Differences in isoprenoid-mediated energy dissipation pathways between coastal and interior Douglas-fir seedlings in response to drought

Abstract

Plants have evolved energy dissipation pathways to reduce photooxidative damage under drought when photosynthesis is hampered. Non-volatile and volatile isoprenoids are involved in non-photochemical quenching of excess light energy and scavenging of reactive oxygen species. A better understanding of trees’ ability to cope with and withstand drought stress will contribute to mitigate the negative effects of prolonged drought periods expected under future climate conditions. Therefore we investigated if Douglas-fir (Pseudotsuga menziesii(Mirb.)) provenances from habitats with contrasting water availability reveal intraspecific variation in isoprenoid-mediated energy dissipation pathways. In a controlled drought experiment with 1-year-old seedlings of an interior and a coastal Douglas-fir provenance, we assessed the photosynthetic capacity, pool sizes of non-volatile isoprenoids associated with the photosynthetic apparatus, as well as pool sizes and emission of volatile isoprenoids. We observed variation in the amount and composition of non-volatile and volatile isoprenoids among provenances, which could be linked to variation in photosynthetic capacity under drought. The coastal provenance exhibited an enhanced biosynthesis and emission of volatile isoprenoids, which is likely sustained by generally higher assimilation rates under drought. In contrast, the interior provenance showed an enhanced photoprotection of the photosynthetic apparatus by generally higher amounts of non-volatile isoprenoids and increased amounts of xanthophyll cycle pigments under drought. Our results demonstrate that there is intraspecific variation in isoprenoid-mediated energy dissipation pathways among Douglas-fir provenances, which may be important traits when selecting provenances suitable to grow under future climate conditions.

Stimulation of isoprene emissions and electron transport rates as key mechanisms of thermal tolerance in the tropical species Vismia guianensis

“…While the mechanisms of isoprene thermotolerance are under investigation, recent literature suggests that isoprene and other isoprenoids protect photosynthesis during abiotic stress by minimizing oxidative damage through a number of mechanisms including, physical stabilization of photosynthetic membranes, the consumption of photosynthetic energy and reducing equivalents, direct antioxidant reactions (e.g., between isoprene and reactive oxygen species including fatty acid peroxyl radicals), and potent phytohormone signaling properties of isoprene including oxidation products such as methyl vinyl ketone and methacrolein which activate defense gene expression (Jardine et al., 2012; Junker‐Frohn et al, 2019; Karl et al., 2010; Morfopoulos et al, 2014; Singsaas et al., 1997; Velikova, Fares, & Loreto, 2008; Vickers, Gershenzon, Lerdau, & Loreto, 2009; Vickers, Possell, et al, 2009; Zuo et al., 2019). For example, in Populus nigra and Phragmites australis leaves exposed to oxidative stress, reduced damage to photosynthesis, accumulation of H 2 O 2 , and membrane denaturation were attributed, in part, to isoprene production (Velikova et al., 2008).…”

Toward the Genetic Improvement of Drought Tolerance in Conifers: An Integrated Approach

“…Water loss can cause multiple damages at the cellular level, such as decreased cell turgor, protein denaturation and changes in membrane fluidity [56]. In order to reduce cellular damage, plants can synthesize protective molecules, including some proteins, such as chaperonins and dehydrins [57], the amino acid proline [58], various carbohydrates [59] and isoprenoids [60]. These compounds act as osmotically active molecules, contributing to the increase in cell turgor when the water potential is low.…”