Search Results (29)

Total Soluble Solids (TSS) in tomatoes is a core indicator for evaluating fruit quality and processing characteristics. Its composition mainly consists of soluble sugars (such as fructose and glucose) and organic acids (such as citric acid and malic acid). The contents of sugars and acids and their ratio directly affect the flavor and nutritional value. Cultivated tomatoes have a TSS of 4–6%, compared with 10–15% in wild varieties. In recent years, with the advancement of molecular biology and genomics technologies, significant progress has been made in the research on the regulatory mechanisms of tomato fruit TSS and major sugars and acids, including the identification of major quantitative trait locus (QTLs) (Lin5, SlALMT9), functional characterization via CRISPR/Cas9 and elucidation of the transporter network. Breaking the negative correlation between TSS and yield remains a major bottleneck in breeding. Analyzing the mechanism by which environmental factors regulate the TSS and optimizing cultivation measures are crucial for increasing the TSS content in tomatoes. The deep integration of cutting-edge technologies (such as Genome-wide association studies (GWAS), metabolome-wide association studies (mGWAS), Genomic selection (GS), genome editing, and crop modeling) with design breeding is expected to accelerate the development of high-TSS tomato varieties. This paper reviews the current research status from the following four aspects: QTL mapping related to tomato TSS and mining of major genes, metabolic and transport mechanisms of major sugars and acids and key genes, the influence of environmental factors on TSS, and application of genetic improvement strategies and technologies. Full article

Aluminum (Al) toxicity is a major constraint on crop production in acidic soils. A key mechanism for aluminum resistance in many plants involves the ALMT1-mediated exudation of malate from the root system. This process hinges on the precise regulation of ALMT1 expression, which is therefore critical for plant tolerance to aluminum toxicity. In a screen for Arabidopsis mutants with altered aluminum resistance, we found that the loss-of-function mutant of the WRKY61 transcription factor exhibited significantly enhanced resistance to aluminum toxicity, indicating that WRKY61 is involved in the plant’s response to aluminum toxicity. Further research revealed that WRKY61 binds to the W-box in the ALMT1 promoter to repress its expression. Mutation of WRKY61 resulted in increased malate secretion from mutant roots, which chelated aluminum ions, leading to a significant reduction in aluminum content within the plant. This, in turn, significantly enhances malate secretion under aluminum toxicity, ultimately conferring heightened aluminum resistance. These results clearly indicate that WRKY61, as a transcriptional repressor of ALMT1, plays a negative regulatory role in plant resistance to aluminum toxicity. Full article

This study aimed to determine the stress mechanisms induced by foliar methyl jasmonate (MeJA) application in Vaccinium corymbosum cultivars subjected to water deficit (WD) and aluminum toxicity (Al). Two V. corymbosum cultivars, Star and Legacy, were subjected to different treatments in an Andisol: control (80% field capacity and low Al saturation), combined WD + Al (50% field capacity and 85% Al saturation), and different concentrations of foliar MeJA application (10 μM, 50 μM, and 100 μM) under WD + Al conditions. The determination of photosynthetic pigments, osmolytes, and organic acids, as well as the auxin levels and the expression of Aluminium-Activated Malate Transporter (ALMT) and Multidrug and Toxic Compound Extrusion (MATE) genes, was analyzed at 7 and 21 days. Foliar MeJA application increased chlorophyll a, b, and carotenoid levels, mainly at 50 µM, exhibiting early Star responses with up to 1.5-fold higher pigment accumulation, and a later increase in Legacy with up to 1.4-fold higher accumulation. Proline increases up to 2.2-fold in roots and sugar by 1.4-fold in leaves of both cultivars. The MeJA application increases the auxin levels by up to 2.3-fold in Star roots at 7 days and by up to 1.4-fold in Legacy leaves at 21 days. MeJA-induced upregulation of ALMT and MATE gene expression facilitated Al detoxification, with malate and citrate levels increasing up to 2-fold. Hierarchical clustering confirmed that the Star cultivar activated resistance mechanisms early, while the Legacy cultivar exhibited delayed but sustained resistance mechanisms. MeJA improves V. corymbosum resistance to combined WD + Al stress by modulating photosynthetic pigments, osmolytes, organic acids, and hormone regulation. This finding underscores the biotechnological potential of MeJA application to improve stress resilience and optimize crop performance under adverse environmental conditions. Full article

Multimodal sentiment analysis aims to utilize multisource information such as text, speech and vision to more comprehensively and accurately identify an individual’s emotional state. However, existing methods still face challenges in practical applications, including modality heterogeneity, insufficient expressive power of non-verbal modalities, and low fusion efficiency. To address these issues, this paper proposes a Modality Enhanced Multimodal Integration Model (MEMMI). First, a modality enhancement module is designed to leverage the semantic guidance capability of the text modality, enhancing the feature representation of non-verbal modalities through a multihead attention mechanism and a dynamic routing strategy. Second, a gated fusion mechanism is introduced to selectively inject speech and visual information into the dominant text modality, enabling robust information completion and noise suppression. Finally, a combined attention fusion module is constructed to synchronously fuse information from all three modalities within a unified architecture, hile a multiscale encoder is used to capture feature representations at different semantic levels. Experimental results on three benchmark datasets—CMU-MOSEI, CMU-MOSI, and CH-SIMS—demonstrate the superiority of the proposed model. On CMU-MOSI, it achieves an Acc-7 of 45.91, with binary accuracy/F1 of 82.86/84.60, MAE of 0.734, and Corr of 0.790, outperforming TFN and MulT by a large margin. On CMU-MOSEI, the model reaches an Acc-7 of 54.17, Acc-2/F1 of 83.69/86.02, MAE of 0.526, and Corr of 0.779, surpassing all baselines, including ALMT. On CH-SIMS, it further achieves 41.88, 66.52, and 77.68 in Acc-5/Acc-3/Acc-2, with F1 of 77.85, MAE of 0.450, and Corr of 0.594, establishing new state-of-the-art performance across datasets. These results confirm that MEMMI achieves state-of-the-art performance across multiple metrics. Furthermore, ablation studies validate the effectiveness of each module in enhancing modality representation and fusion efficiency. Full article

Aluminum (Al) stress is typical for acidic soils and may affect cereals’ yield. Al tolerance in triticale is mostly affected by the aluminum-activated malate transporter (ALMT) gene (7R) and some other QTLs (3R, 5R, and 6R). The trait is heritable in about 36% of cases, indicating that epigenetic factors may impact the phenomenon. This study demonstrates that utilizing different methods to quantify DNA methylation changes induced by Al stress results in detail differences, and the results evaluated should be compared critically. The Common and the basic General approaches are sufficient if general information is needed. The General (extended variant) approach may deliver data on methylation changes affecting symmetric sequence contexts. The markers assigned to DN-CG, DM-CG, and DN-CHG were suggested as the most important in explaining Al tolerance in triticale. Analysis of the maps constructed based on root tips and leaf tissues showed different densities of the epigenetic markers but reflected the comparable patterns of their distribution, supporting the hypothesis that Al stress could be transmitted to other plant tissues due to somatic memory. Methylation changes occur throughout the genome and are not associated with specific genes related to aluminum stress. Full article

ALMT (aluminum-activated malate transporter) proteins play crucial roles in the transport of organic acids and have significant implications for plant stress responses and development. While extensively studied in some plants, the characteristics and functional divergence of the ALMT gene family have not yet been thoroughly explored in Prunus mume and some other Rosaceae species. In this study, we systematically analyzed the ALMT gene family across nine Rosaceae species to explore their evolutionary relationships, structural characteristics, and functional roles. A total of 138 ALMT genes were identified and categorized into four groups based on a phylogenetic analysis. The motif analysis confirmed the accuracy of the phylogenetic grouping. The collinearity analysis indicated that whole-genome duplication events were the primary drivers of ALMT gene expansion in these species. Furthermore, the cis-acting element analysis revealed diverse regulatory elements associated with environmental responses, including abscisic acid, light, and jasmonic acid. The gene expression correlation analysis showed that PmALMT1 is primarily associated with malic acid accumulation, whereas PmALMT8 is related to citric acid accumulation. Further transient expression in Nicotiana benthamiana validated the above conclusion. This comprehensive analysis provides valuable insights into the evolution, function, and regulation of the ALMT gene family in Rosaceae species. Full article

Aluminum-activated malate transporter (ALMT) genes play an important role in aluminum ion (Al³⁺) tolerance, fruit acidity, and stomatal movement. Although decades of research have been carried out in many plants, there is little knowledge about the roles of ALMT in Orchidaceae. In this study, 34 ALMT genes were identified in the genomes of four orchid species. Specifically, ten ALMT genes were found in Dendrobium chrysotoxum and D. catenatum, and seven were found in Apostasia shenzhenica and Phalaenopsis equestris. These ALMT genes were further categorized into four clades (clades 1–4) based on phylogenetic relationships. Sequence alignment and conserved motif analysis revealed that most orchid ALMT proteins contain conserved regions (TM1, GABA binding motif, and WEP motif). We also discovered a unique motif (19) belonging to clade 1, which can serve as a specifically identified characteristic. Comparison with the gene structure of AtALMT genes (Arabidopsis thaliana) showed that the gene structure of ALMT was conserved across species, but the introns were longer in orchids. The promoters of orchid ALMT genes contain many light-responsive and hormone-responsive elements, suggesting that their expression may be regulated by light and phytohormones. Chromosomal localization and collinear analysis of D. chrysotoxum indicated that tandem duplication (TD) is the main reason for the difference in the number of ALMT genes in these orchids. D. catenatum was chosen for the RT-qPCR experiment, and the results showed that the DcaALMT gene expression pattern varied in different tissues. The expression of DcaALMT1-9 was significantly changed after ABA treatment. Combining the circadian CO₂ uptake rate, titratable total acid, and RT-qPCR data analysis, most DcaALMT genes were highly expressed at night and around dawn. The result revealed that DcaALMT genes might be involved in photosynthate accumulation. The above study provides more comprehensive information for the ALMT gene family in Orchidaceae and a basis for subsequent functional analysis. Full article

Centipedegrass (Eremochloa ophiuroides (Munro.) Hack.) is a species originating in China and is an excellent warm-season turfgrass. As a native species in southern China, it is naturally distributed in the phosphorus-deficient and aluminum-toxic acid soil areas. It is important to research the molecular mechanism of centipedegrass responses to phosphorus-deficiency and/or aluminum-toxicity stress. Quantitative Real-Time PCR (qRT-PCR) is a common method for gene expression analysis, and the accuracy of qRT-PCR results depends heavily on the stability of internal reference genes. However, there are still no reported stable and effective reference genes for qRT-PCR analysis of target genes under the acid-soil-related stresses in different organs of centipedegrass. For scientific rigor, the gene used as a reference for any plant species and/or any stress conditions should be first systematically screened and evaluated. This study is the first to provide a group of reliable reference genes to quantify the expression levels of functional genes of Eremochloa ophiuroides under multiple stresses of P deficiency and/or aluminum toxicity. In this study, centipedegrass seedlings of the acid-soil-resistant strain ‘E041’ and acid-soil-sensitive strain ‘E089’ were used for qRT-PCR analysis. A total of 11 candidate reference genes (ACT, TUB, GAPDH, TIP41, CACS, HNR, EP, EF1α, EIF4α, PP2A and actin) were detected by qRT-PCR technology, and the stability of candidate genes was evaluated with the combination of four internal stability analysis software programs. The candidate reference genes exhibited differential stability of expression in roots, stems and leaves under phosphorus-deficiency and/or aluminum-toxicity stress. On the whole, the results showed that GAPDH, TIP41 and HNR were the most stable in the total of samples. In addition, for different tissues under various stresses, the selected reference genes were also different. CACS and PP2A were identified as two stable reference genes in roots through all three stress treatments (phosphate deficiency, aluminum toxicity, and the multiple stress treatment of aluminum toxicity and phosphate deficiency). Moreover, CACS was also stable as a reference gene in roots under each treatment (phosphate deficiency, aluminum toxicity, or multiple stresses of aluminum toxicity and phosphate deficiency). In stems under all three stress treatments, GAPDH and EIF4α were the most stable reference genes; for leaves, PP2A and TIP41 showed the two highest rankings in all three stress treatments. Finally, qRT-PCR analysis of the expression patterns of the target gene ALMT1 was performed to verify the selected reference genes. The application of the reference genes identified as internal controls for qRT-PCR analysis will enable accurate analysis of the target gene expression levels and expression patterns in centipedegrass under acid-soil-related stresses. Full article

As a C4 warm-season turfgrass, centipedegrass (Eremochloa ophiuroides (Munro) Hack.) is known for its exceptional resilience to intensive maintenance practices. In this research, the most stably expressed reference genes in the leaves of centipedegrass under different stress treatments, including salt, cold, drought, aluminum (Al), and herbicide, were screened by the quantitative real-time PCR (RT-qPCR) technique. The stability of 13 candidate reference genes was evaluated by software GeNorm V3.4, NormFinder V20, BestKeeper V1.0, and ReFinder V1.0. The results of this experiment demonstrated that the expression of the UBC (ubiquitin-conjugating enzyme) remained the most stable under cold and Al stress conditions. On the other hand, the MD (malate dehydrogenase) gene exhibited the best performance in leaf tissues subjected to salt and drought stresses. Under herbicide stress, the expression level of the RIP (60S ribosomal protein L2) gene ranked the highest. The expression levels of abiotic stress-associated genes such as PIP1, PAL, COR413, ALMT9, and BAR were assessed to validate the reliability of the selected reference genes. This study provides valuable information and reference points for gene expression under abiotic stress conditions in centipedegrass. Full article

Aluminium toxicity and phosphorus deficiency in soils are the main interconnected problems of modern agriculture. The aluminium-activated malate transporters (ALMTs) comprise a membrane protein family that demonstrates various physiological functions in plants, such as tolerance to environmental Al³⁺ and the regulation of stomatal movement. Over the past few decades, the regulation of ALMT family proteins has been intensively studied. In this review, we summarise the current knowledge about this transporter family and assess their involvement in diverse physiological processes and comprehensive regulatory mechanisms. Furthermore, we have conducted a thorough bioinformatic analysis to decipher the functional importance of conserved residues, structural components, and domains. Our phylogenetic analysis has also provided new insights into the molecular evolution of ALMT family proteins, expanding their scope beyond the plant kingdom. Lastly, we have formulated several outstanding questions and research directions to further enhance our understanding of the fundamental role of ALMT proteins and to assess their physiological functions. Full article

Arsenic is a toxic metal abundantly present in agricultural, industrial, and pesticide effluents. To overcome arsenic toxicity and ensure safety for plant growth, silicon (Si) can play a significant role in its mitigation. Here, we aim to investigate the influence of silicon on date palm under arsenic toxicity by screening antioxidants accumulation, hormonal modulation, and the expression profile of abiotic stress-related genes. The results showed that arsenic exposure (As: 1.0 mM) significantly retarded growth attributes (shoot length, root length, fresh weight), reduced photosynthetic pigments, and raised reactive species levels. Contrarily, exogenous application of Si (Na₂SiO₃) to date palm roots strongly influenced stress mitigation by limiting the translocation of arsenic into roots and shoots as compared with the arsenic sole application. Furthermore, an enhanced accumulation of polyphenols (48%) and increased antioxidant activities (POD: 50%, PPO: 75%, GSH: 26.1%, CAT: 51%) resulted in a significant decrease in superoxide anion (O₂^•−: 58%) and lipid peroxidation (MDA: 1.7-fold), in silicon-treated plants, compared with control and arsenic-treated plants. The Si application also reduced the endogenous abscisic acid (ABA: 38%) under normal conditions, and salicylic acid (SA: 52%) and jasmonic acid levels (JA: 62%) under stress conditions as compared with control and arsenic. Interestingly, the genes; zeaxanthin epoxidase (ZEP) and 9-cis-epoxycarotenoid dioxygenase (NCED-1) involved in ABA biosynthesis were upregulated by silicon under arsenic stress. Likewise, Si application also upregulated gene expression of plant plasma membrane ATPase (PMMA-4), aluminum-activated malate transporter (ALMT) responsible for maintaining cellular physiology, stomatal conductance, and short-chain dehydrogenases/reductases (SDR) involved in nutrients translocation. Hence, the study demonstrates the remarkable role of silicon in supporting growth and inducing arsenic tolerance by increasing antioxidant activities and endogenous hormones in date palm. The outcomes of our study can be employed in further studies to better understand arsenic tolerance and decode mechanism. Full article

Nitric oxide (NO), as a signal molecule, is involved in the mediation of heavy-metal-stress-induced physiological responses in plants. In this study, we investigated the effect of NO on Camellia sinensis pollen tubes exposed to aluminum (Al) stress. Exogenous application of the NO donor decreased the pollen germination rate and pollen tube length and increased the malondialdehyde (MDA) content and antioxidant enzyme activities under Al stress. Simultaneously, the NO donor effectively increased NO content in pollen tube of C. sinensis under Al stress and could aggravate the damage of Al³⁺ to C. sinensis pollen tubes by promoting the uptake of Al³⁺. In addition, application of the NO-specific scavenger significantly alleviated stress damage in C. sinensis pollen tube under Al stress. Moreover, 18 CsALMT members from a key Al-transporting gene family were identified, which could be divided into four subclasses. Pearson correlation analysis showed the expression level of CsALMT8 showed significant positive correlation with the Al³⁺ concentration gradient and NO levels, but a significant negative correlation with pollen germination rate and pollen tube length. The expression level of CsALMT5 was negatively correlated with the Al³⁺ concentration gradient and NO level, and positively correlated with pollen germination rate and pollen tube length. The expression level of CsALMT17 showed a significant negative correlation with Al³⁺ concentration and NO content in pollen tubes, but significant positive correlation with pollen germination rate and pollen tube length. In conclusion, a complex signal network regulated by NO-mediated CsALMTs revealed that CsALMT8 was regulated by environmental Al³⁺ and NO to assist Al³⁺ entry into pollen tubes; CsALMT5 might be influenced by the Al³⁺ signal, stimulate malate efflux in vacuoles and chelate with Al³⁺ to detoxify Al in C. sinensis pollen tube. Full article

Plant-derived pharmacological agents have been used extensively to dissect the structure–function relationships of mammalian GABA receptors and ion channels. Picrotoxin is a non-competitive antagonist of mammalian GABA_A receptors. Here, we report that picrotoxin inhibits the anion (malate) efflux mediated by wheat (Triticum aestivum) ALMT1 but has no effect on GABA transport. The EC₅₀ for inhibition was 0.14 nM and 0.18 nM when the ALMTs were expressed in tobacco BY2 cells and in Xenopus oocytes, respectively. Patch clamping of the oocyte plasma membrane expressing wheat ALMT1 showed that picrotoxin inhibited malate currents from both sides of the membrane. These results demonstrate that picrotoxin inhibits anion efflux effectively and can be used as a new inhibitor to study the ion fluxes mediated by ALMT proteins that allow either GABA or anion transport. Full article

The hollow trait is crucial for commercial quality of cucumber (Cucumis sativus L.) fruit, and its molecular regulatory mechanism is poorly understood due to its environmental sensitivity. In the previous research, we obtained the hollow and the non-hollow materials of ecotype cucumbers of South China, which were not easily affected by the external environment through a systematic breeding method. In this study, first, we proposed to use the percentage of the hollow area as the criterion to compare the hollow characteristics between two materials, and to analyze the formation mechanism of early hollow trait from the perspective of cytology. The results showed that the hollow trait occurred in the early stage of fruit development, and formed with the opening of carpel ventral zipped bi-cell layer, which formed rapidly from 2 to 4 days, and then slowed to a constant rate from 14 to 16 days. Meanwhile, the different genetic populations were constructed using these materials, and fine mapping was performed by bulked segregant analysis (BSA) and kompetitive allele specific PCR (KASP) method. The Csa1G630860 (CsALMT2), encoding protein ALMT2, was determined as a candidate gene for regulating the hollow trait in fruit. Furthermore, the expression profile of CsALMT2 was analyzed by qRT-PCR and fluorescence in situ hybridization. The expression of CsALMT2 had obvious tissue specificity, and it was abundantly expressed in the ovule development zone inside the fruit. In the hollow material of cucumber fruit, the expression of CsALMT2 was significantly downregulated. The subcellular localization in tobacco leaves indicated that CsALMT2 was distributed on the plasma membrane. In conclusion, in this study, for the first time, we found the regulatory gene of hollow trait in cucumber fruit, which laid the foundation for subsequent research on the molecular mechanism of hollow trait formation in cucumber fruit, and made it possible to apply this gene in cucumber breeding. Full article

The current study aimed to understand the synergistic impacts of silicon (Si; 1.0 mM) and boron (B; 10 µM) application on modulating physio-molecular responses of date palm to mitigate aluminum (Al³⁺; 2.0 mM) toxicity. Results revealed that compared to sole Si and B treatments, a combined application significantly improved plant growth, biomass, and photosynthetic pigments during Al toxicity. Interestingly, Si and B resulted in significantly higher exudation of organic acid (malic acids, citric acids, and acetic acid) in the plant’s rhizosphere. This is also correlated with the reduced accumulation and translocation of Al in roots (60%) and shoots (56%) in Si and B treatments during Al toxicity compared to in sole Al³⁺ treatment. The activation of organic acids by combined Si + B application has significantly regulated the ALMT1, ALMT2 and plasma membrane ATPase; PMMA1 and PMMA3 in roots and shoots. Further, the Si-related transporter Lsi2 gene was upregulated by Si + B application under Al toxicity. This was also validated by the higher uptake and translocation of Si in plants. Al-induced oxidative stress was significantly counteracted by exhibiting lower malondialdehyde and superoxide production in Si + B treatments. Experiencing less oxidative stress was evident from upregulation of CAT and Cyt-Cu/Zn SOD expression; hence, enzymatic activities such as polyphenol oxidase, catalase, peroxidase, and ascorbate peroxidase were significantly activated. In the case of endogenous phytohormones, Si + B application demonstrated the downregulation of the abscisic acid (ABA; NCED1 and NCED6) and salicylic acid (SA; PYL4, PYR1) biosynthesis-related genes. Consequently, we also noticed a lower accumulation of ABA and rising SA levels under Al-stress. The current findings illustrate that the synergistic Si + B application could be an effective strategy for date palm growth and productivity against Al stress and could be further extended in field trails in Al-contaminated fields. Full article