Physiologia Plantarum

Strigolactones (SLs) are an important class of plant hormones that play crucial roles in regulating plant branching, root architecture, and organ development. However, the regulatory mechanisms underlying the crosstalk between SLs and other plant hormones remain largely unclear, particularly regarding the key regulatory genes that integrate and coordinate multiple hormonal signaling pathways. In this study, secondary cup seedlings of the Pisang Awak banana cultivar Yufen 6 at the eight-leaf stage were used as experimental materials. The roots were treated with a nutrient solution containing 30 mol/L exogenous SLs, while a nutrient solution supplemented with water served as the control. Tissues near the corm growth point were collected at 0, 15, 30, 60, 90, and 120 days after treatment to measure corm weight, height, and diameter, and transcriptome sequencing was performed using the collected tissues. Differentially expressed genes (DEGs) at different treatment stages were identified, followed by Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses to systematically investigate the crosstalk between SLs and endogenous hormone metabolism and signaling during corm development in Pisang Awak banana. The results showed that SL treatment significantly inhibited the weight, height, and diameter of the corm. The regulatory effect of SLs on Pisang Awak banana corm development exhibited a clear temporal dynamic pattern, representing a gradual accumulation process that ultimately triggers key developmental transitions. The highest number of DEGs was detected at 15 days after treatment, including 3943 upregulated genes and 3704 downregulated genes, indicating that this stage represents a critical phase for SL response initiation. GO enrichment analysis revealed that the DEGs were mainly involved in metabolic processes, biological regulation, response to stimulus, and regulation of biological processes. KEGG pathway analysis indicated that these DEGs were significantly enriched in pathways related to plant hormone signal transduction, starch and sucrose metabolism, and secondary metabolite biosynthesis. Further analysis revealed that the crosstalk between SLs and multiple hormone metabolic and signaling pathways is mediated by the SPL15 gene, involving auxin (IAA), cytokinin (CTK), abscisic acid (ABA), brassinosteroids (BRs), gibberellins (GA), and jasmonic acid (JA) pathways. This study reveals the molecular mechanism by which SLs regulate Pisang Awak banana corm development through SPL15-mediated integration of multiple hormonal signals, providing new insights into the role of SLs in regulating the development of underground organs in banana.

Atmospheric nitrogen (N) deposition is increasingly affecting global ecosystems, with nitrate contributing a growing proportion alongside ammonium. However, the interaction between N forms and leaf developmental stage in shaping physiological and metabolic strategies in Chinese fir remains poorly understood. In this study, a field experiment was conducted to explore the physiological and metabolic responses of young and old leaves to ammonium and nitrate N addition. Our findings showed that N addition enhanced photosynthetic performance in young leaves, with a stronger effect from nitrate. In contrast, old leaves exhibited limited photosynthetic response but accumulated higher non-structural carbohydrates and showed elevated N assimilation enzyme activities, particularly under nitrate addition. Phytohormone profiles varied between leaf ages, with young leaves having higher auxin levels while old leaves exhibiting increased abscisic and salicylic acid contents under N addition. Additionally, N addition induced differential reprogramming of amino acid metabolism, with age-dependent accumulation patterns. Metabolomic analysis identified key amino acids involved in coordinating carbon-nitrogen metabolism. These results highlighted the complementary metabolic strategies by young and old leaves of Chinese fir under contrasting N forms addition and emphasized the importance of considering both N form and leaf age in optimizing N management for sustainable plantation practices. HighlightsO_LINitrate enhanced photosynthesis in young Chinese fir leaves more effectively than ammonium. C_LIO_LIOld leaves prioritized C storage and N assimilation under N addition, especially nitrate. C_LIO_LIComplementary metabolic strategies between leaf ages optimized resource use under different N forms addition. C_LI

Published studies have reported species-variance between profiles of Calvin-Benson cycle (CBC) intermediates, not only between C4 species and C3 species, but also within C3 species (Arrivault et al., 2019, Borghi et al. 2019). It was proposed that this variance reflects lineage-dependent changes in the balance between different reactions, or poising, of the CBC. These earlier studies investigated phylogenetically-unrelated C3 species. In the current study, CBC intermediates were profiled in five closely-related species from Solanum sect. lycopersicon subsect. Lycopersicum. The levels of individual CBC intermediates showed many significant differences. In a principal component analysis, whilst three species (Solanum lycopersicum, Solanum cheesmaniae, Solanum neorickii) overlapped, Solanum pimpinellifolium and especially Solanum pennellii grouped separately, and were at opposing ends of the distribution. When combined with published data, whilst the separation between Solanum species was retained, they formed a group that was separated from five other C3 species, as well as two C4 species. It is discussed that the observed variation in CBC metabolites profiles within Solanum, together with their separation from other C3 species, supports the idea that CBC evolution is shaped both by phylogenetic relatedness and lineage-specific adaptation. HighlightVariance of intermediate levels points to poising of the Calvin-Benson cycle varying between closely-related species in the tomato clade Solanum sect. lycopersicon subsect. Lycopersicum

Aquaporins play a key role in plant responses to drought. Our previous work showed limited embolism in grapevine leaves under mild water stress and suggested that the outside-xylem water pathway plays a dominant role in reducing leaf hydraulic conductance (Kleaf) during dehydration. We used CRISPR-Cas9 to knockout the PIP2;1 aquaporin encoding gene in Vitis vinifera cv. Chardonnay to study how leaf function during dehydration is affected by this aquaporin isoform. We measured functional responses like stomatal and photosynthetic responses as well as Kleaf to compare wild-type and two independent PIP2;1 knockout lines. Under moderate drought, mutants maintained greater stomatal conductance (gs) and photosynthetic rates as {Psi}w declined. No significant differences were observed in mesophyll conductance (gm) across genotypes, however, mutants exhibited slightly higher values under moderate drought. Interestingly, all lines exhibited similar Kleaf vulnerabilities to drought. Our findings show that PIP2;1 induces earlier stomatal closure during dehydration while not modulating Kleaf responses across genotypes. This rapid response in WT plants would prevent further water loss that would lead to higher xylem tensions that can lead to embolism. These findings show that multiple mechanisms collectively limit leaf gas exchange and water loss during dehydration, enhancing our understanding of plant resilience to changing environments.

Woody stems conduct both photosynthetic assimilation and respiration. The two processes work in concert, as stem photosynthesis helps refix CO2 released by stem respiration, thereby increasing carbon-use efficiency and generating a local pool of non-structural carbohydrates supporting cambial growth and stem hydraulic function. Despite its importance, little is known about seasonal variation in stem photosynthesis and the factors underlying its activity throughout the season. To fill this gap, we measured stem gas exchange together with growth activity, water status and photosynthetic pigment contents in two temperate species, Acer platanoides L. and Prunus avium L., over the season. In both species, gross photosynthetic rates (Pg) and dark respiration (Rd) changed significantly over the season in a similar pattern, indicating strong coordination between the two processes. Both Pg and Rd reached the highest values in May, during the period of rapid leaf expansion and secondary growth, and declined later in the growing season. At each measurement date, Rd exceeded Pg, resulting in a net CO2 efflux from the stems. The seasonal changes in Pg and Rd translated into seasonal variability in relative refixation of CO2, ranging from 3 to 59% and gradually decreasing towards the end of the season. Additionally, the Pg corresponded with the tissue hydration and increased significantly with increasing stem water potential. In contrast, total chlorophyll content showed less pronounced seasonal variation and thus explained substantially lower seasonal variability in Pg, except for the chlorophyll a/b ratio, which changed dynamically over the season and reached a minimum during the peak of the growing season. Overall, our results reveal that stem photosynthesis varies seasonally in accord with stem growth and water status, while the chlorophyll content has a lower impact on the seasonal changes. These findings are important for our understanding of the carbon relations of trees.

C4 photosynthesis is a CO2-concentration mechanism that separates CO2 fixation between two cell types, thereby reducing photorespiration and making C4 plants more efficient than their C3 counterparts. While the C4 cycle has evolved multiple times across different genera, this study evaluates very closely related C3 and C4 species within the genus Flaveria. Apart from their carbon metabolism, C4 plants also possess adaptations in their mineral nutrition. One key nutrient which is also directly involved in photosynthesis is phosphorus. It is absorbed by the plant in the form of inorganic phosphate and is an essential component of DNA, ATP, lipids, and carbohydrates. In the Flaveria C4 species, but not in the C3 species, phosphate limitation was shown to affect the dark reactions of photosynthesis. This study investigates how phosphate deficiency impacts the light reactions in C3 and C4 Flaveria plants. We observed a differential response in the functionality of photosynthetic energy conversion between the two species. When exposed to a limited phosphate supply, the C3 species reduced its linear electron transport rate while dissipating excess energy through high-energy quenching, which was regulated by a higher pH gradient across the thylakoid membrane. In contrast, the C4 species did not regulate its photosynthetic light reaction under phosphate limitation. Instead, it exhibited increased stress levels, evidenced by a stronger biomass reduction and the induction of stress markers in the leaves. Additionally, this study uncovered an acceleration in NPQ relaxation during phosphate limitation, regardless of the photosynthesis type. HighlightPhosphate deficiency reduced linear electron transport rates and induced dissipation of excess energy through non-photochemical quenching in the C3 Flaveria species, while in the C4 species, despite elevated stress levels, the photosynthetic light reactions were unaffected.

In this study, the level of Rubisco protein was reduced in wheat using RNAi, to test the hypothesis that photosynthesis, growth, and grain yield could be maintained whilst improving nitrogen use efficiency. The RNAi Rubisco wheat plants, with a Rubisco activity of less than 70% of wild type (WT) plant levels, had reduced photosynthesis, reductions in leaf and stem biomass and decreased seed yield. Interestingly, in the wheat RNAi Rubisco lines that had a small (<30%) reduction in Rubisco activity, the seed number, total seed weight and harvest index were comparable to that of WT type plants. However, no improvement in photosynthetic nitrogen use efficiency (PNUE) was evident in any of the RNAi Rubisco lines. Notably, PNUE was lower than for WT wheat plants in the RNAi lines with more than a 30% reduction in Rubisco activity. This result was unexpected and caused by an accumulation of N in both the leaves and seeds. At present we do not have an explanation for this but one possible hypothesis is that it could be due to slower growth caused by a reduction in source strength in the RNAi plants, which in turn resulted in changes to carbon and nitrogen allocation. HighlightWheat RNAi plants with small reductions in the amount and activity of Rubisco had a similar biomass and total seed weight to that of untransformed controls but no improvement in nitrogen use efficiency was evident.

Cadmium is a very toxic heavy metal. We studied Cd-treated barley plants with especial focus on rare atypical plants with signs of chlorosis. Cd treatment decreased the maximal photochemical activities of both photosystems while the activity of photosystem I decreased more than activity of photosystem II. In photosystem II, Cd treatment inhibited non-photochemical quenching that increased portion of unquenched "closed" complexes of photosystem II. The latter effect increased balance of limitations between the acceptor side of photosystem II (qC) and the donor side of photosystem I (Y(ND)) and raised the ratio qC/Y(ND). All these effects were enhanced in the atypical more damaged plants. Cd treatment reduced K content in the first leaves; in atypical plants, K content decreased even more. Cd treatment changed a pattern of stomatal conductance possibly by means of reducing K content in leaves. The untreated barley plants kept different stomatal conductance at adaxial and abaxial sides of leaves and fulfilled a complicated diurnal dynamics with large ups and downs of stomatal conductance. The typical Cd-treated plants were less flexible and demonstrated medium values. Stomatal conductance in the untreated plants were higher or lower than in the typical Cd-treated plants depending on a particular time; average daytime stomatal conductance was equal in both variants. At 10.00, stomatal conductance in the atypical Cd-treated plants was smaller than in the typical ones. Levels of 13 chloroplast mRNAs remained unchanged, while psbD decreased in both types of Cd-treated plants. HighlightsO_LISeveral Cd effects were enhanced in more damaged (atypical) chlorotic plants C_LIO_LICd treatment decreased activity of photosystem I and non-photochemical quenching C_LIO_LIRatio of limitations between photosystems II and I [qC/Y(ND)] was rather constant C_LIO_LICd treatment reduced K content in the first leaves C_LIO_LICd treatment changed pattern of stomatal conductance C_LI

Soil salinity is a rapidly intensifying abiotic stress that significantly limits wheat productivity, particularly in coastal and irrigated agroecosystems. Although sodium (Na+) ion exclusion has been recognized as a key tolerance mechanism, the integration of physiological performance with Nax1-mediated molecular regulation among regionally adapted wheat genotypes remains insufficiently characterized. The present study aimed to dissect salinity tolerance by combining hydroponic phenotyping, multivariate trait analysis, molecular marker profiling, and quantitative expression analysis of the Na+ ion transporter gene Nax1. Seventeen spring wheat genotypes were evaluated under four salinity levels (0.0, 10, 12, and 14 dS m-{superscript 1}). Germination and survival rate, shoot and root growth, and biomass accumulation were measured. Principal component analysis (PCA) and hierarchical clustering were performed to classify genotypes, while SSR (simple sequence repeat) and Nax-linked markers assessed genetic diversity. Relative Nax1 expression was quantified using qRT-PCR (quantitative real-time polymerase chain reaction). Salinity significantly reduced germination, survival, elongation, and biomass, with strong genotype-dependent variation. Multivariate analyses clearly separated tolerant and sensitive genotypes, with biomass retention and survival contributing most to total variation. Marker analysis revealed moderate genetic polymorphism. Notably, tolerant genotypes exhibited 3-6-fold induction of Nax1 under severe salinity, positively correlating with biomass maintenance. These findings demonstrate that salinity tolerance in wheat is associated with coordinated physiological resilience and enhanced Nax1-mediated Na ion exclusion, thereby advancing mechanistic understanding and supporting molecular-assisted breeding for salt-affected environments.

During drought, numerous compounds accumulate in plant tissues, but their physiological roles remain unclear - they may function as osmolytes, osmoprotectants, or merely arise as by-products of stress-induced metabolic shifts. We developed an experimental approach to link accumulation patterns with specific functions, using Scots pine (Pinus sylvestris L.) saplings subjected to water deprivation and subsequent rewatering as a model system. We monitored changes in relative water content (RWC) and osmotic adjustment dynamics, employed untargeted primary metabolite profiling for preliminary screening of compounds correlated with water status, and performed quantitative GC-MS and LC-MS analyses of selected metabolites. Major inorganic cations (K, Ca{superscript 2}, Mg{superscript 2}) were also quantified to assess their potential roles. Our results revealed that tryptophan, valine, and lysine - though generally present in low abundance - exhibited selective accumulation under severely reduced RWC ([&le;] 70%), suggesting their involvement as osmoprotectants. Major organic acids, particularly shikimic acid, showed trends consistent with osmotic adjustment. Notably, neither sucrose nor inorganic cations appeared to function as primary osmolytes in this context. The proposed approach offers a viable strategy for identifying compounds involved in plant adaptation to water deficit, with potential applications in breeding programs aimed at improving drought tolerance. HighlightsAn approach to identify osmolytes and osmoprotectants was implemented Accumulation of Trp, Val and Lys was consistent with their role in osmoprotection Osmotic adjustment relied predominantly on organic acids than on inorganic ions Monosaccharides but not sucrose correlates with changes in needle water status

Photosynthesis accounts for most of the final grain yield in rice, making improvements in radiation use efficiency (RUE) a key strategy for enhancing productivity. Agronomically, RUE is defined as the biomass produced per unit of total solar radiation or photosynthetically active radiation intercepted by the canopy. However, the interaction between carbon and nitrogen metabolism plays a critical role in determining plant growth and grain yield. Assimilated nitrogen is required for the synthesis of photosynthetic pigments and enzymes, while the reduction of nitrate (NOLL) and nitrite (NOLL), as well as the assimilation of ammonium (NHLL), depend on the reducing power and carbon skeletons generated by photosynthesis. In this study, two high-yielding rice (Oryza sativa) cultivars--an indica-type (El Paso 144) and a japonica-type (INIA Parao) were subjected to two nitrogen treatments (3 mM and 9 mM NOLL/NHLL) and two light intensities (850 and 1500 mol mL{superscript 2} sL{superscript 1}). A strong interaction between light intensity and nitrogen metabolism was observed, with contrasting responses between subspecies. These differences reflect a coordinated regulation of carbon assimilation and primary nitrogen metabolism. The results provide new insights into the metabolic strategies underlying nitrogen compound accumulation under variable irradiance. Such knowledge is essential for improving nitrogen fertilizer use efficiency and yield performance in elite rice genotypes cultivated under commercial field conditions.

Light wavelengths modulate plant growth, metabolism, and physiology. Amaranthus, a C4 underutilized climate resilient crop with promising nutritional properties remained unexplored in terms of metabolite enrichment under monochromatic light wavelengths of visible spectrum. In current study, two cultivars of Amaranthus tricolor (green and red) were exposed to seven light regimes of photosynthetically active radiation (PAR; 400-700 nm): deep blue, blue, green, amber, red, deep red, far red, and their metabolic responses were captured using Gas Chromatography-Mass Spectrometry. The metabolic analysis revealed wavelength-specific reprogramming in the levels of organic acids, sugars, amino acids, fatty acids as well as phenolics. In both the green and red Amaranthus, branched-chain amino acids and phenylalanine, which are nutritionally essential, were significantly elevated under far-red light. While the phenolics such as caffeic acid and ferulic acid were elevated under green and deep blue light respectively in green Amaranthus, amber light wavelengths enhanced these phenolics in red Amaranthus. The study highlighted cultivar-specific metabolic rewiring triggered by specific wavelengths. Altogether, these findings provides insights into metabolic adaptation and demonstrate the ability of light wavelength to specifically enrich the targeted metabolite of nutritional relevance in Amaranthus. It offers strategies to improve the nutritional value of crops in controlled agriculture systems. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=167 HEIGHT=200 SRC="FIGDIR/small/714947v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@1a4477dorg.highwire.dtl.DTLVardef@518550org.highwire.dtl.DTLVardef@7682dorg.highwire.dtl.DTLVardef@4876e2_HPS_FORMAT_FIGEXP M_FIG C_FIG

Malate and fumarate constitute a significant transient carbon stock that is dynamically synthesized during the photoperiod. These organic acids are diurnally stored and remobilised from the vacuole, and they have a key role in the cellular metabolic regulation. This function is well known in C4 and CAM plants. However, in C3 species that are the majority of terrestrial plants, the importance of the vacuolar accumulation/release and its influence on plant growth is still an open question. In Here we addressed this issue generating multiple knockout mutants in Arabidopsis thaliana lacking vacuolar anion channels of the Aluminium-Activated Malate Transporter (ALMT) family, to impair malate and fumarate transport to the vacuole. We show that in these mutants reducing vacuolar transport of malate and fumarate in mesophyll cells leads to a dramatic growth impairment. Metabolic and fluxomic analysis revealed that vacuolar malate and fumarate transport influences plant carbon and nitrogen metabolism as well as cellular pH and ionic homeostasis. In conclusion, our results show that the transport organic acids like malate and fumarate across the vacuolar membrane is essential for plant growth in a C3 plant too. These results establish the importance of the vacuolar pools of malate and fumarate in plant metabolism.

BackgroundNon-optimal temperatures have become a major constraint on plant development under rapidly changing climatic conditions. Both sub- and supra-optimal temperatures reduce physiological activity, alter plant morphology, lead to plant mortality, and ultimately decrease crop productivity. Temperature-tolerant plants employ physiological and morphological mechanisms to mitigate such stress. In this study, we aimed to identify the source of temperature tolerance in warm-climate adapted melon (Cucumis melo L.). ResultsSuboptimal temperature-tolerant accession (Ananas Yoqneam; AY) and susceptible accession (PI414723) were reciprocally grafted and grown under controlled temperature regimes of 16 {degrees}C, 25 {degrees}C, and 35 {degrees}C. Physiological and morphological traits were measured to characterize tolerance mechanisms and whole-plant responses. Temperature emerged as the dominant factor governing plant performance. Whereas non-grafted parental lines maintained consistent differences across all temperature regimes, reciprocal graft combinations diverged mainly under suboptimal (16 {degrees}C) conditions. Under these temperatures, scion identity strongly determined whole-plant performance through biochemical limitations. ConclusionThese results highlight the importance of scion-derived traits in abiotic stress tolerance and their downstream influence on root function.

AimsHarnessing rhizosphere processes offers a valuable opportunity to optimize nutrient use efficiency in agroecosystems. In nutrient-limited soils, plants discharge part of photosynthate surplus via root exudation, including carboxylates, which may enhance mineral dissolution and nutrient mobilization. We aimed to assess how plant responses to nutrient limitation translated into changes in exudate profiles, and how these exudates, in turn, drive bioweathering across soils of contrasting mineralogy and weathering degree. MethodsWe conducted a hydroponic experiment with Lupinus albus grown in a phosphorus (P) gradient over seven weeks. We measured plant biomass and root traits, performed a metabolomics analysis and quantified seven carboxylates in root exudates using gas chromatography-mass spectrometry. To assess bioweathering across contrasted soil domains, we conducted batch dissolution tests with exudates using three soil horizons--each with distinct physicochemical properties: enriched in organic matter, iron oxides, or primary silicates. ResultsAt the intermediate level of P supply, shoot biomass was comparable to that under high P, but plants produced more root biomass and a higher total carboxylate exudation rate. Despite low carboxylate concentrations (<100 ppb), exudates promoted the dissolution of Ca, Mg, Si, Fe, P and K in all soils. Yet, the degree of element released varied among soil types. ConclusionThese findings highlight the importance of root exudates in enhancing mineral dissolution, with effects dependent on soil physicochemical properties. The results suggest that managing agroecosystems under moderate nutrient limitation could be a sustainable strategy to increase root-to-shoot ratios, enhance bioweathering and nutrient release in rhizosphere.

Chickpea is predominantly grown under rainfed conditions in regions where terminal drought limits yield, yet little is known about how this stress influences both vegetative allocation and reproductive dynamics leading to altered grain composition. We imposed a controlled terminal drought, with a rewatered treatment group, on three Desi cultivars (ICC4958, ICC1882 and CBA Captain) reported to have contrasting drought tolerance, quantifying vegetative biomass, reproductive node productivity across developmental regions and grain macronutrient composition. Under drought, vegetative responses reflected genotype-specific resource partitioning strategies particularly evident in severe root degradation and increase stem dry matter content that was only partially alleviated in rewatered plants. Reproductive outcomes were strongly influenced by developmental stage at the time of stress, with increased pod abortion observed particularly at nodes initiating seed development under drought treatment. Grain composition of seeds filled under drought was significantly altered by stress, with increased protein concentration and decreased starch content under both Drought and Recovery treatments independent of cultivar, likely due to water limitation at crucial filling stages. These findings demonstrate that the developmental timing of terminal drought interacts with cultivar growth strategy to influence pod production and grain nutritional quality in chickpea. HighlightThe developmental timing of terminal drought interacts with cultivar-dependent growth strategies to influence pod productivity and grain nutritional quality in chickpea.

Improving photosynthesis is a promising approach to enhance sugar beet productivity. However, genetic variation in leaf photosynthesis and its relationship with disease resistance remain underexplored. We evaluated 98 sugar beet genotypes representing different breeding categories, including commercial F1 hybrids, seed-parent lines, and pollinator lines, in Hokkaido, northern Japan. Leaf gas exchange was measured during early growth under field conditions around the infection period of Cercospora leaf spot (CLS). To account for fluctuating irradiance during large-scale phenotyping, we applied a multilevel mixed-effects light-response model to estimate genotype-specific photosynthetic characteristics. Substantial genotypic variations in photosynthetic characteristics were detected. F1 hybrids exhibited higher photosynthetic capacity than breeding lines, whereas differences among breeding categories were unclear due to large within-category variation. Some breeding lines exhibited photosynthetic rates higher than those of hybrids, indicating exploitable genetic resources within the present genetic panel. We did not detect statistically significant trade-off between leaf photosynthesis and CLS resistance among 98 genotypes; in a subset of 19 genotypes analysed in detail, the relationship was even synergistic. Our results highlight the genetic diversity of leaf photosynthesis and its category-dependent structure, and suggest that selection for enhanced photosynthesis can proceed without substantial trade-off with CLS resistance. HighlightLeaf photosynthesis of 98 sugar beet genotypes showed significant genetic variation and dependence on breeding category. Active photosynthesis incurred minimal trade-off with Cercospora leaf spot resistance.

AO_SCPLOWBSTRACTC_SCPLOWNitrogen fertilizers are essential for crop productivity but cause environmental harm, necessitating the development of cultivars that thrive under limited nitrogen. This study investigates the transcriptomic response to nitrate in Arabidopsis thaliana (a model dicot), Brachypodium distachyon (a model Pooideae), and Hordeum vulgare (barley, a domesticated Pooideae) to identify conserved and species-specific molecular mechanisms. Using RNA-seq after 1.5 and 3 hours of nitrate treatment, we found that core nitrate-responsive biological processes - such as nitrate transport, assimilation, carbon metabolism, and hormone signaling - are largely conserved across species. However, comparative analysis at gene level based on orthology revealed specificities between the species. For instance, rRNA processing was uniquely stimulated in Arabidopsis, while cysteine biosynthesis from serine and gibberellin biosynthesis were specifically regulated in Brachypodium and barley. Orthologs of key nitrate-responsive genes (e.g., NRT, NLP, TCP20) exhibited variable regulation, reflecting potential adaptations linked to domestication or nutrient acquisition strategies. These findings highlight the importance of integrating model and crop species to uncover targets for improving nitrogen use efficiency in cereals. The study provides a pipeline integrating gene ontology and orthology analyses to compare transcriptomic responses between species.

Fluctuating extreme weather events, coupled with rising average temperatures, can severely impact grapevine physiology and yield. While biostimulants have been gaining acceptance as a short-terms tools to enhance grapevine resilience, their adoption is hindered by inconsistent efficacy, partly driven by unpredictable plant stress levels. Over two contrasting seasons, we integrated physiological, transcriptomic, and metabolomic analyses to investigate how a plant-based biostimulant modulates the sensibility of Vitis vinifera under varying intensities of heat, drought, and their combination. This panel of water status, ranging from -0.02 to -1.6 MPa, revealed that the physiological response induced by the biostimulant treatment alleviates water stress within a field-relevant hydraulic window located between -0.4 and -1.2 MPa. Moreover, moderate but constitutive reduction of growth parameters in biostimulant plants, suggests a trade-off between vegetative development and abiotic stress responses. Accordingly, gene expression analysis revealed an interaction between water availability and the plant response to the biostimulant, which suggest an activation of priming mechanisms. Metabolic profiling supported these findings, highlighting the central role of phenylpropanoid pathway modulation, together with adjustments in ROS dynamics and stress-related hormone responses, particularly abscisic acid. Overall, this work emphasizes the need for integrating detailed plant water status and leaf gas exchange to accurately evaluate biostimulant performances under abiotic stress.

Sterol biosynthesis underlies significant physiological functions in plants, including the production of membrane structural sterols and hormones such as brassinosteroids and cytokinins. Inhibition of sterol biosynthesis has been shown to disrupt multiple aspects of Arabidopsis thaliana development. Here, the effects of lovastatin, an inhibitor of HMG-CoA reductase, on root development were investigated, focusing on auxin-cytokinin distribution and transport. Lovastatin inhibited primary root growth, especially cell elongation, in a dose-dependent manner. Additionally, lateral root density was considerably increased and lateral root primordia (LRP) emerged ectopically. In accordance to the above defects, auxin/cytokinin imbalance was recorded by the ectopic presence of the synthetic auxin marker DR5 and a significant decrease of cytokinins, as revealed by depletion of the TCS (two-component signaling) marker. Because auxin distribution appeared disturbed, auxin transport impairment was further examined. Plasma membrane localization of PIN auxin efflux carriers declined significantly, showing additional diffuse cytoplasmic localization in LRP cells. However, the cell-specific localization patterns of several PINs and their abundance at the transcript and protein level appeared unaffected or slightly increased. Fluorescence recovery after photobleaching (FRAP) analysis regarding membrane kinetics of PIN2 revealed altered PIN2 membrane dynamics and transmission electron microscopy (TEM) observations showed structural defects at the plasma membrane-cell wall interface. Together, these results support that sterol biosynthesis is essential for maintaining plasma membrane organization, which, in turn, is key factor for the distribution of hormones that control root development. HighlightsLovastatin treatment inhibits root growth and causes deregulated formation of lateral roots. Consistently, lovastatin causes altered patterns of auxin distribution relevant to PIN protein mis-localization and decreases cytokinin levels. These changes could be attributed to reduced structural sterols as exemplified from alteration in PIN2 membrane dynamics.