English plantain deploys stress tolerance mechanisms at various organization levels across an altitudinal gradient in the Pyrenees

Abstract

High‐mountain plants must withstand high solar irradiation and low temperatures during winter. Furthermore, climate change is increasing drought events, which pose an additional threat to plants. Here, we studied the stress tolerance mechanisms at various levels of biological organization in English plantain (Plantago lanceolata L.), focusing on photoprotective and antioxidant responses. The response of populations from three different altitudes in the Eastern Pyrenees (1030, 1380, and 1660 m. a.s.l.) was compared during both autumn and winter. Results showed that plants not only suffered from photoinhibition due to very low temperatures at the highest elevation during winter, but also from mild drought stress at the lowest altitude during autumn. Individuals growing at the highest elevation showed reductions in the maximum photochemical efficiency of PSII (Fv/Fm ratio), which might be caused by the lack of an increased induction of tolerance mechanisms at the highest elevation compared to the intermediate one. Although most leaves died at the highest elevation, plants could withstand stress at the organism level by generating new leaves once the stress ceased. Drought at the lowest elevation during autumn caused mild stress with small decreases in the Fv/Fm ratio, along with an increase in abscisic acid and jasmonic acid content. This study underlines the great capacity of English plantain to adapt to high elevation by activating not only photo‐ and antioxidant protection mechanisms and adjustments in stress‐related phytohormones, but also by fully regenerating its aboveground biomass through renewed growth once the stress has ceased.

Elucidating the molecular mechanisms underlying grassland species in response to more persistent precipitation regimes

“…Plantago differed from the other three species (especially the two grasses, Holcus and Phleum) under 20D regime by exhibiting recovery at the end of the experiment (wet period) by generating new leaves (Figure 4). This is consistent with Morales et al (2021)…”

Biological outliers: essential elements to understand the causes and consequences of reductions in maximum photochemical efficiency of PSII in plants

“…4 and 5 ). That is a result of this species incapacity to reverse extreme photoinhibitory damage at the leaf level under extreme desiccation periods as those experienced by native Mediterranean flora during the summer of 2023, but it must also be viewed as a successful developmental strategy to avoid too large growth and resources expenses during threatening periods, thus allowing to postpone activity until more favorable conditions occur after rainfalls (Werner et al 1999 ; Morales et al 2021 ).…”

“…3 , 4 and 5 ). The correlation between microclimatic conditions and these minor physiological stresses should be conducted in detail, especially among outliers, as it is known that divergent physiological traits are common at inter-individual level among populations of the same species at different localities (Breza et al 2012 ; Morales et al 2021 ). Altogether, these results show that in terms of leaf stress, not all individuals of white-leaved rockrose communities overcome summer stress conditions the same way, leading to leaf abscission processes that cease once the environmental conditions and physiological conditions recover in September (Fig.…”