Helianthus tuberosus and polyamine research: past and recent applications of a classical growth model

Programmed Cell Death Reversal: Polyamines, Effectors of the U-Turn from the Program of Death in Helianthus tuberosus L

This review describes a 50-year-long research study on the characteristics of Helianthus tuberosus L. tuber dormancy, its natural release and programmed cell death (PCD), as well as on the ability to change the PCD so as to return the tuber to a life program. The experimentation on the tuber over the years is due to its particular properties of being naturally deficient in polyamines (PAs) during dormancy and of immediately reacting to transplants by growing and synthesizing PAs. This review summarizes the research conducted in a unicum body. As in nature, the tuber tissue has to furnish its storage substances to grow vegetative buds, whereby its destiny is PCD. The review's main objective concerns data on PCD, the link with free and conjugated PAs and their capacity to switch the destiny of the tuber from a program of death to one of new life. PCD reversibility is an important biological challenge that is verified here but not reported in other experimental models. Important aspects of PA features are their capacity to change the cell functions from storage to meristematic ones and their involvement in amitosis and differentiation. Other roles reported here have also been confirmed in other plants. PAs exert multiple diverse roles, suggesting that they are not simply growth substances, as also further described in other plants.

Nutritional Supplementation of Yogurt with Jerusalem Artichoke Tubers: Organic Acid Profiles and Quality Parameters

Jerusalem artichoke (Helianthus tuberosus L.), also called wild sunflower, belongs to the Asteraceae family and is cultivated widely across the temperate zone for its nutritious tuber, which is used as a root vegetable. In this study, the Jerusalem artichoke (JA) was used as a supplementary additive for producing a functional yogurt, with enhanced health benefits and improving the microbiological, rheological, and sensorial quality characteristics of the product. The effects of the three different concentrations (1%, 2%, and 3%, w/w) of JA on the physicochemical properties, bacterial counts, sensorial properties, and organic acid profiles of yogurts were determined after 1, 7, 14, and 21 days of storage at ±4 °C. The results obtained revealed that with the addition of different concentrations of JA the overall parameters were statistically significant (p < 0.01 and p < 0.05) except for apparent viscosity, Streptococcus thermophilus, yeast and mold count, pyruvic ratios, and scores of flavor. Similarly, some parameters (fat ratio, yeast and mold count, concentrations of propionic, acetic, pyruvic, orotic, and lactic acids, and scores of appearance, consistency, and odor) changed depending on the storage time, while some did not show any changes regarding storage time. There was a relationship found between the concentration of JA and organic acid ratio (except for pyruvic acid) concentration in the yogurt samples. In conclusion, the research revealed the effect of JA in yogurt production as a thickener, flavor enhancer, prebiotic agent, and source of organic acids and bioactive compounds. The results indicate that JA has a good potential for enhancing the nutritional and physicochemical properties of the studied yogurt.

Translational and post-translational regulation of polyamine metabolic enzymes in plants

Polyamines are small organic and basic polycations that perform essential regulatory functions in all living organisms. Fluctuations in polyamine content have been observed to occur during growth, development and under stress conditions, implying that polyamines play pivotal roles in diverse cellular and physiological processes. To achieve polyamine homeostasis, the entire metabolic pathway is subjected to a fine-tuned regulation of its biosynthetic and catabolic genes and enzymes. In this review, we describe and discuss the most important mechanisms implicated in the translational and post-translational regulation of polyamine metabolic enzymes in plants. At the translational level, we emphasize the role of polyamines in the modulation of upstream open reading frame (uORF) activities that control the translation of polyamine biosynthetic and catabolic mRNAs. At the post-translational level, different aspects of the regulation of polyamine metabolic proteins are depicted, such as the proteolytic activation of enzyme precursors, the importance of dimerization in protein stability as well as in protein intracellular localization.

Anticancer drug impact on DNA – a study by neutron spectroscopy coupled with synchrotron-based FTIR and EXAFS

Complementary information on drug–DNA interplay has been achieved for Pt/Pd anticancer agents, by a combined QENS, SR-FTIR-ATR and EXAFS approach.

Chemotherapeutic response to cisplatin-like drugs in human breast cancer cells probed by vibrational microspectroscopy

Studies of drug-cell interactions in cancer model systems are essential in the preclinical stage of rational drug design, which relies on a thorough understanding of the mechanisms underlying cytotoxic activity and biological effects, at a molecular level. This study aimed at applying complementary vibrational spectroscopy methods to evaluate the cellular impact of two Pt(ii) and Pd(ii) dinuclear chelates with spermine (Pt2Spm and Pd2Spm), using cisplatin (cis-Pt(NH3)2Cl2) as a reference compound. Their effects on cellular metabolism were monitored in a human triple-negative metastatic breast cancer cell line (MDA-MB-231) by Raman and synchrotron-radiation infrared microspectroscopies, for different drug concentrations (2-8 μM) at 48 h exposure. Multivariate data analysis was applied (unsupervised PCA), unveiling drug- and concentration-dependent effects: apart from discrimination between control and drug-treated cells, a clear separation was obtained for the different agents studied - mononuclear vs. polynuclear, and Pt(ii) vs. Pd(ii). Spectral biomarkers of drug action were identified, as well as the cellular response to the chemotherapeutic insult. The main effect of the tested compounds was found to be on DNA, lipids and proteins, the Pd(ii) agent having a more significant impact on proteins while its Pt(ii) homologue affected the cellular lipid content at lower concentrations, which suggests the occurrence of distinct and unconventional pathways of cytotoxicity for these dinuclear polyamine complexes. Raman and FTIR microspectroscopies were confirmed as powerful non-invasive techniques to obtain unique spectral signatures of the biochemical impact and physiological reaction of cells to anticancer agents.

Elicitation of Jerusalem artichoke (Helianthus tuberosus L.) cell suspension culture for enhancement of inulin production and altered degree of polymerisation

BACKGROUND

Plant cell suspension cultures have emerged as a potential source of secondary metabolites for food additives and pharmaceuticals. In this study inulin accumulation and its degree of polymerisation (DP) in the treated cells in the same medium were investigated after treatment with six types of elicitors.

RESULTS

An in vitro cell suspension culture of Jerusalem artichoke (Helianthus tuberosus L.) was optimised by adding an extra nitrogen source. According to the growth kinetics, a maximum biomass of 5.48 g L^-1 was obtained from the optimal cell suspension medium consisted of Murashige and Skoog basic medium (MS) + 1.0 mg L^-1 α-naphthalene acetic acid (NAA) + 1.0 mg L^-1 6-benzylaminopurine (6-BA) + 0.5 mg L^-1 proline + 1.0 mg L^-1 glutamine. Methyl jasmonate (MeJA, 250 µmol L^-1 ) treatment for 15 days led to the highest levels of inulin (2955.27 ± 9.81 mg L^-1 compared to control of 1217.46 ± 0.26 mg L^-1 ). The elicited effect of five elicitors to the suspension cells of Jerusalem artichoke is as follows: AgNO₃ (Ag, 10 µmol L^-1 ), salicylic acid (SA, 75 µmol L^-1 ), chitosan (KJT, 40 mg L^-1 ), Trichoderma viride (Tv, 90 mg L^-1 ), yeast extract (YE, 0.25 mg L^-1 ), and the corresponding content of inulin is increased by 2.05-, 1.93-, 1.76-, 1.44- and 1.18-fold compared to control, respectively. The obvious effect on the percentage of lower DP in inulin was observed in cells treated with 40 mg L^-1 KJT, 0.25 mg L^-1 YE and 10 µmol L^-1 Ag.

CONCLUSIONS

Among the six types of elicitors, the descending order of inulin content is MeJA > Ag > SA > KJT > Tv > YE. For the purpose inulin with lower DP and its application to prebiotic food, three elicitors, including KJT, YE and Ag, can be used for the elicitation. © 2016 Society of Chemical Industry.

Plant growth promotion properties of bacterial strains isolated from the rhizosphere of the Jerusalem artichoke (Helianthus tuberosus L.) adapted to saline-alkaline soils and their effect on wheat growth

The Jerusalem artichoke (JA; Helianthus tuberosus), known to be tolerant to saline-alkaline soil conditions, has been cultivated for many years in the Yellow River delta, Shandong Province coastal zone, in China. The aim of our study was to isolate nitrogen-fixing bacteria colonizing the rhizosphere of JA and to characterize other plant growth promotion properties. The ultimate goal was to identify isolates that could be used as inoculants benefiting an economic crop, in particular for improving wheat growth production in the Yellow River delta. Bacterial strains were isolated from the rhizosphere soil of JA on the basis of growth on nitrogen-free Ashby medium. Identification and phylogenetic analysis was performed after nucleotide sequencing of 16S rRNA gene. Plant-growth-promoting traits, such as nitrogen fixation activity, phosphate solubilization activity, indole-3-acetic acid production, were determined using conventional methods. Eleven strains were isolated and 6 of them were further examined for their level of salt tolerance and their effect on plant growth promotion. Inoculation of Enterobacter sp. strain N10 on JA and wheat led to significant increases in both root and shoot dry mass and shoot height. Enterobacter sp. strain N10 appeared to be the best plant-growth-promoting rhizobacteria to increase wheat productivity in future field applications.

The prospects of Jerusalem artichoke in functional food ingredients and bioenergy production

Jerusalem artichoke, a native plant to North America has recently been recognized as a promising biomass for bioeconomy development, with a number of advantages over conventional crops such as low input cultivation, high crop yield, wide adaptation to climatic and soil conditions and strong resistance to pests and plant diseases. A variety of bioproducts can be derived from Jerusalem artichoke, including inulin, fructose, natural fungicides, antioxidant and bioethanol. This paper provides an overview of the cultivation of Jerusalem artichoke, derivation of bioproducts and applicable production technologies, with an expectation to draw more attention on this valuable crop for its applications as biofuel, functional food and bioactive ingredient sources.

Senescence and programmed cell death in plants: polyamine action mediated by transglutaminase

Research on polyamines (PAs) in plants laps a long way of about 50 years and many roles have been discovered for these aliphatic cations. PAs regulate cell division, differentiation, organogenesis, reproduction, dormancy-break and senescence, homeostatic adjustments in response to external stimuli and stresses. Nevertheless, the molecular mechanisms of their multiple activities are still matter of research. PAs are present in free and bound forms and interact with several important cell molecules; some of these interactions may occur by covalent linkages catalyzed by transglutaminase (TGase), giving rise to "cationization" or cross-links among specific proteins. Senescence and programmed cell death (PCD) can be delayed by PAs; in order to re-interpret some of these effects and to obtain new insights into their molecular mechanisms, their conjugation has been revised here. The TGase-mediated interactions between proteins and PAs are the main target of this review. After an introduction on the characteristics of this enzyme, on its catalysis and role in PCD in animals, the plant senescence and PCD models in which TGase has been studied, are presented: the corolla of naturally senescing or excised flowers, the leaves senescing, either excised or not, the pollen during self-incompatible pollination, the hypersensitive response and the tuber storage parenchyma during dormancy release. In all the models examined, TGase appears to be involved by a similar molecular mechanism as described during apoptosis in animal cells, even though several substrates are different. Its effect is probably related to the type of PCD, but mostly to the substrate to be modified in order to achieve the specific PCD program. As a cross-linker of PAs and proteins, TGase is an important factor involved in multiple, sometimes controversial, roles of PAs during senescence and PCD.

Platinum and Palladium Polyamine Complexes as Anticancer Agents: The Structural Factor

Since the introduction of cisplatin to oncology in 1978, Pt(II) and Pd(II) compounds have been intensively studied with a view to develop the improved anticancer agents. Polynuclear polyamine complexes, in particular, have attracted special attention, since they were found to yield DNA adducts not available to conventional drugs (through long-distance intra- and interstrand cross-links) and to often circumvent acquired cisplatin resistance. Moreover, the cytotoxic potency of these polyamine-bridged chelates is strictly regulated by their structural characteristics, which renders this series of compounds worth investigating and their synthesis being carefully tailored in order to develop third-generation drugs coupling an increased spectrum of activity to a lower toxicity. The present paper addresses the latest developments in the design of novel antitumor agents based on platinum and palladium, particularly polynuclear chelates with variable length aliphatic polyamines as bridging ligands, highlighting the close relationship between their structural preferences and cytotoxic ability. In particular, studies by vibrational spectroscopy techniques are emphasised, allowing to elucidate the structure-activity relationships (SARs) ruling anticancer activity.

Novel Pt(II) and Pd(II) complexes with polyamine analogues: synthesis and vibrational analysis

A vibrational spectroscopy study (infrared and Raman) is reported for the biogenic polyamine analogues norspermidine (NSpd), N(1),N(11)-bis(ethyl)norspermine (BENSpm) and N(1)-cyclo-propylmethyl-N(11)-ethylnorspermine (CPENSpm), as well as for their newly synthesised Pt(II) and Pd(II) complexes. Attending to the potential antineoplastic properties of this kind of systems, their full conformational characterization is essential for understanding the molecular basis of their cytotoxic activity and the mechanisms through which they are transported into the cell. The all-trans geometry was found to be favoured for all the alkylated polyamines, in their totally protonated state, while their polynuclear complexes presented a stable geometry very similar to that previously obtained for the analogous chelates with spermidine (M(3)Spd(2)) and spermine (M(2)Spm), comprising two or three cisplatin-like (MCl(2)NH(2)) moieties.