Populus alba L., an Autochthonous Species of Spain: A Source for Cellulose Nanofibers by Chemical Pretreatment

In order to identify new sustainable sources for producing cellulose nanofibers (CNFs), fast-growing poplar (Populus alba L.) wood was evaluated herein. For that purpose, bleached poplar kraft pulp was produced and submitted to TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) mediated oxidation (TEMPO-ox) chemical pretreatment followed by microfluidization. The resulting CNFs were thoroughly characterized, including a rheological study at different pH values. Poplar CNFs showed properties comparable to eucalypt CNFs (reference material for CNFs production), showing high carboxylate content (1048 ± 128 µmol g−1), fibrillation yield (87.3% ± 8.1%), optical transmittance (83% at 700 nm) and thermal stability (up to more than 200 °C). Regarding the rheological study, whereas pH from 4 to 10 did not produce significant changes in rheological behavior, a reduction of pH down to 1 led to an order-of-magnitude increase on the viscoelastic functions. Therefore, poplar CNF shows potential in the pH-sensitive hydrogels application field. Finally, the possible ecotoxicity of poplar CNF was assessed. The decrease in cell viability was very low so that only concentrations causing a 10% cytotoxicity could be calculated for the assay detecting alterations in cell metabolism (10 µg mL−1) and plasma membrane integrity (60 µg mL−1).

Chromosome-level genome assembly of a triploid poplar Populus alba ’Berolinensis’

Related studies have provided significant insights into polyploid breeding in recent years, but limited research was focused on trees. The genomic information for the growth and response to abiotic stress in polyploidy trees is still largely unknown. Populus alba ’Berolinensis’, also named “Yinzhong poplar”, is a triploid poplar in the northeast of China. This hybrid triploid poplar is widely used as landscape ornamentals in urban areas because of its fast growth and high tolerance to abiotic stress. As an artificially synthesized male allotriploid hybrid, the three monoploid genomes of P. alba ’Berolinensis’ originated from different poplar species, so it is the desired material for studying polyploidy genomic collaboration mechanisms. Therefore, we intensively studied the allelic genomic collaboration mechanism in P. alba ’Berolinensis’. This study generated a high-quality chromosome-level genome assembly for the P. alba ’Berolinensis’ consisting of 19 allelic chromosomes. Its three monoploid chromosomes are polymorphic with an average of 42.22 variant sites per allelic gene locus. Meanwhile, we found that stress related genes such as RD22 and LEA7 exhibited structure variations. The above information has all been deployed to our polyploid genome online analysis website TreeGenomes (https://www.treegenomes.com). These polyploid genomic related resources will provide critical foundations for the molecular breeding of P. alba ’Berolinensis’ and help us uncover the allopolyploidization effects on the resistance and traits of polyploidy species deeper in the future.

Metal Based-oxide Nanoparticles Assisted the Uptake of the Essential Elements and Phytoremediation of Populus Alba : Essential Metabolic Processes and Genetic Stability

The present study evaluated the phytoremediation activities of Populus alba upon using nano metal-based-oxides (i.e., Fe2O3, ZnO, and Mn2O3-NPs) as analogues of three main heavy metals Fe, Zn and Mn exist in soil as micronutrients at three different concentrations (i.e., 20, 40, and 60 mg/L) compared to the control. The as-prepared nanoparticles have been prepared via co-precipitation method. In addition, the physico-chemical properties were investigated using transmission electron microscopy, Fourier transform infrared spectra, X-ray diffraction and dynamic light scattering techniques. Overall, a significant difference in the biomass production-related parameters such as fresh weight, shoot length, root length, and root number compared to control upon the treatment with micronutrients-based nano-metal-oxides (i.e., Mn2O3 > Fe2O3 > ZnO NPs, respectively), except a significant increase in the root number of Populus alba plant upon their treatment with ZnO NPs compared to other prepared nano-metal-oxides and control. Also, a remarkable increase in the chlorophyll index was monitored upon treatment with Fe2O3 than other used Mn2O3 and ZnO NPs, respectively. Moreover, RAPD-PCR bioassays were applied and the actual 6 primers showed a genetic variation percentage of 34.17% indicating that Populus alba is highly genetically stable even in a highly contaminated environment/soil. All these data enhance the idea of using the Populus alba plant in phytoremediation and heavy metal uptake as micronutrients to clean up the surroundings.

Impact on Growth and Secondary Metabolites in White Poplar (Populusalba L.) Callus using SeNPs@Moringa

Background: Green synthesis of nanoparticles has provided a cost-effective, environmentally friendly method, as well as raised safe strategies for the synthesis of nanomaterials. In this study, we investigated the synthesis of selenium nanoparticles from the leaf aqueous extract of Moringa oleifera (MO-SeNPs) and studied the effect of MO-SeNPs and Moringa extract with various concentrations on growth, active constituents, and antioxidant activity (scavenging DPPH) of Populus alba callus. MS medium supplemented with 2, 4-D at 2 mg/l + 0.5 mg/l BA took the maximum callus induction percentage (100%), increasing the callus fresh weight, dry weight, and degree of callus formation compared with 2.0 mg/l 2,4-D + 0.5 mg/l Kin. Methods: The highest values of callus fresh and dry weight were recorded on MS containing 20% MO-SeNPs. Regarding the active constituents, the GC-MS chromatogram revealed the presence of 23 major compounds identified in the chloroform extract. The phytoconstituents with maximum peak area in callus extract are Tetradecane, Hexadecen-1-ol,trans-9-, 5-Octadecene, (Benzene, 1-pentyloctyl), (Benzene, 1-butylnonyl), Cycloeicosane, and 10-Heneicosene in all treatments. Moringa extract and MO-SeNPs stimulate the increase of compounds in the callus compared to control. In this regard, MO-SeNPs 5% led to a higher increase in the area percent of active substances compared to the treatment of Moringa extract and control. Results: Concerning the antioxidant activity, the results indicated that Moringa extract and MO-SeNPs had a positive effect on scavenging DPPH compared with the control. Conclusion : The highest percentages of scavenging DPPH were recorded when Populus alba L. callus was treated with MO-SeNPs 20%, 10%, and Moringa extract 20%, percentages reached 84.65, 75.35, and 71.94 %, respectively.

MOLECULAR-GENETIC ANALYSIS OF PROPAGATED IN VITRO CLONES OF POPULUS ALBA L. AND POPULUS TREMULA L. USING MICROSATELLITE MARKERS

Use of planting material of forest trees with improved hereditary characteristics is one of the ways to increase the productivity and biological stability of forest stands. It requires taking measures to develop and improve selection base using modern approaches and methods of genetics and biotechnology. A molecular genetics assessment of clone plants of aspen (Populus tremula L.) and white poplar (Populus alba L.) from a long-term in vitro collection (up to 24 years), planted in a greenhouse and field conditions (nursery), was carried out. SSR loci of the PTR series (PTR5, PTR7, PTR8, PTR12, PTR14) were used as DNA markers. Evaluation of clones' ploidy was carried out on the basis of the diagnosis of "loss of heterozygosity" (LOH) effect. Analysis of 5 microsatellite loci of the specimens showed their high intraclonal genotypic stability and homogeneity in vitro and ex vitro. For the first time, data on the results of a comparative determination of ploidy using karyological and microsatellite analysis were presented. Based on the results of the SSR analysis, it can be concluded that the structure of molecular markers is stable among the samples of one clone that are in long-term cultivation. The ratio of the representation (dose) of electrophoretic variants of PCR products serves as an indirect sign of determining ploidy, but for its reliable assessment it is necessary to study the number of loci that are three times larger than the main set of chromosomes. The specimen also requires information on the amplification coefficient of the markers under study. Thus, it is necessary to use both chromosomal and microsatellite analyzes for reliable assessment of intraclonal homogeneity of various specimens, the development of understanding of clone genotypes formation and determination of their ploidy

CALIDAD DE PÉLETS A PARTIR DE BIOMASA DE OCHO ESPECIES DENDROENERGÉTICAS DE CRECIMIENTO RÁPIDO

La productividad de biomasa en especies de crecimiento rápido es una de las mejores alternativas para la elaboración de biocombustibles dendroenergéticos. Uno de los pretratamientos de la biomasa más importantes es el peletizado y con esto aumenta el poder calorífico. El objetivo de este estudio fue evaluar la calidad de pélets de ocho especies dendroenergéticas de crecimiento rápido. Las especies evaluadas fueron Eucalyptus globulus, Pinus greggii, Populus alba, Acacia retinoides, Ricinus communis, Populus deltoides, Pennisetum sp. y Salix sp. El diseño experimental fue completamente aleatorio; las especies analizadas como tratamientos. Con los datos se realizó un ANDEVA y las medias de los tratamientos se compararon con la prueba de Tukey (p≤0.05). Las variables evaluadas fueron: contenido de humedad (CH), cenizas, material volátil (CV), carbón fijo (CF) y poder calorífico superior (PCS); diámetro, longitud, peso, volumen, densidad a granel (DG) y densidad básica (DP); índice de resistencia, pérdida de biomasa y friabilidad (F). Las diferencias entre especies fueron significativas (p ≤0.05), para todas las variables. Ocho de las nueve especies cumplieron con valores mínimos del PCS (19.2 MJ kg-1 y 20.1 MJ kg-1) requerido en normas internacionales de calidad en pélets (18.0 MJ kg-1). Los pélets de ocho especies mostraron las dimensiones solicitadas en las normas de calidad. Todas las especies presentaron densidad aceptable, con base en la norma internacional. En la densidad básica se observaron valores altos y significativos en Pennisetum sp (1.4 g cm-3) y Pinus greggii (1.4 g cm-3), mientras que P. deltoides registró el valor más bajo (1.0 g cm-3). En las pruebas de resistencia, los pélets de P. greggii mostraron valores altos para el número de partes al rompimiento (2.4) y pérdida de biomasa (41.6%); así como valores bajos de friabilidad (0.45). Los pélets obtenidos a partir de la biomasa de las especies evaluadas cumplieron con los estándares internacionales de calidad.

Influence of Cellulose Characteristics on Pyrolysis Suitability

Cellulose is the most abundant component of biomass and the one that requires the most activation energy (Ea) for pyrolysis. In this study, the dependence of Ea on the intrinsic cellulose characteristics, such as the degree of polymerization (DP), crystallinity, and crystal size, was studied in different cellulose samples, including samples from Eucalyptus globulus, Ulmus minor, Linun usitatissimum, Olea europaea, Robinia pseudoacacia, and Populus alba. Then, to describe the pyrolytic degradation of cellulose, the Ozawa–Flynn–Wall kinetic method was the most appropriate among the isoconversional models studied. An acceptable quadratic relationship of R2 > 0.9 between the Ea values of the different cellulose samples with their corresponding DP, crystallinity index, and crystal size values was found. Therefore, low crystallinity and low-to-medium crystal size values are desired to obtain lower Ea values for cellulose pyrolysis. On the other hand, DP did not present a clear effect on Ea in the studied DP range.

Особливості зростання та поширення мохоподібних в умовах міста Запоріжжя

У статті наведені результати досліджень бріофлори двох антропогенних комплексів (культурофітоценозу та селітебного ландшафту) міста Запоріжжя. Визначали місцезнаходження, частоту трапляння, проективне покриття та приуроченість бріофітів до конкретних форофітів на досліджених територіях. Досліджені особливості поширення епіфітних мохоподібних, виявлено їх субстратну приуроченість до найбільш поширених деревних порід. Виділено екологічні групи мохів, їх життєві форми, здійснено оцінку видів за ступенем урбанофільності. Встановлено, що видовий склад досліджених антропогенних комплексів міста представлений 11 видами мохоподібних, з-поміж яких 7 видів є епіфітними, інші види були виявлені на інших субстратах. Серед виявлених мохоподібних 2 види є рідкісними. Найбільша кількість епіфітних бріофітів виявлена на корі Ulmus minor Mill., Populus alba L. та Robinia pseudoacacia L. Середнє видове різноманіття епіфітів характерне для Acer negundo L. та Salix sp. Мохи досліджених територій міста Запоріжжя реалізують життєві стратегії бріоексплерентів піонерних та бріопатієнтів (екотопічних і ценотичних). Встановлений сильний позитивний кореляційний зв’язок між площею проективного покриття бріофітів та висотою їх розташування на форофітах. За результатами розрахунків індексу чистоти повітря, який коливався від 3,4 до 5,0, території селітебного ландшафту та культуроценозу відповідають середньо й слабко забрудненим бріоіндикаційним зонам відповідно. Порівняльний аналіз видового складу бріофітів двох антропогенних комплексів міста Запоріжжя показав високий коефіцієнт спорідненості (0,60) бріофлор досліджених територій. Отже, видовий склад бріофітів цих територій є досить однорідним. Отримані дані свідчать про значну роль епіфітних мохоподібних, які здатні швидко заселяти деревні насадження антропогенних комплексів міста, що є одним із чинників стабілізації урбоекосистеми.