Enterobacter sp. DBA51 produces ACC deaminase and promotes the growth of tomato (Solanum lycopersicum L.) and tobacco (Nicotiana tabacum L.) plants under greenhouse condition.

Bacterial isolated from rhizospheric soil associated with the semi-desertic plant Coronilla juncea L. were screened for 1-aminocyclopropane-1-carboxylate deaminase (ACCD) activity, a common trait for plant-growth-promoting rhizobacteria (PGPR). Among bacterial isolates, strain DBA51 showed phosphate solubilizing index (PSI), producing indole acetic acid (IAA), and with the hemolysis-negative test. Sequencing and analysis of the 16S rDNA gene identified DBA51 as Enterobacter. DBA51 did not show antagonistic activity in vitro against bacterial (Clavibacter michiganensis, Pseudomonas syringae pv. tomato DC3000 and Pectobacterium cacticidum FHLGJ22) and fungal phytopathogens (Alternaria sp., Fusarium oxysporum fsp. lycopersici, Fusarium oxysporum fsp. cubense M5, and Rhizoctonia sp.). Root inoculations with DBA51 in tomato (Solanum lycopersicum L.) and tobacco (Nicotiana tabacum L.) plants were performed under greenhouse conditions. Plant height (20 %) and root biomass (40 %) were significantly enhanced in tomato plants inoculated with DBA51 compared to non-inoculated plants, although for tobacco plants, only root biomass (27 %) showed significant differences with DBA51. In addition, physiological parameters such as photosynthetic rate (µmol CO2 m-2 s-1), stomatal conductance (mol H2O m-2 s-1), and transpiration rate (mmol H2O m-2 s-1) were also evaluated, and no differences were detected between DBA51-inoculated and control treatment in tomato and tobacco leaves. The observed results indicate that the DBA51 strain could be used as a biofertilizer to improve yields of horticultural crops.

Role of a LORELEI- like gene from Phaseolus vulgaris during a mutualistic interaction with Rhizobium tropici.

Reactive oxygen species (ROS), produced by NADPH oxidases known as RBOHs in plants, play a key role in plant development, biotic and abiotic stress responses, hormone signaling, and reproduction. Among the subfamily of receptor-like kinases referred to as CrRLK, there is FERONIA (FER), a regulator of RBOHs, and FER requires a GPI-modified membrane protein produced by LORELEI (LRE) or LORELEI-like proteins (LLG) to reach the plasma membrane and generate ROS. In Arabidopsis, AtLLG1 is involved in interactions with microbes as AtLLG1 interacts with the flagellin receptor (FLS2) to trigger the innate immune response, but the role of LLGs in mutualistic interactions has not been examined. In this study, two Phaseolus vulgaris LLG genes were identified, PvLLG2 that was expressed in floral tissue and PvLLG1 that was expressed in vegetative tissue. Transcripts of PvLLG1 increased during rhizobial nodule formation peaking during the early period of well-developed nodules. Also, P. vulgaris roots expressing pPvLLG1:GFP-GUS showed that this promoter was highly active during rhizobium infections, and very similar to the subcellular localization using a construct pLLG1::PvLLG1-Neon. Compared to control plants, PvLLG1 silenced plants had less superoxide (O2-) at the root tip and elongation zone, spotty hydrogen peroxide (H2O2) in the elongation root zone, and significantly reduced root hair length, nodule number and nitrogen fixation. Unlike control plants, PvLLG1 overexpressing plants showed superoxide beyond the nodule meristem, and significantly increased nodule number and nodule diameter. PvLLG1 appears to play a key role during this mutualistic interaction, possibly due to the regulation of the production and distribution of ROS in roots.

TETRASPANIN 8-1 from Phaseolus vulgaris plays a key role during mutualistic interactions.

Arbuscular mycorrhizal (AM) fungi and rhizobia form two of the most important plant-microbe associations for the assimilation of phosphorus (P) and nitrogen (N). Symbiont-derived signals are able to coordinate the infection process by triggering multiple responses in the plant root, such as calcium influxes and oscillations, increased reactive oxygen species (ROS), cytoskeletal rearrangements and altered gene expression. An examination was made of the role of tetraspanins, which are transmembrane proteins that self-organize into tetraspanin web regions, where they recruit specific proteins into platforms required for signal transduction, membrane fusion, cell trafficking, and ROS generation. In plant cells, tetraspanins are scaffolding proteins associated with root radial patterning, biotic and abiotic stress responses, cell fate determination, plasmodesmata and hormonal regulation. Some plant tetraspanins, such as Arabidopsis thaliana TETRASPANIN 8 and TETRASPANIN 9 (AtTET8 and AtTET9) are associated with exosomes during inter-kingdom communication. In this study, a homolog of AtTET8, PvTET8-1, in common bean (Phaseolus vulgaris L. var. Negro Jamapa) was examined in roots during interactions with Rhizobium tropici and Rhizophagus irregularis. The promoter of PvTET8-1 contained several cis-acting regulatory DNA elements potentially related to mutualistic interactions, and PvTET8-1 was transcriptionally activated during AM fungal and rhizobial associations. Silencing it decreased the size and number of nodules, nitrogen fixation, and mycorrhizal arbuscule formation, whereas overexpressing it increased the size and number of nodules, and mycorrhizal arbuscule formation but decreased nitrogen fixation. PvTET8-1 appears to be an important element in both of these mutualistic interactions, perhaps through its interaction with NADPH oxidase and the generation of ROS during the infection processes.

Genome-wide characterization of the xyloglucan endotransglucosylase/hydrolase gene family in Solanum lycopersicum L. and gene expression analysis in response to arbuscular mycorrhizal symbiosis.

Xyloglucan endotransglucosylase/hydrolases (XTHs) are a glycoside hydrolase protein family involved in the biosynthesis of xyloglucans, with essential roles in the regulation of plant cell wall extensibility. By taking advantage of the whole genome sequence in Solanum lycopersicum, 37 SlXTHs were identified in the present work. SlXTHs were classified into four subfamilies (ancestral, I/II, III-A, III-B) when aligned to XTHs of other plant species. Gene structure and conserved motifs showed similar compositions in each subfamily. Segmental duplication was the primary mechanism accounting for the expansion of SlXTH genes. In silico expression analysis showed that SlXTH genes exhibited differential expression in several tissues. GO analysis and 3D protein structure indicated that all 37 SlXTHs participate in cell wall biogenesis and xyloglucan metabolism. Promoter analysis revealed that some SlXTHs have MeJA- and stress-responsive elements. qRT-PCR expression analysis of nine SlXTHs in leaves and roots of mycorrhizal colonized vs. non-colonized plants showed that eight of these genes were differentially expressed in leaves and four in roots, suggesting that SlXTHs might play roles in plant defense induced by arbuscular mycorrhiza. Our results provide valuable insight into the function of XTHs in S. lycopersicum, in addition to the response of plants to mycorrhizal colonization.

Using DCP-Rho1 as a fluorescent probe to visualize sulfenic acid-containing proteins in living plant cells.

Among the biologically relevant reactive oxygen species (ROS), hydrogen peroxide (H2O2) has special properties. H2O2 can diffuse across membranes, has a low reactivity, and is very stable. Deprotonated cysteine residues in proteins can be oxidized by H2O2 into a highly reactive sulfenic acid derivative (-SOH), which can react with another cysteine to form a disulfide. Under higher oxidative stress the sulfenic acid undergo further oxidation to sulfinic acid (Cys-SO2H), which can subsequently be reduced. The sulfinic acid can be hyperoxidized to sulfonic acid (Cys-SO3H), whose reduction is irreversible. Formation of sulfenic acids can have a role in sensing oxidative stress, signal transduction, modulating localization and activity to regulate protein functions. Therefore, there is an emerging interest in trying to understand the pool of proteins that result in these sorts of modification in response to oxidative stress. This is known as the sulfenome and several approaches have been developed in animal and plant cells to analyze the sulfenome under different stress responses. These approaches can be proteomic, molecular, immunological (i.e., antibodies), or expressing genetically encoded probes that specifically react to sulfenic modifications. In this chapter, we describe an additional approach that allows visualization of sulfenic modification in vivo. This is newly developed fluorescent probe DCP-Rho1 can be implemented in any plant cell to analyze the sulfenic modification.

Soil Type Influences Novel "Milpa" Isolates of Trichoderma virens and Aspergillus tubingensis That Promote Solubilization, Mineralization, and Phytoabsorption of Phosphorus in Capsicum annuum L.

The Capsicum genus has significant economic importance since it is cultivated and consumed worldwide for its flavor and pungent properties. In 2021, Mexico produced 3.3 billion tons on 45,000 hectares which yielded USD 2 billion in exports to the USA, Canada, Japan, etc. Soil type has a dramatic effect on phosphorus (P) availability for plantsdue to its ion retention.In a previous study, novel fungal isolates were shown to solubilize and mineralize P in different kinds of soils with different P retention capacities. The aim of this work was to study the effects of the mineralogy of different kinds of "milpa" soils on the germination, biomass production, and P absorption of chili plants (Capsicum annuum). The germination percentage, the germination speed index, and the mean germination time were significantly increased in the plants treated with dual inoculation. Foliar phosphorus, growth variables, and plant biomass of chili plants grown in a greenhouse were enhanced in different soil types and with different inocula. Correlation studies suggested that the most significant performance in the foliar P concentration and in the growth response of plants was achieved in Vertisol with dual inoculation of 7 × 106 mL-1 spores per chili plant, suggesting this would be an appropriate approach to enhance chili cultivation depending on the soil type. This study stresses the importance of careful analysis of the effect of the soil type in the plant-microbe interactions.

Enhanced specialized metabolite, trichome density, and biosynthetic gene expression in Stevia rebaudiana (Bertoni) Bertoni plants inoculated with endophytic bacteria Enterobacter hormaechei.

Stevia rebaudiana (Bertoni) Bertoni is a plant of economic interest in the food and pharmaceutical industries due its steviol glycosides (SG), which are rich in metabolites that are 300 times sweeter than sucrose. In addition, S. rebaudiana plants contain phenolic compounds and flavonoids with antioxidant activity. Endophytic bacteria promote the growth and development and modulate the metabolism of the host plant. However, little is known regarding the role of endophytic bacteria in the growth; synthesis of SG, flavonoids and phenolic compounds; and the relationship between trichome development and specialized metabolites in S. rebaudiana, which was the subject of this study. The 12 bacteria tested did not increase the growth of S. rebaudiana plants; however, the content of SG increased with inoculation with the bacteria Enterobacter hormaechei H2A3 and E. hormaechei H5A2. The SG content in leaves paralleled an increase in the density of glandular, short, and large trichome. The image analysis of S. rebaudiana leaves showed the presence of SG, phenolic compounds, and flavonoids principally in glandular and short trichomes. The increase in the transcript levels of the KO, KAH, UGT74G1, and UGT76G1 genes was related to the SG concentration in plants of S. rebaudiana inoculated with E. hormaechei H2A3 and E. hormaechei H5A2. In conclusion, inoculation with the stimulating endophytes E. hormaechei H2A3 and E. hormaechei H5A2 increased SG synthesis, flavonoid content and flavonoid accumulation in the trichomes of S. rebaudiana plants.

Production of indole-3-acetic acid by Bacillus circulans E9 in a low-cost medium in a bioreactor.

Bacillus circulans E9 (now known as Niallia circulans) promotes plant growth-producing indole-3-acetic acid (IAA), showing potential for use as a biofertilizer. In this work, the use of a low-cost medium containing industrial substrates, soybean, pea flour, Solulys, Pharmamedia, yeast extract, and sodium chloride (NaCl), was evaluated as a substitute for microbiological Luria Broth (LB) medium for the growth of B. circulans E9 and the production of IAA. In Erlenmeyer flasks with pea fluor medium (PYM), the maximum production of IAA was 7.81 ± 0.16 µg mL-1, while in microbiological LB medium, it was 3.73 ± 0.15 µg mL-1. In addition, an oxygen transfer rate (OTR) of 1.04 kg O2 m-3 d-1 allowed the highest bacterial growth (19.3 ± 2.18 × 1010 CFU mL-1) and IAA production (10.7 µg mL-1). Consequently, the OTR value from the flask experiments was used to define the conditions for the operation of a 1 L stirred tank bioreactor. The growth and IAA production of B. circulans cultured in a bioreactor with PYM medium were higher (8 and 1.6 times, respectively) than those of bacteria cultured in Erlenmeyer flasks. IAA produced in a bioreactor by B. circulans was shown to induce the root system in Arabidopsis thaliana, similar to synthetic IAA. The results of this study demonstrate that PYM medium may be able to be used for the mass production of B. circulans E9 in bioreactors, increasing both bacterial growth and IAA production. This low-cost medium has the potential to be employed to grow other IAA-producing bacterial species.

Photosynthetic performance and stevioside concentration are improved by the arbuscular mycorrhizal symbiosis in Stevia rebaudiana under different phosphate concentrations.

In plants, phosphorus (P) uptake occurs via arbuscular mycorrhizal (AM) symbiosis and through plant roots. The phosphate concentration is known to affect colonization by AM fungi, and the effect depends on the plant species. Stevia rebaudiana plants are valuable sources of sweetener compounds called steviol glycosides (SGs), and the principal components of SGs are stevioside and rebaudioside A. However, a detailed analysis describing the effect of the phosphate concentration on the colonization of AM fungi in the roots and the relationship of these factors to the accumulation of SGs and photochemical performance has not been performed; such an analysis was the aim of this study. The results indicated that low phosphate concentrations (20 and 200 µM KH2PO4) induced a high percentage of colonization by Rhizophagus irregularis in the roots of S. rebaudiana, while high phosphate concentrations (500 and 1,000 µM KH2PO4) reduced colonization. The morphology of the colonization structure is a typical Arum-type mycorrhiza, and a mycorrhiza-specific phosphate transporter was identified. Colonization with low phosphate concentrations improved plant growth, chlorophyll and carotenoid concentration, and photochemical performance. The transcription of the genes that encode kaurene oxidase and glucosyltransferase (UGT74G1) was upregulated in colonized plants at 200 µM KH2PO4, which was consistent with the observed patterns of stevioside accumulation. In contrast, at 200 µM KH2PO4, the transcription of UGT76G1 and the accumulation of rebaudioside A were higher in noncolonized plants than in colonized plants. These results indicate that a low phosphate concentration improves mycorrhizal colonization and modulates the stevioside and rebaudioside A concentration by regulating the transcription of the genes that encode kaurene oxidase and glucosyltransferases, which are involved in stevioside and rebaudioside A synthesis in S. rebaudiana.

Production of anti-inflammatory compounds in Sphaeralcea angustifolia cell suspension cultivated in stirred tank bioreactor.

Sphaeralcea angustifolia is a plant used for the treatment of inflammatory processes. Scopoletin, tomentin, and sphaeralcic acid were identified as the compounds with anti-inflammatory and immunomodulatory effects. Successful establishment of the cell culture in Erlenmeyer flasks has been reported previously. The aim of this study was to evaluate the ability of cells in suspension from S. angustifolia grown in a stirred tank bioreactor and demonstrate their capacity to produce bioactive compounds. Cells in suspension grown at 200 rpm reached a maximal cell biomass in dry weight at 19.11 g/L and produced 3.47 mg/g of sphaeralcic acid. The mixture of scopoletin and tomentin was only detected at the beginning of the culture (12.13 µg/g). Considering that the profile of dissolved oxygen during the cultures was lesser than 15%, it is possible that the low growth at 100 rpm could be due to oxygen limitations or to cell sedimentation. At 400 rpm, a negative effect on cell viability could be caused by the increase in the hydrodynamic stress, including the impeller tip, average shear rate, and Reynolds number. The sphaeralcic acid content in the cell suspension of S. angustifolia obtained in the bioreactor was two orders of magnitude greater than that reported for the culture grown in Erlenmeyer flasks.

Prevalencia de fiebre reumática en Pinar del Río. Una década de experiencia / Prevalence of rheumatic fever in Pinar del Río. A decade of experience

Se estudió la prevalencia de la fiebre reumática en 1986 y 1996 entre los residentes habituales del municipio Pinar del Río con edades entre 5 y 14 años. Se examinaron todos los sospechosos de la enfermedad en consulta especial creada a los efectos de la investigación. Se aplicaron los criterios de Jones modificados para verificar el diagnóstico. Las tasas de prevalencia disminuyeron: en 1986 fue de 8,05 × 1 000 habitantes (5,78 para los portadores de fiebre reumática inactiva y 2,37 para los que padecían de cardiopatía reumática) y en 1996 fue de 1,99 × 1 000 habitantes (1,75 para la fiebre reumática inactiva y 0,24 para la cardiopatía reumática). La insuficiencia mitral fue la valvulopatía más diagnosticada y hubo un decremento en las tasas de valvulopatías, lo que también explica porqué la magnitud de la enfermedad ha disminuido

Prevalencia de fiebre reumática en Pinar del Río: una década de experiencia / Prevalence of rheumatic fever in Pinar del Río: a decade of experience

Se estudió la prevalencia de la fiebre reumática en 1986 y 1996 entre los residentes habituales del municipio Pinar del Río con edades entre 5 y 14 años. Se examinaron todos los sospechosos de la enfermedad en consulta especial creada a los efectos de la investigación. Se aplicaron los criterios de Jones modificados para verificar el diagnóstico. Las tasas de prevalencia disminuyeron: en 1986 fue de 8,05 × 1 000 habitantes (5,78 para los portadores de fiebre reumática inactiva y 2,37 para los que padecían de cardiopatía reumática) y en 1996 fue de 1,99 × 1 000 habitantes (1,75 para la fiebre reumática inactiva y 0,24 para la cardiopatía reumática). La insuficiencia mitral fue la valvulopatía más diagnosticada y hubo un decremento en las tasas de valvulopatías, lo que también explica porqué la magnitud de la enfermedad ha disminuido(AU)