Jose Ignacio Garcia Plazaola

University of the Basque Country | UPV/EHU · Vegetal Biology and Ecology

Early stress detection of crops requires a thorough understanding of the signals showing the very first symptoms of the alterations in the photosynthetic light reactions. Detection of the activation of the regulated heat dissipation mechanism is crucial to complement passively induced fluorescence to resolve ambuiguities in energy partitioning. Usi...

Drought‐related die‐off events have been observed throughout Europe in Scots pine ( Pinus sylvestris L.). Such events are exacerbated by carbon starvation that is, an imbalance of photosynthetic productivity and resource usage. Recent evidence suggests that optically measurable photosynthetic pigments such as chlorophylls and carotenoids respond to...

Bryophytes desiccate rapidly when relative humidity decreases. The capacity to withstand dehydration depends on several ecological and physiological factors. Volatile organic compounds (VOCs) may have a role in enhancing tolerance to desiccating bryophytes. However, the functions of VOCs in bryophytes have received little attention so far. We aimed...

The quantification of phytochemicals with nutritional benefits relies on accuracy yet time-consuming, expensive and destructive methodologies. In contrast, optical indices widely employed in disciplines such as ecology can serve as fast, low-cost, and non-destructive tools for tracking pigment changes. However, their potential application in postha...

The determination of physiological tolerance ranges of photosynthetic species and of the biochemical mechanisms underneath are fundamental to identify target processes and metabolites that will inspire enhanced plant management and production for the future. In this context, the terrestrial green algae within the genus Prasiola represent ideal mode...

Terrestrialization by photosynthetic eukaryotes took place in the two branches of green microalgae: Chlorophyta and Charophyta. Within the latter, the paraphyletic streptophytic algae divide into two clades. These are named Klebsormidiophyceae‐Chlorokybophyceae‐Mesostigmatophyceae (KCM), which is the oldest, and Zygnematophyceae‐Coleochaetophyceae‐...

Gesneriaceae is a pantropical family of plants that, thanks to their lithophytic and epiphytic growth forms, have developed different strategies for overcoming water scarcity. Desiccation tolerance or “resurrection” ability is one of them: a rare phenomenon among angiosperms that involves surviving with very little relative water content in their t...

Wood formation during the growing season is shaped by the intra-annual variability of climatic conditions. In the Mediterranean, the cambial activity is seasonally constrained by winter low temperature and summer drought, resulting in bimodal growth patterns. Although bimodal growth is an ecologically important adaptation of woody species to season...

Resurrection plants are able to deal with complete dehydration of their leaves and then recover normal metabolic activity after rehydration. Only a few resurrection species are exposed to freezing temperatures in their natural environments, making them interesting models to study the key metabolic adjustments of freezing tolerances. Here, we invest...

Antarctic macroalgal communities of the upper intertidal zone are particularly poor compared with other coastal regions. Exposure to desiccation and freezing combined with the abrasive effect of ice threatens the life of sessile organisms. One of the few species able to colonize this environment is the rhodophyte Pyropia endiviifolia. It belongs to...

Los manglares son ecosistemas únicos que crecen en aguas salobres en las fronteras de los litorales tropicales; representan un enorme valor científico, ecológico, económico y cultural. En Nicaragua representan una gran fuente de recursos económicos para las poblaciones locales. Las especies más afectadas por la tala son Rizophora mangle L, Rhizopho...

The summer climate in Maritime Antarctica is characterised by high humidity and cloudiness with slightly above zero temperatures. Under such conditions, photosynthetic activity is temperature-limited and plant communities are formed by a few species. These conditions could prevent the operation of the photoprotective xanthophyll (VAZ) cycle as low...

Leaves of Mediterranean evergreen tree species experience a reduction in net CO2 assimilation (AN) and mesophyll conductance to CO2 (gm) during aging and senescence, which would be influenced by changes in leaf anatomical traits at cell level. Anatomical modifications can be accompanied by the dismantling of photosynthetic apparatus associated to l...

Circadian rhythms affect many aspects of a plant’s metabolism including, but not limited to, photosynthesis. Here, we provide a complete protocol for determining changes in the composition of photosynthetic pigments (chlorophyll and carotenoids), and we also consider its implementation within circadian experiments. We describe how to design a circa...

Main conclusion Plastoglobules are ubiquitous under non-stress conditions and their morphology, closely related to their composition, changes differently depending on the specific stress that the plant undergoes. Abstract Plastoglobules are lipoprotein structures attached to thylakoid membranes, which participate in chloroplast metabolism and stre...

Evergreen plants growing at high latitudes or high elevations may experience freezing events in their photosynthetic tissues. Freezing events can have physical and physiological effects on the leaves which alter leaf optical properties affecting remote and proximal sensing parameters. We froze leaves of six alpine plant species ( Soldanella alpina...

For decades, the dynamic nature of chlorophyll a fluorescence (ChlaF) has provided insight into the biophysics and ecophysiology of the light reactions of photosynthesis from the subcellular to leaf scales. Recent advances in remote sensing methods enable detection of ChlaF induced by sunlight across a range of larger scales, from using instruments...

Desiccation tolerant plants can survive extreme water loss in their vegetative tissues. The fern Anemia caffrorum produces desiccation tolerant (DT) fronds in the dry season and desiccation sensitive (DS) fronds in the wet season, providing a unique opportunity to explore the physiological mechanisms associated with desiccation tolerance. Anemia ca...

Dehesas, human-shaped savannah-like ecosystems, where the overstorey is mainly dominated by the evergreen holm oak (Quercus ilex L. subsp. ballota [Desf.] Samp.), are classified as a global conservation priority. Despite being Q. ilex a species adapted to the harsh Mediterranean environmental conditions, recent decades have witnessed worrisome tren...

While most ferns avoid freezing by living in the tropics or shedding their fronds, wintergreen species in temperate and boreoalpine ecosystems deal with sub-zero temperatures. Increasing evidence has revealed overlapping mechanisms of desiccation and freezing-tolerance in angiosperms, but physiological mechanisms behind freezing tolerance in ferns...

Xanthophyll cycles are broadly important in photoprotection, and the reversible de‐epoxidation of xanthophylls typically occurs in excess light conditions. However, as presented in this review, compiling evidence in a wide range of photosynthetic eukaryotes shows that xanthophyll de‐epoxidation also occurs under diverse abiotic stress conditions in...

Carotenoids (Cars) regulate the energy flow towards the reaction centres in a versatile way whereby the switch between energy harvesting and dissipation is strongly modulated by the operation of the xanthophyll cycles. However, the cascade of molecular mechanisms during the change from light harvesting to energy dissipation remains spectrally poorl...

Snowmelt in alpine ecosystems brings ample water, and together with above‐freezing temperatures, initiates plant growth. In this scenario, rapid activation of photosynthesis is essential for a successful life‐history strategy. But, strong solar radiation in late spring enhances the risk of photodamage, particularly before photosynthesis is fully fu...

Resurrection plants recover physiological functions after complete desiccation. Almost all of them are native to tropical warm environments. However, the Gesneriaceae include four genera, remnant of the past palaeotropical flora, which inhabit temperate mountains. One of these species is additionally freezing‐tolerant: Ramonda myconi. We hypothesis...

In this work, we review the physiological and molecular mechanisms that allow vascular plants to perform photosynthesis in extreme environments, such as deserts, polar and alpine ecosystems. Specifically, we discuss the morpho/anatomical, photochemical and metabolic adaptive processes that enable a positive carbon balance in photosynthetic tissues...

Background: Non-invasive procedures for the diagnosis of viability of plant or fungal tissues would be valuable for scientific, industrial and biomonitoring purposes. Previous studies showed that infrared thermography (IRT) enables non-invasive assessment of the viability of individual "orthodox" (i.e. desiccation tolerant) seeds upon water uptake...

Members of the cosmopolitan streptophycean genus Klebsormidium live in various habitats including sand dunes and polar/alpine environments. To survive in these harsh areas they must contain an array of physiological and structural adaptive mechanisms, for example, to face chilling and photochilling stresses, which however have not been studied in d...

Background and Aims Lichens represent a symbiotic relationship between at least one fungal and one photosynthetic partner. The association between the lichen-forming fungus Mastodia tessellata (Verrucariaceae) and different species of Prasiola (Trebouxiophyceae) has an amphipolar distribution and represents a unique case study for the understanding...

Background and aims: Lichens represent a symbiotic relationship between at least one fungal and one photosynthetic partner. The association between the lichen-forming fungus Mastodia tessellata (Verrucariaceae) and different species of Prasiola (Trebouxiophyceae) has an amphipolar distribution and represents a unique case study for the understandi...

Fern spores of most species are desiccation tolerant (DT) and, in some cases, are photosynthetic at maturation, the so-called chlorophyllous spores (CS). The lifespan of CS in the dry state is very variable among species. The physiological, biochemical, and biophysical mechanisms underpinning this variability remain understudied and their interpret...

Vegetables, once harvested and stored on supermarket shelves, continue to perform biochemical adjustments due to their modular nature and their ability to retain physiological autonomy. They can live after being harvested. In particular, the content of some essential nutraceuticals, such as carotenoids, can be altered in response to environmental o...

Galactolipids (GLs) are the main lipids in chloroplast membranes and by default are also the most abundant polar lipids on earth. GLs with one or two galactose residues, monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG), are ubiquitous and essential for photosynthesis. GLs with a headgroup formed by three to five galactoses,...

Plants in the high Arctic are exposed to a 24-h photoperiod for several months. These conditions can be damaging for plants at lower latitudes. When common crops are artificially maintained under continuous light (CL), photosynthetic processes maintain endogenous circadian rhythms, but it is unclear whether plants naturally acclimated to CL also ma...

The consumption of zeaxanthin (Z) through a vegetable-rich diet is recommended to reduce the progression of age-related macular degeneration. Due to Z’s intrinsic dynamic character that results from its participation in the photoprotective xanthophyll cycle involving the carotenoids violaxanthin, antheraxanthin and zeaxanthin (VAZ), post-harvest ha...

Desiccation tolerant (DT) plants withstand complete cellular dehydration, reaching relative water contents (RWC) below 30% in their photosynthetic tissues. Desiccation sensitive (DS) plants exhibit different degrees of dehydration tolerance (DHT), never surviving water loss >70%. To date, no procedure for the quantitative evaluation of DHT extent e...

The accumulation of red pigments, frequently carotenoids, under chronic stress is a response observed in diverse kinds of eukaryotic photoautotrophs. It is thought that red pigments protect the chlorophyll located underneath by a light-shielding mechanism. However, the synthesis or degradation of carotenoids is a slow process and this response is u...

Fern spores are unicellular structures produced by the sporophyte generation that give rise to the haploid gametophyte. When released from the sporangium, spores are desiccation tolerant (DT) in the royal fern (Osmunda regalis) and contain fully developed chloroplasts. As a consequence, this type of spores is called chlorophyllous spores (CS). Upon...

Chloroplast of green photosynthetic tissues in the Viridiplantae (monophyletic group that includes green algae and terrestrial plants) is characterised by a relatively conserved composition of pigments (Esteban et al. 2015). Leaves of virtually all plant species invariably contain chlorophyll (Chl) a and Chl b, and six carotenoids. Five of them are...

The main role of lichen anthraquinones is in protection against biotic and abiotic stresses, such as UV radiation. These compounds are frequently deposited as crystals outside the fungal hyphae and most of them emit visible fluorescence when excited by UV. We wondered whether the conversion of UV into visible fluorescence might be photosyntheticall...

Key message Subarctic plants in summer (subjected to continuous light) showed photosynthetic pigment contents mainly driven by PPFD (unrelated to day/night cycles) and a xanthophyll cycle responsiveness to PPFD exacerbated during night-times. Abstract Composition and content of photosynthetic pigments is finely tuned by plants according to a subtl...

Desiccation tolerance (DT) represents an ecophysiological strategy probably developed during land conquest by primitive plants that have been progressively lost in photosynthetic tissues throughout evolution, in parallel to the development of mechanisms for the control of water content (i.e., vascular system, cuticle, stomata). Currently, DT of pho...

The photoprotective mechanisms of desiccation tolerance and freezing tolerance and their relation to molecular mobility (cell vitrification) were assessed in a single model: the exceptional subalpine and resurrection plant Ramonda myconi. Dehydrated leaves showed a drop in Fv/Fm accompanied by synthesis of zeaxanthin (Z), even in the dark, which wa...

The photosynthetic apparatus must cope with the excess energy when light exceeds what plant can use. Under these conditions, plants, including oaks, can activate an array of “photoprotection mechanisms”, which are crucial to understand the relationships between plants and their environment. First, this chapter gives a general description of the dif...

Plants that are tolerant of extreme low temperatures, and plants that are tolerant of desiccation, face similar physiological challenges, as low temperatures often result in extracellular ice formation resulting in desiccation of cells. Desiccation due to either low temperatures or water loss leads to severe mechanical as well as oxidative stress,...

Poplar species are economically important sources of timber and bioenergy and they also have a valuable application in phytoremediation and in forest restoration programmes. The characterization of their responses in the face of environmental constraints is essential to ascertain their adaptation capacity. Quantification of chloroplast pigments and...

Carotenoids distribution and function in seeds have been very scarcely studied, notwithstanding their pivotal roles in plants that include photosynthesis and phytohormone synthesis, pigmentation, membrane stabilization and antioxidant activity. Their relationship with tocochromanols, whose critical role in maintaining seed viability has already bee...

Lichens and free-living terrestrial algae are widespread across many habitats and develop successfully in ecosystems where a cold winter limits survival. With the goal of comparing photoprotective responses in free-living and lichenized algae, the physiological responses to chilling and photochilling conditions were studied in three lichens and the...

Despite being a small geographic extension, Mediterranean Basin is characterized by an exceptional plant biodiversity. Adaptive responses of this biocoenosis are delineated by an unusual temporal dissociation along the year between optimal temperature for growth and water availability. This fact generates the combination of two environmental stress...

Winter evergreens living in mountainous areas have to withstand a harsh combination of high light levels and low temperatures in wintertime. In response, evergreens can activate a photoprotective process that consists of the down-regulation of photosynthetic efficiency, referred to as winter photoinhibition (WPI). WPI has been studied mainly in woo...

There is increasing evidence that the circadian clock is a significant driver of photosynthesis that becomes apparent when environmental cues are experimentally held constant. We studied whether the composition of photosynthetic pigments is under circadian regulation, and whether pigment oscillations lead to rhythmic changes in photochemical effici...

Haplophyllum linifolium (L.) G. Don fil. Iberiar Penintsulako endemismoa da, Euskal Autonomia Erkidegoko flora mehatxatuaren zerrendan galtzeko arriskuan bezala katalogatzen dena. Ikerketa honen helburuak izan dira, batetik espezie honen hozidura protokoloak lortzea eta, bestetik, espezie horren hazien bideragarritasuna ikustea Tetrazolio Testaren...

Carotenoids constitute a major target of chloroplastic photooxidative reactions, leading to the formation of several oxidized derivatives and cleavage products, some of which are volatile (VCCPs). Among them, β-cyclocitral (β-CC), at least, is a retrograde signaling molecule that modulates the activity of many key physiological processes. In the pr...