Fungal Endophytes Exert Positive Effects on Colobanthus quitensis Under Water Stress but Neutral Under a Projected Climate Change Scenario in Antarctica

Abstract

Functional symbiosis is considered one of the successful mechanisms by which plants that inhabit extreme environment improve their ability to tolerate different types of stress. One of the most conspicuous type of symbiosis is the endophyticism. This interaction has been noted to play a role in the adaptation of the native vascular plant Colobanthus quitensis to the stressful environments of Antarctica, characterized by low temperatures and extreme aridity. Projections of climate change for this ecosystem indicate that abiotic conditions will be less limiting due to an increase in temperature and water availability in the soil. Due to this decrease in stress induced by the climate change, it has been suggested that the positive role of fungal endophytes on performance of C. quitensis plants would decrease. In this study, we evaluated the role of endophytic fungi on osmoprotective molecules (sugar production, proline, oxidative stress) and gene expression (CqNCED1, CqABCG25, and CqRD22) as well as physiological traits (stomatal opening, net photosynthesis, and stomatal conductance) in individuals of C. quitensis. Individual plants of C. quitensis with (E+) and without (E−) endophytic fungi were exposed to simulated conditions of increased water availability (W+), having the current limiting water condition (W−) in Antarctica as control. The results reveal an endophyte-mediated lower oxidative stress, higher production of sugars and proline in plants. In addition, E+ plants showed differential expressions in genes related with drought stress response, which was more evident in W− than in W+. These parameters corresponded with increased physiological mechanisms such as higher net photosynthesis, stomatal opening and conductance under presence of endophytes (E+) as well as the projected water condition (W+) for Antarctica. These results suggest that the presence of fungal endophytes plays a positive role in favoring

Genome‐wide association study of cyanogenic glycosides, proline, sugars, and pigments in Eucalyptus cladocalyx after 18 consecutive dry summers

“…Our study found an inverse relationship between CNglcs and either proline or TSS in leaves of E. cladocalyx, mainly at the levels of provenances and genetically differentiated groups. Soluble sugars and proline are osmoregulatory molecules and are accumulated in plant cells to maintain the cell turgor pressure in response to water deficit (Hereme et al, 2020;Moustakas et al, 2011). In this study, the five study provenances were evaluated in a dry condition with similar rainfall regime to the area of Cowell (Eyre Peninsula), where a water stress condition has been demonstrated with stable isotopes .…”

Fungal Symbionts Enhance N-Uptake for Antarctic Plants Even in Non-N Limited Soils

“…in previous experiments made by our research group (Ramos et al, 2018;Barrera et al, 2020;Hereme et al, 2020). After 4 weeks, endophyte infection was assessed by counting aniline blue-stained fungal hyphaes in root cross-sections in 10% of the produced plants as the percentage of infested root length (Bacon and White, 2000).…”

Maternal Exposure to Ozone Modulates the Endophyte-Conferred Resistance to Aphids in Lolium multiflorum Plants

“…These are suggested to explain the usually documented higher performance of endophyte-symbiotic plants, relative to endophyte-free plants, under conditions of stress caused by biotic (competing plants, herbivores, pathogens) and abiotic factors (drought, heavy metal, herbicides) [38][39][40][42][43][44][45]. Nonetheless, the endophyte effects on host plant performance have been shown to depend on the ecological context and thus, symbiosis outcome can yield positive, neutral, or even negative [46][47][48].…”