Abstract: Rice is a widely cultivated staple crop that serves as the primary source of carbohydrates for more than half of the global population. Elite parents with superior agronomic traits play a crucial role in rice breeding systems. In this study, we performed whole-genome resequencing of the rice cultivar GuiHeFeng and its nine derivative lines, identifying a total of 6,633,507 high-quality single-nucleotide polymorphisms (SNPs). The percentage of GuiHeFeng traceable blocks (GTBs) in the 9 derivatives ranged from 48.94% to 63.2%. Based on SNP analysis, we found 1310 key GuiHeFeng traceable blocks, which were derived from GuiHeFeng and present in all 9 derivatives. Moreover, 375 selective sweeps (SSWs) were identified, of which 20 were also located within the kGTBs. These 20 SSWs were regarded as key genomic regions for rice breeding. After the association test, 20 alleles including 17 genes were identified on the kGTBs, and 38 significant genes were found within the key genomic regions. A total of 295 SNPs related to agronomic traits were detected by GWAS analysis. This research identifies genomic segments and agronomically important genes/QTLs that will serve as essential targets for genomic selection in rice breeding.

Abstract: Verticillium wilt (VW) of cotton caused by the soilborne pathogen Verticillium dahliae is a major disease across cotton production worldwide. The disease can result in yield reductions up to 80% in some occasions. V. dahliae is an asexual fungus and belongs to a relatively small Verticillium genus in the Ascomycota, though both of the mating type idiomorphs are present within some populations. Diversity of V. dahliae is widely associated with vegetative compatibility groups (VCGs), of which six different VCGs are recognised. Of these, isolates belonging to VCGs 1, 2 and 4 are globally distributed and associated with a broad host range including cotton. Approximately 400 plant species have been recorded as hosts of V. dahliae. Pathogenicity and virulence of V. dahliae in many cases are correlated with VCG designations and hosts of origin. Disease risk management of VW of cotton still relies on accurate, rapid detection and quantification of V. dahliae using both conventional and molecular approaches. The use of resistant cultivars is the most effective and economical control strategy; however, no cultivars confer complete resistance to the disease. Control strategies including cultural, biological, chemical and induced resistance approaches have indicated certain degrees of success in minimising disease damage and diminishing the build-up of pathogen inoculum. In this review, we discuss insights into the VW disease of cotton, the associated pathogen and current control approaches, as well as future research perspectives.

Abstract:

Background: Flavin cofactors, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), are indispensable for plant metabolism, supporting photosynthesis, photorespiration, mitochondrial electron transport, nitrogen assimilation and cellular redox balance. Both cofactors derive from riboflavin (vitamin B₂), which plants synthesize de novo, unlike animals that rely on dietary intake. While the riboflavin biosynthetic pathway has been biochemically well characterized, its transcriptional regulation and cellular organization remain poorly understood. Methods: Here, using large-scale transcriptomic datasets, co-expression and cis-element analyses, we systematically investigated the expression dynamics of riboflavin metabolism genes in Arabidopsis thaliana. In addition, HPLC was employed to monitor flavin level fluctuations in plants under abiotic stresses. Results: Most genes displayed strong expression in photosynthetic and reproductive tissues, consistent with elevated metabolic demands for flavins in redox reactions and energy metabolism. Under osmotic stress, RIBA1, RIBA3, PYRD, PYRR, COS1/LS and RS, genes encoding enzymes involved in the early and intermediate steps of riboflavin biosynthesis were transcriptionally repressed. In contrast, RIBA2, FHY1/PYRP1 and FMN/FHY were upregulated, whereas FADS1 and NUDX23, genes encoding enzymes responsible for interconversion between FMN and FAD, were repressed. Gene expression responses are consistent with maintenance of flavin homeostasis and coincide with changes in flavin levels under abiotic stress. Conclusions: This study establishes a comprehensive framework for the transcriptional regulation of flavin biosynthesis in plants. The findings reveal stress-responsive reprogramming of flavin metabolism and identify promising strategies for engineering crop biofortification, metabolic efficiency, and stress resilience.

Abstract: Male sterility is an important trait in heterosis breeding in a number of crops. The main advantage is low-cost seed production. Five types of male sterility have been discovered in melon, which are applied in seed production schemes. Bulgarian hybrid melon varieties were developed based on ms-4 type male sterility. The maternal parent component in nu-clear male sterility segregates into fertile to sterile plants 50%:50%. Therefore, fertile plants must be removed at the beginning of flowering period, which is a labor-intensive practice. This question provokes us to investigate for other ways to distinguish fertile from sterile plants. Fluorescence spectroscopy is a non-contact, fast-acting, selective, and non-destructive method of the sample being examined. The development of a method for evaluating melon seeds with its application is an important scientific and applied ad-vantage. To date, there is no data on a study. The aim of this study was to establish relia-ble parameters of fluorescence spectroscopy with the indicators of male sterility type ms-4. To establish the applicability of the method in primary screening for checking male steril-ity in the seed phase of melon, seeds from three breeding lines VK/1-5-5, K/15-6 and 11/9С were examined in March (sowing) and May (flowering) 2025, and June (sowing) to July (flowering) 2025. The results of the analysis reflect both a difference in signal intensity and shift in the emission maximum of the spectral distributions of the seeds from the different lines. Based on the generated clear and distinct differences in the spectral distribution in all seeds from the three breeding lines. It was established that fluorescence spectroscopy is applicable in screening melon seeds immediately before sowing to check their fertility or sterility.

Abstract:

The repeatome is composed of satellite DNA (satDNA) and transposable elements (TEs), and variation in its composition is important for shaping genome architecture and driving evolutionary processes in plants. As no repeatome assessment exists for Epidendrum, the largest genus of Orchidaceae in the Neotropics, we aim to describe repetitive sequences across its species. We performed phylogenetic analyses based on plastid (matK and rbcL) and nuclear (ITS) markers using maximum likelihood and Bayesian inference methods, and characterized the repeatome of 34 species using the RepeatExplorer2 pipeline. Our results reveal substantial variation in satDNA content among species, with a total of 208 individually identified satDNAs, which were used to build a custom database for repeatome comparative analysis. We found that 73 satDNA clusters are shared among species, while only three are species-specific (CL359 and CL82 in E. rigidum, and CL430 in E. gasteriferum), supporting the library hypothesis. Regarding TEs, Class I elements were the most abundant repeats identified in Epidendrum, primarily long terminal repeat retrotransposons of the Ty3-gypsy superfamily. Elements of the Ty1-copia superfamily were the least abundant. Only two Class II TIR superfamilies were identified, namely EnSpm_CACTA and hAT. The heterogeneous distribution of satDNAs and TEs among closely related species suggests lineage-specific patterns of expansion and contraction, potentially influenced by evolutionary processes such as hybridization and environmental adaptation. Our findings represent the first comprehensive characterization of the repeatome in Epidendrum and provide a basis for future studies on the composition and cytogenomic variation within the mega-genus.

Abstract: High Nature Value (HNV) mountain grasslands in the Eastern Carpathians are sensitive to fertilization intensification. This study evaluated the effects of organic and mineral inputs on the floristic composition, vegetation types, and diversity of an oligotrophic grassland with Nardus stricta in a long-term experiment established in 2002, with results presented here from three recent experimental years (2022–2024) with nine variants (unfertilized control, 10–30 t ha⁻¹ manure applied in autumn/spring, and 200–300 kg ha⁻¹ nitrocalcar). Vegetation composition was analyzed using hierarchical classification, PCoA, MRPP, Indicator Species Analysis, and α-diversity indices (species richness, Shannon, Simpson, and evenness). The results revealed six floristic types arranged along a clear trophic gradient, ranging from oligotrophic to eutrophic communities. Specifically, low-moderate manure treatments (10–20 t ha⁻¹) simultaneously maximized community diversity and balance, maintaining a rich core of oligotrophic and mesotrophic species. Conversely, high doses of manure (30 t ha⁻¹) and mineral fertilization led to a marked reduction in species richness and the dominance of a few competitive-grass species. Ultimately, this study demonstrates that moderate organic fertilization is compatible with the adaptive management of HNV grasslands, whereas intensive mineral fertilization is incompatible with conservation objectives.

Abstract: Abstract Green leaf volatiles (GLVs) are significant volatile signals that have been shown to protect plants against biotic and abiotic stresses including insect herbivory and pathogen infec-tions, but also drought, cold, and heat stress. Since all these stresses are affected by climate change, GLVs provide an important target for research into their broad activities and their potential applications in agricultural settings. Therefore, to gain further insights into the protective properties of GLVs and their regulation under changing environmental con-ditions, we investigated whether climate-related changes alter the capacity to produce and the responsiveness to GLVs. Specifically, we studied the effects of limited nutrient supply, drought, and higher temperature. Neither significantly affected the capacity of plants to produce Z-3-hexenal as the first metabolite of the pathway, but elevated temperature increased E-2-hexenal production. We further identified changes in the effectiveness of plants to respond to GLV under changing abiotic conditions by monitoring glucose levels and typical GLV-responsive genes covering metabolism, direct defense, indirect defense, and water stress. The results provide first evidence that plant responses to GLVs under defined environmentally challenging conditions are highly context-dependent and can vary substantially. The implications of these first findings as well as potential conse-quences will be discussed.

Abstract: Salinity stress is an abiotic threat that affects crop growth, development, and productivity, placing a heavy burden on global agriculture. Therefore, researchers must thoroughly understand the various mechanisms by which crops tolerate salinity. This knowledge enables biotechnological strategies to enhance crop resilience and yield, helping to secure sustainable food supplies for the growing world population. Several organic osmolytes greatly influence how crop plants respond to salinity stress. Trehalose is one such osmolyte that has gained increasing attention because it effectively improves crop salinity response and tolerance by influencing physiological, biochemical, and signaling processes. Beyond trehalose itself, its metabolite trehalose-6-phosphate (T6P), along with key biosynthetic enzymes such as trehalose-6-phosphate synthase (TPS) and trehalose-6-phosphate phosphatase (TPP), is vital for helping crops adapt to salinity, especially when applied externally or via genetic modifications. Trehalose performs multiple roles: it acts as a cell hydration agent, an antioxidant, a gene regulator, a source of energy and carbon, a precursor for metabolic pathways, a signaling molecule, and a detoxifier of excess reactive oxygen species (ROS) in cells and organelles. This review carefully explores the structure of trehalose, its biosynthesis, protective molecular mechanisms, and the important functions of its metabolites in crop adaptation to salinity. Strategies focused on increasing trehalose levels and functions or boosting its metabolites are promising approaches for researchers aiming to enhance crop tolerance and yield in saline environments, which we highlight. We suggest that trehalose, its precursor, and the biosynthesis pathway play various roles under both normal and stressed conditions, potentially serving as biomarkers to assess crop tolerance and productivity under saline conditions. This review offers valuable insights into trehalose metabolism, paving the way for future engineering techniques to improve crop tolerance and yield in saline soils.

Abstract: The meta-analysis examines the effects of eCO₂ on the growth, yield, and nutritional composition of two widely consumed leafy vegetables: kale (Brassica oleracea) and spinach (Spinacia oleracea). Following the Collaboration for Environmental Evidence (CEE) guidelines, we systematically reviewed studies that reported on the impacts of eCO₂ on these crops and conducted a meta-analysis to quantify the overall as well as sub-group responses via moderator analyses. A random-effects model was used to calculate effect sizes (Hedges' g), and confidence intervals (CI) were set at 95%. Our results reveal that eCO₂ significantly increased the biomass of spinach (g = 1.21, p < 0.01, CI [0.88, 1.54]) and kale (g = 0.97, p < 0.05, CI [0.65, 1.29]). However, the analysis also detected a significant decrease in protein content in both crops under eCO₂ conditions (spinach: g = -0.76, p = 0.03, CI [-1.10, -0.42]; kale: g = -0.61, p = 0.04, CI [-0.95, -0.27]). Additionally, calcium and magnesium concentrations declined in kale (g = -0.55, p = 0.05, CI [-0.89, -0.21]), and spinach showed a stronger reduction in nutrient content overall. The variability in response across different CO2 concentrations and exposure times further underscores the complexity of eCO2 effects. These findings suggest that while eCO₂ may enhance crop yields, it also leads to a dilution of essential nutrients, raising concerns about the trade-offs between productivity and nutritional quality. The study concludes that targeted breeding programmes, strategic precision agriculture, sustainable agricultural practices and policy interventions will be critical in mitigating the negative nutritional effects of eCO₂ to ensure food security in a changing climate.

Abstract: Anthocyanins are well known as colorants of flowers, but many other invisible functions might have been more important during the evolution of complex biosynthesis networks in plants. The number of anthocyanin decorating enzymes, the subtle control of structural genes by numerous transcription factors, and routes of intracellular anthocyanin transport are reviewed here. Various ecological functions of anthocyanins hold the key to understanding evolutionary trajectories that lead to the success of these pigments. Proposed functions include carbon sinks that prevent excessive sugar levels, sun blockers protecting the photosynthesis apparatus, antioxidants scavenging reactive oxygen species, providing camouflage, and attraction of pollinators and seed dispersers. Anthocyanins clearly fulfill different functions in different plant organs. It is currently believed that protective functions in leaves gave rise to the biosynthesis network and that flower and fruit coloration evolved later. Despite decades of research on the anthocyanin biosynthesis, there is still substantial potential for fundamental discoveries.

Abstract:

Based on the genome and transcriptome data of Lonicera japonica Thunb., this study identified six LjDFR gene family members at the genome-wide level. These genes were located on Chr.04 and Chr.09, and the full-length coding sequences of LjDFR1 to LjDFR6 were successfully cloned. The proteins encoded by the cloned genes are all hydrophilic, with secondary structures dominated by α-helices and random coils. The subcellular localization analysis indicated that LjDFRs are primarily localized in the cell membrane and nucleus. Phylogenetic analysis classified the LjDFR proteins into four subfamilies, clustering with DFR homologs from species such as Capsicum annuum and Camellia sinensis, reflecting a high degree of evolutionary conservation. Promoter analysis identified multiple cis-acting elements associated with light response, hormone signaling, and stress-responses. Expression pattern analysis demonstrated that LjDFR genes exhibit tissue-specific and stage-specific expression patterns during flower development in L. japonica varieties with different floral colors. Notably, LjDFR2 expression was significantly higher in the deeply pigmented tissues of Lonicera japonica Thunb. var. chinensis (Wats.) Bak. than in L. japonica. Together with its phylogenetic clustering with the anthocyanin-related CsDFRa and CaDFR5 genes, this finding suggests that LjDFR2 potentially positively correlated with anthocyanin accumulation. Furthermore, the expression of LjDFR2 and LjDFR4 was significantly induced under both drought and salt stress, indicating their involvement in abiotic stress responses. This study provides a foundation for further functional characterization of LjDFR genes in anthocyanin metabolism and stress resistance, and offers valuable candidate genes for molecular breeding of L. japonica.

Abstract: Maize plants challenged by insect herbivores activate an array of defense measures, all aimed to reduce damage and repel. Among those are the activation of proteins that in-terfere with the digestion of consumed plant material in the herbivore (proteinase in-hibitors), the production of toxic compounds like benzoxazinoids, and the biosynthesis and emission of herbivore-induced plant volatiles (HIPV). Among those HIPVs are mainly a variety of terpenoids, green leaf volatiles (GLVs), and indole. While often serving as attractants for natural enemies of the attacking herbivores, many of those volatiles have also been found to induce defense responses in neighboring plants and/or prime them against future menace. Indole is of particular interest since it can be involved in a variety of biosynthetic pathways including those leading to auxin, benzoxazinoids, and tryp-tophan. Here, we demonstrate that indole emissions in response to simulated insect herbivory strongly depends on the developmental status of the affected leaf. Outgrown leaves emit significantly higher amounts of indole compared to the next younger, still growing leaves, distinguishing indole from other herbivore-induced plant volatiles (HIPVs), which are typically released at higher levels by young leaves. As a central and flexible metabolic intermediate, indole emissions appear to be mediated though variable allocation between growth-related processes and defense-associated outcomes, depending on developmental stage of the damaged leaf. These findings highlight the importance of considering plants as inherently dynamic organisms.

Abstract:

The pepper Bs2 resistance gene confers resistance to susceptible Solanaceae plants against pathogenic strains of Xanthomonas campestris pv. vesicatoria carrying the avrBs2 avirulence gene. Previously, we generated Bs2-transgenic Citrus sinensis plants that exhibited enhanced resistance to citrus canker caused by Xanthomonas citri subsp. citri (Xcc), although the underlying mechanisms remained unknown. To elucidate the molecular basis of the early defense response, we performed a comparative transcriptomic analysis of Bs2-expressing and non-transgenic plants 48 hours after Xcc inoculation. A total of 2,022 differentially expressed genes (DEGs) were identified, including 1,356 up-regulated and 666 down-regulated genes. In Bs2-plants, 36.8% of the up-regulated DEGs were associated with defense responses and biotic stress. Functional annotation revealed major changes in genes encoding receptor-like kinases, transcription factors, hormone biosynthesis enzymes, pathogenesis-related proteins, secondary metabolism, and cell wall modification. Among hormone-related pathways, genes linked to ethylene biosynthesis and signaling were the most strongly regulated. Consistently, endogenous ethylene levels increased in Bs2-plants following Xcc infection, and treatment with an ethylene-releasing compound enhanced resistance in non-transgenic plants. Overall, our results indicate the Bs2 expression activates a complex defense network in citrus and may represent a valuable strategy for controlling canker and other Xanthomonas-induced diseases.

Abstract: Low temperature is one of the major environmental challenges for most crops, especially from tropical and semitropical origin. The present work aimed to study low temperatures tolerance in tomato plants when previously these were inoculated with Trichoderma asperellum. Here, it was demonstrated that tomato plants inoculated with fungal isolate exhibited an alleviation of the injuries caused by low temperatures. The increasement of chilling tolerance was accompanied by a strong reduction in oxidative stress, but also by an enhancement of proline and soluble sugar accumulation. Additionally, leaf stomata features were also measured, and found that both bioinoculant and low temperatures increased leaf stomatal densities indexes but decreased the stomatal area, suggesting leaf traits may also contribute to alleviating the damage caused by the low temperatures in tomato plants. The results of the present study demonstrate that T. asperellum provokes physiological and biochemical changes in tomato plants that together enhance tolerance to low temperature, proposing the use of T. asperellum as an agroecological strategy confronting crop damage to low temperatures.

Abstract: Drought is a major threat to global food security, with climate change enhancing its severity. Living organisms employ various adaptation strategies against loss of water, with desiccation tolerance representing the most extreme ones. The present study provides an analysis of desiccation response mechanisms in Pisum sativum L., focusing on the early seedling development. The experiments were carried out on 3-day-old seedlings with radicle up to 20 mm and similar seedlings with cotyledons removed, each subjected to the 'desiccation and rehydration' treatment. We assessed stress responses using growth and electrolyte leakage tests, and by measuring ascorbate content and lipid peroxidation products. The results demonstrated that while all desiccated seedlings experienced oxidative stress, seedlings with cotyledons exhibited superior recovery capacity, e.g. maintaining membrane integrity, ascorbate status and the ability to form the adventitious roots. We also monitored the ABA-dependent stress response by registering expression of several genes associated with "response to water deprivation" (ABI3, ABI4, ABI5, HVA22, PER1, LEA14, RD22-1/2/3, LTI65, and LTP4). Intrudingly, 'desiccation and rehydration' treatment resulted in the 40-fold up-regulation of ABI5 in hypocotyls of seedlings both with removed and intact cotyledons and the 108-fold up-regulation of this gene only in roots of seedlings with intact cotyledons. We propose that the post-germination stage represents a ‘resilience window’ where embryonic protective mechanisms remain partially active while the plant prepares for autotrophic growth. Herewith, the role of cotyledons extends beyond their classical role as nutrient reserves by coordinating both developmental and stress responses under conditions of severe water stress.

Abstract:

• Jasmonates (JAs)-mediated pathways are central signaling hubs in plant defense response. However, the identification of mobile and non-mobile signals involved in downstream systemic signaling is still less studied. • Here, we investigate the role of the jasmonic acid-isoleucine conjugating enzyme, JAR1, and the mobility of jasmonic acid-isoleucine (JA-Ile) in wound-induced local and systemic defense using LC-MS/MS for targeted jasmonate analysis and untargeted metabolomics in Arabidopsis thaliana leaves. • The use of jarin-1, a specific inhibitor of JA-Ile biosynthesis, suggested that JA-Ile is synthesized de novo in the particular tissues, rather than being a mobile signal. In addition, inhibition of JAR1 enzyme activity affected an array of downstream metabolic pathways, locally and systemically, such as amino acids and carbohydrate metabolism. • This study demonstrates that the occurrence and spread of local and systemic downstream signals depend on JAR1 activity, and this enzyme exclusively regulates a series of metabolic pathways under both wounding and non-wounding conditions.

Abstract:

The genus Allium L. (Amaryllidaceae) comprises ecologically flexible species widespread across mountain ecosystems, yet the relationships among morphology, environment, and genetics within section Schoenoprasum in Central Asia remain poorly understood. This study investigated four taxa – A. ledebourianum, A. ivasczenkoae, A. ubinicum, and A. schoenoprasum – from the Kazakhstan Altai to assess their morphological variation, ecological preferences, phytochemical activity, and genetic relationships. Populations occurred on gentle chernozem slopes under humid, nutrient-rich conditions and showed stable regeneration dominated by young individuals. Morphometric analyses revealed pronounced interspecific differentiation: A. ledebourianum attained the greatest height and umbel size, whereas A. ubinicum was smallest but possessed proportionally larger floral organs. Principal component analysis explained 94% of total variance, distinguishing A. ubinicum and A. schoenoprasum from the remaining taxa. Floral traits correlated significantly with temperature, moisture, and soil reaction, indicating strong environmental influence on phenotype. Extract assays showed variable bioactivity, with A. ubinicum displaying the highest antioxidant potential (IC₅₀ = 88 µL) and highest cytotoxicity (LC₅₀ of 5.9 μg/mL), while A. ledebourianum shows no antioxidant activity and the lowest toxicity (LC₅₀ of 10.9 μg/mL). Phylogenetic reconstruction using matK, rbcL, and psbA–trnH chloroplast markers confirmed close affinity between A. ledebourianum and A. ivasczenkoae, while A. ubinicum formed a distinct lineage. Together, morphological, ecological, and molecular data highlight the Kazakhstan Altai as a center of diversification for section Schoenoprasum. These results emphasize the adaptive plasticity of endemic Allium species and their potential as sources of valuable bioactive compounds, underscoring the importance of conserving genetically and morphologically diverse populations in mountain ecosystems.

Abstract: Climate change and the resulting abiotic stresses that emerge due to anthropogenic activities are the main causes of agricultural losses worldwide. Abiotic stresses such as water scarcity, extreme temperatures, high irradiance, saline soils, nutrient deprivation and heavy metal contamination compromise the development and productivity of crops on a global scale. In this scenario, understanding the response of C4 plants to different abiotic stresses is of utmost importance, as they constitute major pillars of the global economy. To further our understanding of the response of C4 monocots, Setaria viridis and Setaria italica have gradually emerged as powerful model species for elucidating the physiological, biochemical, and molecular mechanisms of plant adaptation to abiotic stresses. This review integrates recent findings on the morphophysiological, transcriptomic, and metabolic responses of S. viridis and S. italica to drought, elevated heat and light, saline soils, nutrient deficiencies and heavy metal contamination. Comparative analyses highlight conserved and divergent stress-response pathways between the domesticated S. italica and its wild progenitor S. viridis. Together, these findings reinforce Setaria as a versatile C4 model for unraveling mechanisms of abiotic stress tolerance and highlight its potential as a genetic resource for developing climate-resilient cereal and bioenergy crops.

Abstract: Drought is a major constraint to Cannabis sativa productivity and cannabinoid yield, yet the physiological mechanisms underlying genotypic variation in drought responses remain poorly understood. We hypothesized that (i) more vigorous genotypes would sustain higher photosynthetic rates, (ii) drought would constrain photosynthesis through both diffusional and non-diffusional limitations, and (iii) water deficit would alter cannabinoid production in a genotype-dependent manner. To test these hypoth-eses, two contrasting genotypes (one tetrahydrocannabinol- (THC) dominant and an-other cannabidiol- (CBD) dominant) were grown under greenhouse conditions, with water deficit imposed at early flowering. Leaf water relations remained stable across genotypes and treatments. Although CBD plants accumulated more biomass, they did not exhibit higher photosynthetic rates under well-watered conditions. Under drought, THC plants relied primarily on stomatal regulation, whereas CBD plants showed addi-tional mesophyll and biochemical impairments, resulting in stronger declines in pho-tosynthesis. Despite contrasting photoprotective adjustments, both genotypes con-verged to similar oxidative damage, suggesting that photoprotection was not decisive for their physiological divergence. At the agronomic level, THC plants maintained a higher harvest index under drought, greater baseline cannabinoid concentrations, and inflorescence biomass with higher energetic value. In CBD plants, drought-induced reductions in cannabinoid content and harvest index largely reflected greater photo-synthetic impairment and less efficient carbon use. Overall, resilience of C. sativa to drought imposed at early flowering appears to depend less on hydraulic stability and more on sustaining photosynthetic performance, secondary metabolism, and efficient biomass partitioning. These traits represent key targets for breeding genotypes better adapted to cultivation under increasingly variable water availability.

Abstract:

Alfalfa (Medicago sativa L.), a perennial leguminous herb, exhibits robust cold and saline-alkali tolerance. In this study, two alfalfa cultivars, LJ and 218TR, were treated with saline-alkali stress, cold stress, and combined saline-alkali-cold stress, and phenotype, physiology, key metabolite and stress-responsive genes were analyzed. The results showed malondialdehyde, soluble sugar, proline content, and the activities of phenylalanine ammonia-lyase (PAL), superoxide dismutase, catalase, and peroxidase initially increased under individual stresses but declined after combined stress. The maximum photochemical efficiency of photosystem II and chlorophyll content declined under individual and combined stresses. The staining of leaves revealed that combined stress induced significantly higher cell mortality and accumulation of superoxide anion compared to individual stresses. LJ exhibited superior resistant to saline-alkali, cold, and combined stress compared to 218TR. Metabolite analysis showed salicylic acid (SA) in two alfalfa was the most responsive metabolite to combined stress. The isochorismate synthase (ICS) and PAL as critical genes for SA biosynthesis were up-regulated in expression under single or combined stress, and promoted SA accumulation, thereby improving alfalfa resilience to combined saline-alkali-cold stress. This study elucidates the physiological and molecular mechanisms underlying alfalfa’s response to combined saline-alkali and cold stress, providing a theoretical basis for breeding stress-tolerant cultivars.