Populus Bolleana Research Articles

Identification of Damaged Canopies in Farmland Artificial Shelterbelts Based on Fusion of Unmanned Aerial Vehicle LiDAR and Multispectral Features

With the decline in the protective function for agricultural ecosystems of farmland shelterbelts due to tree withering and dying caused by pest and disease, quickly and accurately identifying the distribution of canopy damage is of great significance for forestry management departments to implement dynamic monitoring. This study focused on Populus bolleana and utilized an unmanned aerial vehicle (UAV) multispectral camera to acquire red–green–blue (RGB) images and multispectral images (MSIs), which were fused with a digital surface model (DSM) generated by UAV LiDAR for feature fusion to obtain DSM + RGB and DSM + MSI images, and random forest (RF), support vector machine (SVM), maximum likelihood classification (MLC), and a deep learning U-Net model were employed to build classification models for forest stand canopy recognition for the four image types. The model results indicate that the recognition performance of RF is superior to that of U-Net, and U-Net performs better overall than SVM and MLC. The classification accuracy of different feature fusion images shows a trend of DSM + MSI images (Kappa = 0.8656, OA = 91.55%) > MSI images > DSM + RGB images > RGB images. DSM + MSI images exhibit the highest producer’s accuracy for identifying healthy and withered canopies, with values of 95.91% and 91.15%, respectively, while RGB images show the lowest accuracy, with producer’s accuracy values of 79.3% and 78.91% for healthy and withered canopies, respectively. This study presents a method for identifying the distribution of Populus bolleana canopies damaged by Anoplophora glabripennis and healthy canopies using the feature fusion of multi-source remote sensing data, providing a valuable data reference for the precise monitoring and management of farmland shelterbelts.

Comprehensive genome-wide analyses of R2R3-MYB transcription factors and tolerance to drought stress in Populus davidiana × Populus bolleana

Comprehensive genome-wide analyses of R2R3-MYB transcription factors and tolerance to drought stress in Populus davidiana × Populus bolleana

Ontogenetic changes in the mechanical stability of the main species of woody plants in the ecosystems of the city of Donetsk

The paper considers the issues of ontogenetic changes in the mechanical stability of 18 species of woody plants growing in the ecosystems of the industrial city of Donetsk: Acer campestre L., Acer negundo L., Acer platanoides L., Acer pseudoplatanus L., Acer saccharinum L., Aesculus hippocastanum L., Betula pendula Roth, Fraxinus excelsior L., Fraxinus lanceolata Borkh., Gleditsia triacanthos L., Populus simonii Carriere, Populus nigra L., Populus balsamifera L., Populus bolleana Lauche, Quercus robur L., Robinia pseudoacacia L., Tilia cordata Mill., Ulmus laevis Pall. It has been established that at the initial stages of the ontogenesis of woody plants, their biomechanics ensures survival through high flexibility. This is due to the low critical mass and load, which are easily achieved when static and dynamic factors act on the plant. Only a significant increase in linear dimensions makes it possible to maintain its own mass weighing several tons and above, as well as withstand the effects of adverse climatic factors. The studied ontogenetic dependences of the mechanical stability of the main species of woody plants in the ecosystems of the city of Donetsk should be used in landscaping the city.

Arid Urban Green Areas Reimagined: Transforming Landscapes with Native Plants for a Sustainable Future in Aksu, Northwest China

The exponential growth of the economy and society has resulted in a substantial need for superior urban green spaces, consequently fostering a significant surge in urban landscape construction. The integration of plant landscapes in urban landscape construction is crucial. The rational use of plant landscape resources to create high-quality urban green spaces is of great significance for promoting urban sustainable development. Hence, the primary aim of this study was to investigate the landscape and ecological functions of indigenous plants in the context of urban landscape implementation and then provide utilization strategies of indigenous plants for urban landscape construction. This research focuses on the utilization of native plants in Aksu’s urban green spaces (a city in northwest China). Through a contrastive analysis of the dust retention, windbreak and sand fixation, and landscaping capabilities of these native plants, certain indigenous species are identified as suitable candidates. Specifically, Styphnolobium japonicum and Ulmus densa exhibit a dust adhering per plant of 656.50 and 388.46 g·m−2, respectively. Consequently, augmenting their planting proportion can effectively augment the overall dust adhering within the garden. The windbreak distances of Populus bolleana, Populus euphratica, and Styphnolobium japonicum were found to exceed 60 m, indicating their effectiveness in mitigating wind and sand erosion. Therefore, strategically planting these species can contribute to the establishment of a robust urban windbreak forest. Additionally, optimizing the arrangement of Rosa multiflora, Hippophae rhamnoides, Berberis thunbergii, and Salix matsudana can enhance the aesthetic appeal of urban gardens. The utilization of native plants holds promise in enhancing the ecological and landscape functions of urban gardens in Aksu. The effective enhancement of the ecological function and the landscape effect of urban gardens can be achieved through the appropriate reconstruction with native plants. The findings of this study hold significant reference value for the urban landscape architecture in arid urban areas.

Внутривидовые скрещивания выделенных биотипов родов вяз и тополь для получения гетерозисных селекционных форм

Abstract. The purpose of the study is hybridization and breeding of tree species resistant to environmental conditions in conditions of desertification. Research methodology included the study of the growth, condition and durability of forms and hybrids, the identification of biological properties (drought, salt and frost resistance), the quality of trunks and decorativeness, the selection of parent pairs for crossing; the development of crossing techniques on cut branches. The order of work consisted of harvesting plant catkins, collecting pollen and cleaning it from impurities, harvesting branches and pollen, determining the viability of pollen, applying it to the mature stigma of the plant. The flowers of the ilmovs are bisexual, as a result of which they were castrated during crosses. Results. Parental pairs were selected and hybridization was carried out among the following breeds: Ulmus carpinifolia, Ulmus laevis, Ulmus pumila, Populus alba, Populus alba × Populus alba v. Populus piramidalis, Populus deltoides, Populus bolleana, Populus berolinensis, Populus nivea × Populus tremula, Populus nigra piramidalis. Hybrid seedlings were obtained between different types of elms and between different types of poplars. The variant of crossing the white poplar Pervenets Uzbekistana with the Bolle F. pyramidal poplar (FGUP “Volgogradskoe”) showed the best results. Scientific novelty lies in the selection of breeding material resistant to various stress factors. Selection of initial and promising varieties of tree crops for further use in breeding, introduction, competitive and production tests.

Monitoring of the condition of woody plants in the central part of the city of Donetsk

The dendroflora of Donetsk has been studied the species composition of trees in stands has been determined, the age structure of plantings has been analyzed, the life condition of green spaces has been assessed, as well as morphometric parameters of trees have been evaluated and models of age dependences of the allometric coefficient of trees, characterized by high indicators of adequacy to the initial data, have been proposed for the first time. As part of the linear plantings of the surveyed streets, 45 species of trees were identified, including 13 species of the indigenous fraction of the local flora belonging to 24 genera and 17 families. Dominant are Populus bolleana Lauche, Acer platanoides L., Betula pendula Roth, Acer pseudoplatanus L., Robinia pseudoacacia L., Aesculus hippocastanum L. and Picea pungens Engelm. The plantings are dominated by species of European (48,85%), North American (22,49%) and Central Asian (18,02%) origin. The most numerous in trees is the age group of 4049 years. The vital condition of 41% of trees with a fast and medium growth rate is assessed as good with minor signs of weakening, and 59% of plants are marked as severely weakened or dying. For slow-growing trees, 91% of the sample consists of healthy plants with minor signs of weakening.

Heterologous expression of Arabidopsis pattern recognition receptor RLP23 increases broad-spectrum resistance in poplar to fungal pathogens.

The pattern recognition receptor AtRLP23 from Arabidopsis thaliana recognizes the epitopes (nlp24s) of necrosis and ethylene-inducing peptide 1-like proteins (NLPs) and triggers pattern-triggered immunity (PTI). Here, we established methods for studying the early events of PTI in the hybrid poplar cultivar Shanxin (Populus davidiana × Populus bolleana) in response to the flagellin epitope. We confirmed that wild-type Shanxin cannot generate PTI responses on nlp24 treatment. Four NLP homologues were characterized from two common fungal pathogens of Shanxin, namely Marssonina brunnea f. sp. monogermtubi (MbMo) and Elsinoë australis (Ea), which cause black leaf spot and anthracnose disease, respectively, and the nlp24s of three of them could be responded to by Nicotiana benthamiana leaves expressing AtRLP23. We then created AtRLP23 transgenic Shanxin lines and confirmed that the heterologous expression of AtRLP23 conferred on transgenic Shanxin the ability to respond to one nlp24 of each fungal pathogen. Consistently, infection assays with MbMo or Ea showed obviously lower levels of disease symptoms and significantly inhibited the growth of fungi on the transgenic poplar compared with that in wild-type poplar. Overall, our results indicated that the heterologous expression of AtRLP23 allowed transgenic Shanxin to generate a PTI response to nlp24s, resulting in increased broad-spectrum fungal disease resistance.

Stem canker pathogen Botryosphaeria dothidea inhibits poplar leaf photosynthesis in the early stage of inoculation.

Fungal pathogens can induce canker lesions, wilting, and even dieback in many species. Trees can suffer serious physiological effects from stem cankers. In this study, we investigated the effects of Botryosphaeria dothidea (B. dothidea) on Populus bolleana (P. bolleana) leaves photosynthesis and stomatal responses, when stems were inoculated with the pathogen. To provide experimental and theoretical basis for preventing poplar canker early. One-year-old poplar stems were inoculated with B. dothidea using an epidermal scraping method. In the early stage of B. dothidea inoculation (2–14 days post inoculation, dpi), the gas exchange, stomatal dynamics, hormone content, photosynthetic pigments content, chlorophyll fluorescence parameters, and non-structural carbohydrate (NSC) were evaluated to elucidate the pathophysiological mechanism of B. dothidea inhibiting photosynthesis. Compared with the control groups, B. dothidea noteworthily inhibited the net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci), transpiration rate (Tr), and other photosynthetic parameters of poplar leaves, but stomatal limit value (Ls) increased. Consistent with the above results, B. dothidea also reduced stomatal aperture and stomatal opening rate. In addition, B. dothidea not only remarkably reduced the content of photosynthetic pigments, but also decreased the maximum photochemical efficiency (Fv/Fm), actual photochemical efficiency (ΦPSII), electron transfer efficiency (ETR), and photochemical quenching coefficient (qP). Furthermore, both chlorophyll and ΦPSII were positively correlated with Pn. In summary, the main reason for the abated Pn under stem canker pathogen was that B. dothidea not merely inhibited the stomatal opening, but hindered the conversion of light energy, electron transfer and light energy utilization of poplar leaves. In general, the lessened CO2 and Pn would reduce the synthesis of photosynthetic products. Whereas, sucrose and starch accumulated in poplar leaves, which may be due to the local damage caused by B. dothidea inoculation in phloem, hindering downward transport of these products.

Within-crown plasticity of hydraulic properties influence branch dieback patterns of two woody plants under experimental drought conditions

In recent year, widespread declines of Populus bolleana Lauche trees (P. bolleana, which dieback from the top down) and Haloxylon ammodendron shrubs (H. ammodendron, which dieback starting from their outer canopy) have occurred. To investigate how both intra-canopy hydraulic changes and plasticity in hydraulic properties create differences in vulnerability between these two species, we conducted a drought simulation field experiment. We analyzed branch hydraulic vulnerability, leaf water potential (Ψ), photosynthesis (A), stomatal conductance (gs), non-structural carbohydrate (NSCs) contents and morphological traits of the plants as the plants underwent a partial canopy dieback. Our results showed that: (1) the hydraulic architecture was very different between the two life forms; (2) H. ammodendron exhibited a drought tolerance response with weak stomatal control, and thus a sharp decline in Ψ while P. bolleana showed a drought avoidance response with tighter stomatal control that maintained a relatively stable Ψ; (3) the Ψ of H. ammodendron showed relative consistent symptoms of drought stress with increasing plant stature, but the Ψ of P. bolleana showed greater drought stress in higher portions of the crown; (4) prolonged drought caused P. bolleana to consume and H. ammodendron to accumulate NSCs in the branches of their upper canopy. Thus, the prolonged drought caused the shoots of the upper canopy of P. bolleana to experience greater vulnerability leading to dieback of the upper branches first, while all the twigs of the outer canopy of H. ammodendron experienced nearly identical degrees of vulnerability, and thus dieback occurred uniformly. Our results indicate that intra-canopy hydraulic change and their plasticity under drought was the main cause of the observed canopy dieback patterns in both species. However, more work is needed to further establish that hydraulic limitation as a function of plant stature was the sole mechanism for causing the divergent canopy dieback patterns.

Применение современных биостимуляторов и регуляторов роста для питомниководства в условиях деградации и опустынивания

The results of testing the preparations «Biostim Start», «Kornevin», «Agrovit Core» on experimental samples of tree species growing in various districts of the Volgograd region for the period 2019–2021 are presented. The method of grafting into the cleft, simple and for the bark on the сaragana variety of the selection of the Federal Research Centre of Agroecology of the Russian Academy of Sciences has been tested. The objects of research were 10 species from the genera Populus, Gleditsia, Caragána, Tamarix, Robinia, Ulmus. It was found that the soil germination of gledichia vulgaris was the best in the variant with the introduction of the super fertilizer «Agrovit Core» at a dose of 5...90 g/m2. The best result was noted in the experiment with the use of the drug «Biostim Start» with different doses of application in poplar and Tamarix species, which showed a record increase in arid conditions (from 80 to 100 cm), which was 2 times higher than in control samples. It was determined that during cuttings, an increased dose of introduction of growth regulators and biostimulators can reduce the percentage of preservation and development of green cuttings of woody species. The best result is given (up to 70% survival rate of rootstocks of experimental plants), in particular, autumn grafting for bark — the best autumn preservation and gains with a rootstock thickness of 0,3...0,8 cm. For further breeding work and experiments on the breeding of new varieties, the best species were selected — Caragana arborescens Lam., Populus nigra L., Populus bolleana Lauche., Tamarix L., Gleditsia triacanthos f. Inermis L. They have shown the best results in the conditions of the sharply continental climate of the arid region and are suitable for agroforestry development of the territory of the Lower Volga region.

Variation of Chromosome Composition in a Full-Sib Population Derived From 2x × 3x Interploidy Cross of Populus.

Interploidy cross commonly results in complex chromosome number and structural variations. In our previous study, a progeny with segregated ploidy levels was produced by an interploidy cross between diploid female parent Populus tomentosa × Populus bolleana clone TB03 and triploid male parent Populus alba × Populus berolinensis ‘Yinzhong’. However, the chromosome compositions of aneuploid genotypes in the progeny were still unclear. In the present study, a microsatellite DNA allele counting–peak ratios (MAC-PR) method was employed to analyze allelic configurations of each genotype to clarify their chromosome compositions, while 45S rDNA fluorescence in situ hybridization (FISH) analysis was used to reveal the mechanism of chromosome number variation. Based on the MAC-PR analysis of 47 polymorphic simple sequence repeat (SSR) markers distributed across all 19 chromosomes of Populus, both chromosomal number and structural variations were detected for the progeny. In the progeny, 26 hypo-triploids, 1 hyper-triploid, 16 hypo-tetraploids, 10 tetraploids, and 5 hyper-tetraploids were found. A total of 13 putative structural variation events (duplications and/or deletions) were detected in 12 genotypes, involved in chromosomes 3, 6, 7, 14, 15, 16, and 18. The 46.2% (six events) structural variation events occurred on chromosome 6, suggesting that there probably is a chromosome breakpoint near the SSR loci of chromosome 6. Based on calculation of the allelic information, the transmission of paternal heterozygosity in the hypo-triploids, hyper-triploid, hypo-tetraploids, tetraploids, and hyper-tetraploids were 0.748, 0.887, 0.830, 0.833, and 0.836, respectively, indicating that the viable pollen gains of the male parent ‘Yinzhong’ were able to transmit high heterozygosity to progeny. Furthermore, 45S rDNA–FISH analysis showed that specific-chromosome segregation feature during meiosis and chromosome appointment in normal and fused daughter nuclei of telophase II of ‘Yinzhong,’ which explained that the formation of aneuploids and tetraploids in the progeny could be attributed to imbalanced meiotic chromosomal segregation and division restitution of ‘Yinzhong,’ The data of chromosomal composition and structural variation of each aneuploid in the full-sib progeny of TB03 × ‘Yinzhong’ lays a foundation for analyzing mechanisms of trait variation relying on chromosome or gene dosages in Populus.

Overexpression of Ginkgo BBX25 enhances salt tolerance in Transgenic Populus

B-box (BBX) genes play important roles in plant growth, light morphogenesis, and environmental stress responses. Ginkgo (Ginkgo biloba L.) is known as a living fossil species that has a strong ability to adapt to environmental changes and tolerate harsh conditions. In this study, we chose this species to investigate the function of the GbBBX25 gene. We isolated the BBX gene from ginkgo and named it GbBBX25; this gene consists of an 819 bp open reading frame (ORF) that encodes 273 amino acids with two B-box domains but no CCT domain. GbBBX25 was localized in only the nucleus. The expression of GbBBX25 transcripts was observed in the leaves and was significantly enhanced under salt stress conditions. To further verify its function, we overexpressed the GbBBX25 gene in Populus davidiana × Populus bolleana and found that the transgenic Populus had greater soluble sugar levels and higher peroxidase (POD) activity in response to salt stress than nontransgenic (NT) Populus. Five genes related to salt stress were induced in transgenic plants with significantly higher expression levels than those in NT plants. This finding suggests that GbBBX25 improves the salt adaptation abilities of transgenic Populus and provides a scientific basis for related research.

Overexpression of antisense phosphatase 2C affords cold resistance in hybrid Populus davidiana × Populus bolleana.

Overexpression of the abiotic and biotic stress-resistance genes of the plant signaling pathway is well known for its significant role in the regulation of plant growth and enhancement of the productivity of agricultural land under changing climatic conditions. This research aimed to clone Populus davidiana × Populus bolleana PP2C (PdPP2C) gene and analyze its structure and function, and downregulate PdPP2C by overexpression of its antisense PdPP2C (AS-PdPP2C) gene for enhancing cold resistance in transgenic lines of hybrid P. davidiana × P. bolleana. PdPP2C was cloned and transformed to identify its function, and its antisense was overexpressed via downregulation to increase the cold resistance in transgenic lines of hybrid P. davidiana × P. bolleana. Antisense inhibition of protein phosphatase 2C accelerates the cold acclimation of Poplar (P. davidiana × P. bolleana) gene in terms of antifreeze. PdPP2C was expressed in the roots, stems, and leaves of P. davidiana × P. bolleana, and the expression was higher in the leaves. The expression of PdPP2C was also significantly downregulated at low-temperature (0°C and 4°C) stress. The relative conductivity and malondialdehyde content of non-transgenic lines were higher than those of AS-PdPP2C lines after 2days of cold treatment at - 1°C. The leaves of the transgenic lines were not wilted and showed no chlorosis compared with those of the non-transgenic lines. The AS-PdPP2C transgenic lines also showed higher freezing resistance than the non-transgenic lines. AS-PdPP2C participated in the regulation of freezing resistance.

Acclimation to nitrogen × salt stress in Populus bolleana mediated by potassium/sodium balance

Nitrogen plays an important role in plant tolerance to salt stress, but it remains largely unknown how the young and old leaves in woody plants differently respond to salinity under different nitrogen supplies. In this study, the young saplings of Populus bolleana Lauche were exposed to moderate salt condition and different nitrogen levels, and the young and old leaves were separately analysed to compare their responses in ion balance, carbon/nitrogen balance, and redox balance. NaCl stress alone profoundly affected the old leaves but only exerted mild effects on young leaves, showing in the former lower K+/Na+ ratio, ion imbalance, lipid peroxidation, chlorophyll degradation, and reduction of carbon and nitrogen concentration. There is an important strategy for the effective distribution of nutrition (K+ and NO3−) to young leaves when P. bolleana suffer salt stress, displayed by the differential regulation of K+ / Na+ and NO3- transporters across leaf ages. When salt stress was accompanied by nitrogen deficiency, the young leaves displayed similar damaged effects with old leaves, with a comparable K+/Na+ ratio in all the damaged leaves. Conversely, high nitrogen supply modestly alleviated salt toxicity in both leaf type, accompanying with modest change of K+/Na+ concentrations. The present study demonstrated that K+/Na+ ratio plays a vital role against salt stress across nitrogen levels in both young and old leaves, and ion imbalance in young leaves can serve as an indicator related to the survival of plants under salt stress. Nitrogen deficiency significantly endanger the survival of salt-stressed poplar for its protection strategy on the young leaves has been lost in this condition.

Transcriptomic Analysis of Seasonal Gene Expression and Regulation during Xylem Development in “Shanxin” Hybrid Poplar (Populus davidiana × Populus bolleana)

Xylem development is a key process for wood formation in woody plants. To study the molecular regulatory mechanisms related to xylem development in hybrid poplar P. davidiana × P. bolleana, transcriptome analyses were conducted on developing xylem at six different growth stages within a single growing season. Xylem development and differentially expressed genes in the six time points were selected for a regulatory analysis. Xylem development was observed in stem sections at different growth stages, which showed that xylem development extended from the middle of April to early August and included cell expansion and secondary cell wall biosynthesis. An RNA-seq analysis of six samples with three replicates was performed. After transcriptome assembly and annotation, the differentially expressed genes (DEGs) were identified, and a Gene Ontology (GO) enrichment analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and expression analysis of the DEGs were performed on each sample. On average, we obtained >20 million clean reads per sample, which were assembled into 84,733 nonredundant transcripts, of which there were 17,603 unigenes with lengths >1 kb. There were 14,890 genes that were differentially expressed among the six stages. The upregulated DEGs were enriched in GO terms related to cell wall biosynthesis between S1 vs. S2 or S3 vs. S4 and, in GO terms, related to phytohormones in the S1 vs. S2 or S4 vs. S5 comparisons. The downregulated DEGs were enriched in GO terms related to cell wall biosynthesis between S4 vs. S5 or S5 vs. S6 and, in GO terms, related to hormones between S1 vs. S2 or S2 vs. S3. The KEGG pathways in the DEGs related to “phenylpropanoid biosynthesis”, “plant hormone signal transduction” and “starch and sucrose metabolism” were significantly enriched among the different stages. The DEGs related to cell expansion, polysaccharide metabolism and synthesis, lignin synthesis, transcription factors and hormones were identified. The identification of genes involved in the regulation of xylem development will increase our understanding of the molecular regulation of wood formation in trees and, also, offers potential targets for genetic manipulation to improve the properties of wood.

Аналіз життєвості вуличних насаджень після омолоджувальної обрізки (на прикладі м. Дніпро)

The influence of pruning of the crown on the state of five tree species has been studied (Robinia pseudoacacia L., Ulmus pumila L., Gleditsia triacanthos L., Acer pseudoplatanus L. and Populus bolleana Lauch.). The trees were pruning at a height of 8 meters, leaving only the trunk and lower branches. Control plants were not pruned. All plants are growing on the boulevard near the highway with high traffic. It was found that among the rejuvenated trees there are more both healthy plants and severely damaged ones. Dead plants appeared among species such as G. triacanthos, A. pseudoplatanus, and R. pseudoacacia also. The best vital state was found in P. bolleana and U. pumila. Plants after crowning have more water content in leaves. U. pumila and G. triacanthos have the greatest difference in water content between the two variants. The intensity of transpiration in pruning plants P. bolleana and G. triacanthos is 2 times higher, and in U. pumila – by 20 %. In A. pseudoplatanus and R. pseudoacacia, there is no difference in this indicator between the variants. Pruned plants have a lower water-holding capacity by an average of 30 % compared to control (except for P. bolleana, in which the difference between the variants is insignificant). The content of green pigments is higher than in the control samples in the leaves of the rejuvenated plants. The exception is R. pseudoacacia, which has a reverse reaction. Thus, the intensification of the processes of water exchange and the pigment system does not occur in all species to the same extent. It is most pronounced in U. pumila and G. triacanthos. The activity of photosynthesis and water exchange in both variants differs insignificantly at P. bolleana. R. pseudoacacia have deterioration in all parameters. This probably explains the poor condition of pruned trees of this species.

Modeling water consumption of Populus bolleana by artificial neural network based on fuzzy rules

To explore the water consumption characteristics of trees, the thermal dissipation probe technology was used to monitor sap flow of Populus bolleana in east sandy land of Yellow River, from July to November in 2017. Microclimate variables were monitored. We analyzed the diurnal and seasonal variations of water consumption, and proposed the models for water consumption with back propagation neural network (BPNN) and Elman neural network (ENN) based on fuzzy rules. Results showed that the average sap flow rate of P. bolleana was 4.98 g·cm-2·h-1 in growing season (July to October), with solar radiation (Rs), temperature (T), vapor pressure deficit (VPD) and relative humidity (RH) as the main factors affecting sap flow. Due to the influence of meteorological factors, water consumption was characterized by obvious seasonal variation, with that in summer (July-August) being 1.4 times of that in autumn (September-October). BPNN and ENN models based on fuzzy rules were used to simulate water consumption of P. euphratica. The optimal parameter calibration of two models explained more than 80% of the total variation, which indicated that these two models could more accurately simulate water consumption. Compared with the BP neural network model, the simulated results of ENN model showed that the relative error was reduced by 27.0%, RMSE was reduced by 24.3%, Nash-Sutclife efficiency coefficient increased by 67.9%, R2 was higher than 0.80. The ENN model performed better than BPNN model with a higher efficiency and goodness of fitness. ENN model effectively improved the simulating accuracy of water consumption. Therefore, it could be used as an optimal model to estimate water consumption of P. bolleana in east sandy land of Yellow River.

The Development of Populus alba L. and Populus tremula L. Species Specific Molecular Markers Based on 5S rDNA Non-Transcribed Spacer Polymorphism

The Populus L. genus includes tree species that are botanically grouped into several sections. This species successfully hybridizes both in the same section and among other sections. Poplar hybridization widely occurs in nature and in variety breeding. Therefore, the development of poplar species’ specific molecular markers is very important. The effective markers for trees of the Aigeiros Duby section have recently been developed using the polymorphism of 5S rDNA non-transcribed spacers (NTSs). In this article, 5S rDNA NTS-based markers were designed for several species of the Leuce Duby section. The alb9 marker amplifies one fragment with the DNA matrix of P. alba and P. × canescens (natural hybrid P. alba × P. tremula). The alb2 marker works the same way, except for the case with Populus bolleana. In this case, the amplification of three fragments was observed. The tremu1 marker amplification was detected with the DNA matrix of P. tremula and P. × canescens. Thus, the developed markers may be applied as a useful tool for P. alba, P. tremula, P. × canescens, and P. bolleana identification in various areas of plant science such as botany, dendrology, genetics of populations, variety breeding, etc.

ANTIMICROBIAL PROPERTIES OF BIOGENIC VOLATILE ORGANIC COMPOUNDS FROM TREE PLANTS

The article analyzes and summarizes scientific sources about the antimicrobial properties of phytoncides of common tree plants, the possibilities of rational use of them for preservation and improvement of human health and optimization of the microbial composition of the air environment. It has been discovered that the study of biogenic volatile organic compounds of plant origin has attracted the attention of many scholars of the last decades for the purpose of their wide use in various spheres of the national economy, particularly in medicine.It is noted that in the process of life higher plants release volatile organic substances that are one of the factors of natural immunity of plants, regulators of the sanitary state of the biosphere, play a significant role in the interaction of organisms in urbanized phytocoenoses, maintaining the balance of pathogenic microflora in atmospheric air of an urbanized ecosystem and residential apartments. Phytoncides are a mean of prevention and therapy a number of diseases, because when they enter the human body, they actively influence on different groups of microorganisms (Staphylococcus aureus, Bacillus subtilis, Esсherichia coli, Corynebacterium diphtheriae, Bordetella pertussis, Paramaecium caudatum, Stillonima millibus, etc.), which are the causative agents of bacterial, viral, fungal or protozoal infections.Many scientists have proven that volatile organic compounds of plant origin varies by their chemical composition and power of action, while the degree of their antimicrobial activity depends not only on the species belonging of plants and the phenological phase of seasonal development, but also on the vital state of the plant organism, meteorological conditions.Analysis of literary sources showed that all species of coniferous plants (in particular, genera Abies, Pínus, Picea, etc.) are characterized by high bactericidality of primary and secondary phytoncides, and among the deciduous ones it is necessary to note the following species: Betula pendula Roth, Padus avium Mill., Morus alba L., Acer platanoides L., A. pseudoplatanus L., Syringa vulgaris L., Ulmus pumila L., Vaccіnium vіtis-idaеa e L., tc. Such species, as Populus bolleana Lauche, Salix alba L., Quercus robur L., Sorbus aucuparia L., Spiraea×vanhouttei (Briot) Carrière, Viburnum opulus L., Aesculus hippocastanum L., Fraxinus excelsior L., Tillia cordata Mill., which possess both secondary and primary volatile secretions, are characterized by medium antimicrobial action.

Overexpression of PeHKT1;1 Improves Salt Tolerance in Populus.

Soil salinization is an increasingly serious threat that limits plant growth and development. Class I transporters of the high-affinity K+ transporter (HKT) family have been demonstrated to be involved in salt tolerance by contributing to Na+ exclusion from roots and shoots. Here, we isolated the PeHKT1;1 gene from hybrid poplar based on the sequences of the Populus trichocarpa genome. The full-length PeHKT1;1 gene was 2173 bp, including a 1608 bp open reading frame (ORF) encoding 535 amino acids and containing eight distinct transmembrane domains. Multiple sequence alignment and phylogenetic analysis suggested that the PeHKT1;1 protein had a typical S–G–G–G signature for the P-loop domains and belonged to class I of HKT transporters. PeHKT1;1 transcripts were mainly detected in stem and root, and were remarkably induced by salt stress treatment. In further characterization of its functions, overexpression of PeHKT1;1 in Populus davidiana × Populus bolleana resulted in a better relative growth rate in phenotypic analysis, including root and plant height, and exhibited higher catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) activities than non-transgenic poplar under salt stress conditions. These observations indicated that PeHKT1;1 may enhance salt tolerance by improving the efficiency of antioxidant systems. Together, these data suggest that PeHKT1;1 plays an important role in response to salt stress in Populus.