Enrique Ostria-Gallardo

In the 19th century it was proposed that ecophysiology was best studied in regions with extreme climatic conditions. In the present perspective, we argue that perhaps this is more timely than ever. The main reason is the need to improve crops to be simultaneously more productive—due to the increased population—and more stress tolerant—due to climate change. Climate change induces plants to face not just harsh but also ‘unexpected’ (unpredictable) climatic conditions. In this sense, we hypothesize that ‘sherplants’, namely plants living in the extremes of plant life (e.g. hot deserts, Arctic and Antarctica, or high elevations) can provide cues on how to break the trade-off between productivity and stress tolerance, as they need to be produced quickly due to the very short growing period while being stress tolerant due to the harsh and unpredictable climate endured during most of the year. We present glimpses of results from three consecutive projects developed over the last 10 years, in which hundreds of species from different regions of the world have been studied. In particular, we propose a pathway for developing ‘shercrops’ learning from ‘sherplants’, debate whether some of the already studied species may have really broken the aforementioned trade-off, and present a number of interesting unforeseen discoveries made when studying plants from extreme climates.

In the north and center of Chile, there has been a significant environmental contamination by copper due to natural factors, mining activities and use of agricultural fertilizers and pesticides. Copper (Cu) soil contamination is of important concern in agriculture, food safety, and human health. Soil copper concentrations higher than 100–150 mg/kg can be toxic for plants and other organisms. Therefore, identification of copper-tolerant crops is of great interest for sustainable cultivation purposes. Quinoa is a promising candidate as a copper-tolerant crop, owing to its wide genetic diversity, high adaptability to different environmental conditions, and tolerance to abiotic stresses. In this work, we evaluated the effect of copper on 21 accessions of quinoa (including 19 accessions from different geographical locations of Chile) in order to identify tolerant and sensitive accessions. Our results show that (1) Germination parameters of quinoa are negatively affected in the presence of increasing Cu concentrations, with differential inhibition values among accessions. (2) Early seedling growth of accessions was differentially affected in the presence of Cu. (3) Plant biomass production (relative fresh and dry weights) was also affected by Cu, with significant differences between accessions. A Principal Component Analysis (PCA) of these data identified accessions based on Cu tolerance. (4) A clear regional pattern was observed when comparing accessions from northern, central, and southern Chile, suggesting local adaptation to Cu-rich soils. Thus, significant differences in copper tolerance between accessions were observed, revealing genetic diversity in copper tolerance among quinoa accessions. Tolerant accessions of quinoa can have important applications in sustainable agriculture.

Article Enrique Ostria-Gallardo ^1,*, Valentina Cabrera ¹, Estrella Zúñiga-Contreras ², José Ortiz¹, León Bravo ³, Teodoro Coba de La Peña ², Jaime G. Cuevas ² and Luisa Bascuñán-Godoy ^{1 1} Laboratorio de Fisiología Vegetal, Departamento de Botánica, Facultad de Cs. Naturales y Oceanográficas, Universidad de Concepción, Concepción 4030000, Chile ² Centro de Estudios Avanzados en Zonas Áridas, CEAZA, La Serena 1700000, Chile ³ Laboratorio de Fisiología y Biología Molecular Vegetal, Instituto de Agroindustria, Departamento de Ciencias Agronómicas y Recursos Naturales, Facultad de Ciencias Agropecuarias y Medioambiente, Universidad de La Frontera, Temuco 4780000, Chile * Correspondence: eostria@udec.cl; Tel.: +56-41-2661032 Received: 10 August 2024; Revised: 6 March 2025; Accepted: 12 March 2025; Published: 14 March 2025 Abstract: Nitrogen is crucial for plant development and crop production. Amaranthus cruentus, a C₄ species, has been pointed out as a high-nutritious and stress resilient crop. Here we studied the effects of sufficient and low nitrogen supplementation on the photosynthetic efficiency and metabolic responses of A. cruentus. Photochemical parameters from dark-adapted and transient chlorophyll fluorescence measurements, antioxidant enzymes activity, and metabolomic analysis, were evaluated to depict the impact of nitrogen availability. Photochemical parameters showed a significant decrease compared to those from gas exchange. The antioxidant enzymes activity revealed variations among treatments, being important at low nitrogen availability. At the metabolic level, there is a significant accumulation of L-glutamine, aromatic amino acids and ascorbic acid in A. cruentus with sufficient nitrogen. At low nitrogen, the metabolic profile of A. cruentus suggests stabilization of membrane structure and efficient use of available nitrogen by accumulating L-glutamic acid. The differential accumulation of L-glutamine and L-glutamic acid reflects an adaptive strategy for maintaining nitrogen. Nitrogen-rich conditions, the plant stores excess nitrogen as L-glutamine, while in deficiency, it utilizes L-glutamic acid for essential metabolic functions. Overall, A. cruentus activates a coordinated metabolic strategy under LN to optimize nitrogen use. This includes effective ROS detoxification via both enzymatic and non-enzymatic antioxidants, structural reinforcement through membrane-stabilizing lipids, and efficient nitrogen storage and redistribution to meet metabolic demands during nitrogen limitation.

Plants have developed various strategies to deal with abiotic stresses throughout their lifetimes. However, environmental stresses can have long‐lasting effects, positively modifying plant physiological responses to subsequent stress episodes, a phenomenon known as preconditioning or stress memory. Intriguingly, this memory can even be transmitted to offspring, referred to as “inter‐ or transgenerational memory”.Chenopodium quinoa is a pseudocereal that can withstand several abiotic stresses, including nitrogen (N) limitation. This research highlights the critical role of maternal N conditions in shaping the physiological and metabolic responses of their offspring. Mother quinoa plants (F0) were grown under High N (HN) or Low N (LN) conditions. LN_F0 plants exhibited lower panicle biomass, net photosynthesis, and yield compared to HN_F0 plants. Seeds from LN_F0 retained proteins, reduced amino acids’ levels, and increased lipids (such as PI 34:2), especially phosphatidylcholines, and their unsaturation level, which was associated with faster germination compared to HN_F0 seeds. Offsprings seedlings (F1) grown under either HN or LN had similar proteins and amino acid proportions of their seeds. However, LN_F0LN_F1 seedlings displayed significantly higher biomass and number of root tips. These changes were significantly correlated with transpiration, net photosynthesis, and stomatal conductance, as well as with starch content, suggesting higher CO₂ fixation at the whole plant level in LN_F0LN_F1 plants.Our findings suggest that quinoa transmits maternal environmental stress information to its offspring, modulating their resilience. This work underscores the potential of utilizing maternal environmental conditions as a natural priming tool to enhance crop resilience against nutritional stress.

Desert shrubs are keystone species for plant diversity and ecosystem function. Atriplex clivicola and Atriplex deserticola (Amaranthaceae) are native shrubs from the Atacama Desert that show contrasting altitudinal distribution (A. clivicola: 0–700 m.a.s.l.; A. deserticola: 1500–3000 m.a.s.l.). Both species possess a C4 photosynthetic pathway and Kranz anatomy, traits adaptive to high temperatures. Historical records and projections for the near future show trends in increasing air temperature and frequency of heat wave events in these species’ habitats. Besides sharing a C4 pathway, it is not clear how their leaf-level physiological traits associated with photosynthesis and water relations respond to heat stress. We studied their physiological traits (gas exchange, chlorophyll fluorescence, water status) before and after a simulated heat wave (HW). Both species enhanced their intrinsic water use efficiency after HW but via different mechanisms. A. clivicola, which has a higher LMA than A. deserticola, enhances water saving by closing stomata and maintaining RWC (%) and leaf Ψ_md potential at similar values to those measured before HW. After HW, A. deserticola showed an increase of A_max without concurrent changes in g_s and a significant reduction of RWC and Ψ_md. A. deserticola showed higher values of Chla fluorescence after HW. Thus, under heat stress, A. clivicola maximizes water saving, whilst A. deserticola enhances its photosynthetic performance. These contrasting (eco)physiological strategies are consistent with the adaptation of each species to their local environmental conditions at different altitudes.

Induced systemic resistance (ISR) is one of the most studied mechanisms of plant–microbe interaction and is considered a very promising alternative for integrated pest management programs. In our study, we explored the plant defense response induced by Bacillus velezensis BBC047 in relation to its application before or after Botrytis cinerea infection of tomato plants. The inoculation of BBC047 did not considerably alter the gene expression of the tomato tissues, whereas infection with B. cinerea in BBC047-primed plants induced expression of LRR and NBS-LRR receptors, which are highly related to the ISR response. As expected, B. cinerea infection generated molecular patterns typical of a defense response to pathogen infection as the overexpression of pathogenesis-related proteins (PRs) in leaflets distant to the point of infection. The curative treatment (P + F + B) allowed us to gain insights into plant response to an inverted priming. In this treatment, B. cinerea caused the m tissue damage, extending nearly entirely across the entire infected leaves. Additionally, genes generally associated with early SAR response (<16 h) were overexpressed, and apparently, the beneficial strain was not perceived as such. Therefore, we infer that the plant defense to the curative treatment represents a higher degree of biological stress triggered by the incorporation of strain BBC047 as second arriving microorganism. We highlight the importance the phytosanitary status of plants prior to inoculation of beneficial microorganism for the biocontrol of pathogens.

Throughout evolution, plants have developed different strategies of responses and adaptations that allow them to survive in different conditions of abiotic stress. Aloe vera (L.) Burm.f. is a succulent CAM plant that can grow in warm, semi-arid, and arid regions. Here, we tested the effects of preconditioning treatments of water availability (100, 50, and 25% of soil field capacity, FC) on the response of A. vera to prolonged drought growing in the hyper-arid core of the Atacama Desert. We studied leaf biomass, biochemical traits, and photosynthetic traits to assess, at different intervals of time, the effects of the preconditioning treatments on the response of A. vera to seven months of water deprivation. As expected, prolonged drought has deleterious effects on plant growth (a decrease of 55–65% in leaf thickness) and photosynthesis (a decrease of 54–62% in E_max). There were differences in the morphophysiological responses to drought depending on the preconditioning treatment, the 50% FC pretreatment being the threshold to better withstand prolonged drought. A diurnal increase in the concentration of malic acid (20–30 mg mg⁻¹) in the points where the dark respiration increased was observed, from which it can be inferred that A. vera switches its C3-CAM metabolism to a CAM idling mode. Strikingly, all A. vera plants stayed alive after seven months without irrigation. Possible mechanisms under an environmental context are discussed. Overall, because of a combination of morphophysiological traits, A. vera has the remarkable capacity to survive under severe and long-term drought, and further holistic research on this plant may serve to produce biotechnological solutions for crop production under the current scenario of climatic emergency.

As consequence of global change, there has been an intensification of syndromes such as land desertification in several regions of the world. Plant functioning is threatened by this scenario.

Hymenoglossum cruentum (Hymenophyllaceae) is a poikilohydric, homoiochlorophyllous desiccation-tolerant (DT) epiphyte fern. It can undergo fast and frequent dehydration-rehydration cycles. This fern is highly abundant at high-humidity/low-light microenvironments within the canopy, although rapid changes in humidity and light intensity are frequent. The objective of this research is to identify genes associated to desiccation-rehydration cycle in the transcriptome of H. cruentum to better understand the genetic dynamics behind its desiccation tolerance mechanism. H. cruentum plants were subjected to a 7 days long desiccation-rehydration process and then used to identify key expressed genes associated to its capacity to dehydrate and rehydrate. The relative water content (RWC) and maximum quantum efficiency (F_v/F_m) of H. cruentum fronds decayed to 6% and 0.04, respectively, at the end of the desiccation stage. After re-watering, the fern showed a rapid recovery of RWC and F_v/F_m (ca. 73% and 0.8, respectively). Based on clustering and network analysis, our results reveal key genes, such as UBA/TS-N, DYNLL, and LHC, orchestrating intracellular motility and photosynthetic metabolism; strong balance between avoiding cell death and defense (CAT3, AP2/ERF) when dehydrated, and detoxifying pathways and stabilization of photosystems (GST, CAB2, and ELIP9) during rehydration. Here we provide novel insights into the genetic dynamics behind the desiccation tolerance mechanism of H. cruentum.

Background: Filmy-ferns (Hymenophyllaceae) are poikilohydric, homoiochlorophyllous desiccation-tolerant (DT) epiphytes. They can colonize lower and upper canopy environments of humid forest. Filmy-ferns desiccate rapidly (hours), contrasting with DT angiosperms (days/weeks). It has been proposed that desiccation tolerance in filmy-ferns would be associated mainly with constitutive features rather than induced responses during dehydration. However, we hypothesize that the inter-specific differences in vertical distribution would be associated with different dynamics of gene expression within the dehydration or rehydration phases. A comparative transcriptomic analysis with an artificial neural network was done on Hymenophyllum caudiculatum (restricted to lower canopy) and Hymenophyllum dentatum (reach upper canopy) during a desiccation/rehydration cycle. Results: Raw reads were assembled into 69,599 transcripts for H. dentatum and 34,726 transcripts for H. caudiculatum. Few transcripts showed significant changes in differential expression (DE). H. caudiculatum had ca. twice DE genes than H. dentatum and higher proportion of increased-and-decreased abundance of genes occurs during dehydration. In contrast, the abundance of genes in H. dentatum decreased significantly when transitioning from dehydration to rehydration. According to the artificial neural network results, H. caudiculatum enhanced osmotic responses and phenylpropanoid related pathways, whilst H. dentatum enhanced its defense system responses and protection against high light stress. Conclusions: Our findings provide a deeper understanding of the mechanisms underlying the desiccation tolerance responses of two filmy ferns and the relationship between the species-specific response and the microhabitats these ferns occupy in nature.