Phytohormone Biosynthesis Research Articles

Characterization and Whole-Genome Sequencing of Phytobacter palmae WL65, a Plant Growth-Promoting Rhizobacterium First Isolated from Rice Rhizosphere Soil in Thailand

Phytobacter palmae WL65, isolated from the rice rhizosphere, was confirmed as P. palmae through whole-genome analysis. WL65 exhibited key plant growth-promoting (PGP) characteristics, including nitrogen fixation (nifA, nifB, nifD, nifE, nifF, nifH, nifJ, nifK, nifL, nifS, nifU, nifW, and nifX), phosphate solubilization (pstA, pstB, pstC, pstS, phnC, phnD, phnE, and phnV), siderophore production (fhuA, fhuB, fhuC, fhuD, fhuF, feoA, feoB, feoC, acrA, acrB, acrE, acrR, and acrZ), and phytohormone biosynthesis (trpA, trpB, trpC, trpE, trpGD, trpR, and trpS). WL65 also contains an enterobactin biosynthetic gene cluster, essential for iron acquisition and enhancing both bacterial survival and plant growth. This study provides the first genomic insights into the PGP characteristics of P. palmae. The application of WL65 in rice cultivation as a biostimulant resulted in effective root colonization, supported by biofilm formation genes (pgaA, pgaB, pgaC), which enhance bacterial adhesion. The treatment significantly improved rice growth, increasing plant height (5.8%), panicle length (10.2%), and seed yield (34.5%). Soil analysis revealed improved nutrient availability, including increased organic matter (21%), phosphorus (38.4%), potassium (29.8%), and calcium (27%) levels. These findings suggest that WL65 is a promising biofertilizer candidate for improving soil fertility and nutrient uptake in sustainable agriculture.

Transcriptional Regulation Mechanisms in AsAFL1-mediated Drought Tolerance for Creeping Bentgrass (Agrostis stolonifera).

Drought stress is a major environmental stress that impairs plant growth and development. The At14a-like1 (AFL1) gene encodes a stress-induced membrane protein involved in endocytosis, signal transduction, and proline accumulation. The objective of the present study was to investigate biological functions and underlying mechanisms of AFL1 regulation of drought tolerance in a perennial grass species, creeping bentgrass (Agrostis stolonifera). AsAFL1 was cloned from creeping bentgrass, and its expression was induced by drought stress. Motif analysis showed that AsAFL1 has five epidermal growth factor structural domains and one β1-integrin structural domain. Transient expression in tobacco epidermal cells indicated that AsAFL1 was localized at the plasma membrane. Overexpression of AsAFL1 in creeping bentgrass significantly enhanced drought tolerance, as manifested by significantly increased leaf relative water content, chlorophyll and proline contents but lower electrolyte leakage and malondialdehyde content. Comparative transcriptomic and weighted correlation network analysis (WGCNA) revealed that AsAFL1-mediated drought tolerance was related to transcriptional regulation of genes involved in phytohormone (abscisic acid, auxin, and strigolactone) biosynthesis and signaling, redox homeostasis, and biosynthesis of second metabolites (lignin, cutin, suberin and wax), as well as nutrient transport and mobilization.

Transcriptomic and biochemical analysis of pummelo x finger lime hybrids in response to Huanglongbing (HLB)

BackgroundHuanglongbing (HLB) is a devastating bacterial disease caused by the bacterium Candidatus Liberibacter asiaticus (CaLas) that affects the citrus industry worldwide. This study investigated the response of two pummelo x finger lime hybrid siblings to natural infection with CaLas. The hybrids were identified primarily using leaf morphology and molecular marker assessments and were selected for further studies on the basis of the CaLas titers in leaf petioles.ResultsHLB-infected budwood from the selected hybrids (PFL 2–61 and PFL 1–11), as well as the two parental plants, were propagated by grafting onto Swingle citrumelo rootstocks for further evaluation. Plant samples were collected two years after grafting for analysis. Leaves of PFL2-61 exhibited decreased CaLas titers compared with those of PFL 1–11. Additionally, we recorded increased chlorophyll content, total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity in PFL 2–61 compared to PFL 1–11 and the parents. We subsequently conducted a detailed investigation of these two hybrid siblings using transcriptome analysis. Among the 20,675 differentially expressed genes (DEGs) identified, 1,416 were downregulated in PFL 2–61 compared with PFL 1–11, whereas 326 were upregulated. Transcriptome analysis revealed that many of the DEGs were associated with the cell wall structure, redox homeostasis, and biotic stress responses. Moreover, key genes related to the biosynthesis of secondary metabolites and phytohormones, including PAL1, jasmonate-related genes, and WRKY transcription factors, were upregulated in the tolerant hybrid (PFL 2–61). In contrast, three transcripts associated with the Sieve Element Occlusion N-Terminus (SEO_N) domain were downregulated in the tolerant hybrid (PFL 2–61).ConclusionsOur findings provide valuable insights into the molecular mechanisms of tolerance and susceptibility to HLB in finger lime derived hybrids, highlighting the potential of this citrus species towards developing disease-tolerant varieties.Graphical

Arbuscular Mycorrhizal Fungi Alleviate Cadmium Phytotoxicity by Regulating Cadmium Mobility, Physiological Responses, and Gene Expression Patterns in Malus hupehensis Rehd.

Arbuscular mycorrhizal fungi (AMF) affect cadmium (Cd) accumulation and tolerance in host plants. However, the effects of AMF on Cd accumulation and phytotoxicity and their underlying mechanism in apples remain uncharacterized. In this study, the comprehensive physiological and molecular responses of uninoculated and Rhizophagus intraradices-inoculated Malus hupehensis Rehd. rootstocks exposed to 0 or 300 μM Cd were investigated. AMF inoculation mitigated Cd-induced growth and photosynthesis inhibition and nutrient ion disorders. It also lowered the concentrations of Cd in all tissues and reduced Cd transport to the shoots. Compared to uninoculated apple plants, those inoculated with mycorrhizal fungi reduced the mobility and toxicity of Cd by altering its form and binding it to the cell walls of the roots and leaves. AMF inoculation ameliorated Cd stress by altering endogenous phytohormone levels and triggering enzymatic and non-enzymatic antioxidant systems. Transcriptome analysis revealed that the differentially expressed genes (DEGs) associated with AMF under Cd stress regulated carbohydrate and amino acid biosynthesis and metabolism, as well as phytohormone biosynthesis and signal transduction. Furthermore, AMF inoculation downregulated certain genes involved in Cd uptake and transport while upregulating other genes involved in detoxification. These results suggest that AMF alleviate Cd phytotoxicity by orchestrated physiological and transcriptomic regulation in M. hupehensis Rehd., providing valuable insights into the efficacy of AMF inoculation in improving the heavy metal resistance of fruit trees.

Integrative analyses of morpho-physiological, biochemical, and transcriptomic reveal the seedling growth response of Pinus yunnanensis to nitrogen and phosphorus fertilization.

Appropriate nitrogen (N) and phosphorus (P) fertilization is critical for plant growth and production. Pinus yunnanensis, a silvicultural tree in southwestern China, faces economic and ecological limitations due to nutrient deficiency in the soils in its distribution areas. The slow growth of this species during the seedling stage exacerbates these problems. Therefore, it is important to realize the regulating effects of N and P proportioning fertilization on seedling growth to enhance nutrient-use efficiency. In this study, variations in morphological, physiological, and biochemical characteristics of seedlings were analyzed under nine treatments of NP proportioning in an open nursery using a regression design. Growth in height and basal diameter increased and showed an approximate tendency in all treatments. The maximum biomass accumulation was observed at 480 d after treatment in roots of T5 (14.714 g) (application N 0.4 g·per-1 and P 3 g·per-1), stems of T5 (12.654 g), leaves of T9 (24.261 g) (application N 0.8 g·per-1 and P 6 g·per-1), aboveground parts of T9 (35.402 g) and individuals of T5 (49 g). The total chlorophyll content peaked in the leaves at 120 d and was correlated with the peak levels of N, P, and K in leaves. The content and reserves of nutrient elements in the organs of seedlings subjected to NP proportioning were significantly higher than those in unfertilized seedlings. Analysis of nutrient utilization efficiency revealed that T5 demonstrated superior seedling growth performance. Appropriate fertilization dosage of N and P for P. yunnanensis seedlings in this study was 0.32 g·per-1-0.58 g·per-1 and 3.02 g·per-1-4.95 g·per-1 respectively, using path analysis and regression equation. Transcriptomic sequencing revealed that there were 2,301 DEGs between T5 and T1 (control), which were involved in the uptake and assimilation of nutrients, biosynthesis of phytohormones and secondary metabolites, and photosynthesis. Additionally, the abundance of genes involved in cell division and proliferation, cellulose biosynthesis, and cell wall extension were dramatically upregulated, which potentially correlated with enhanced seedling growth. In conclusion, this study provides comprehensive information on the response of seedlings to varying proportions of N and P and may promote the growth of P. yunnanensis seedlings by optimizing the proportion of N and P in fertilizers.

Systems analysis of long-term heat stress responses in the C4 grass Setaria viridis.

Many C4 plants are used as food and fodder crops and often display improved resource use efficiency compared to C3 plants. However, the response of C4 plants to future extreme conditions such as heatwaves is less understood. Here, Setaria viridis, an emerging C4 model grass, was grown under long-term high temperature stress for two weeks (42°C, compared to 28°C). This resulted in stunted growth, but surprisingly had little impact on leaf thickness, leaf area-based photosynthetic rates and bundle sheath leakiness. Dark respiration rates increased and there were major alterations in carbon and nitrogen metabolism in the heat-stressed plants. Abscisic acid and indole-acetic acid-amino acid conjugates accumulated in the heat-stressed plants, consistent with transcriptional changes. Leaf transcriptomics, proteomics and metabolomics analyses were carried out and mapped onto the metabolic pathways of photosynthesis, respiration, carbon/nitrogen metabolism and phytohormone biosynthesis and signaling. An in-depth analysis of correlations between transcripts and their corresponding proteins revealed strong differences between groups in the strengths and signs of correlations. Overall, many stress signaling pathways were upregulated, consistent with multiple signals leading to reduced plant growth. A systems-based model of the plant response to long-term heat stress is presented based on the oxidative stress, phytohormone and sugar signaling pathways.

Time-Course Transcriptomics Analysis Reveals Molecular Mechanisms of Salt-Tolerant and Salt-Sensitive Cotton Cultivars in Response to Salt Stress.

Salt stress is an environmental factor that limits plant seed germination, growth, and survival. We performed a comparative RNA sequencing transcriptome analysis during germination of the seeds from two cultivars with contrasting salt tolerance responses. A transcriptomic comparison between salt-tolerant cotton cv Jin-mian 25 and salt-sensitive cotton cv Su-mian 3 revealed both similar and differential expression patterns between the two genotypes during salt stress. The expression of genes related to aquaporins, kinases, reactive oxygen species (ROS) scavenging, trehalose biosynthesis, and phytohormone biosynthesis and signaling that include ethylene (ET), gibberellin (GA), abscisic acid (ABA), jasmonic acid (JA), and brassinosteroid (BR) were systematically investigated between the cultivars. Despite the involvement of these genes in cotton's response to salt stress in positive or negative ways, their expression levels were mostly similar in both genotypes. Interestingly, a PXC2 gene (Ghir_D08G025150) was identified, which encodes a leucine-rich repeat receptor-like protein kinase (LRR-RLK). This gene showed an induced expression pattern after salt stress treatment in salt-tolerant cv Jin-mian 25 but not salt-sensitive cv Su-mian 3. Our multifaceted transcriptome approach illustrated a differential response to salt stress between salt-tolerant and salt-sensitive cotton.

Nanosilica and salicylic acid synergistically regulate cadmium toxicity in rice

Nanosilica and salicylic acid synergistically regulate cadmium toxicity in rice

Circadian Regulation of the Rice Immune Response during Rice Blast Infection via Metabolic and Calcium Signaling.

The circadian clock is crucial in plant immunity and metabolism, yet the coordinating mechanisms remain elusive. In the present study, transcriptome analysis of M. oryzae-infected rice leaves and rhythmic analysis showed reduced amplitudes of circadian and phytochrome genes, impacting immune response, metabolic pathways, and calcium signaling. The amplitudes of pattern-triggered immunity (PTI)-related genes declined, while the rhythmicity of effector-triggered immunity (ETI)-related genes disappeared. Moreover, alterations in the phases of metabolic pathways were observed, potentially involved in immune response regulation like phytohormone biosynthesis. Calcium signaling exhibited a circadian pattern similar to that of the whole-transcriptome analysis. The administration of CaCl2 alleviated, whereas the calcium ion chelator EGTA aggravated, the phenotypes of rice blasts, suggesting their role in regulating the circadian clock-mediated immune response in rice. Our study highlighted the significance of circadian regulation in rice blast-induced immune modulation, which may contribute to developing immunomodulators and the formulation of chronobiology-based precise therapeutic regimens.

Molecular basis of resistance to leaf spot disease in oil palm

IntroductionLeaf spot disease caused by the fungal pathogen Curvularia oryzae is one of the most common diseases found in oil palm (Elaeis guineensis) nurseries in South East Asia, and is most prevalent at the seedling stage. Severe infections result in localized necrotic regions of leaves that rapidly spread within nurseries leading to poor quality seedlings and high economic losses.MethodsTo understand the molecular mechanisms of this plant-pathogen interaction, RNA-Seq was used to elucidate the transcriptomes of three oil palm genotypes with contrasting pathogen responses (G10 and G12, resistant and G14, susceptible) following infection with C. oryzae spores. Transcriptomes were obtained from Illumina NovaSeq 6000 sequencing of mRNA at four different time points (day 0, before treatment; day 1, 7, and 21 post treatment).Results and discussionAnalysis of differentially expressed gene (DEG) profiles in these three genotypes provided an overview of the genes involved in the plant defence. Genes involved in disease resistance, phytohormone biosynthesis, gene regulation (transcription factors), and those encoding proteins associated with cell wall hardening were identified and likely contribute to the resistance of oil palm to C. oryzae. Such genes represent good candidates for targets to enhance oil palm productivity and resilience through molecular breeding approaches.

Deciphering the ABA and GA biosynthesis approach of Bacillus pumilus, mechanistic approach, explaining the role of metabolic region as an aid in improving the stress tolerance

Bacillus pumilus plays an essential role in agricultural applications as a beneficial microbe and for sustainable agriculture production. However, the underlying mechanisms of B. pumilus strains remain unclear as to how they are beneficial for plants as stress tolerant and growth promoters. Bacillus pumilus was isolated from the rhizosphere soil of Artemisia vulgaris. NGS (next-generation sequencing) was performed for the strain to gain new insights into the molecular mechanisms underlying plant-microbial interactions. NGS revealed 3,910 genes, 3294 genes with protein-coding, and 11 functional genomic regions related to diverse agronomic traits including stress tolerance. We identified the two possible phytohormone biosynthesis approaches from metabolic regions1(terpense→diterpense→betacarotene→xanthoxin→ABA)2(terpense→diterpense→geranyl diphosphate →C20 →GA). Several gene clusters related to the biosynthesis of phytohormones, stress tolerance, and agricultural diversification were predicted. The genome provides insights into the possible mechanisms of this bacterium for stress tolerance and its future applications. The genomic organization of B. pumilus revealed several hallmarks of its plant growth promotion and pathogen suppression activities. Our results provide detailed genomic information for the strain and reveal its potential stress tolerance mechanisms, laying the foundation for developing effective stress tolerance strategies against abiotic stress.

Effect of Rhizospheric Bacteria Capable of Biosynthesis and/or Destruction of Phytohormones on the Growth Characteristics and Hormonal Status of Wheat Plants in Conditions of Water Scarcity

The ability of various strains of soil bacteria to synthesize and/or destroy plant growth regulators: indolyl-3-acetic acid (IAA), cytokinins (CK) and abscisic acid (ABA) has been shown. Bacteria stimulated the growth of shoots and roots of soft wheat under normal conditions of moisture and drought, had a significant effect on the content of phytohormones in shoots and roots of plants. The most promising growth stimulators were strains with an average level of IAA production in combination with the ability to destroy phytohormones: Pseudomonas protegens DA1.2, P. plecoglossicida 2.4-D and the cytokinin-producing strain P. chlororaphis IB-6.

Functional Divergence of the Closely Related Genes PhARF5 and PhARF19a in Petunia hybrida Flower Formation and Hormone Signaling.

The ARF gene family plays a vital role in regulating multiple aspects of plant growth and development. However, detailed research on the role of the ARF family in regulating flower development in petunia and other plants remains limited. This study investigates the distinct roles of PhARF5 and PhARF19a in Petunia hybrida flower development. Phylogenetic analysis identified 29 PhARFs, which were grouped into four clades. VIGS-mediated silencing of PhARF5 and PhARF19a led to notable phenotypic changes, highlighting their non-redundant functions. PhARF5 silencing resulted in reduced petal number and limb abnormalities, while PhARF19a silencing disrupted corolla tube formation and orientation. Both genes showed high expression in the roots, leaves, and corollas, with nuclear localization. The transcriptomic analysis revealed significant overlaps in DEGs between PhARF5 and PhARF19a silencing, indicating shared pathways in hormone metabolism, signal transduction, and stress responses. Phytohormone analysis confirmed their broad impact on phytohormone biosynthesis, suggesting involvement in complex feedback mechanisms. Silencing PhARF5 and PhARF19a led to differential transcription of numerous genes related to hormone signaling pathways beyond auxin signaling, indicating their direct or indirect crosstalk with other phytohormones. However, significant differences in the regulation of these signaling pathways were observed between PhARF5 and PhARF19a. These findings reveal the roles of ARF genes in regulating petunia flower development, as well as the phylogenetic distribution of the PhARFs involved in this process. This study provides a valuable reference for molecular breeding aimed at improving floral traits in the petunia genus and related species.

Genomic insights into bamboo witches' broom disease: pathogenicity and phytohormone biosynthesis in Aciculosporium take.

Bamboo witches' broom disease (WBD), caused by Aciculosporium take Miyake, devastates bamboo forests. Understanding the genome and pathogenic factors of pathogen is crucial for disease control. We employed single-molecule real-time sequencing, Illumina paired-end sequencing, and chromatin interaction mapping techniques to assemble the genome of A. take CCTCC-M2023413, analyze pathogenicity- and phytohormone-biosynthesis-related genes, and compare it to 12 other WBD pathogens. The genome of A. take is 59.24 Mb in size, with 54.32% repeats, 7 chromosomes, 7,105 protein-coding genes, 84 ribosomal RNAs, and 115 transfer RNAs. Predictive analysis of pathogenicity genes found 237 carbohydrate-active enzymes, 1,069 membrane transport proteins, 1,040 pathogen-host interaction genes, 315 virulence factors, and 70 effectors. Most of pathogenicity genes overlapped with repeat-rich regions. Additionally, 172 genes were linked to auxin biosynthesis, 53 to brassinosteroid biosynthesis, and 2 to cis-zeatin biosynthesis. Comparative genomic analysis identified 77 core orthogroups shared by 13 WBD pathogens, played roles in metabolites, genetic information processing, pathogenesis, cis-zeatin biosynthesis, lifespan, and quorum sensing. The miaA gene, crucial for cis-zeatin biosynthesis, is structurally conserved and sequence-diverse among 13 WBD pathogens, with upregulated expression during bamboo WBD pathogenesis. This highlights that cis-zeatin is significant contributor to host pathogenesis, and miaA is a new potential target for controlling WBD. This study provides important insights on preventing and controlling bamboo WBD.

Biochemical Defence of Plants against Parasitic Nematodes.

Plant parasitic nematodes (PPNs), such as Meloidogyne spp., Heterodera spp. and Pratylenchus spp., are obligate parasites on a wide range of crops, causing significant agricultural production losses worldwide. These PPNs mainly feed on and within roots, impairing both the below-ground and the above-ground parts, resulting in reduced plant performance. Plants have developed a multi-component defence mechanism against diverse pathogens, including PPNs. Several natural molecules, ranging from cell wall components to secondary metabolites, have been found to protect plants from PPN attack by conferring nematode-specific resistance. Recent advances in omics analytical tools have encouraged researchers to shed light on nematode detection and the biochemical defence mechanisms of plants during nematode infection. Here, we discuss the recent progress on revealing the nematode-associated molecular patterns (NAMPs) and their receptors in plants. The biochemical defence responses of plants, comprising cell wall reinforcement; reactive oxygen species burst; receptor-like cytoplasmic kinases; mitogen-activated protein kinases; antioxidant activities; phytohormone biosynthesis and signalling; transcription factor activation; and the production of anti-PPN phytochemicals are also described. Finally, we also examine the role of epigenetics in regulating the transcriptional response to nematode attack. Understanding the plant defence mechanism against PPN attack is of paramount importance in developing new, effective and sustainable control strategies.

Small chemical molecules regulating the phytohormone signalling alter the plant's physiological processes to improve stress adaptation, growth and productivity.

Small chemical molecules are attractive agents for improving the plant processes associated with plant growth and stress tolerance. Recent advances in chemical biology and structure-assisted drug discovery approaches have opened up new avenues in plant biology to discover new drug-like molecules to improve plant processes for sustained food production. Several compounds targeting phytohormone biosynthesis or signalling cascades were designed to alter plant physiological mechanisms. Altering Abscisic acid synthesis and its signalling process can improve drought tolerance, and the processes targeted are reversible. Molecules targeting cytokinin, Auxin, and gibberellic acid regulate plant physiological processes and can potentially improve plant growth, biomass and productivity. The potential of molecules may be exploited as agrochemicals to enhance agricultural productivity. The discovery of small molecules provides new avenues to improve crop production in changing climatic conditions and the nutritional quality of foods. We present the rational combinations of small molecules with inhibitory and co-stimulatory effects and discuss future opportunities in this field.

Comparative Analysis of Phytohormone Biosynthesis Genes Responses to Long-Term High Light in Tolerant and Sensitive Wheat Cultivars.

Phytohormones are vital for developmental processes, from organ initiation to senescence, and are key regulators of growth, development, and photosynthesis. In natural environments, plants often experience high light (HL) intensities coupled with elevated temperatures, which pose significant threats to agricultural production. However, the response of phytohormone-related genes to long-term HL exposure remains unclear. Here, we examined the expression levels of genes involved in the biosynthesis of ten phytohormones, including gibberellins, cytokinins, salicylic acid, jasmonic acid, abscisic acid, brassinosteroids, indole-3-acetic acid, strigolactones, nitric oxide, and ethylene, in two winter wheat cultivars, Xiaoyan 54 (XY54, HL tolerant) and Jing 411 (J411, HL sensitive), when transferred from low light to HL for 2-8 days. Under HL, most genes were markedly inhibited, while a few, such as TaGA2ox, TaAAO3, TaLOG1, and TaPAL2, were induced in both varieties. Interestingly, TaGA2ox2 and TaAAO3 expression positively correlated with sugar content but negatively with chlorophyll content and TaAGP expression. In addition, we observed that both varieties experienced a sharp decline in chlorophyll content and photosynthesis performance after prolonged HL exposure, with J411 showing significantly more sensitivity than XY54. Hierarchical clustering analysis classified the phytohormone genes into the following three groups: Group 1 included six genes highly expressed in J411; Group 2 contained 25 genes drastically suppressed by HL in both varieties; and Group 3 contained three genes highly expressed in XY54. Notably, abscisic acid (ABA), and jasmonic acid (JA) biosynthesis genes and their content were significantly higher, while gibberellins (GA) content was lower in XY54 than J411. Together, these results suggest that the differential expression and content of GA, ABA, and JA play crucial roles in the contrasting responses of tolerant and sensitive wheat cultivars to leaf senescence induced by long-term HL. This study enhances our understanding of the mechanisms underlying HL tolerance in wheat and can guide the development of more resilient wheat varieties.

Fermentation broth of a novel endophytic fungus enhanced maize salt tolerance by regulating sugar metabolism and phytohormone biosynthesis or signaling

Fermentation broth of a novel endophytic fungus enhanced maize salt tolerance by regulating sugar metabolism and phytohormone biosynthesis or signaling

Transcriptome Analysis Reveals the Mechanism of Cold-Induced Sweetening in Chestnut during Cold Storage.

Chestnuts become sweetened with better tastes for fried products after cold storage, but the possible mechanism is not clear. The dynamics of sugar components and related physiological responses, as well as the possible molecular mechanism in chestnuts during cold storage, were investigated. Sucrose accumulation and starch degradation contributed to taste improvement. Sucrose content reached the peak after two months of cold storage, along with the accumulation of reducing sugars of maltose, fructose and glucose to a much lesser extent. Meanwhile, alpha-amylase and beta-amylase maintained high levels, and the activities of acid invertase and sucrose synthase increased. Transcriptome data demonstrated that differentially expressed genes (DEGs) were significantly enriched in the process of starch and sucrose metabolism pathway, revealing the conversion promotion of starch to sucrose. Furthermore, DEGs involved in multiple phytohormone biosynthesis and signal transduction, as well as the transcription regulators, indicated that sucrose accumulation might be interconnected with the dormancy release of chestnuts, with over 90% germinated after two months of cold storage. Altogether, the results indicated that cold storage improved the taste of chestnuts mainly due to sucrose accumulation induced by DEGs of starch and sucrose metabolism pathway in this period, and the sweetening process was interconnected with dormancy release.

Integrative analysis of transcriptome and metabolome reveals how ethylene increases natural rubber yield in Hevea brasiliensis.

Hevea brasiliensis is an important cash crop with the product named natural rubber (NR) for markets. Ethylene (ET) is the most effective yield stimulant in NR production but the molecular mechanism remains incomplete. Here, latex properties analysis, transcriptome analysis, and metabolic profiling were performed to investigate the mechanism of NR yield increase in four consecutive tappings after ET stimulation. The results revealed that sucrose and inorganic phosphate content correlated positively with dry-rubber yield and were induced upon ET stimulation. Stimulation with ET also led to significant changes in gene expression and metabolite content. Genes involved in phytohormone biosynthesis and general signal transduction as well as 51 transcription factors potentially involved in the ET response were also identified. Additionally, KEGG annotation of differentially accumulated metabolites suggested that metabolites involved in secondary metabolites, amino-acid biosynthesis, ABC transporters, and galactose metabolism were accumulated in response to ET. Integrative analysis of the data collected by transcriptomics and metabolomics identified those differentially expressed genes and differentially accumulated metabolites are mainly involved in amino-acid biosynthesis and carbohydrate metabolism. Correlation analysis of genes and metabolites showed a strong correlation between amino-acid biosynthesis during ET stimulation. These findings provide new insights into the molecular mechanism underlying the ET-induced increase in rubber yield and further our understanding of the regulatory mechanism of ethylene signaling in rubber biosynthesis.