Testing intra-species variation in allocation to growth and defense in rubber tree (Hevea brasiliensis).

Background: Plants allocate resources to growth, defense, and stress resistance, and resource availability can affect the balance between these allocations. Allocation patterns are well-known to differ among species, but what controls possible intra-specific trade-offs and if variation in growth vs. defense potentially evolves in adaptation to resource availability. Methods: We measured growth and defense in a provenance trial of rubber trees (Hevea brasiliensis) with clones originating from the Amazon basin. To test hypotheses on the allocation to growth vs. defense, we relate biomass growth and latex production to wood and leaf traits, to climate and soil variables from the location of origin, and to the genetic relatedness of the Hevea clones. Results: Contrary to expectations, there was no trade-off between growth and defense, but latex yield and biomass growth were positively correlated, and both increased with tree size. The absence of a trade-off may be attributed to the high resource availability in a plantation, allowing trees to allocate resources to both growth and defense. Growth was weakly correlated with leaf traits, such as leaf mass per area, intrinsic water use efficiency, and leaf nitrogen content, but the relative investment in growth vs. defense was not associated with specific traits or environmental variables. Wood and leaf traits showed clinal correlations to the rainfall and soil variables of the places of origin. These traits exhibited strong phylogenetic signals, highlighting the role of genetic factors in trait variation and adaptation. The study provides insights into the interplay between resource allocation, environmental adaptations, and genetic factors in trees. However, the underlying drivers for the high variation of latex production in one of the commercially most important tree species remains unexplained.

ECPUB5 Polyubiquitin Gene in Euphorbia characias: Molecular Characterization and Seasonal Expression Analysis.

The spurge Euphorbia characias is known for its latex, which is rich in antioxidant enzymes and anti-phytopathogen molecules. In this study, we identified a novel polyubiquitin protein in the latex and leaves, leading to the first molecular characterization of its coding gene and expressed protein in E. characias. Using consensus-degenerate hybrid oligonucleotide primers (CODEHOP) and rapid amplification of cDNA ends (5'/3'-RACE), we reconstructed the entire open reading frame (ORF) and noncoding regions. Our analysis revealed that the polyubiquitin gene encodes five tandemly repeated sequences, each coding for a ubiquitin monomer with amino acid variations in four of the five repeats. In silico studies have suggested functional differences among monomers. Gene expression peaked during the summer, correlating with high temperatures and suggesting a role in heat stress response. Western blotting confirmed the presence of polyubiquitin in the latex and leaf tissues, indicating active ubiquitination processes. These findings enhance our understanding of polyubiquitin's regulatory mechanisms and functions in E. characias, highlighting its unique structural and functional features.

BpAFP, a Broussonetia papyrifera latex chitinase, exhibits a dual role in resisting to both Verticillium wilt disease and lepidopterous pests, Plutella xylostella and Prodenia litura.

Paper mulberry (Broussonetia papyrifera) is a fast-growing tree known for its tolerance to diverse biotic and abiotic stresses. To explore genes combating Verticillium wilt, a devasting and formidable disease damage to cotton and many economically significant crops, we purified an antifungal protein, named BpAFP, from the latex of paper mulberry. Based on peptide fingerprint, we cloned the full cDNA sequence of BpAFP and revealed that BpAFP belongs to Class I chitinases, sharing 74 % identity with B. papyrifera leaf chitinase, PMAPII. We further introduced BpAFP into Arabidopsis, tobacco, and cotton. Transgenic plants exhibited significant resistance to Verticillium wilt. Importantly, BpAFP also demonstrated insecticidal activity against herbivorous pests, Plutella xylostella, and Prodenia litura, when feeding the larvae with transgenic leaves. Our finding unveils a dual role of BpAFP in conferring resistance to both plant diseases and lepidopterous pests.

Computational investigation of cis-1,4-polyisoprene binding to the latex-clearing protein LcpK30.

Latex clearing proteins (Lcps) catalyze the oxidative cleavage of the C = C bonds in cis-1,4-polyisoprene (natural rubber), producing oligomeric compounds that can be repurposed to other materials. The active catalytic site of Lcps is buried inside the protein structure, thus raising the question of how the large hydrophobic rubber chains can access the catalytic center. To improve our understanding of hydrophobic polymeric substrate binding to Lcps and subsequent catalysis, we investigated the interaction of a substrate model containing ten carbon-carbon double bonds with the structurally characterized LcpK30, using multiple computational tools. Prediction of the putative tunnels and cavities in the LcpK30 structure, using CAVER-Pymol plugin 3.0.3, fpocket and Molecular Dynamic (MD) simulations provided valuable insights on how substrate enters from the surface to the buried active site. Two dominant tunnels were discovered that provided feasible routes for substrate binding, and the presence of two hydrophobic pockets was predicted near the heme cofactor. The larger of these pockets is likely to accommodate the substrate and to determine the size distribution of the oligomers. Protein-ligand docking was carried out using GOLD software to predict the conformations and interactions of the substrate within the protein active site. Deeper insight into the protein-substrate interactions, including close-contacts, binding energies and potential cleavage sites in the cis-1,4-polyisoprene, were obtained from MD simulations. Our findings provide further justification that the protein-substrate complexation in LcpK30 is mainly driven by the hydrophobic interactions accompanied by mutual conformational changes of both molecules. Two potential binding modes were identified, with the substrate in either extended or folded conformations. Whilst binding in the extended conformation was most favorable, the folded conformation suggested a preference for cleavage of a central double bond, leading to a preference for oligomers with 5 to 6 C = C bonds. The results provide insight into further enzyme engineering studies to improve catalytic activity and diversify the substrate and product scope of Lcps.

Review: Laticifer as a plant defense mechanism.

Laticifers have been utilized as paradigms to enhance comprehension of specific facets of plant ecology and evolution. From the beginning of seedling growth, autonomous laticifer networks are formed throughout the plant structure, extending across all tissues and organs. The vast majority of identified products resulting from laticifer chemistry and metabolism are linked to plant defense. The latex, which is the fluid contained within laticifers, is maintained under pressure and has evolved to serve as a defense mechanism against both aggressors and invaders, irrespective of their capabilities or tactics. Remarkably, the latex composition varies among different species. The current goal is to understand the specific functions of various latex components in combating plant enemies. Therefore, the study of latex's chemical composition and proteome plays a critical role in advancing our understanding about plant defense mechanisms. Here, we will discuss some of these aspects.

Nematicidal Activity of 20-Deoxyingenol-3-angelate from Euphorbia peplus Latex Through Protein Kinase C Isotype TPA-1.

The latex of Euphorbia peplus and its major component 20-deoxyingenol-3-angelate (DI3A) displayed significant nematicidal activity against Caenorhabditis elegans and Panagrellus redivivus. DI3A treatment inhibited the growth and development of nematodes and caused significantly negative effects on locomotion behavior, reproduction, and accumulation of reactive oxygen species. Transcriptome analysis indicated that differential expression genes in DI3A-treated C. elegans were mainly associated with the metabolism, growth, and development process, which were further confirmed by RT-qPCR experiments. The expression level of TPA-1 gene encoding a protein kinase C isotype was obviously upregulated by DI3A treatment, and knockdown of TPA-1 by RNAi technology in the nematode could relieve the growth-inhibitory effect of DI3A. Metabolic analysis indicated that DI3A was hardly metabolized by C. elegans, but a glycosylated indole derivative was specifically accumulated likely due to the activation of detoxification. Overall, our findings suggested that DI3A from E. peplus latex exerted a potent nematicidal effect through the gene TPA-1, which provides a potential target for the control of nematodes and also suggests the potential application value of E. peplus latex and DI3A as botanical nematicides.

Genome-Wide Characterization and Expression Analyses of Major Latex Protein Gene Family in Populus simonii × P. nigra.

Major latex proteins, or MLPs, are crucial to plants' capacity to grow, develop, and endure biotic and abiotic stresses. The MLP gene family has been found in numerous plants, but little is known about its role in Populus simonii × P. nigra. This study discovered and assessed 43 PtMLP genes that were unevenly dispersed throughout 12 chromosomes in terms of their physicochemical characteristics, gene structure, conserved motifs, and protein localization. Based on their phylogeny and protein structural characteristics, three separate subclasses of PtMLP family were identified. Segmental and tandem duplication were found to be essential variables in the expansion of the PtMLP genes. The involvement of the PtMLP genes in growth and development, as well as in the responses to different hormones and stresses, was demonstrated by cis-regulatory element prediction. The PtMLP genes showed varying expression patterns in various tissues and under different conditions (cold, salt, and drought stress), as demonstrated in RNA-Seq databases, suggesting that PsnMLP may have different functions. Following the further investigation of the genes demonstrating notable variations in expression before and after the application of three stresses, PsnMLP5 was identified as a candidate gene. Subsequent studies revealed that PsnMLP5 could be induced by ABA treatment. This study paves the way for further investigations into the MLP genes' functional mechanisms in response to abiotic stressors, as well as the ways in which they can be utilized in poplar breeding for improved stress tolerance.

Cleavage of natural rubber by rubber oxygenases in Gram-negative bacteria.

Bacterial degradation of natural rubber (NR) in an oxic environment is initiated by oxidative cleavage of double bonds in the NR-carbon backbone and is catalyzed by extracellular haem-containing rubber oxygenases. NR-cleavage products of sufficiently low molecular mass are taken up by the cells and metabolized for energy and biomass formation. Gram-negative and Gram-positive NR-degrading bacteria (usually) employ different types of rubber oxygenases such as RoxA and/or RoxB (most Gram-negative NR-degraders) or latex clearing protein Lcp (most Gram-positive NR-degraders). In order to find novel orthologues of Rox proteins, we have revisited databases and provide an update of Rox-like proteins. We describe the putative evolution of rubber oxygenases and confirm the presence of a third subgroup of Rox-related proteins (RoxCs), the biological function of which remains, however, unclear. We summarize the knowledge on the taxonomic position of Steroidobacter cummioxidans 35Y and related species. Comparison of genomic and biochemical features of strain 35Y with other species of the genus Steroidobacter suggests that strain 35Y represents a species of a novel genus for which the designation Aurantibaculum gen. nov. is proposed. A short summary on the capabilities of NR-degrading consortia, that could be superior in biotechnological applications compared to pure cultures, is also provided. KEY POINTS: • Three types of rubber oxygenases exist predominantly in Gram-negative microbes • S. cummioxidans 35Y contains RoxA and RoxB which are superior in activity • S. cummioxidans 35Y represents a species of a novel genus.

Integrated physiology, transcriptome and proteome analyses highlight the potential roles of multiple hormone-mediated signaling pathways involved in tapping panel dryness in rubber tree.

Currently, one of the most serious threats to rubber tree is the tapping panel dryness (TPD) that greatly restricts natural rubber production. Over-tapping or excessive ethephon stimulation is regarded as the main cause of TPD occurrence. Although extensive studies have been carried out, the molecular mechanism underlying TPD remains puzzled. An attempt was made to compare the levels of endogenous hormones and the profiles of transcriptome and proteome between healthy and TPD trees. Results showed that most of endogenous hormones such as jasmonic acid (JA), 1-aminocyclopropanecarboxylic acid (ACC), indole-3-acetic acid (IAA), trans-zeatin (tZ) and salicylic acid (SA) in the barks were significantly altered in TPD-affected rubber trees. Accordingly, multiple hormone-mediated signaling pathways were changed. In total, 731 differentially expressed genes (DEGs) and 671 differentially expressed proteins (DEPs) were identified, of which 80 DEGs were identified as putative transcription factors (TFs). Further analysis revealed that 12 DEGs and five DEPs regulated plant hormone synthesis, and that 16 DEGs and six DEPs were involved in plant hormone signal transduction pathway. Nine DEGs and four DEPs participated in rubber biosynthesis and most DEGs and all the four DEPs were repressed in TPD trees. All these results highlight the potential roles of endogenous hormones, signaling pathways mediated by these hormones and rubber biosynthesis pathway in the defense response of rubber trees to TPD. The present study extends our understanding of the nature and mechanism underlying TPD and provides some candidate genes and proteins related to TPD for further research in the future.

Genome-wide identification of rubber tree pathogenesis-related 10 (PR-10) proteins with biological relevance to plant defense.

Pathogenesis-related 10 (PR-10) is a group of small intracellular proteins that is one of 17 subclasses of pathogenesis-related proteins in plants. The PR-10 proteins have been studied extensively and are well-recognized for their contribution to host defense against phytopathogens in several plant species. Interestingly, the accumulation of PR-10 proteins in the rubber tree, one of the most economically important crops worldwide, after being infected by pathogenic organisms has only recently been reported. In this study, the homologous proteins of the PR-10 family were systemically identified from the recently available rubber tree genomes in the NCBI database. The sequence compositions, structural characteristics, protein physical properties, and phylogenetic relationships of identified PR-10 proteins in rubber trees support their classification into subgroups, which mainly consist of Pru ar 1-like major allergens and major latex-like (MLP) proteins. The rubber tree PR10-encoding genes were majorly clustered on chromosome 15. The potential roles of rubber tree PR-10 proteins are discussed based on previous reports. The homologous proteins in the PR-10 family were identified in the recent genomes of rubber trees and were shown to be crucial in host responses to biotic challenges. The genome-wide identification conducted here will accelerate the future study of rubber tree PR-10 proteins. A better understanding of these defense-related proteins may contribute to alternative ways of developing rubber tree clones with desirable traits in the future.

Biochemical characterization of Euphorbia resinifera floral cyathia.

Euphorbia resinifera O. Berg is a plant endemic to the Northern and Central regions of Morocco known since the ancient Roman and Greek times for secreting a poisonous latex containing resiniferatoxin. However, E. resinifera pseudo-inflorescences called cyathia are devoid of laticifers and, therefore, do not secrete latex. Instead, they exudate nectar that local honey bees collect and craft into honey. Honey and cyathium water extracts find a broad range of applications in the traditional medicine of Northern Africa as ointments and water decoctions. Moreover, E. resinifera monofloral honey has received the Protected Geographic Indication certification for its outstanding qualities. Given the relevance of E. resinifera cyathia for bee nutrition, honey production, and the health benefit of cyathium-derived products, this study aimed to screen metabolites synthesized and accumulated in its pseudo-inflorescences. Our analyses revealed that E. resinifera cyathia accumulate primary metabolites in considerable abundance, including hexoses, amino acids and vitamins that honey bees may collect from nectar and craft into honey. Cyathia also synthesize volatile organic compounds of the class of benzenoids and terpenes, which are emitted by flowers pollinated by honey bees and bumblebees. Many specialized metabolites, including carotenoids, flavonoids, and polyamines, were also detected, which, while protecting the reproductive organs against abiotic stresses, also confer antioxidant properties to water decoctions. In conclusion, our analyses revealed that E. resinifera cyathia are a great source of antioxidant molecules and a good food source for the local foraging honeybees, revealing the central role of the flowers from this species in mediating interactions with local pollinators and the conferral of medicinal properties to plant extracts.

Identification and Characterization of the HbPP2C Gene Family and Its Expression in Response to Biotic and Abiotic Stresses in Rubber Tree.

Plant PP2C genes are crucial for various biological processes. To elucidate the potential functions of these genes in rubber tree (Hevea brasiliensis), we conducted a comprehensive analysis of these genes using bioinformatics methods. The 60 members of the PP2C family in rubber tree were identified and categorized into 13 subfamilies. The PP2C proteins were conserved across different plant species. The results revealed that the HbPP2C genes contained multiple elements responsive to phytohormones and stresses in their promoters, suggesting their involvement in these pathways. Expression analysis indicated that 40 HbPP2C genes exhibited the highest expression levels in branches and the lowest expression in latex. Additionally, the expression of A subfamily members significantly increased in response to abscisic acid, drought, and glyphosate treatments, whereas the expression of A, B, D, and F1 subfamily members notably increased under temperature stress conditions. Furthermore, the expression of A and F1 subfamily members was significantly upregulated upon powdery mildew infection, with the expression of the HbPP2C6 gene displaying a remarkable 33-fold increase. These findings suggest that different HbPP2C subgroups may have distinct roles in the regulation of phytohormones and the response to abiotic and biotic stresses in rubber tree. This study provides a valuable reference for further investigations into the functions of the HbPP2C gene family in rubber tree.

Characterization of an antifungal ß-1,3-glucanase from Ficus microcarpa latex and comparison of plant and bacterial ß-1,3-glucanases for fungal cell wall ß-glucan degradation.

MAIN CONCLUSION: Each ß-1,3-glucanase with antifungal activity or yeast lytic activity hydrolyzes different structures of ß-1,3-glucans in the fungal cell wall, respectively. Plants express several glycoside hydrolases that target chitin and ß-glucan in fungal cell walls and inhibit pathogenic fungal infection. An antifungal ß-1,3-glucanase was purified from gazyumaru (Ficus microcarpa) latex, designated as GlxGluA, and the corresponding gene was cloned and expressed in Escherichia coli. The sequence shows that GlxGluA belongs to glycoside hydrolase family 17 (GH17). To investigate how GlxGluA acts to degrade fungal cell wall ß-glucan, it was compared with ß-1,3-glucanase with different substrate specificities. We obtained recombinant ß-1,3-glucanase (designated as CcGluA), which belongs to GH64, from the bacterium Cellulosimicrobium cellulans. GlxGluA inhibited the growth of the filamentous fungus Trichoderma viride but was unable to lyse the yeast Saccharomyces cerevisiae. In contrast, CcGluA lysed yeast cells but had a negligible inhibitory effect on the growth of filamentous fungi. GlxGluA degraded the cell wall of T. viride better than CcGluA, whereas CcGluA degraded the cell wall of S. cerevisiae more efficiently than GlxGluA. These results suggest that the target substrates in fungal cell walls differ between GlxGluA (GH17 class I ß-1,3-glucanase) and CcGluA (GH64 ß-1,3-glucanase).

Genome-Wide Evolutionary Characterization and Expression Analysis of Major Latex Protein (MLP) Family Genes in Tomato.

Major latex proteins (MLPs) play a key role in plant response to abiotic and biotic stresses. However, little is known about this gene family in tomatoes (Solanum lycopersicum). In this paper, we perform a genome-wide evolutionary characterization and gene expression analysis of the MLP family in tomatoes. We found a total of 34 SlMLP members in the tomato genome, which are heterogeneously distributed on eight chromosomes. The phylogenetic analysis of the SlMLP family unveiled their evolutionary relationships and possible functions. Furthermore, the tissue-specific expression analysis revealed that the tomato MLP members possess distinct biological functions. Crucially, multiple cis-regulatory elements associated with stress, hormone, light, and growth responses were identified in the promoter regions of these SlMLP genes, suggesting that SlMLPs are potentially involved in plant growth, development, and various stress responses. Subcellular localization demonstrated that SlMLP1, SlMLP3, and SlMLP17 are localized in the cytoplasm. In conclusion, these findings lay a foundation for further dissecting the functions of tomato SlMLP genes and exploring the evolutionary relationships of MLP homologs in different plants.

Interactions of REF1 and SRPP1 rubber particle proteins from Hevea brasiliensis with synthetic phospholipids: Effect of charge and size of lipid headgroup.

According to the fatty acid and headgroup compositions of the phospholipids (PL) from Hevea brasiliensis latex, three synthetic PL were selected (i.e. POPA: 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphate POPC: 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and POPG: 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol) to investigate the effect of PL headgroup on the interactions with two major proteins of Hevea latex, i.e. Rubber Elongation Factor (REF1) and Small Rubber Particle Protein (SRPP1). Protein/lipid interactions were screened using two models (lipid vesicles in solution or lipid monolayers at air/liquid interface). Calcein leakage, surface pressure, ellipsometry, microscopy and spectroscopy revealed that both REF1 and SRPP1 displayed stronger interactions with anionic POPA and POPG, as compared to zwitterionic POPC. A particular behavior of REF1 was observed when interacting with POPA monolayers (i.e. aggregation + modification of secondary structure from α-helices to ß-sheets, characteristic of its amyloid aggregated form), which might be involved in the irreversible coagulation mechanism of Hevea rubber particles.

Investigate the anaerobic degradation of high-acetone latex wastewater with magnetite supplement.

This study evaluated the effects of acetone on the anaerobic degradation of synthetic latex wastewater, which was simulated from the wastewater of the deproteinized natural rubber production process, including latex, acetate, propionate, and acetone as the main carbon sources, at a batch scale in 5 cycles of a total of 60 days. Fe3O4 was applied to accelerate the treatment performance from cycle 3. Acetone was added in concentration ranges of 0%, 0.05%, 0.1%, 0.15%-included latex, and 0.15%-free latex (w/v). In the Fe3O4-free cycles, for latex-added vials, soluble chemical oxygen demand (sCOD) was removed at 43.20%, 43.20%, and 12.65%, corresponding to the input acetone concentrations varying from 0.05% to 0.15%, indicating the interference of acetone for COD reduction. After adding Fe3O4, all flasks reported a significant increase in COD removal efficiency, especially for acetone-only and latex-only vials, from 36.9% to 14.30%-42.95% and 83.20%, respectively. Other highlighted results of COD balance showed that Fe3O4 involvement improved the degradation process of acetate, propionate, acetone, and the other COD parts, including the intermediate products of latex reduction. Besides, during the whole batch process, the order of reduction priority of the carbon sources in the synthetic wastewater was acetate, propionate and acetone. We also found that the acetate concentration appeared to be strongly related to reducing other carbon sources in natural rubber wastewater. Microbial community analysis revealed that protein-degrading bacteria Bacteroidetes vadinHA17 and Proteinniphilum and methylotrophic methanogens might play key roles in treating simulated deproteinized-natural-rubber wastewater.

Peptidomic Analysis and Antimicrobial Activity of Serum Peptide from Hevea brasiliensis Clone BPM24.

BACKGROUND: Hevea brasiliensis is severely affected by the fungal disease caused by Phytophthora spp. Significant loss of rubber yield is widespread and extensive use of chemical fungicides has resulted in health and environmental problems. OBJECTIVE: This work aims to extract and identify the latex serum peptides from a disease tolerant clone of H. brasiliensis, and study the inhibitory efficacy against pathogenic bacteria and fungi. METHODS: Serum peptides were extracted from H. brasiliensis BPM24 using mixed lysis solution. Low molecular weight peptides were screened and fractionated by solid-phase extraction and then identified by tandem mass spectrometry. Total and fractionated serum peptides were assayed for bacterial and fungal inhibition using broth microdilution and poisoned food methods. An inhibitory control study in the greenhouse was also performed using susceptible clones for pre and postinfection with Phytophthora spp. RESULTS: Forty-three serum peptide sequences were successfully identified. Thirty-four peptides matched with the proteins associated with plant defense response signaling, host resistance, and adverse environmental factors. The inhibitory study of total serum peptides demonstrated antibacterial and anti-fungal properties. The greenhouse study exhibited disease inhibitory efficacy of 60% for the treatment of Phytophthora spp. in post-infected plants and 80% for pre-treated samples. CONCLUSION: Latex serum peptides from disease tolerant H. brasiliensis revealed several proteins and peptides associated with plant defense and disease resistance. The peptides play a vital role for defense against bacteria and fungi pathogens, including Phytophthora spp. Enhanced disease protection can be obtained when the extracted peptides were applied to the susceptible plants before exposure to the fungi. These findings provided an insight and may pave the way for the development of biocontrol peptides from natural resources.

Latex derived from Ficus carica L. inhibited the growth of NSCLC by regulating the caspase/gasdermin/AKT signaling pathway.

Previous studies reported the latex from the fruit of Ficus carica L. (fig) has anti-tumor and antioxidant activities in animal models. However, its active constituents, mechanism of action, and safety remain unknown. The alcohol-precipitated fraction of fig fruit latex (AFFL) was purified and prepared for testing against non-small cell lung cancer (NSCLC). UPLC-TOF-MS/MS was used to examined the components of AFFL. We validated efficacy by researching antitumor phenotypes in vitro and constructing subcutaneous grafts of nude mice with NSCLC, as well as showing the underlying mechanism at the protein level. The results showed that 11 components of AFFL were screened. AFFL significantly inhibited the proliferation, migration, invasion, and clonogenesis of NSCLC cells, promoted cell apoptosis, inhibited tumor growth in A549 xenograft mice, but induced no obvious damage to normal mouse tissues (liver or kidney). Molecular mechanism studies revealed that AFFL could increase Caspase-1 expression in cancer cells by activating the cleavage of Caspase-3 and Caspase-9, inhibiting the activity of Bcl-2, and promoting tumor cell apoptosis. These processes cause gasdermin proteins (GSDMD and GSDME) to be cleaved, releasing N-terminal domain proteins to accumulate and perforate the cell membrane, and promoting tumor cell pyroptosis. In conclusion, our findings suggested that AFFL may promote tumor cell apoptosis and pyroptosis via the Caspase/Gasdermin/AKT signaling pathway and inhibit NSCLC growth in vitro and in vivo, demonstrating that fig latex can be developed as a functional food and drug with anti-NSCLC properties.

Comprehensive Analysis of Major Latex-Like Protein Family Genes in Cucumber (Cucumis sativus L.) and Their Potential Roles in Phytophthora Blight Resistance.

Major latex-like proteins (MLPs) play crucial roles in abiotic and biotic stresses. However, little was known about this gene family in cucumbers. In this study, a total of 37 putative cucumber MLP genes were identified on a genome-wide level and classified into three groups by sequence homologous comparison with Arabidopsis thaliana. Chromosome mapping suggested that only tandem duplication occurred in evolution. The multiple regulatory cis-elements related to stress, hormone, light and growth response were found in the promoter region of these CsMLP genes, indicating that CsMLPs might be widely involved in the process of plant growth, development and various stress conditions. Transcriptome analysis indicated a strong reprogramming of MLPs expression in response to Phytophthora melonis infection in cucumber. Knockdown of CsMLP1 reduced the P. melonis tolerance, while transient overexpression of CsMLP1 improved disease tolerance in cucumber. Conversely, the silence of CsMLP5 decreased the lesion area caused by P. melonis in the cotyledons, and overexpression of CsMLP5 promoted lesion expansion. Taken together, our results provide a comprehensive basis for further mining the function of CsMLP members and will also be significant for elucidating the evolutionary relationship in cucumber.

Natural rubber reduces herbivory and alters the microbiome below ground.

Laticifers are hypothesized to mediate both plant-herbivore and plant-microbe interactions. However, there is little evidence for this dual function. We investigated whether the major constituent of natural rubber, cis-1,4-polyisoprene, a phylogenetically widespread and economically important latex polymer, alters plant resistance and the root microbiome of the Russian dandelion (Taraxacum koksaghyz) under attack of a root herbivore, the larva of the May cockchafer (Melolontha melolontha). Rubber-depleted transgenic plants lost more shoot and root biomass upon herbivory than normal rubber content near-isogenic lines. Melolontha melolontha preferred to feed on artificial diet supplemented with rubber-depleted rather than normal rubber content latex. Likewise, adding purified cis-1,4-polyisoprene in ecologically relevant concentrations to diet deterred larval feeding and reduced larval weight gain. Metagenomics and metabarcoding revealed that abolishing biosynthesis of natural rubber alters the structure but not the diversity of the rhizosphere and root microbiota (ecto- and endophytes) and that these changes depended on M. melolontha damage. However, the assumption that rubber reduces microbial colonization or pathogen load is contradicted by four lines of evidence. Taken together, our data demonstrate that natural rubber biosynthesis reduces herbivory and alters the plant microbiota, which highlights the role of plant-specialized metabolites and secretory structures in shaping multitrophic interactions.