Isolation and expression analysis of a novel major latex-like protein (MLP151) gene from Panax ginseng

Characterisation of the MLP genes in peach postharvest cold storage and the regulatory role of PpMLP10 in the chilling stress response

The major latex proteins/ripening-related proteins are a subfamily of the Bet v 1 protein superfamily and are commonly involved in plant development and responses to various stresses. However, the functions of MLPs in the postharvest cold storage of fruits remain uninvestigated. Herein, we identified 30 MLP genes in the peach (Prunus persica) genome that were clustered into three subgroups. Chromosomal location analysis revealed that the PpMLP genes were unevenly distributed on five of the eight peach chromosomes. Synteny analysis of the MLP genes between peach and seven other plant species (five dicotyledons and two monocotyledons) explored their evolutionary characteristics. Furthermore, the PpMLP promoters contained cis-elements for multiple hormones and stress responses. Gene expression analysis revealed that PpMLPs participated in chilling stress responses. Ectopic expression of PpMLP10 in Arabidopsis improved chilling stress tolerance by decreasing membrane damage and maintaining membrane stability. Additional research confirmed that PpWRKY2 participates in PpMLP10-mediated chilling stress by binding to its promoter. Collectively, these results suggest the role of PpMLP10 in enhancing chilling stress tolerance, which is significant for decreasing chilling injury during the postharvest cold storage of peaches.

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.

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.

Proteomics analysis of a tobacco variety resistant to brown spot disease and functional characterization of NbMLP423 in Nicotiana benthamiana

BACKGROUND

Tobacco brown spot disease is an important disease caused by Alternaria alternata that affects tobacco production and quality worldwide. Planting resistant varieties is the most economical and effective way to control this disease. However, the lack of understanding of the mechanism of tobacco resistance to tobacco brown spot has hindered progress in the breeding of resistant varieties.

METHODS AND RESULTS

In this study, differentially expressed proteins (DEPs), including 12 up-regulated and 11 down-regulated proteins, were screened using isobaric tags for relative and absolute quantification (iTRAQ) by comparing resistant and susceptible pools and analyzing the associated functions and metabolic pathways. Significantly up-regulated expression of the major latex-like protein gene 423 (MLP 423) was detected in both the resistant parent and the population pool. Bioinformatics analysis showed that the NbMLP423 cloned in Nicotiana benthamiana had a similar structure to the NtMLP423 in Nicotiana tabacum, and that expression of both genes respond rapidly to Alternaria alternata infection. NbMLP423 was then used to study the subcellular localization and expression in different tissues, followed by both silencing and the construction of an overexpression system for NbMLP423. The silenced plants demonstrated inhibited TBS resistance, while the overexpressed plants exhibited significantly enhanced resistance. Exogenous applications of plant hormones, such as salicylic acid, had a significant inducing effect on NbMLP423 expression.

CONCLUSIONS

Taken together, our results provide insights into the role of NbMLP423 in plants against tobacco brown spot infection and provide a foundation for obtaining resistant tobacco varieties through the construction of new candidate genes of the MLP subfamily.

Inter and intraspecific variability of dieldrin accumulation in Cucurbita fruits: New perspectives for food safety and phytomanagement of contaminated soils

Due to past agricultural practices, it is common to identify arable soils contaminated with persistent and potentially toxic organochlorine pesticides (OCPs). Occurrence of OCPs, including dieldrin, in vegetables can lead to chronic exposure of the consumers. Some market vegetables, particularly the Cucurbitaceae, are known to accumulate high OCP concentrations. Dieldrin concentration in Cucurbita fruits can exceed the Maximal Residue Limit (MRL) resulting in cultivation and sale restrictions for market gardeners. To assess the intra- and interspecific variability of Cucurbitaceae species for low dieldrin concentration in fruits could be a solution. Here, 24 varieties from seven Cucurbitaceae species were cultivated outdoors in large pots, until fruiting, in soils historically contaminated with dieldrin. More than 330 fruits were harvested and analyzed for determining the inter and intraspecific variability of dieldrin accumulation. Significant interspecific differences occurred with mean fruit concentration ranging between 4.2 ± 7.0 and 85.0 ± 19.4 μg dieldrin kg^-1 fresh weigh (FW) in watermelons (C. lanatus L.) and cucumbers (C. sativus L.), respectively. Intraspecific differences only occurred for Cucurbita pepo L. with mean concentration ranging between 4.9 ± 1.1 and 70.3 ± 3.6 μg dieldrin kg^-1 FW for the varieties Noire maraîchère and Orélia, respectively. For this plant species, the influence of soil concentration, plant exposure time and biomass on fruit dieldrin concentration depended mainly on varieties.

Functional Studies of Plant Latex as a Rich Source of Bioactive Compounds: Focus on Proteins and Alkaloids

Latex, a sticky emulsion produced by specialized cells called laticifers, is a crucial part of a plant's defense system against herbivory and pathogens. It consists of a broad spectrum of active compounds, which are beneficial not only for plants, but for human health as well, enough to mention the use of morphine or codeine from poppy latex. Here, we reviewed latex's general role in plant physiology and the significance of particular compounds (alkaloids and proteins) to its defense system with the example of Chelidonium majus L. from the poppy family. We further attempt to present latex chemicals used so far in medicine and then focus on functional studies of proteins and other compounds with potential pharmacological activities using modern techniques such as CRISPR/Cas9 gene editing. Despite the centuries-old tradition of using latex-bearing plants in therapies, there are still a lot of promising molecules waiting to be explored.

Transport enhancement of hydrophobic pollutants by the expression of zucchini major latex-like protein genes in tobacco plants

The environmental spread of hydrophobic pollutants has been receiving attention because of specific characteristics of these compounds that make them resistant to degradation, thus causing various toxic effects on humans as a result of their bioaccumulation. Here, we report the role of zucchini major-latex like proteins (MLPs) on the accumulation of hydrophobic pollutants, as consumption of contaminated crops is one of the main routes for accumulation. Transgenic tobacco plants expressing an aryl hydrocarbon receptor (AhR) gene with a β-glucuronidase (GUS) inducible expression system were transformed with one of the three zucchini MLP genes (PG1, GR1, and GR3). MLP transgenic plants showed a significant increase in the fold induction of GUS activity compared to the parental AhR tobacco plants when one of the most toxic polychlorinated biphenyl (PCB) congeners, 3,3',4,4',5-pentachlorobiphenyl (CB126), was applied. GUS activity was detected in both aerial parts and roots after treatment with the strong carcinogen 3-methylcholanthrene. Phenotypic changes in the MLP tobacco during incubation with CB126 were also observed. The MLP transgenic plant PG1 responded to treatment with 0.32 nM CB126, whereas vector control plants significantly induced GUS activity at 200 nM CB126. Moreover, GUS activities in the MLP plants treated with other PCB congeners were significantly higher than those in the plants given the mock treatment. As GUS activities in the aerial parts of the plants were significantly correlated with the accumulation level of PCBs, these results strongly suggest that zucchini MLPs are related to the translocation of hydrophobic pollutants from the roots to the aerial parts through their binding affinity.

Comparative transcriptome analysis of resistant and cultivated tomato lines in response to Clavibacter michiganensis subsp. michiganensis

Clavibacter michiganensis subsp. michiganensis (Cmm) is a gram-positive bacterium causing destructive bacterial wilt and canker disease in tomato. Herein, a comparative transcriptome analysis was performed on Cmm-resistant and -susceptible tomato lines. Tomato seedlings were inoculated with Cmm and harvested for transcriptome analysis after 4 and 8 day time-points. Twenty-four transcriptome libraries were profiled by RNA sequencing approach. Total of 545 million clean reads was generated. 1642 and 2715 differentially expressed genes (DEG) were identified in susceptible lines within 4 and 8 days after inoculation (DAI), respectively. In resistant lines, 1731 and 1281 DEGs were found following 4 and 8 DAI, respectively. Gene Ontology analysis resulted in a higher number of genes involved in biological processes and molecular functions in susceptible lines. On the other hand, such biological processes, "defense response", and "response to stress" were distinctly indicated in resistant lines which were not found in susceptible ones upon inoculation, according to the gene set enrichment analyses. Upon Cmm-inoculation, several defense responsive genes were found to be differentially expressed. Of which 26 genes were in the resistant line and three were in the susceptible line. This study helps to understand the transcriptome response of Cmm-resistant and -susceptible tomato lines. The results provide comprehensive data for molecular breeding studies, for the purpose to control of the pathogen in tomato.

Review: Biological functions of major latex-like proteins in plants

Major latex-like proteins (MLPs) have been identified in dicots and monocots. They are members of the birch pollen allergen Bet v 1 family as well as pathogenesis-related proteins class 10. MLPs have two main features. One is binding affinity toward various hydrophobic compounds, such as long-chain fatty acids, steroids, and systemic acquired resistance signals, via its internal hydrophobic cavity or hydrophobic residues on its surface. MLPs transport such compounds to other organs via phloem and xylem vessels and contribute to the expression of physiologically important ligands' activity in the particular organs. The second feature is responses to abiotic and biotic stresses. MLPs are involved in drought and salt tolerance through the mediation of plant hormone signaling pathways. MLPs generate resistance against pathogens by the induction of pathogenesis-related protein genes. Therefore, MLPs play crucial roles in drought and salt tolerance and resistance against pathogens. However, knowledge of MLPs is fragmented, and an overview of them is needed. Herein, we summarize the current knowledge of the biological functions of MLPs, which to our knowledge, is the first review about MLPs that has been reported.

Comparative analysis of long noncoding RNAs in angiosperms and characterization of long noncoding RNAs in response to heat stress in Chinese cabbage

Long noncoding RNAs (lncRNAs) are widely present in different species and play critical roles in response to abiotic stresses. However, the functions of lncRNAs in Chinese cabbage under heat stress remain unknown. Here, we first conducted a global comparative analysis of 247,242 lncRNAs among 37 species. The results indicated that lncRNAs were poorly conserved among different species, and only 960 lncRNAs were homologous to 524 miRNA precursors. We then carried out lncRNA sequencing for a genome-wide analysis of lncRNAs and their target genes in Chinese cabbage at different stages of heat treatment. In total, 18,253 lncRNAs were identified, of which 1229 differentially expressed (DE) lncRNAs were characterized as being heat-responsive. The ceRNA network revealed that 38 lncRNAs, 16 miRNAs, and 167 mRNAs were involved in the heat response in Chinese cabbage. Combined analysis of the cis- and trans-regulated genes indicated that the targets of DE lncRNAs were significantly enriched in the "protein processing in endoplasmic reticulum" and "plant hormone signal transduction" pathways. Furthermore, the majority of HSP and PYL genes involved in these two pathways exhibited similar expression patterns and responded to heat stress rapidly. Based on the networks of DE lncRNA-mRNAs, 29 and 22 lncRNAs were found to interact with HSP and PYL genes, respectively. Finally, the expression of several critical lncRNAs and their targets was verified by qRT-PCR. Overall, we conducted a comparative analysis of lncRNAs among 37 species and performed a comprehensive analysis of lncRNAs in Chinese cabbage. Our findings expand the knowledge of lncRNAs involved in the heat stress response in Chinese cabbage, and the identified lncRNAs provide an abundance of resources for future comparative and functional studies.

Ginseng gintonin, aging societies, and geriatric brain diseases

BACKGROUND

A dramatic increase in aging populations and low birth rates rapidly drive aging societies and increase aging-associated neurodegenerative diseases. However, functional food or medicinal formulations to prevent geriatric brain disorders are not readily available. Panax ginseng is a candidate, since ginseng has long-been consumed as a rejuvenating agent. However, the underlying molecular mechanisms and the components of ginseng that are responsible for brain rejuvenation and human longevity are unknown. Accumulating evidence shows that gintonin is a candidate for the anti-aging ingredient of ginseng, especially in brain senescence.

METHODS

Gintonin, a glycolipoprotein complex, contains three lipid-derived G protein-coupled receptor ligands: lysophosphatidic acids (LPAs), lysophosphatidylinositols (LPIs), and linoleic acid (LA). LPA, LPI, and LA act on six LPA receptor subtypes, GPR55, and GPR40, respectively. These G protein-coupled receptors are distributed within the nervous and non-nervous systems of the human body.

RESULTS

Gintonin-enriched fraction (GEF) exhibits anti-brain senescence and effects against disorders such as Alzheimer's disease (AD), Huntington's disease (HD), and Parkinson's disease (PD). Oral administration of gintonin in animal models of d-galactose-induced brain aging, AD, HD, and PD restored cognitive and motor functions. The underlying molecular mechanisms of gintonin-mediated anti-brain aging and anti-neurodegenerative diseases include neurogenesis, autophagy stimulation, anti-apoptosis, anti-oxidative stress, and anti-inflammatory activities. This review describes the characteristics of gintonin and GEF, and how gintonin exerts its effects on brain aging and brain associated-neurodegenerative diseases.

CONCLUSION

Finally, we describe how GEF can be applied to improve the quality of life of senior citizens in aging societies.

High temperatures promote the uptake of hydrophobic pollutants by Cucurbita pepo via altered gene expression levels of major latex-like proteins

Cucurbitaceae family members are accumulators of hydrophobic pollutants. Such pollutants have been detected in cucurbits at levels above the maximum residue limit. Since major latex-like proteins (MLPs) are involved in hydrophobic pollutant uptake, changes in MLP expression can increase or decrease contamination. MLP expression levels were altered in the roots of Cucurbita pepo 'Magda,' and MLP-PG1 was detected in the xylem sap of Magda when cultivated at a high temperature (35°C). Day length also influenced MLP expression levels but only induced minor changes in the amount of MLPs. The concentration of pyrene, a hydrophobic pollutant, significantly increased with increasing MLP levels in the xylem sap of Magda when cultivated at 35°C. Thus, high temperatures promote the pollution of cucurbits by hydrophobic pollutants. These results can be used to develop novel techniques to reduce crop contamination and establish efficient phytoremediation.

Exploring dynamic protein-protein interactions in cassava through the integrative interactome network

Protein-protein interactions (PPIs) play an essential role in cellular regulatory processes. Despite, in-depth studies to uncover the mystery of PPI-mediated regulations are still lacking. Here, an integrative interactome network (MePPI-Ux) was obtained by incorporating expression data into the improved genome-scale interactome network of cassava (MePPI-U). The MePPI-U, constructed by both interolog- and domain-based approaches, contained 3,638,916 interactions and 24,590 proteins (59% of proteins in the cassava AM560 genome version 6). After incorporating expression data as information of state, the MePPI-U rewired to represent condition-dependent PPIs (MePPI-Ux), enabling us to envisage dynamic PPIs (DPINs) that occur at specific conditions. The MePPI-Ux was exploited to demonstrate timely PPIs of cassava under various conditions, namely drought stress, brown streak virus (CBSV) infection, and starch biosynthesis in leaf/root tissues. MePPI-Ux_drought and MePPI-Ux_CBSV suggested involved PPIs in response to stress. MePPI-Ux_SB,leaf and MePPI-Ux_SB,root suggested the involvement of interactions among transcription factor proteins in modulating how leaf or root starch is synthesized. These findings deepened our knowledge of the regulatory roles of PPIs in cassava and would undeniably assist targeted breeding efforts to improve starch quality and quantity.

Genome-wide identification and expression analysis of major latex protein (MLP) family genes in the apple (Malus domestica Borkh.) genome

Major latex protein/ripening-related proteins (MLP/RRP) subfamily are a class of proteins that play crucial roles in response to defense and stress response. However, their biological function is still not clear, the identification and characterization will provide essential information for understanding their roles. Here, we carried out a genome-wide evolutionary characteristics and gene expression analysis of the MLP family in apple (Malus domestica, Borkh.). A total of 36 MdMLP genes were screened in apple genome. They were uneven located on 5 chromosomes, where were mainly arranged in tandem clusters, and the phylogenetic analysis put forward further views on the evolutionary relationship and putative functions among the genes. The conserved motifs showed that the MLP proteins which contained motif 1 had the potential function, and tissue-specific expression analysis showed that apple MLP members had diverse biological roles. Furthermore, the results showed seven of the MdMLPs that harbored cis-acting regulatory elements in response to defense and stress, and our expression data proved that they were involved in biotic stresses. The present study provides new views to the evolution and regulation of MdMLP genes, which represent objectives of future research and incorporate in resistance-related molecular breeding projects.

Major Latex Protein MdMLP423 Negatively Regulates Defense against Fungal Infections in Apple

Major latex proteins (MLPs) play critical roles in plants defense and stress responses. However, the roles of MLPs from apple (Malus × domestica) have not been clearly identified. In this study, we focused on the biological role of MdMLP423, which had been previously characterized as a potential pathogenesis-related gene. Phylogenetic analysis and conserved domain analysis indicated that MdMLP423 is a protein with a ‘Gly-rich loop’ (GXGGXG) domain belonging to the Bet v_1 subfamily. Gene expression profiles showed that MdMLP423 is mainly expressed in flowers. In addition, the expression of MdMLP423 was significantly inhibited by Botryosphaeria berengeriana f. sp. piricola (BB) and Alternaria alternata apple pathotype (AAAP) infections. Apple calli overexpressing MdMLP423 had lower expression of resistance-related genes, and were more sensitive to infection with BB and AAAP compared with non-transgenic calli. RNA-seq analysis of MdMLP423-overexpressing calli and non-transgenic calli indicated that MdMLP423 regulated the expression of a number of differentially expressed genes (DEGs) and transcription factors, including genes involved in phytohormone signaling pathways, cell wall reinforcement, and genes encoding the defense-related proteins, AP2-EREBP, WRKY, MYB, NAC, Zinc finger protein, and ABI3. Taken together, our results demonstrate that MdMLP423 negatively regulates apple resistance to BB and AAAP infections by inhibiting the expression of defense- and stress-related genes and transcription factors.

Transcriptomic Responses to Water Deficit and Nematode Infection in Mycorrhizal Tomato Roots

Climate changes include the intensification of drought in many parts of the world, increasing its frequency, severity and duration. However, under natural conditions, environmental stresses do not occur alone, and, in addition, more stressed plants may become more susceptible to attacks by pests and pathogens. Studies on the impact of the arbuscular mycorrhizal (AM) symbiosis on tomato response to water deficit showed that several drought-responsive genes are differentially regulated in AM-colonized tomato plants (roots and leaves) during water deficit. To date, global changes in mycorrhizal tomato root transcripts under water stress conditions have not been yet investigated. Here, changes in root transcriptome in the presence of an AM fungus, with or without water stress (WS) application, have been evaluated in a commercial tomato cultivar already investigated for the water stress response during AM symbiosis. Since root-knot nematodes (RKNs, Meloidogyne incognita) are obligate endoparasites and cause severe yield losses in tomato, the impact of the AM fungal colonization on RKN infection at 7 days post-inoculation was also evaluated. Results offer new information about the response to AM symbiosis, highlighting a functional redundancy for several tomato gene families, as well as on the tomato and fungal genes involved in WS response during symbiosis, underlying the role of the AM fungus. Changes in the expression of tomato genes related to nematode infection during AM symbiosis highlight a role of AM colonization in triggering defense responses against RKN in tomato. Overall, new datasets on the tomato response to an abiotic and biotic stress during AM symbiosis have been obtained, providing useful data for further researches.

Bioactive Proteins in Panax notoginseng Roots and Other Panax Species

The genus Panax consists of a group of prized medicinal herbs. Major members of the Panax genus include P. ginseng, P. notoginseng, P. quinquefolius, and P. vietnamensis. They possess various bioactive constituents such as ginsenosides, saponins, polysaccharides and proteins. Many of them were reported to show beneficial effects on human health. Ginsenosides and saponins of ginsengs caught the sight of most researchers. Precise investigations revealed their roles on improvement of the functioning of the nervous system, cardiovascular system, and other functions. In contrast, our knowledge of the bioactive Panax proteins is relatively limited. A number of proteins from P. ginseng, the most valuable member of Panax species, have been investigated and proved to be beneficial to our body. Meanwhile, a few bioactive P. notoginseng proteins, such as ribonucleases and antifungal proteins, have been characterized and reported. We summarize herein the proteins present in P. notoginseng that have been identified, and try to compare them with those from other Panax species with a similar structure or bioactivity, and conclude whether the proteins in P. notoginseng have any distinctive features.

Dissecting Pistil Responses to Incompatible and Compatible Pollen in Self-Incompatibility Brassica oleracea Using Comparative Proteomics

Angiosperms have developed self-incompatibility (SI) systems to reject self-pollen, thereby promoting outcrossing. The Brassicaceae belongs to typical sporophytic system, having a single S-locus controlled SI response, and was chosen as a model system to study SI-related intercellular signal transduction. In this regard, the downstream factor of EXO70A1 was unknown. Here, protein two-dimensional electrophoresis (2-DE) method and coupled with matrix-assisted laser desorption ionization/time of flight of flight mass spectrometry (MALDI-TOF -MS) and peptide mass fingerprinting (PMF) was used to further explore the mechanism of SI responses in Brassica oleracea L. var. capitata L. at protein level. To further confirm the time point of protein profile change, total proteins were collected from B. oleracea pistils at 0 min, 1 h, and 2 h after self-pollination. In total 902, 1088 and 1023 protein spots were separated in 0 min, 1 h and 2 h 2-DE maps, respectively. Our analyses of self-pollination profiles indicated that proteins mainly changed at 1 h post-pollination in B. oleracea. Moreover, 1077 protein spots were separated in cross-pollinated 1 h (CP) pistil 2-DE map. MALDI-TOF-MS and PMF successfully identified 34 differentially-expressed proteins (DEPs) in SP and CP 1 h 2-DE maps. Gene ontology and KEGG analysis revealed an array of proteins grouped in the following categories: stress and defense response (35%), protein metabolism (18%), carbohydrate and energy metabolism (12%), regulation of translation (9%), pollen tube development (12%), transport (9%) and cytoskeletal (6%). Sets of DEPs identified specifically in SP or only up-regulated expressed in CP pistils were chosen for funther investigating in floral organs and during the process of self- and cross-pollination. The function of these DEPs in terms of their potential involvement in SI in B. oleracea is discussed.

Proteomic comparison of Chelidonium majus L. latex in different phases of plant development

Chelidonium majus L. (Papaveraceae) latex is used in traditinonal folk medicine to treat papillae, warts, condylomas, which are visible effects of human papilloma virus (HPV) infections. The aim of this work was to provide new insights into the biology and medicinal use of C. majus milky sap in the flowering and fruit ripening period of the plant by comparing the protein content between samples collected on respective developmental stages using LC-MS-based label-free proteome approach. For quantification, the multiplexed LC-MS data were processed using comparative chemometric approach. Progenesis LC-MS results showed that in green fruit phase (stage IV), comparing to flowering phase (stage III) of plant development, a range of proteins with higher abundance were identified as stress- and defense-related. On the other hand at stage III very intense protein synthesis, processes of transcription, protein folding and active transport of molecules (ABC transporters) are well represented. 2-DE protein maps showed an abundant set of spots with similar MWs (about 30-35 kDa) and pIs (ca. 5.5-6.5), which were identified as major latex proteins (MLPs). Therefore we suggest that biological activity of C. majus latex could be related to its protein content, which shifts during plant development from intense biosynthetic processes (biosynthesis and transport of small molecules, like alkaloids) to plant defense mechanisms against pathogens. Further studies will help to elucidate if these defense-related and pathogenesis-related proteins, like MLP, together with small-molecule compounds, could inhibit viral infection, what could be a step to fully understand the medicinal activity of C. majus latex.

Dissecting stylar responses to self-pollination in wild tomato self-compatible and self-incompatible species using comparative proteomics

Self-incompatibility (SI), a phenomenon that is widespread among flowering plants (angiosperms), promotes outbreeding, resulting in increased genetic diversity and species survival. SI is also important in establishing intra- or interspecies reproductive barriers, such as those that are evident in the tomato clade, Solanum section Lycopersicon, where they limit the use of wild species inbreeding programs to improve cultivated tomato. However, the molecular mechanisms underlying SI are poorly understood in the tomato clade. In this study, an SI (Solanum chilense, LA0130) and a self-compatible (SC, Solanum pimpinellifolium, LA1585) tomato species were chosen to dissect the mechanism of SI formation using a comparative proteomics approach. A total of 635 and 627 protein spots were detected in two-dimensional electrophoresis (2-DE) maps of proteins from the SI and SC species, respectively. In the SC species, 22 differently expressed proteins (DEPs) were detected in SCP versus SCUP (self-pollination versus non-pollination in SC species). Of these, 3 and 18 showed an up-or down-regulated expression in the SCP protein sample, respectively, while only one DEP (MSRA, Solyc03g111720) was exclusively expressed in the SCP sample. In the SI species, 14 DEPs were found between SIP/SIUP, and 5 of these showed higher expression in SIP, whereas two DEPs (MLP-like protein 423-like, gene ID, 460386008 and (ATP synthase subunit alpha, gene ID, Solyc00g042130) were exclusively expressed in SIP or SIUP, respectively. Finally, two S-RNases (gene IDs, 313247946 and 157377662) were exclusively expressed in the SI species. Sequence homology analysis and a gene ontology tool were used to assign the DEPs to the 'metabolism', 'energy', 'cytoskeleton dynamics', 'protein degradation', 'signal transduction', 'defence/stress responses', 'self-incompatibility' and 'unknown' protein categories. We discuss the putative functions of the DEPs in different biological processes and how these might be associated with the regulation of SI formation in the tomato clade.

Development of interspecies hybrids to increase ginseng biomass and ginsenoside yield

Interspecific hybrids between Panax ginseng and P. quinquefolius results in hybrid vigor and higher ginsenoside contents. Ginseng is one of the most important herbs with valued pharmaceutical effects contributing mainly by the presence of bioactive ginsenosides in the roots. However, ginseng industry is impeded largely by its biological properties, because ginseng plants are slow-growing perennial herbs with lower yield. To increase the ginseng yield and amounts of ginsenosides, we developed an effective ginseng production system using the F(1) progenies obtained from the interspecific reciprocal cross between two Panax species: P. ginseng and P. quinquefolius. Although hybrid plants show reduced male fertility, F(1) hybrids with the maternal origin either from P. ginseng or P. quinquefolius displayed heterosis; they had larger roots and higher contents of ginsenosides as compared with non-hybrid parental lines. Remarkably, the F(1) hybrids with the maternal origin of P. quinquefolius had much higher ginsenoside contents, especially ginsenoside Re and Rb1, than those with the maternal origin of P. ginseng. Additionally, non-targeted metabolomic profiling revealed a clear increase of a large number of primary and secondary metabolites including fatty acids, amino acids and ginsenosides in hybrid plants. To effectively identify the F(1) hybrids for the large-scale cultivation, we successfully developed a molecular marker detection system for discriminating F(1) reciprocal hybrids. In summary, this work provided a practical system for reciprocal hybrid ginseng production, which would facilitate the ginseng production in the future.

Proteomic Analyses Provide Novel Insights into Plant Growth and Ginsenoside Biosynthesis in Forest Cultivated Panax ginseng (F. Ginseng)

F. Ginseng (Panax ginseng) is planted in the forest to enhance the natural ginseng resources, which have an immense medicinal and economic value. The morphology of the cultivated plants becomes similar to that of wild growing ginseng (W. Ginseng) over the years. So far, there have been no studies highlighting the physiological or functional changes in F. Ginseng and its wild counterparts. In the present study, we used proteomic technologies (2DE and iTRAQ) coupled to mass spectrometry to compare W. Ginseng and F. Ginseng at various growth stages. Hierarchical cluster analysis based on protein abundance revealed that the protein expression profile of 25-year-old F. Ginseng was more like W. Ginseng than less 20-year-old F. Ginseng. We identified 192 differentially expressed protein spots in F. Ginseng. These protein spots increased with increase in growth years of F. Ginseng and were associated with proteins involved in energy metabolism, ginsenosides biosynthesis, and stress response. The mRNA, physiological, and metabolic analysis showed that the external morphology, protein expression profile, and ginsenoside synthesis ability of the F. Ginseng increased just like that of W. Ginseng with the increase in age. Our study represents the first characterization of the proteome of F. Ginseng during development and provides new insights into the metabolism and accumulation of ginsenosides.

Structure of ginseng major latex-like protein 151 and its proposed lysophosphatidic acid-binding mechanism

Lysophosphatidic acid (LPA) is a phospholipid growth factor with myriad effects on biological systems. LPA is usually present bound to animal plasma proteins such as albumin or gelsolin. When LPA complexes with plasma proteins, it binds to its cognate receptors with higher affinity than when it is free. Recently, gintonin from ginseng was found to bind to LPA and to activate mammalian LPA receptors. Gintonin contains two components: ginseng major latex-like protein 151 (GLP) and ginseng ribonuclease-like storage protein. Here, the crystal structure of GLP is reported, which belongs to the plant Bet v 1 superfamily, and a model is proposed for how GLP binds LPA. Amino-acid residues of GLP recognizing LPA were identified using site-directed mutagenesis and isothermal titration calorimetry. The resulting GLP mutants were used to study the activation of LPA receptor-dependent signalling pathways. In contrast to wild-type GLP, the H147A mutant did not bind LPA, elicit intracellular Ca2+transients in neuronal cells or activate Ca2+-dependent Cl−channels inXenopusoocytes. Based on these results, a mechanism by which GLP recognizes LPA and its requirement to activate G protein-coupled LPA receptors to elicit diverse biological responses were proposed.

Differential uptake and translocation of β-HCH and dieldrin by several plant species from hydroponic medium

To compare the uptake and translocation of hydrophobic organic chemicals by plant species, the authors performed uptake experiments with β-1,2,3,4,5,6-hexachlorocyclohexane (β-HCH) and 1,2,3,4,10,10-Hexachloro-6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydro-endo-1,4-exo-5,8-dimethanonaphthalene (dieldrin) using 5 species: Hordeum vulgare, Glycine max, Solanum lycopersicum, Brassica oleracea, and Cucurbita pepo. The present study evaluated uptake ability using root concentration factor (RCF) and translocation ability by transpiration stream concentration factor (TSCF). The RCFs of β-HCH and dieldrin did not differ remarkably among species, except that the RCF of β-HCH in B. oleracea was high. The TSCFs of β-HCH and dieldrin were high in C. pepo, which was not superior in uptake as estimated by RCF. The TSCF of dieldrin in C. pepo was decreased in darkness and was markedly decreased by heating of roots. These results support the hypothesis that transport proteins produced in the root contribute to dieldrin translocation. In contrast, TSCF of β-HCH was not decreased by these treatments. Therefore, translocation of β-HCH might not need the contribution of transport proteins. It is possible that C. pepo has a certain function to transport hydrophobic organic chemicals smoothly in root tissues.

Transcriptome and proteome analysis of Eucalyptus infected with Calonectria pseudoreteaudii

Cylindrocladium leaf blight is one of the most severe diseases in Eucalyptus plantations and nurseries. There are Eucalyptus cultivars with resistance to the disease. However, little is known about the defense mechanism of resistant cultivars. Here, we investigated the transcriptome and proteome of Eucalyptus leaves (E. urophylla×E. tereticornis M1), infected or not with Calonectria pseudoreteaudii. A total of 8585 differentially expressed genes (|log2 ratio| ≥1, FDR ≤0.001) at 12 and 24hours post-inoculation were detected using RNA-seq. Transcriptional changes for five genes were further confirmed by qRT-PCR. A total of 3680 proteins at the two time points were identified using iTRAQ technique.The combined transcriptome and proteome analysis revealed that the shikimate/phenylpropanoid pathway, terpenoid biosynthesis, signalling pathway (jasmonic acid and sugar) were activated. The data also showed that some proteins (WRKY33 and PR proteins) which have been reported to involve in plant defense response were up-regulated. However, photosynthesis, nucleic acid metabolism and protein metabolism were impaired by the infection of C. pseudoreteaudii. This work will facilitate the identification of defense related genes and provide insights into Eucalyptus defense responses to Cylindrocladium leaf blight.

BIOLOGICAL SIGNIFICANCE

In this study, a total of 130 proteins and genes involved in the shikimate/phenylpropanoid pathway, terpenoid biosynthesis, signalling pathway, cell transport, carbohydrate and energy metabolism, nucleic acid metabolism and protein metabolism in Eucalyptus leaves after infected with C. pseudoreteaudii were identified. This is the first report of a comprehensive transcriptomic and proteomic analysis of Eucalyptus in response to Calonectria sp.

Structural and functional aspects of PR-10 proteins

Physical, chemical and biological stress factors, such as microbial infection, upregulate the transcription levels of a number of plant genes, coding for the so-called pathogenesis-related (PR) proteins. For PR proteins of class-10 (PR-10), the biological function remains unclear, despite two decades of scientific research. PR-10 proteins have a wide distribution throughout the plant kingdom and the class members share size and secondary structure organization. Throughout the years, we and other groups have determined the structures of a number of PR-10 proteins, both in the crystalline state by X-ray diffraction and in solution by NMR spectroscopy. Despite the accumulating structural information, our understanding of PR-10 function is still limited. PR-10 proteins are rather small (~ 160 amino acids) with a fold consisting of three α helices and seven antiparallel β strands. These structural elements enclose a large hydrophobic cavity that is most probably the key to their functional relevance. Also, the outer surface of these proteins is of extreme interest, as epitopes from a PR-10 subclass cause allergic reactions in humans.

Gintonin, newly identified compounds from ginseng, is novel lysophosphatidic acids-protein complexes and activates G protein-coupled lysophosphatidic acid receptors with high affinity

Recently, we isolated a subset of glycolipoproteins from Panax ginseng, that we designated gintonin, and demonstrated that it induced [Ca2+]i transients in cells via G protein-coupled receptor (GPCR) signaling pathway(s). However, active components responsible for Ca2+ mobilization and the corresponding receptor(s) were unknown. Active component(s) for [Ca2+]i transients of gintonin were analyzed by liquid chromatography-electrospray ionization-tandem mass spectrometry and ion-mobility mass spectrometry, respectively. The corresponding receptor(s)were investigated through gene expression assays. We found that gintonin contains LPA C18:2 and other LPAs. Proteomic analysis showed that ginseng major latex-like protein and ribonuclease-like storage proteins are protein components of gintonin. Gintonin induced [Ca2+]i transients in B103 rat neuroblastoma cells transfected with human LPA receptors with high affinity in order of LPA2 >LPA5 > LPA1 > LPA3 > LPA4. The LPA1/LPA3 receptor antagonist Ki16425 blocked gintonin action in cells expressing LPA1 or LPA3. Mutations of binding sites in the LPA3 receptor attenuated gintonin action. Gintonin acted via pertussis toxin (PTX)-sensitive and -insensitive G protein-phospholipase C (PLC)-inositol 1,4,5-trisphosphate (IP3)-Ca2+ pathways. However, gintonin had no effects on other receptors examined. In human umbilical vein endothelial cells (HUVECs) gintonin stimulated cell proliferation and migration. Gintonin stimulated ERK1/2 phosphorylation. PTX blocked gintonin-mediated migration and ERK1/2 phosphorylation. In PC12 cells gintonin induced morphological changes, which were blocked by Rho kinase inhibitorY-27632. Gintonin contains GPCR ligand LPAs in complexes with ginseng proteins and could be useful in the development of drugs targeting LPA receptors.

Distribution and expression characteristics of triterpenoids and OSC genes in white birch (Betula platyphylla suk.)

Betulin and oleanolic acids (pentacyclic triterpenoid secondary metabolites) have broad pharmacological activities and can be potentially used for the development of anti-cancer and anti-AIDS drugs. In this study, we detected the accumulation and the distribution characteristics of betulin and oleanolic acid in various organs of white birch at different ages. We also determined the expression of 4 OSC genes (LUS, β-AS, CAS1 and CAS2) involved in the triterpenoid synthesis pathways by real time RT-PCR. The result showed that the 1-year old birch can synthesize betulin and oleanolic acid. In addition, betulin and oleanolic acids were mainly distributed in the bark, while the content in the root skin and leaf was very low. The content of betulin and oleanolic acid in birch varied in different seasons. The content of betulin and oleanolic acid and their corresponding LUS and β-AS gene expression were very low in 1-year old birch. With increasing age of birch, betulin content was increased, while oleanolic acid was decreased. Similar changes were also observed for their corresponding synthesis genes LUS and β-AS. In the leaf of 1-year old plant, the highest expression of CAS1 and CAS2 occurred at end of September, while expression of LUS and the β-AS was low from June to October. In the stem skin,high expression of β-AS and the LUS genes occurred from the end of July to September. In the root, high expression of the β-AS gene was observed at the end of October. These results indicated that triterpenoid gene expression was similar to the triterpene accumulation. Expression of LUS gene and β-AS gene in birch with different ages were corresponding to the betulinic and oleanolic acid accumulation. Expression of CAS1 and CAS2 genes were elevated with increasing age of birch. This study provides molecular mechanisms of triterpenes synthesis in birch plants.