the foliar metabolome, altered by MeJA were not only relevant for plant defences but also for primary growth, for instance the TCA metabolism.…”

Ectopic Defense Gene Expression Is Associated with Growth Defects in Medicago truncatula Lignin Pathway Mutants

“…The JA family of signaling molecule plays a central role in the coordination of a remarkably diverse set of defensive traits in different plant species. These include interference with cell division, cell expansion, and seed development, induction of trichome development, and induction of a range of defensive phytochemicals, particularly terpenoids (Wasternack and Hause, 2013;Havko et al, 2016;Züst and Agrawal, 2017;Li et al, 2018). In view of the striking changes in development, seed number, trichome number, and terpene saponin production, as well as changes in some JA signaling gene transcripts in our monolignol pathway mutants, it is perhaps surprising that JA levels were relatively unaffected, at least at the growth stages measured.…”

Defence priming in Arabidopsis – a Meta-Analysis

“…Li, et al . 78 found that MeJA applications may also cause changes in cuticle thickness and composition, and increases in densities of trichomes and stomata, as well as reductions in height and biomass, in various species (e.g., tomato, sunflower and soybean). Thus, although application of MeJA efficiently enhances herbivore resistance its value as a priming agent is questionable due to its undesirable phenotypic effects.…”