Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title><jats:p>Drought tolerance varies greatly across <jats:italic>Vitis vinifera</jats:italic> cultivars, depending on physiological responses and structural and morphological adaptations. In this study, responses to water stress were examined in three extensively cultivated varieties from Northern Italy. Over the course of two seasons, mature potted vines were subjected to a 12 or 13‐day period of water restriction. Vine water relations were investigated using measures of water potential, gas exchanges, and leaf ABA content. Leaf angle response to increasing water stress was analysed in the four cultivars as a mechanism that improves stress tolerance. Different physiological responses were observed among cultivars, suggesting a near‐isohydric water‐use strategy for Moscato and a near‐anisohydric one for Garganega, Glera and Merlot. Results of leaf ABA analysis highlighted a variability among the studied varieties, indicating higher contents and lower sensitivity to ABA for the anisohydric ones. In all varieties, a similar increase in midday leaf inclination was observed in response to decreasing stem water potentials, indicating that leaf angle adjustments may represent a common adaptive response to drought. These findings increase the understanding of the leaf physiological and structural mechanisms that contribute to water stress tolerance in grapevine, supporting a more efficient cultivar selection to cope with the expected changes in Mediterranean climate.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Green tea made from albino buds and leaves has a strong umami taste and aroma. The cultivar ‘Zhonghuang 2’ (ZH2, <jats:italic>Camellia sinensis</jats:italic>) is a natural mutant with young shoots that are yellow in spring and green or yellow‐green in summer. However, the mechanism of leaf color change remains unclear. Here, we found that young shoots of ZH2 were yellow at low temperature (LT) and green at high temperature (HT), indicating that ZH2 is a temperature‐sensitive cultivar. Transmission electron microscopy analysis showed that the grana in the chloroplasts of young shoots grown at LT were poorly stacked, which caused a lack of photoreactions and chlorophyll. RNA‐seq results showed 1279 genes differentially expressed in the young shoots grown at LT compared with those at HT, including genes related to cytochrome synthesis, chloroplast development, photosynthesis, and DNA methylation. A whole‐genome bisulfite sequencing assay revealed that the dynamics of DNA methylation levels in the CG, CHG, and CHH contexts decreased under LT, and the change was most obvious in the CHH context. Furthermore, 72 genes showed significant changes in both expression and DNA methylation levels, and most of them were related to cytochrome synthesis, chloroplast development, photosynthesis, transcription factors, and signaling pathways. These results demonstrate that DNA methylation is involved in the LT‐regulated albino processes of ZH2. Changes in DNA methylation levels were associated with changes in gene expression levels, affecting the structure and function of chloroplasts, which may have a phenotypic impact on shoot and leaf color.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Water scarcity can be considered a major stressor on land, with desiccation being its most extreme form. Land plants have found two different solutions to this challenge: avoidance and tolerance. The closest algal relatives to land plants, the Zygnematophyceae, use the latter, and how this is realized is of great interest for our understanding of the conquest of land. Here, we worked with two representatives of the Zygnematophyceae, <jats:italic>Zygnema circumcarinatum</jats:italic> SAG 698‐1b and <jats:italic>Mesotaenium endlicherianum</jats:italic> SAG 12.97, who differ in habitats and drought resilience. We challenged both algal species with severe desiccation in a laboratory setup until photosynthesis ceased, followed by a recovery period. We assessed their morphological, photophysiological, and transcriptomic responses. Our data pinpoint global differential gene expression patterns that speak of conserved responses, from calcium‐mediated signaling to the adjustment of plastid biology, cell envelopes, and amino acid pathways, between Zygnematophyceae and land plants despite their strong ecophysiological divergence. The main difference between the two species appears to rest in a readjustment of the photobiology of <jats:italic>Zygnema</jats:italic>, while <jats:italic>Mesotaenium</jats:italic> experiences stress beyond a tipping point.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Patchouli alcohol, a significant bioactive component of the herbal plant <jats:italic>Pogostemon cablin</jats:italic>, has considerable medicinal and commercial potential. Several genes and transcription factors involved in the biosynthesis pathway of patchouli alcohol have been identified. However, so far, regulatory factors directly interacting with patchouli synthase (PTS) have not been reported. This study was conducted to analyze the interaction between PcENO3 and PcPTS to explore the molecular regulation effect of PcENO3 on patchouli alcohol biosynthesis. PcENO3, a homologous protein of <jats:italic>Arabidopsis</jats:italic> ENO3 belonging to the enolase family, was identified and characterized. Subcellular localization experiments in <jats:italic>Arabidopsis</jats:italic> protoplast cells indicated that the PcENO3 protein was localized in both the cytoplasm and nucleus. The physical interaction between PcENO3 and PcPTS was confirmed through yeast two‐hybrid (Y2H), GST pull‐down, and bimolecular fluorescence complementation assays. Furthermore, the Y2H assay demonstrated that PcENO3 could also interact with JAZ proteins in the JA pathway. Enzymatic assays showed that the interaction with PcENO3 increased the catalytic activity of patchoulol synthase. Additionally, suppression of <jats:italic>PcENO3</jats:italic> expression with VIGS (virus‐induced gene silencing) decreased patchouli alcohol content compared to the control. These findings suggest that PcENO3 interacts with patchoulol synthase and modulates patchoulol biosynthesis by enhancing the enzymatic activity of PcPTS.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Climate change‐induced concurrent drought and salinity stresses significantly threaten global crop yields, yet the physio‐biochemical responses to combined stress in quinoa remain elusive. This study evaluated quinoa responses under four growth conditions: well‐watered, drought stress, salt stress, and drought + salt stress with (15 mM) or without (0 mM) exogenous hydrogen peroxide (H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub>) application. All examined stresses (alone or in combination) reduce quinoa growth and net photosynthesis, although salt stress was found to be less destructive than drought and combined stress. Strikingly, superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), stomatal conductance (g<jats:sub>s</jats:sub>), photosynthetic rate (P<jats:sub>N</jats:sub>), K<jats:sup>+</jats:sup> uptake, shoot height, shoot fresh, and dry weight were increased by 46.1%, 22.2%, 101.6%, 12.9%, 12.1%, 22.4%, 7.1%, 14%, and 16.4%, respectively, under combined stress compared to drought alone. In addition, exogenous H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub> effectively improved gaseous exchange, osmolytes' accumulation, and antioxidant activity, resulting in reduced lipid peroxidation, which eventually led to higher plant growth under all coercive conditions. The principle component analysis (PCA) indicated a strong positive correlation between antioxidant enzymes and inorganic ions, which contributed efficiently to osmotic adjustment, particularly under conditions of salinity followed by combined stress. In short, in combination, salt stress has the potential to mitigate drought‐induced injuries by promoting the absorption of inorganic solutes for osmoregulation in quinoa plants. Furthermore, exogenous application of H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub> could be opted to enhance quinoa performance to increase its tolerance mechanism against drought and salinity, even under combined stress.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Cyanobacteria utilize CO<jats:sub>2</jats:sub> and HCO<jats:sub>3</jats:sub><jats:sup>−</jats:sup> as inorganic carbon (Ci) sources. In low Ci, like in ambient air, cyanobacteria efficiently collect Ci using a carbon concentrating mechanism (CCM). The CCM includes bicarbonate transporters SbtA, BicA and BCT1; the specialized NDH complexes NDH‐1<jats:sub>3</jats:sub> and NDH‐1<jats:sub>4</jats:sub>, which convert CO<jats:sub>2</jats:sub> to HCO<jats:sub>3</jats:sub><jats:sup>−</jats:sup> in the cytoplasm; and carboxysomes that are protein shell encapsulated ribulose‐1,5‐bisphosphate carboxylase/oxygenase (RuBisCo) and carbonic anhydrase containing bodies in which the first reaction of carbon fixation occurs. Ci‐dependent regulation of bicarbonate transporters and specialized NDH complexes, especially the regulation of the SbtA transporter, are well understood. CcmR (also called NdhR), CyAbrB2, CmpR and RbcR act as transcription factors regulating CCM genes. Ci signalling molecules detecting the metabolic status of the cells include 2‐oxoglutarate, which accumulates when the Ci/nitrogen ratio of the cell is high, and 2‐phosphoglycolate, the first intermediate of the photorespiration pathway, whose accumulation indicates low Ci. These signalling molecules act as corepressors and coactivators of the CcmR repressor protein, whereas 2‐phosphoglycolate and ribulose‐1,5‐bisphosphate activate transcription activator CmpR. In addition, bicarbonate or CO<jats:sub>2</jats:sub> activates the adenylyl cyclase that produces cAMP, and ATP/ADP/AMP provide information about the energy status of the cell. Less is known about the molecular mechanisms regulating carboxysome dynamics or how production, activity and degradation of photosynthetic complexes are regulated by prevailing Ci conditions or which mechanisms adjust cell division according to Ci. This minireview summarizes the present knowledge about molecular mechanisms regulating cyanobacterial acclimation to prevailing Ci.</jats:p>

<jats:title>Abstract</jats:title><jats:p>Plants must face various environmental stresses that they cannot avoid, and they have developed numerous mechanisms to survive these challenges. Phosphate‐mediated signal transduction is a common method for regulating gene expression and protein activity in response to stresses. Phosphate groups can be transferred to other proteins by proteins called kinases. MAP3Ks are the largest kinase family in plants, and they comprise various group and individual pathways collectively known as MAPK cascades. When plants encounter environmental stresses, several MAP3Ks act as positive or negative regulators by phosphorylating downstream proteins within the MAPK cascade, as well as transcription factors, cytoskeletal proteins, enzymes, and kinases, through their kinase activity. In addition, other upstream kinases and phosphatases regulate MAP3Ks by adding or removing phosphate groups. Various MAP3Ks have been isolated in many plant species, and evidence suggests that they function as post‐translational modulators under various abiotic stresses, including ABA responses as well as salinity, osmotic, drought, oxidative, cold, and heat stress. This review focuses on how plant MAP3Ks affect various abiotic stresses as regulators and substrates through post‐translational phosphorylation.</jats:p>

<jats:title>Abstract</jats:title><jats:p>It is hypothesized that ‘hydraulic vulnerability segmentation’ (the vulnerability of expendable organs is higher compared to the vulnerability of nonexpendable organs) can enhance the drought‐tolerance of trees. However, prediction of positive segmentation (leaf minus branch) did not gain undisputed support in field observations. Further, the main organs of trees (leaf/trunk/root) are vital to test the hypothesis at the individual level. Unfortunately, most verifications of the hypothesis focus on the hydraulic vulnerabilities between leaves and terminal branches of mature trees. In this study, we grew three deciduous oak (<jats:italic>Quercus mongolica</jats:italic>, <jats:italic>Q. variabilis</jats:italic> and <jats:italic>Q. aliena</jats:italic>) seedlings (6 months old), and measured the hydraulic vulnerabilities of leaves (by rehydration method), main stems and main roots (by bench dehydration method). The sensitivity of stomata to water potential was obtained by monitoring the stomata conductance response to drought stress. The xylem anatomy of main stem and main root was also measured. It was found that the leaves of all three oak species exhibited greater vulnerability than the main stems and main roots. The leaf‐stem segmentation was more pronounced than the stem‐root one, and the stem‐root in <jats:italic>Q. aliena</jats:italic> even showed a reversed segmentation. Further, we found that higher stomatal sensitivity was associated with higher P<jats:sub>50,leaf</jats:sub> (water potential at 50% loss of leaf hydraulic conductivity), and narrower segmentation between leaf and the most embolism‐resistant organ. Collectively, our results support the ‘hydraulic vulnerability segmentation’ hypothesis at the individual level, and highlight the importance of stomatal regulation in hydraulic vulnerability segmentation.</jats:p>