Xanthomonas albilineans, although it is an essential phytopathogen for sugar cane, is capable of producing xanthan gum (XG). This macromolecule is used in the food, pharmaceutical, and gas production industries, but its production is expensive when considering the substrate and its purity. On the other hand, the possibility of using the material for disposal, such as the infected sugar cane stalk, can be attractive since this substrate can produce XG and has no value for cultivation. Thus, we describe the possibility of its production in different culture media using immobilized cells from sugar cane stalk tissues supplemented with glycoproteins or sucrose. Using molecular patterns associated with bacterial pathogens (PAMPs), the presence of gum in isopropyl alcohol precipitate is obtained after incubation and culture improvement. This production model describes a new possibility of gum production, contributing to the potential for sustainability and diversification of the sugar cane industry.

Sugar cane smut (Sporisorium scitamineum) interactions have been traditionally considered from the plant's point of view: How can resistant sugar cane plants defend themselves against smut disease? Resistant plants induce several defensive mechanisms that oppose fungal attacks. Herein, an overall view of Sporisorium scitamineum's mechanisms of infection and the defense mechanisms of plants are presented. Quorum sensing effects and a continuous reorganization of cytoskeletal components, where actin, myosin, and microtubules are required to work together, seem to be some of the keys to a successful attack.

Sugarcane is a C4 plant from the NADP-ME family, which performs a double photosynthetic carboxylation. It is a plant specialized in accumulating and storing large amounts of sucrose in the parenchymatous cells of its stalks. Perhaps because of these characteristics, this species shows to be extremely sensitive to a large number of diseases caused by viruses, bacteria, phytoplasmas, fungi, insects and nematodes, as well as to various abiotic stresses. A large number of varieties and cultivars resistant to many of these diseases have been achieved through conventional plant breeding techniques and also through biotechnological applications. In addition to this, the ability of the plant itself to produce pathogen resistance factors has been a field of research that has provided excellent weapons to combat crop-destroying pests This review describes those proteins that are synthesized by the plant as resistance factors against different diseases from the point of view of conventional biochemistry and also with the tools that modern genomics and proteomics provide. Special emphasis has been placed on the study of those proteins aimed at increasing the physical resistance of the plant that hinders the entry of the pathogen as well as those proteins related to the synthesis of bioactive phenols, polysaccharide hydrolysis enzymes, bacteriocins, oxygenases, oxidases and oxido-reductases.

Bionts isolated from Cladonia salzmannii, immobilized in calcium alginate, were used to assay their ability to produce barbatic acid and other orcinol derivatives, as well as other active soluble substances, and to test their antioxidant and antimicrobial activities. Immobilisates were supplied with sodium or calcium acetate as precursors for phenol biosynthesis. Barbatic acid was actively produced during incubation of immobilisates, although cell vitality progressively decreased on calcium acetate, producing cell plasmolysis of phycobionts. Thamnolic acid and other orcinol derivates also were secreted to the medium, the concentration of each one depending on the time of immobilization, exogenous acetate supply and the type of biont isolated. The role of lichen algae in phenolic metabolism was also studied. Antioxidant capacity of acetone and chloroform extracts of C. salzmannii was also reported (89.56 and 80.92 % oxidation inhibition, respectively). The soluble extract of the products secreted by lichen immobilisates incubated on sodium acetate during 15 days, contained only proteins and exhibited a potent antioxidant capacity (96.35%). The soluble extract of the products secreted by from fungal immobilisates during 6 and 18 days of incubation showed ranges of 90-94% inhibition. Similar values were found for the soluble extracts of algal immobilisates incubated during 8 and 11 days. On the other hand, the growth of Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae was inhibited by barbatic acid secreted from immobilisates, although organic lichen extracts showed highest antimicrobial activity due to a possible synergism between their different components. Thus, substances produced by immobilized bionts of C. salzmannii are a potential source of different natural antioxidant and antimicrobial compounds.

Bionts isolated from thalli of Cladonia verticillaris, immobilized in calcium alginate, produce two depsidones, fumarprotocetraric and protocetraric acids, and the depside atranorin, that exhibit antimicrobial activity against Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae. Organic lichen extract (acetone/ether/chloroform) shows the highest antimicrobial activity due to a possible synergism between these substances. Antioxidant capacity of soluble metabolites secreted from the immobilisates to the bath medium of incubation during the first 12 days of immobilization has been found (˃80% oxidation inhibition). The concentration of soluble phenolic substances depends on the immobilization time (during 32 days), exogenous supply of acetate (1.0m mM sodium or calcium acetate) and on the type of isolated biont (phycobionts, mycobionts, whole thallus or immobilized phycobionts co-incubated with the mycobionts ones). The role of phycobionts in phenol production has been interpreted as a possible modification of the polymalonyl pathway; for example, atranorin is actively produced and secreted during immobilization while it is not detected in thallus in natura. Co-incubated bionts secrete higher amounts of atranorin to the media during the first 12 days of immobilization. Immobilization of isolated bionts could be used as a biotechnological technique to obtain a potential source of biological active compounds. On the other hand, the physiological state detected of C. verticillaris in the Cerrado is much better for experimentation than that of the specimens collected in Caatinga since, in this case, the thalli showed the fragility that the extreme environmental conditions of the semi-arid region of NE Brazil impose on this lichen species. To date, no priority has been defined for lichen conservation in Brazilian ecosystems. It is therefore suggested that it imust important to include lichen ecophysiology studies in public conservation policies.

The effects of different environmental stresses on growth, efficiency in biomass production, and on the accumulation of sucrose in sugarcane cultivars are studied. Thermal, nutritional, saline, and drought stresses have similar effects on sensitive cultivars: decrease in size of the plant; decrease in the photosynthetic efficiency, possibly accompanied by chlorosis of the leaf; alterations in the integrity of membrane systems; loss of the ability of sucrose accumulation; and accumulation of reactive oxygen species. In the case of wound stress, these phenomena are accompanied by an enhanced production of soluble carbohydrates and glycoproteins that appear to act as healing molecules or protective responses against casual infections. A good number of resistance genes have been characterized that encode for the synthesis of osmoregulatory small molecules, such as proline or trehalose, for proteins that ensure the integrity of photosystems and for enzymes that produce antioxidant metabolites. The possibility of using these cloned genes in the production of transgenic plants with high resistance to stress is discussed.

This study demonstrates the involvement of the cytoskeleton in the movement of cyanobacteria and fungal spores to their hosts to establish a state of symbiosis or pathogenicity. The term symbiosis sensu lato is referred not only to commensalism and mutualism but also to the parasitic aberrations. The establishment of association implies that the endohabitant can move on a wet surface until finding an entry point in the exohabitant surface. In aqueous media, the exohabitant secretes glycoproteins that form a chemoattraction gradient for the invading cells. In lichens, the gradient consists of fungal lectins whose function is to recognize a compatible green alga or cyanobacterium. In the case of pathogens, the secreted proteins usually are a mixture that includes false quorum and chemoattractant signals, and cell wall digestive enzymes. The results indicate that fungal lectins and defense proteins bind to specific cell wall receptors for signaling the activation of cytoskeleton, causing successive cycles of cell contraction-relaxation that permits the migration of the endohabitant. In this study, different biochemical and microscopy techniques have been used. The mechanisms through which the cytoskeleton carries out these cycles of cell contractionrelaxation are described, being this a remarkable advance compared to previous results.

Aims and Objectives:This study aimed to characterize a coniferyl alcohol dehydrogenase from sugarcane stalks. Also, the purification of CAD from sugarcane stalks was also carried out to study kinetic properties and substrate specificity.Background:Sugarcane plants contain an alcohol dehydrogenase able to reduce both coniferyl and sinapyl aldehydes to their correspondent alcohols, although there are reasonable grounds for suspecting that these are two distinct enzymes.Methods:The enzyme, coniferyl alcohol dehydrogenase was 125-fold purified from sugarcane stalks. Its activity was estimated by HPLC by calculating the amount of product formed.Results:The enzyme showed an optimum pH value of 7.9, at an optimum temperature of 20-22°C and a molecular mass of 48 kDa. The Km value for coniferyl alcohol was 3.03 µM and the enzyme was shown to be inhibited by an excess of the substrate from 17 µM. This dehydrogenase showed a similar affinity to sinapyl alcohol (Km 1.78 µM).Conclusions:This paper provides circumstantial evidence about the existence of two different alcohol dehydrogenases, specific to each of the substrates.

Sporisorium scitamineum teliospores possess an organized cytoskeleton involved in important developmental and physiological processes. It has been described that microtubules appear to be fundamental for nucleus translocation during germination and hyphal growth, whereas actin polymerization is necessary for the formation of invaginations during teliospore displacement. Here, a global vision of the actin cytoskeleton organization throughout the life cycle of S. scitamineum cells is shown, providing evidence that a perfectly structured F-actin network is necessary to trigger smut pathogenicity. Moreover, although myosin presence in teliospores had been previously described, herein actin and myosin co-locations are demonstrated by confocal microscopy during both invaginations formation and germination. In turn, F-actin and microtubules (MTs) interact, jointly participating in the establishment of cell polarity. The resistant sugarcane cultivar Mayari 55-14 produces high molecular mass glycoproteins (HMMG) that differently affect F-actin organization at different stages of fungal development. HMMG first supported F-actin to induce the movement of teliospores towards the cytoagglutination points. At later stages of fungal development, HMMG disorganized F-actin which prevented the protrusion of germinative tube. A continuous exposure to HMMG provoked apoptosis in pathogenic, diploid cells and a delay in sporidia conjugation that could be crucial for plant resistance.

Science permeates practically every aspect of our lives thanks to the speed with which scientific knowledge is generated, the speed with which this knowledge is transmitted and the profound technification of our daily lives. Speed that many times does not allow that moment of reflection that is necessary to be correctly understood the concept and incorporated into the cultural heritage of our person. In this work, we analyze the sources of information, their credibility and the availability of sources of knowledge that our daily life puts at our disposal in relation to the science of plants.

Previous studies have already highlighted the correlation between Sporisorium scitamineum pathogenicity and sugarcane polyamine accumulation. It was shown that high infectivity correlates with an increase in the amount of spermidine, spermine and cadaverine conjugated to phenols in the sensitive cultivars whereas resistant plants mainly produce free putrescine. However, these previous studies did not clarify the role of these polyamides in the disorders caused to the plant. Therefore, the purpose of this research is to clarify the effect of polyamines on the development of smut disease. In this paper, commercial polyamines were firstly assayed on smut teliospores germination. Secondly, effects were correlated to changes in endogenous polyamines after contact with defense sugarcane glycoproteins. Low concentrations of spermidine significantly activated teliospore germination, while putrescine had no activating effect on germination. Interestingly, it was observed that the diamine caused nuclear decondensation and breakage of the teliospore cell wall whereas the treatment of teliospores with spermidine did not induce nuclear decondensation or cell wall breakdown. Moreover, the number of polymerized microtubules increased in the presence of 7.5 mM spermidine but it decreased with putrescine which indicates that polyamines effects on Sporisorium scitamineum teliospore germination could be mediated through microtubules interaction. An increased production of polyamines in smut teliospores has been related to sugarcane resistance to the disease. Teliospores incubation with high molecular mass glycoproteins (HMMG) from the uninoculated resistant variety of sugarcane, Mayari 55-14, caused an increase of the insoluble fraction of putrescine, spermidine and spermine inside the teliospore cells. Moreover, the level of the soluble fraction of spermidine (S fraction) increased inside teliospores and the excess was released to the medium. The HMMG glycoproteins purified from Mayarí 55-14 plants previously inoculated with the pathogen significantly increased the levels of both retained and secreted soluble putrescine and spermidine. Polyamines levels did not increase in teliospores after incubation with HMMG produced by non resistant variety Barbados 42231 which could be related to the incapacity of these plants to defend themselves against smut disease. Thus, a hypothesis about the role of polyamines in sugarcane-smut interaction is explained.

Smut infection alters the transcription of dirigent proteins (DIR) by sugarcane plants. Here, we show that these alterations are associated to an elevated production of cytotoxic lignans. Smut-resistant sugarcane varieties display a fivefold increase in pinoresinol and also produce elevated amounts of secoisolariciresinol. Conversely, smut-sensitive varieties do not produce pinoresinol or secoisolariciresinol upon infection, synthesizing instead small amounts of matairesinol. Our data indicate that commercial pinoresinol and secoisolariciresinol seem to prevent smut teliospore germination and sporidia release from sprouted teliospores. Consistently, we observed abundant morphological alterations of sporidia incubated in the presence of these lignans. However, commercial lignans do not block the development of the pathogen in a definitive way. Additional experiments demonstrate that only the extracts from healthy or smut-exposed resistant plants inhibit sporidia growth in vitro, indicating that a specific mixture of lignans from resistant plants is necessary to constitute an effective defense mechanism.

Lichens are organisms capable of interacting with the environment, playing an important role in the modification of their substrate. In coastal areas of northeastern Brazil with sandy soils, as an extension of Atlantic rainforest, or in an interface with semi-arid Caatinga biome and high mountain humid forests, named brejos , lichens of the family Cladoniaceae are found forming pillows on these soils. They interact with their substrate, influencing the chemical composition and biota. In this study, we summarize data about the interaction of these lichens with Quartzarenic Neosols, which occurs in this phytophysiognomy named tabuleiros or cerrados .

Proteomic profiling of the stalk of a smut resistant and a susceptible sugarcane cultivars revealed the presence of dirigent and dirigent-like proteins in abundance in the pool of high molecular mass (HMMG) and mid-molecular mass (MMMG) glycoproteins, produced as part of the defensive response to the fungal smut pathogen. Quantitative RT-PCR analysis showed that expression levels of SofDIR16 (sugarcane dirigent16) and SofCAD (sugarcane cinnamyl alcohol dehydrogenase) were higher in the smut resistant My 55-14 cultivar than in the sensitive B 42231 cultivar prior to infection. Inoculation with fungal sporidia or water decreased the level of SofCAD transcripts in My 55-14, indicating that regulation of SofCAD expression does not take part of the specific response to smut infection. In contrast, SofDIR16 expression was almost nullified in My 55-14 after inoculation with fungal sporidia, but not after water injection. It is proposed that the decreased expression of dirigent proteins induces the formation of lignans, which are involved in the defense response of the smut resistant My 55-14 cultivar.

In this work, new biotechnological procedures have been optimized on the basis of immobilization in alginate of bionts isolated from the lichen C. substellata. From these immobilizates, soluble and biologically active phenolics can be obtained. During bionts-immobilization, stictic, norstictic and usnic acids were secreted to the medium. The amount produced of each of them differed depending on the immobilization time, the precursor supplied and the type of biont used. Greater amounts of stictic acid were detected and maintained over time in all bioreactors. The opposite occurs in non-immobilized thallus. Virtually, all lichen phenols exhibit antioxidant activity to a greater or lesser degree, so that the antioxidant capacity of stictic acid (82.13% oxidation inhibition) was tested. The soluble extract of immobilized algae co-incubated in sodium acetate with fungal hyphae contained carbohydrates and exhibited a potent antioxidant capacity after 13 days of immobilization (94.87%). Therefore, attempts have been made to relate both parameters. On the other hand, the growth of Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae was inhibited by phenolic compounds produced by immobilizates, although the organic extract of the whole lichen showed the highest activity due to a possible synergy with other indeterminate compounds. Thus, C. substellata immobilized bionts are a potential source of different natural antioxidant and antimicrobial compounds.

Sporisorium scitamineum cells, that causes smut disease in sugar cane, respond to Concanavalin A (ConA). This lectin stimulates the cytoagglutination of teliospores, an excessive elongation of germinative tubes and induces morphological changes in hyphae, in the same way that it occurs in other cellular types. These events seem to play a defensive role in plants against pathogenic infections. In fact, ConA prevents S. scitamineum germination. Binding assays reveal that the distribution of ConA specific receptors is heterogeneous in both location and stage of cycle. Generally, it seems that the lectin activates mitotic events during the life cycle of cells that have been previously able to germinate. For example, increased cell budding is observed in released sporidia after contact with high concentration of the lectin. Moreover, desorption assays indicate that bound ConA is partially desorbed by methyl-mannose and by sugar cane glycoproteins, suggesting that important polysaccharide ligands involved in the defensive response against smut disease could be contained in sugar cane juice produced by resistant varieties.

Sugarcane plants, subjected to environmental stress, mechanical injuries, or infection by pathogens, produce glycoproteins containing heterofructans, composed of a fairly extensive domain of β-1,2-fructofuranoside chains in which galactitol units intercalated. They could act as signaling molecules for cell recognition, able to discriminate between beneficial endophytes and bacterial or fungal pathogens. Infection mechanisms and disease progress are very different for different pathogens. Xanthomonas albilineans produces a gum, a xanthanlike polymer, which obliterates the xylem elements producing desiccation and leaf yellowing, and this disease has been termed “leaf scald.” Sporisorium scitamineum, on the other hand, uses stomata to penetrate the host tissues or secretes hydrolytic enzymes of cell wall polymers, which enable mycelial entry through any point on the surface of the plant. Pathogen spores also secrete quorum signals that increase the number of cells in the inoculum. However, some of the glycoproteins produced by infected cane act as false quorum signals. Then the probability of inhibiting germination increases by increasing the aggregation of the teliospores caused by noxious false signals. Alternatively, infection of sugarcane plants by smut teliospores elicits lignification by activating monolignol production. Lignin deposits increase in the cell walls of the infected plant and impede the entry of the pathogen. Teliospores must displace on the wet surface of the plant, either to find a natural way of entry or to be grouped by the effect of quorum sensing. The displacement occurs by successive contractions and relaxations of the actomyosin complex that composes the cytoskeleton.