Populus Euphratica Research Articles

New potential transporter CIPAS8 enhances cadmium hypersensitivity and cobalt tolerance.

CIPAS8 is a novel Cd-influx and Co-efflux transporters, and Ser86 and Cys128 might play a decisive role in Co-binding and translocation. Cadmium (Cd) is among the most toxic heavy metals and is a widespread environmental pollutant. Cobalt (Co) is a mineral nutrient that is essential for plant growth and development, but high concentrations may be toxic. Cadmium-induced protein AS8 (CIPAS8) is widely distributed among plant species and might be induced by heavy metals, but its function has not been studied previously. In this study, Populus euphratica PeCIPAS8 and Salix linearistipularis SlCIPAS8 were investigated. The transcription of both genes was significantly enhanced under Cd and Co stresses. PeCIPAS8 and SlCIPAS8 conferred sensitivity to Cd in transgenic yeast, allowing higher quantities of Cd to accumulate within the cells, whereas SlCIPAS8 also conferred tolerance to Co and reduced Co accumulation. The determinants of substrate selectivity of the SlCIPAS8 protein were examined by site mutagenesis, which indicated that the Ser at 86th (S86) substituted for Arg (R) [S86R] and Cys at 128th (C128) substituted for Ser [C128S] mutations limited the protein's capability for Co translocation. These results suggested that PeCIPAS8 and SlCIPAS8 may be involved in Cd uptake into the plant cell. SlCIPAS8 can reduce excess Co accumulation to maintain intracellular Co homeostasis, and the site mutations S86R and C128S were essential for Co transport. These findings provide insight into the function of CIPAS8 and highlight its potential for utilization in phytoremediation applications.

Populus euphratica GLABRA3 Binds PLDδ Promoters to Enhance Salt Tolerance

High NaCl (200 mM) increases the transcription of phospholipase Dδ (PLDδ) in roots and leaves of the salt-resistant woody species Populus euphratica. We isolated a 1138 bp promoter fragment upstream of the translation initiation codon of PePLDδ. A promoter-reporter construct, PePLDδ-pro::GUS, was introduced into Arabidopsis plants (Arabidopsis thaliana) to demonstrate the NaCl-induced PePLDδ promoter activity in root and leaf tissues. Mass spectrometry analysis of DNA pull-down-enriched proteins in P. euphratica revealed that PeGLABRA3, a basic helix-loop-helix transcription factor, was the target transcription factor for binding the promoter region of PePLDδ. The PeGLABRA3 binding to PePLDδ-pro was further verified by virus-induced gene silencing, luciferase reporter assay (LRA), yeast one-hybrid assay, and electrophoretic mobility shift assay (EMSA). In addition, the PeGLABRA3 gene was cloned and overexpressed in Arabidopsis to determine the function of PeGLABRA3 in salt tolerance. PeGLABRA3-overexpressed Arabidopsis lines (OE1 and OE2) had a greater capacity to scavenge reactive oxygen species (ROS) and to extrude Na+ under salinity stress. Furthermore, the EMSA and LRA results confirmed that PeGLABRA3 interacted with the promoter of AtPLDδ in transgenic plants. The upregulated AtPLDδ in PeGLABRA3-transgenic lines resulted in an increase in phosphatidic acid species under no-salt and saline conditions. We conclude that PeGLABRA3 activated AtPLDδ transcription under salt stress by binding to the AtPLDδ promoter region, conferring Na+ and ROS homeostasis control via signaling pathways mediated by PLDδ and phosphatidic acid.

Identification of Fungal Species Associated with Apple Canker in Tarim Basin, China.

Apple canker has decreased yields of the economically important apple (Malus domestica) crop in China in recent years. Pathogen identity is highly challenging and the disease is poorly understood. Specimens of 339 fungi were isolated from apple trees in the primary apple-producing region in the Tarim Basin during the current study. In total, nine species of Cytospora and five species of the family Botryosphaeriaceae were identified by morphological observation and multilocus phylogenetic analyses: internal transcribed spacer (ITS), actin, translation elongation factor (TEF), and β-tubulin (TUB) gene regions for Cytospora and ITS, TEF, and TUB for Botryosphaeriaceae. Cytospora pyri from the Cytospora genus was the dominant species causing apple canker in the Tarim Basin. C. melnikii, C. tritici, C. euonymina, Diplodia seriata, and Botryosphaeria dothidea have been described as the cause of apple canker in China. Apple (Red Fuji) branches were utilized to assess the pathogenicity of 24 representative fungal isolates from the 14 species, and branches from seven distinct woody plants (Korla pear, walnut, Chinese date, Xinjiang poplar, sand jujube, Populus euphratica, and willow) were utilized to analyze the host range. The main pathogenic fungal species of apple canker around the Tarim Basin were identified and biological characteristics explored. Pathogen diversity and regional source diversity were assessed with host range and pathogenicity. The aim was to provide a theoretical foundation for the prevention and treatment of apple canker.

Xylem formation of Populus euphratica and its response to water-heat factors in the lower reaches of Tarim River, China.

To deeply understand the effects of water and temperature factors on the xylem formation of Populus euphratica, taking the Yingsu section in the lower reaches of Tarim River as an example, we selected micro-coring samples of P. euphratica around monitoring wells F2 and F10 in the 100 and 1500 m distance from the channel of Tarim River. We used wood anatomy method to analyze the xylem anatomy of P. euphratica and its response to water and temperature factors. The results showed that the changes of the total anatomical vessel area and the vessel number of P. euphratica in the two plots were basically consistent during the whole growing season. The vessel number of xylem conduits of P. euphratica increased slowly with the increases of groundwater depth, while the total conduit area increased firstly and then decreased. The total vessel area, minimum vessel area, average vessel area, and maximum vessel area of P. euphratica xylem increased significantly with the increases of temperature in the growing season. The contribution of groundwater depth and air temperature to P. euphratica xylem varied among different growth stages. In the early growing season, air temperature had the largest contribution to the number and total area of xylem conduits of P. euphratica. During the middle growing season, air temperature and groundwater depth jointly affected the parameters of each conduit. During the later growing season, groundwater depth had the largest contribution to the number and total area of conduits. Results of the sensitivity analysis indicated that the groundwater depth sensitive to xylem vessel number change of P. euphratica was 5.2 m and that to the change in the total conduit area was 5.9 m. The temperature sensitive to total vessel area of P. euphratica xylem was 22.0 ℃, and that to average vessel area was 18.5 ℃. Therefore, the sensitive groundwater depth affecting xylem growth was at the range of 5.2-5.9 m, and the sensitive temperature was at the range of 18.5-22 ℃. This study could provide scientific basis for the restoration and protection of P. euphratica forest in the lower reaches of Tarim River.

Coordination in functional traits of Populus euphratica leaves under salt stress

Leaf functional traits allow plant survival and maintain their ecosystem function. Salinity affects leaf functional traits, but coordination among leaf functional traits is poorly known and may depend on salt severity. To increase our understanding of the coordination of leaf functional traits under salt stress, we determined hydraulic, gas exchange, and physiological and biochemical parameters in Populus euphratica Oliv. (P. euphratica) grown under salinity treatments, as well as gas exchange parameters under different CO2 concentrations. We found that P. euphratica can reinforce its hydraulic capacity by increasing the water transfer efficiency of both its leaves and stems when a salinity threat occurs for a specific duration of stress. Its stems were more adaptable than leaves. The economic and hydraulic traits of P. euphratica leaves were consistent during the middle stages of salt stress, but inconsistent during the onset and late stages of salt stress. There was almost no biochemical limitation under severe salinity conditions, and CO2 enrichment of P. euphratica had a greater effect on leaf economic traits. The mechanism of toxic ion exclusion based on water availability and intracellular mechanisms in leaves contributed to salt tolerance when P. euphratica was exposed to salinity stress. There was also a coordination mechanism for the plants during increasing salt stress. The leaf intracellular traits of P. euphratica can coordinate with the leaf economic and hydraulic traits and form a defense mechanism to reduce salt damage and guarantee growth under saline conditions. In conclusion, P. euphratica, the main constructional species of riparian forests, adapts to saline environments by adjustment and coordination of leaf functional traits, ensuring survival. These results provide a scientific basis for riparian forest restoration.

Differences in ecophysiological responses of Populus euphratica females and males exposed to salinity and alkali stress

Soil salinity is usually accompanied by alkalization in northwest China, and they both negatively impact plant growth and result in severe ecological problems. Some studies have reported tree responses to salinity or alkali stress alone, however, the interactive salinity and alkali effects are still unclear, especially in dioecious trees. In this study, we measured growth, morphology, leaf stomata, gas exchange, carbon isotope composition (δ13C), total soluble sugar and starch contents, Na+ accumulation and allocation, oxidative stress, and antioxidants of female and male Populus euphratica seedlings in response to salinity, alkali and their interaction. Our study showed no significant sexual differences in studied traits under control conditions. In addition, P. euphratica females showed greater inhibitory and negative effects, such as bigger decreases in growth and gas exchange, lower stomatal density and water use efficiency (as described by δ13C), and lower levels of soluble sugars and antioxidant enzyme activities compared with males under salinity, alkali and interactive stress conditions. Furthermore, P. euphratica males had a greater ability of ion exclusion and Na + transport restriction. For example, males allocated more Na+ to stems and roots than females, whereas females had higher Na+ contents in leaves under stress conditions. In conclusion, our results indicated that P. euphratica males have superior resistance and they perform better than females under salinity, alkali and their interactive stress conditions.

The genetic architecture of trait covariation in Populus euphratica, a desert tree.

The cooperative strategy of phenotypic traits during the growth of plants reflects how plants allocate photosynthesis products, which is the most favorable decision for them to optimize growth, survival, and reproduction response to changing environment. Up to now, we still know little about why plants make such decision from the perspective of biological genetic mechanisms. In this study, we construct an analytical mapping framework to explore the genetic mechanism regulating the interaction of two complex traits. The framework describes the dynamic growth of two traits and their interaction as Differential Interaction Regulatory Equations (DIRE), then DIRE is embedded into QTL mapping model to identify the key quantitative trait loci (QTLs) that regulate this interaction and clarify the genetic effect, genetic contribution and genetic network structure of these key QTLs. Computer simulation experiment proves the reliability and practicability of our framework. In order to verify that our framework is universal and flexible, we applied it to two sets of data from Populus euphratica, namely, aboveground stem length - underground taproot length, underground root number - underground root length, which represent relationships of phenotypic traits in two spatial dimensions of plant architecture. The analytical result shows that our model is well applicable to datasets of two dimensions. Our model helps to better illustrate the cooperation-competition patterns between phenotypic traits, and understand the decisions that plants make in a specific environment that are most conducive to their growth from the genetic perspective.

LncRNA expression analysis by comparative transcriptomics among closely related poplars and their regulatory roles in response to salt stress.

Long noncoding RNAs (lncRNAs) play crucial roles in regulating key biological processes; however, our knowledge of lncRNAs' roles in plant adaptive evolution is still limited. Here, we determined the divergence of conserved lncRNAs in closely related poplar species that were either tolerant or sensitive to salt stress by comparative transcriptome analysis. Among the 34,363 identified lncRNAs, approximately 3% were shared among poplar species with conserved sequences but diversified in their function, copy number, originating genomic region and expression patterns. Further cluster analysis revealed that the conserved lncRNAs showed more similar expression patterns within salt-tolerant poplars (P. euphratica and P. pruinosa) than between salt-tolerant and salt-sensitive poplars. Among these lncRNAs, the antisense lncRNA lncERF024 was induced by salt and differentiated expression between salt-sensitive and salt-tolerant poplars. Overexpression of lncERF024 in P. alba var. pyramidalis enhanced poplar tolerance to salt stress. Furthermore, RNA pull-down and RNA-seq analysis showed that numerous candidate genes or proteins associated with stress response and photosynthesis might be involved in salt resistance in PeulncERF024-OE poplars. Altogether, our study provided novel insight into how the diversification of lncRNA expression contributes to plant adaptation traits and showed that lncERF024 may be involved in the regulation both of gene expression and protein function conferring salt tolerance in Populus.

Phenotypic Diversity and Variation in Natural Populus euphratica Populations Shaped by Environmental Factors

Phenotypic Diversity and Variation in Natural Populus euphratica Populations Shaped by Environmental Factors

CiteSpace Software Visualization Analyses of the Last Thirty Years of Research on Populus euphratica

Populus euphratica is the only tall tree species that adapts to the desert environment. It has strong drought tolerance and is the subject of extreme concern at home and abroad. After 30 years of development, the scope of research on Populus euphratica is very extensive, but the research content has not yet been crystalized into a mature field, and research directions at home and abroad differ. In this study, we retrieved research references on ‘P. euphratica’ published from 1992 to 2022 in both the China National Knowledge Infrastructure core journals database and the Web of Science core collection database, and CiteSpace software was employed to conduct keyword-centered bibliometric analysis in both the spatial and temporal dimensions. The purpose of this study is to clarify the research areas, developmental changes, differences between domestic and international research priorities in the last 30 years, and future trends in the field of P. euphratica research. The results show that there were 1619 domestic papers published in China related to the field of P. euphratica research, while there were only 656 foreign papers in the same field. The development of domestic P. euphratica research went through three stages initiation (1992–2000), growth (2001–2008) and stability (2009–2021), whereas no significant international trend change was observed. The domestic disciplines focus on biology, while international research focuses on crop science. In terms of content, domestic research focuses on sustainable uses of P. euphratica forests and their response to drought, intending to improve P. euphratica ecosystems. International research, on the other hand, focuses on revealing mechanisms of environmental stresses, including genetic and physiological–morphological characteristics, to exploit the excellent characteristics of P. euphratica to serve agriculture and other fields. The development process of P. euphratica research in the past 30 years has generally evolved from an initial focus on its natural conditions towards the study of the relationship between environmental factors and P. euphratica physiological and morphological characteristics and, finally, the study of stress tolerance mechanisms and gene expression of P. euphratica. There is a trend towards ‘applications of P. euphratica tolerance genes’, which may represent a direction for future growth research.

A 195-Year Growing Season Relative Humidity Reconstruction Using Tree-Ring Cellulose δ13C in the Upper Tarim River Basin, NW China

Reconstruction of relative humidity changes in the upper Tarim River using carbon isotopic tree-ring chronology bridges the gap in historical observations on the Tarim River Basin in Arid Central Asia. Populus euphratica Olivier (P. euphratica), growing in the Tarim River Basin of Xinjiang, is an excellent record of past climate change. Based on precise dating, we analysed alpha-cellulose stable carbon isotopes in four cores of P. euphratica taken from the Alaer region of the upper Tarim River Basin. The four stable carbon isotope series records were corrected by the “pin method” and then combined into a carbon isotopic discrimination (Δ13C) series by the “numerical mix method”. The discrimination (Δ13C) series were clearly correlated with the mean relative humidity (RHAS) in April–September of the growing season (n = 60, r = −0.78, p < 0.001), and according to the climate response analysis, we designed a simple regression equation to reconstruct the mean relative humidity (RHAS) in April–September from 1824 to 2018 on the Alaer region. The reconstructed sequence showed mainly dry periods in the last 195 years, 1857–1866 and 1899–1907, while primarily wet periods from 1985 to 2016. Due to increased global warming and human activities, the climate shifted from “warm–dry” to “warm–wet” in the mid-to-late 1980s, when there were signs of a shift from “warm–wet” to “warm–dry” in the 2010s, with an increasing trend towards aridity. The RHAS series of Alaer compares well to other hydroclimate series’ surrounding the research area, and the spatial correlation analysis indicates that the reconstructed series has good regional representativeness. On an interdecadal scale, the revamped RHAS series is positively correlated with the Atlantic Multidecadal Oscillation (AMO) and negatively correlated with the North Atlantic Oscillation (NAO), reflecting the influence of westerly circulation on regional wet and dry variability. At the same time, the RHAS may also be influenced by The Pacific Decadal Oscillation (PDO).

Effects of Leaf Hydrophilicity and Stomatal Regulation on Foliar Water Uptake Capacity of Desert Plants

Foliar water uptake (FWU) is one of the primary water sources for desert plants. Desert plants’ water uptake capacity is essential in maintaining the balance of carbon and water. However, there are few studies on FWU capacity in desert plants and the physiological and ecological characteristics that lead to differences in FWU capacity. In order to clarify FWU strategies and the influencing factors of plants in desert ecosystems, this study measured the contact angle, FWU parameters, and hydraulic parameters to explore six desert plants’ FWU capacity and the effects of leaf wettability and hydraulic parameters on FWU capacity. The results showed that all six plants had FWU capacity, among which the leaves of Nitraria sibirica Pall. and Halimodendron halodendron (Pall.) Voss had a high foliar water uptake rate (k) and high foliar water uptake accumulation (FWU storage), and the leaves of Glycyrrhiza uralensis Fisch. had a high k and low FWU storage. The leaves of Populus euphratica Oliv., Apocynum hendersonii Hook. f., and Alhagi sparsifolia Shap. had a low k and low FWU storage. Additionally, FWU capacity was mainly affected by stomatal regulation compared with leaf wettability and leaf structure. The results of this study will help to improve the understanding of the physiological and ecological adaptability of desert plants.

The reallocation of water and ecosystem service values in arid ecosystems with the implementation of an ecological water diversion project

The rational allocation of the water resources in drylands and the scientific evaluation of their values are important for the regional sustainable development. We estimated the water consumption of each ecosystem in Ejina Oases in the arid area in northwest China based on the water balance equation, then assessed their ecosystem service values (ESVs) using the value per unit area method and the value equivalent factor per unit area method considering the cost of water consumption, respectively, and calculated their water productivities from 1990 to 2015. With the implementation of the ecological water diversion project (EWDP) in 2000, the deciduous broadleaf forest dominated by Populus euphratica had an increasing trend, meanwhile, lakes had a changing process from shrinking and drying up to recovery and expansion from 1990 to 2015. The total water consumption in Ejina Oases decreased from 5.26*108 m3 in 1990 to 4.79*108 m3 in 2000, and then increased continually to 5.97*108 m3 in 2015. The water consumption of forest, grassland and cultivated land hardly changed, while the water consumption of water or wetland changed obviously. The total ESVs estimated using the value per unit area method in Ejina Oases decreased from 1052.6 to 787.3 million ¥ in the period of 1990–2000, then increased to 1500.6 million ¥ in 2015, while the ESVs estimated using the value equivalent factor per unit area method decreased from 6368.7 million ¥ in 1990 to 5892.0 million ¥ in 2000, then increased to 7139.9 million ¥ in 2015, and the latter method was more reasonable. The results showed that the EWDP started in 2000 led to the reallocation of water resources and transfer of ESVs among ecosystems, which had obvious performance in the ecological environment and social economy. This study provided a comprehensive view of water use and management, ecological restoration and socio-economic development in this key ecological function zone, and will help decision-makers to formulate the scheme of rational allocation and efficient utilization of water resources in the basin.

Introduction of trees plants in nurseries of Northern Kazakhstan from of the China

The manuscript presents the results of monitoring during the introduction near the capital of Kazakhstan of trees plants imported from China and planted in the nursery of the Akkol State Forestry Enterprise in the northern part of the Akmola region. Fraxinus Bungeana, Fraxinus Americana, Populus Euphratica were used as the object of study in the experiment. The adaptive characteristics of the selected plants were compared according to various bioecological indicators. Taxation and biometric indicators of these trees amounted to 60.1; 47.7; 22.3 percent. In samples of tree leaves of different sizes, the level of photosynthetic activity was determined. This indicator among the studied species was the lowest in Populus Euphratica (0.63 µg/g), average in Fraxinus Americana (0.76±0.01) and high in Fraxinus Bungeana (0.80 µg/g). The resistance of trees plants to the new environment was assessed by the amount of accumulation of heavy metals in their leaf blades. An increased concentration of copper and iron accumulated American ash, Bunge ash. The content of cadmium, lead, zinc did not exceed the MPC. In general, the monitoring showed that different types of trees introduced in the vicinity of the city of Nur-Sultan in the north of the Akmola region show different adaptive responses. It is shown that heavy metals accumulate more intensively in ash leaves. Populus Euphratica turned out to be the most resistant to this ecological environmental factor, and Fraxinus Bungeana is the most sensitive among ash representatives. In general, the adaptation of trees introduced from abroad in the region of northern Kazakhstan, near the city of Nur-Sultan, is carried out in accordance with their biological characteristics. It has been observed that Populus Euphratica is more resistant and Fraxinus Bungeana is the most sensitive species when introduced. In general, based on our research, an algorithm for short-term monitoring of introduced trees has been developed to preserve the biodiversity of ornamental plants. Key words: China, tree plants, nurseries, Northern Kazakhstan, introduction, photosynthesis, heavy metals crops

Constructing a new irrigation model for desert riparian forests based on response of canopy EVI loss and tree rings growth to groundwater fluctuation

Vegetation in arid desert areas plays an extremely important role in maintaining biodiversity and inhibiting desertification. Quantitative understanding of vegetation response to groundwater is essential to priming drought prevention and mitigation, which is a topic that is attracting considerable attention. However, previous studies have rarely assessed the response of vegetation to groundwater from probabilistic or stoichiometric chemical perspective. To address this question, a highly sensitive copula joint distribution of the response of enhanced vegetation index (EVI) loss to groundwater was constructed and a stoichiometric chemistry indicator of the Nitrogen (N) and Phosphorus (P) concentrations in tree rings was innovatively put forward to verify its sensitivity to groundwater. The results obtained revealed that the correlation of EVI with groundwater was better than that with SPEI and TVDI; Furthermore, the critical groundwater thresholds of the EVI loss rate, described as “beginning”, “reaching the maximum”, and “the slowest” were 3.85 m, 6.18–6.75 m, and 7.89 m, respectively. At the inter-annual scale, by measuring the N and P contents of Populus euphratica tree rings, and constructing response model of element contents to groundwater/rainfall, the key thresholds were determined at 5.20–5.31 m and 60 mm, which challenges the traditional understanding that rainfall does not bring ecological benefits to desert riparian forests. To further promote vegetation restoration, based on the response rule of EVI loss and stoichiometric chemical elements of tree rings to groundwater and the intermediate overflow rotation irrigation method, a more advanced desert riparian forest irrigation mode, named “branch-infiltration-rotation-irrigation”, is here proposed.

Cloning and expression analysis of JrGI gene in walnut

GI (GIGANTEA) is one of the output key genes for circadian clock in the plant. The JrGI gene was cloned and its expression in different tissues was analyzed to facilitate the functional research of JrGI. RT-PCR (reverse transcription-polymerase chain reaction) was used to clone JrGI gene in present study. This gene was then analyzed by bioinformatics, subcellular localization and gene expression. The coding sequence (CDS) full length of JrGI gene was 3 516 bp, encoding 1 171 amino acids with a molecular mass of 128.60 kDa and a theoretical isoelectric point of 6.13. It was a hydrophilic protein. Phylogenetic analysis showed that JrGI of 'Xinxin 2' was highly homologous to GI of Populus euphratica. The result of subcellular localization showed that JrGI protein was located in nucleus. The JrGI, JrCO and JrFT genes in female flower buds undifferentiated and early differentiated of 'Xinxin 2' were analyzed by RT-qPCR (real-time quantitative PCR). The results showed that the expression of JrGI, JrCO and JrFT genes were the highest on morphological differentiation, implying the temporal and special regulation of JrGI in the differential process of female flower buds of'Xinxin 2'. In addition, RT-qPCR analysis showed that JrGI gene was expressed in all tissues examined, whereas the expression level in leaves was the highest. It is suggested that JrGI gene plays a key role in the development of walnut leaves.

Simulation of potential endangered species distribution in drylands with small sample size based on semi-supervised models

Identifying suitable habitats for endangered species is critical in order to promote their recovery. However, conventional species distribution models (SDMs) need large amounts of labeled sample data to learn the relationship between species and environmental conditions, and are difficult to fully detangle the role of the environment in the distribution of the endangered species, which are very sparsely distributed and have environmental heterogeneity. This study’s first innovation used the semi-supervised model to accurately simulate the suitable habitats for endangered species with a small sample size. The model performance was compared with three conventional SDMs, namely Maxent, the generalized linear model, and a support vector machine. Applying the model to the endangered species Populus euphratica (P. euphratica) in the lower Tarim River basin (TRB), Northwest China. The results showed that the semi-supervised model exhibited better performance than conventional SDMs with an accuracy of 85% when only using 443 P. euphratica samples. All models developed using smaller sample sizes exhibit worse performance in the prediction of habitat suitability areas for endangered species while the semi-supervised model is still excellent. The results showed that the suitable habitat for P. euphratica is mainly near the river channel of the lower TRB, accounting for 13.49% of the study area. The lower Tarim River still has enormous land potential for the restoration of endangered P. euphratica. The model developed here can be used to evaluate a suitable habitat for endangered species with only a small sample size, and provide a basis for the conservation of endangered species.

The effects of phenological change on Populus euphratica under the background of climate change

The effects of phenological change on Populus euphratica under the background of climate change

PeCLH2 Gene Positively Regulate Salt Tolerance in Transgenic Populus alba × Populus glandulosa.

Salt is an important environmental stress factor, which seriously affects the growth, development and distribution of plants. Chlorophyllase plays an important role in stress response. Nevertheless, little is known about the physiological and molecular mechanism of chlorophyll (Chlase, CLH) genes in plants. We cloned PeCLH2 from Populus euphratica and found that PeCLH2 was differentially expressed in different tissues, especially in the leaves of P. euphratica. To further study the role of PeCLH2 in salt tolerance, PeCLH2 overexpression and RNA interference transgenic lines were established in Populus alba × Populus glandulosa and used for salt stress treatment and physiologic indexes studies. Overexpressing lines significantly improved tolerance to salt treatment and reduced reactive oxygen species production. RNA interference lines showed the opposite. Transcriptome analysis was performed on leaves of control and transgenic lines under normal growth conditions and salt stress to predict genes regulated during salt stress. This provides a basis for elucidating the molecular regulation mechanism of PeCLH2 in response to salt stress and improving the tolerance of poplar under salt stress.

Multi-omics analysis reveals spatiotemporal regulation and function of heteromorphic leaves in Populus.

Despite the high economic and ecological importance of forests, our knowledge of the adaptive evolution of leaf traits remains very limited. Euphrates poplar (Populus euphratica), which has high tolerance to arid environment, has evolved four heteromorphic leaf forms, including narrow (linear and lanceolate) and broad (ovate and broad-ovate) leaves on different crowns. Here, we revealed the significant functional divergence of four P. euphratica heteromorphic leaves at physiological and cytological levels. Through global analysis of transcriptome and DNA methylation across tree and leaf developmental stages, we revealed that gene expression and DNA epigenetics differentially regulated key processes involving development and functional adaptation of heteromorphic leaves, such as hormone signaling pathways, cell division, and photosynthesis. Combined analysis of gene expression, methylation, ATAC-seq, and Hi-C-seq revealed longer interaction of 3D genome, hypomethylation, and open chromatin state upregulates IAA-related genes (such as PIN-FORMED1 and ANGUSTIFOLIA3) and promotes the occurrence of broad leaves while narrow leaves were associated with highly concentrated heterochromatin, hypermethylation, and upregulated abscisic acid pathway genes (such as Pyrabactin Resistance1-like10). Therefore, development of P. euphratica heteromorphic leaves along with functional divergence was regulated by differentially expressed genes, DNA methylation, chromatin accessibility, and 3D genome remodeling to adapt to the arid desert. This study advances our understanding of differential regulation on development and functional divergence of heteromorphic leaves in P. euphratica at the multi-omics level and provides a valuable resource for investigating the adaptive evolution of heteromorphic leaves in Populus.