In situ localization of alkaline phosphatase activity in tumor cells by an aggregation-induced emission fluorophore-based probes.

In situ detection of certain specific enzyme activities in cells is deeply attached to tumor diagnosis. Conventional enzyme-responsive fluorescent probes have difficulty detecting targeted enzymes in situ in cells due to the low detection accuracy caused by the spread of fluorescence probes. In order to solve this problem, we have designed and synthesized an enzyme-responsive, water-soluble fluorescent probe with AIE characteristics, which could aggregate and precipitate to produce in situ fluorescence when reacting with the targeted enzyme in cells. The AIE fluorophore (TPEQH) was utilized to design the enzyme-responsive, fluorescent probe (TPEQHA) by introducing a phosphate group on to it, which could be specifically decomposed by the targeted enzyme, namely alkaline phosphatase (ALP). In tumor cells, TPEQH was highly produced due to the interaction of phosphate on the TPEQHA and the overexpressed ALP. Water-insoluble TPEQH then precipitated and release fluorescence in situ, thereby successfully detecting the ALP. Furthermore, the expression level of ALP could be determined by the fluorescence intensity of TPEQH with higher accuracy due to the inhibition of TPEQH leak, which demonstrated a potential application of in suit ALP detection in both clinical diagnosis and scientific research of tumor.

Transgenic creeping bentgrass plants expressing a Picea wilsonii dehydrin gene (PicW) demonstrate improved freezing tolerance.

Agrostis stolonifera L. 'Penn A-4' is a common creeping bentgrass species that is widely used in urban landscaping and golf courses. To prolong the green stage of this grass, a dehydrin gene PicW isolated from Wilson's spruce (Picea wilsonii) was transformed into plants of 'Penn A-4' cultivar via a straightforward stolon node infection system. A putative transgenic plant was obtained and its tolerance to low-temperature stress was evaluated. When the transgenic line was subjected to a freezing (- 5 °C) treatment, it showed better viability and more robust physiology than wild type, as evidenced by higher soluble sugar and proline contents, and lower relative electrical conductivity and malondialdehyde content. The transgenic line also showed tolerance to a chilling treatment (5 °C), although its performance was not significantly different from that of wild-type plants. Overall, the research here clearly revealed the explicit role of PicW in increasing freezing tolerance of grass at the whole-plant level, and demonstrated that the straightforward stolon node transformation method could be well used to genetically modify turfgrass. The obtained transgenic line might be as genetic resource for breeding program and practiced to grow in cold temperate zones.

An allometric model for mapping seed development in plants.

Despite a tremendous effort to map quantitative trait loci (QTLs) responsible for agriculturally and biologically important traits in plants, our understanding of how a QTL governs the developmental process of plant seeds remains elusive. In this article, we address this issue by describing a model for functional mapping of seed development through the incorporation of the relationship between vegetative and reproductive growth. The time difference of reproductive from vegetative growth is described by Reeve and Huxley's allometric equation. Thus, the implementation of this equation into the framework of functional mapping allows dynamic QTLs for seed development to be identified more precisely. By estimating and testing mathematical parameters that define Reeve and Huxley's allometric equations of seed growth, the dynamic pattern of the genetic effects of the QTLs identified can be analyzed. We used the model to analyze a soybean data, leading to the detection of QTLs that control the growth of seed dry weight. Three dynamic QTLs, located in two different linkage groups, were detected to affect growth curves of seed dry weight. The QTLs detected may be used to improve seed yield with marker-assisted selection by altering the pattern of seed development in a hope to achieve a maximum size of seeds at a harvest time.

Systems mapping: how to map genes for biomass allocation toward an ideotype.

The recent availability of high-throughput genetic and genomic data allows the genetic architecture of complex traits to be systematically mapped. The application of these genetic results to design and breed new crop types can be made possible through systems mapping. Systems mapping is a computational model that dissects a complex phenotype into its underlying components, coordinates different components in terms of biological laws through mathematical equations and maps specific genes that mediate each component and its connection with other components. Here, we present a new direction of systems mapping by integrating this tool with carbon economy. With an optimal spatial distribution of carbon fluxes between sources and sinks, plants tend to maximize whole-plant growth and competitive ability under limited availability of resources. We argue that such an economical strategy for plant growth and development, once integrated with systems mapping, will not only provide mechanistic insights into plant biology, but also help to spark a renaissance of interest in ideotype breeding in crops and trees.

[Bioinformatics analysis of the expansin gene family in rice].

Expansin refers to a family of nonenzymatic proteins found in the plant cell wall with important roles in plant cell growth, developmental processes, and resistance to stress. Whole rice genome sequencing revealed that it contains 58 expansin genes, which belong to 4 subfamilies (A (34), B (19), LA (4) and LB (1)). All the genes were located on 10 of 12 rice chromosomes where several subfamily members clustered. Each of expansin genes ranged from 687 bp to 1128 bp in size. Sequence alignment showed that all expansins had three structural domains with two conserved amino acids of cystine in N-terminus and tryptophan in C-terminus. The amino acid identity of members among different subfamilies was less than 35%, while that among the same subfamily was more than 35%. Most genes of A subfamily had 1 or 2 introns, while genes of B, LA and LB subfamily had 3, 4 and 4 introns, respectively. Statistics analysis of codon usage showed that expansins in rice have 26 high-frequency codons which are more biased than those in other species. These bioinformatics findings will be helpful for the further study of the function and evolution of expansin genes.

Regulation of SmEXPA13 expression by SmMYB1R1-L enhances salt tolerance in Salix matsudana Koidz.

Expansins, cell wall proteins, play a significant role in plant stress resistance. Our previous study confirmed the expression of the expansin gene SmEXPA13 from Salix matsudana Koidz. enhanced salt tolerance of plants. This report presented an assay that the expression of SmEXPA13 was higher in the salt-resistant willow variety 9901 than in the salt-sensitive variety Yanjiang. In order to understand the possible reasons, a study of the regulation process was conducted. Despite being cloned from both varieties, SmEXPA13 and its promotor showed no significant differences in the structure and sequence. A transcription factor (TF), SmMYB1R1-L, identified through screening the yeast library of willow cDNA, was found to regulate SmEXPA13. Yeast one-hybrid (Y1H) assay confirmed that SmMYB1R1-L could bind to the MYB element at the -520 bp site on the SmEXPA13 promotor. A dual-luciferase reporter assay also demonstrated that SmMYB1R1-L could greatly activate SmEXPA13 expression. The willow calli with over-expression of SmMYB1R1-L exhibited better physiological performance than the wild type under salt stress. Further testing the expression of SmMYB1R1-L displayed it significantly higher in 9901 willow than that in Yanjiang under salt stress. In conclusion, the high accumulation of SmMYB1R1-L in 9901 willow under salt stress led to the high expression of SmEXPA13, resulting in variations in salt stress resistance among willow varieties. The SmMYB1R1-L/SmEXPA13 cascade module in willow offers a new perspective on plant resistance mechanisms.

Hepatic and portal vein segmentation with dual-stream deep neural network.

BACKGROUND: Liver lesions mainly occur inside the liver parenchyma, which are difficult to locate and have complicated relationships with essential vessels. Thus, preoperative planning is crucial for the resection of liver lesions. Accurate segmentation of the hepatic and portal veins (PVs) on computed tomography (CT) images is of great importance for preoperative planning. However, manually labeling the mask of vessels is laborious and time-consuming, and the labeling results of different clinicians are prone to inconsistencies. Hence, developing an automatic segmentation algorithm for hepatic and PVs on CT images has attracted the attention of researchers. Unfortunately, existing deep learning based automatic segmentation methods are prone to misclassifying peripheral vessels into wrong categories. PURPOSE: This study aims to provide a fully automatic and robust semantic segmentation algorithm for hepatic and PVs, guiding subsequent preoperative planning. In addition, to address the deficiency of the public dataset for hepatic and PV segmentation, we revise the annotations of the Medical Segmentation Decathlon (MSD) hepatic vessel segmentation dataset and add the masks of the hepatic veins (HVs) and PVs. METHODS: We proposed a structure with a dual-stream encoder combining convolution and Transformer block, named Dual-stream Hepatic Portal Vein segmentation Network, to extract local features and long-distance spatial information, thereby extracting anatomical information of hepatic and portal vein, avoiding misdivisions of adjacent peripheral vessels. Besides, a multi-scale feature fusion block based on dilated convolution is proposed to extract multi-scale features on expanded perception fields for local features, and a multi-level fusing attention module is introduced for efficient context information extraction. Paired t-test is conducted to evaluate the significant difference in dice between the proposed methods and the comparing methods. RESULTS: Two datasets are constructed from the original MSD dataset. For each dataset, 50 cases are randomly selected for model evaluation in the scheme of 5-fold cross-validation. The results show that our method outperforms the state-of-the-art Convolutional Neural Network-based and transformer-based methods. Specifically, for the first dataset, our model reaches 0.815, 0.830, and 0.807 at overall dice, precision, and sensitivity. The dice of the hepatic and PVs are 0.835 and 0.796, which also exceed the numeric result of the comparing methods. Almost all the p-values of paired t-tests on the proposed approach and comparing approaches are smaller than 0.05. On the second dataset, the proposed algorithm achieves 0.749, 0.762, 0.726, 0.835, and 0.796 for overall dice, precision, sensitivity, dice for HV, and dice for PV, among which the first four numeric results exceed comparing methods. CONCLUSIONS: The proposed method is effective in solving the problem of misclassifying interlaced peripheral veins for the HV and PV segmentation task and outperforming the comparing methods on the relabeled dataset.

Functional analysis of Pid3-A4, an ortholog of rice blast resistance gene Pid3 revealed by allele mining in common wild rice.

The rice blast resistance gene Pid3 encodes a nucleotide-binding-site leucine-rich repeat (NBS-LRR) protein. This gene was cloned from the rice 'Digu' (indica) by performing a genome-wide comparison of the NBS-LRR gene family between two genome-sequenced varieties, '9311' (indica) and 'Nipponbare' (japonica). In this study, we performed functional analysis of Pid3-A4, an ortholog of Pid3 revealed by allele mining in the common wild rice A4 (Oryza rufipogon). The predicted protein encoded by Pid3-A4 shares 99.03% sequence identity with Pid3, with only nine amino-acid substitutions. In wild rice plants, Pid3-A4 is constitutively expressed, and its expression is not induced by Magnaporthe oryzae isolate Zhong-10-8-14 infection. Importantly, in transgenic plants, Pid3-A4, as compared with Pid3, displays a distinct resistance spectrum to a set of M. oryzae isolates, including those that prevail in the rice fields of Sichuan Province. Therefore, Pid3-A4 should be quite useful for the breeding of rice blast resistance, especially in southwestern China.

Lymphoma Recognition in Histology Image of Gastric Mucosal Biopsy with Prototype Learning.

Lymphomas are a group of malignant tumors developed from lymphocytes, which may occur in many organs. Therefore, accurately distinguishing lymphoma from solid tumors is of great clinical significance. Due to the strong ability of graph structure to capture the topology of the micro-environment of cells, graph convolutional networks (GCNs) have been widely used in pathological image processing. Nevertheless, the softmax classification layer of the graph convolutional models cannot drive learned representations compact enough to distinguish some types of lymphomas and solid tumors with strong morphological analogies on H&E-stained images. To alleviate this problem, a prototype learning based model is proposed, namely graph convolutional prototype network (GCPNet). Specifically, the method follows the patch-to-slide architecture first to perform patch-level classification and obtain image-level results by fusing patch-level predictions. The classification model is assembled with a graph convolutional feature extractor and prototype-based classification layer to build more robust feature representations for classification. For model training, a dynamic prototype loss is proposed to give the model different optimization priorities at different stages of training. Besides, a prototype reassignment operation is designed to prevent the model from getting stuck in local minima during optimization. Experiments are conducted on a dataset of 183 Whole slide images (WSI) of gastric mucosa biopsy. The proposed method achieved superior performance than existing methods.Clinical relevance- The work proposed a new deep learning framework tailored to lymphoma recognition on pathological image of gastric mucosal biopsy to differentiate lymphoma, adenocarcinoma and inflammation.

Genome-wide identification of cold-responsive and new microRNAs in Populus tomentosa by high-throughput sequencing.

MicroRNAs (miRNAs) are small, non-coding RNAs that regulate the expression of target mRNAs in plant growth, development, abiotic stress responses, and pathogen responses. Cold stress is one of the most common abiotic factors affecting plants, and it adversely affects plant growth, development, and spatial distribution. To understand the roles of miRNAs under cold stress in Populus tomentosa, we constructed two small RNA libraries from plantlets treated or not with cold conditions (4°C for 8 h). High-throughput sequencing of the two libraries identified 144 conserved miRNAs belonging to 33 miRNA families and 29 new miRNAs (as well as their corresponding miRNA(∗)s) belonging to 23 miRNA families. Differential expression analysis showed that 21 miRNAs were down-regulated and nine miRNAs were up-regulated in response to cold stress. Among them, 19 cold-responsive miRNAs, two new miRNAs and their corresponding miRNA(∗)s were validated by qRT-PCR. A total of 101 target genes of the new miRNAs were predicted using a bioinformatics approach. These target genes are involved in growth and resistance to various stresses. The results demonstrated that Populus miRNAs play critical roles in the cold stress response.

Genome-wide profiling of novel and conserved Populus microRNAs involved in pathogen stress response by deep sequencing.

MicroRNAs (miRNAs) are small RNAs, generally of 20-23 nt, that down-regulate target gene expression during development, differentiation, growth, and metabolism. In Populus, extensive studies of miRNAs involved in cold, heat, dehydration, salinity, and mechanical stresses have been performed; however, there are few reports profiling the miRNA expression patterns during pathogen stress. We obtained almost 38 million raw reads through Solexa sequencing of two libraries from Populus inoculated and uninoculated with canker disease pathogen. Sequence analyses identified 74 conserved miRNA sequences belonging to 37 miRNA families from 154 loci in the Populus genome and 27 novel miRNA sequences from 35 loci, including their complementary miRNA* strands. Intriguingly, the miRNA* of three conserved miRNAs were more abundant than their corresponding miRNAs. The overall expression levels of conserved miRNAs increased when subjected to pathogen stress, and expression levels of 33 miRNA sequences markedly changed. The expression trends determined by sequencing and by qRT-PCR were similar. Finally, nine target genes for three conserved miRNAs and 63 target genes for novel miRNAs were predicted using computational analysis, and their functions were annotated. Deep sequencing provides an opportunity to identify pathogen-regulated miRNAs in trees, which will help in understanding the regulatory mechanisms of plant defense responses during pathogen infection.

Root carbon and protein metabolism associated with heat tolerance.

Extensive past efforts have been taken toward understanding heat tolerance mechanisms of the aboveground organs. Root systems play critical roles in whole-plant adaptation to heat stress, but are less studied. This review discusses recent research results revealing some critical physiological and metabolic factors underlying root thermotolerance, with a focus on temperate perennial grass species. Comparative analysis of differential root responses to supraoptimal temperatures by a heat-adapted temperate C3 species, Agrostis scabra, which can survive high soil temperatures up to 45 °C in geothermal areas in Yellow Stone National Park, and a heat-sensitive cogeneric species, Agrostis stolonifera, suggested that efficient carbon and protein metabolism is critical for root thermotolerance. Superior root thermotolerance in a perennial grass was associated with a greater capacity to control respiratory costs through respiratory acclimation, lowering carbon investment in maintenance for protein turnover, and efficiently partitioning carbon into different metabolic pools and alternative respiration pathways. Proteomic analysis demonstrated that root thermotolerance was associated with an increased maintenance of stability and less degradation of proteins, particularly those important for metabolism and energy production. In addition, thermotolerant roots are better able to maintain growth and activity during heat stress by activating stress defence proteins such as those participating in antioxidant defence (i.e. superoxide dismutase, peroxidase, glutathione S-transferase) and chaperoning protection (i.e. heat shock protein).

Polymorphism and methylation of four genes expressed in salivary glands of Russian wheat aphid (Homoptera: Aphididae).

DNA methylation is a general epigenetic mechanism for plants, animals, and fungi to adapt to environmental variation. Two biotypes of the Russian wheat aphid (Diuraphis noxia), Biotype 1 and Biotype 2, have different virulence to host plants. In this study, in addition to a high polymorphism, DNA methylation at cytosines were observed in genomic fragments of four genes in Biotype 1 and Biotype 2, after the genomic DNA was treated with sodium bisulfite. These genes presumably encode proteins and enzymes in salivary glands of aphids. The two Biotype 1 showed different methylation levels, that is, Biotype 1 showed a higher methylation on the four genes. Two thirds of methyl cytosines were in a sequence context of CHH (H = A, C, or T). Some polymorphism and methylation sites were located at important positions in terms of enzyme function, such as close to catalytic residues or inhibitor binding residues. These findings may provide clues to explore the evolutionary mode between Russian wheat aphid virulence and resistance genes of host plants.

The complete mitochondrial genome of Zelkova schneideriana Hand-Mazz (Ulmaceae) and phylogenetic analysis.

Zelkova schneideriana Hand-Mazz is a second-class key protected wild plant in China. Here, the complete mitochondrial genome of Zelkova schneideriana Hand-Mazz was sequenced using Nanopore Sequel and Illumina NovaSeq platform. The mitochondrial genome was assembled into three circular-mapping molecules with the genome sizes of 154,640 bp, 192,388 bp and 146,907 bp, including 36 protein-coding genes, 19 tRNA genes, and 3 rRNA genes. Phylogenetic analysis indicated that Zelkova schneideriana Hand-Mazz is close with Hemiptelea davidii, a species in same Ulmaceae Mirb.

Expression, Purification, and Preliminary Protection Study of Dehydrin PicW1 From the Biomass of Picea wilsonii.

Dehydrins (DHNs) belong to group II of late embryogenesis-abundant (LEA) proteins, which are up-regulated in most plants during cold, drought, heat, or salinity stress. Despite the importance of dehydrins for the plants to resist abiotic stresses, it is necessary to obtain plant-derived dehydrins from different biomass. Generally, dehydrin PicW1 from Picea wilsonii is involved in Kn-type dehydrin with five K-segments, which has a variety of biological activities. In this work, Picea wilsonii dehydrin PicW1 was expressed in Escherichia coli and purified by chitin-affinity chromatography and size-exclusion chromatography, which showed as a single band by SDS-PAGE. A cold-sensitive enzyme of lactate dehydrogenase (LDH) is used to explore the protective activities of other proteins. Temperature stress assays showed that PicW1 had an effective protective effect on LDH activity, which was better than that of bovine serum albumin (BSA). This study provides insights into the purification and protective activity of K5 DHNs for the advancement of dehydrin structure and function from biomass.

Codon usage by chloroplast gene is bias in Hemiptelea davidii.

The base composition of the chloroplast genes is of great interest because they play a highly significant role in the evolutionary development of the plants. Evaluation of the 48 chloroplast protein-coding genes of Hemiptelea davidii showed that the average GC content was about 37.32%, while at the third codon base position alone the average GC content was only 27.80%. The 48 genes were classified into five groups based on the gene function and each group displayed specific codon characteristics. Based on the relative synonymous codon usage analysis, a total of 30 high-frequency codons and 11 optimal codons were identified, most of them ended with A or T. Neutrality plot, ENC-plot and PR2-plot analyses showed that the codon usage bias of the chloroplast genes of H. davidii was greatly influenced by natural selection pressures. Meanwhile, the frequency of codon usage of chloroplast genes among different plant species displayed similarities, with some synonymous codons were preferred to be used in H. davidii. In this study, the codon usage pattern of the chloroplast protein coding genes of H. davidii provides us with a better understanding of the expression of chloroplast genes, and may advice the future molecular breeding programmes.

Genome-wide profiling of alternative splicing genes in hybrid poplar (P.alba×P.glandulosa cv.84K) leaves.

Alternative splicing (AS) is a post-transcriptional process common in plants and essential for regulation of environmental fitness of plants. In the present study, we focus on the AS events in poplar leaves to understand their effects on plant growth and development. The hybrid poplar (P.alba×P.glandulosa cv.84K) leaves were collected for RNA extraction. The extracted RNA was sequenced using on an Illumina HiSeq™ 2000 platform. Using the Populus trichocarpa genome as the reference, a total of 3810 AS genes were identified (9225 AS events), which accounted for 13.51% of all the expressed genes. Intron retention was the most common AS event, accounting for 43.86% of all the AS events, followed by alternative 3' splice sites (23.75%), alternative 5' splice sites (23.71%), and exon skipping (8.68%). Chromosomes 10 had the most condensed AS events (33.67 events/Mb) and chromosome 19 had the least (12.42 events/Mb). Association analysis showed that AS in the poplar leaves was positively correlated with intron length, exon number, exon length, and gene expression level, and was negatively correlated with GC content. AS genes in the poplar leaves were associated mainly with inositol phosphate metabolism and phosphatidylinositol signaling system pathways that would be significant on wooden plant production.

Cavitation characteristics of flowing low and high boiling-point perfluorocarbon phase-shift nanodroplets during focused ultrasound exposures.

This work investigated and compared the dynamic cavitation characteristics between low and high boiling-point phase-shift nanodroplets (NDs) under physiologically relevant flow conditions during focused ultrasound (FUS) exposures at different peak rarefactional pressures. A passive cavitation detection (PCD) system was used to monitor cavitation activity during FUS exposure at various acoustic pressure levels. Root mean square (RMS) amplitudes of broadband noise, spectrograms of the passive cavitation detection signals, and normalized inertial cavitation dose (ICD) values were calculated. Cavitation activity of low-boiling-point perfluoropentane (PFP) NDs and high boiling-point perfluorohexane (PFH) NDs flowing at in vitro mean velocities of 0-15 cm/s were compared in a 4-mm diameter wall-less vessel in a transparent tissue-mimicking phantom. In the static state, both types of phase-shift NDs exhibit a sharp rise in cavitation intensity during initial FUS exposure. Under flow conditions, cavitation activity of the PFH NDs reached the steady state less rapidly compared to PFP NDs under the lower acoustic pressure (1.35 MPa); at the higher acoustic pressure (1.65 MPa), the RMS amplitude increased more sharply during the initial FUS exposure period. In particular, the RMS-time curves of the PFP NDs shifted upward as the mean flow velocity increased from 0 to 15 cm/s; the RMS amplitude of the PFH ND solution increased from 0 to 10 cm/s and decreased at 15 cm/s. Moreover, amplitudes of the echo signal for the low boiling-point PFP NDs were higher compared to the high boiling-point PFH NDs in the lower frequency range, whereas the inverse occurred in the higher frequency range. Both PFP and PFH NDs showed increased cavitation activity in the higher frequency under the flow condition compared to the static state, especially PFH NDs. At 1.65 MPa, normalized ICD values for PFH increased from 0.93 ± 0.03 to 0.96 ± 0.04 and from 0 to 10 cm/s, then decreased to 0.86 ± 0.05 at 15 cm/s. This work contributes to our further understanding of cavitation characteristics of phase-shift NDs under physiologically relevant flow conditions during FUS exposure. In addition, the results provide a reference for selecting suitable phase-shift NDs to enhance the efficiency of cavitation-mediated ultrasonic applications.

Genome sequencing and phylogenetic analysis of allotetraploid Salix matsudana Koidz.

Polyploidy is a common phenomenon among willow species. In this study, genome sequencing was conducted for Salix matsudana Koidz (also named Chinese willow), an important greening and arbor tree species, and the genome of this species was compared with those of four other tree species in Salicaceae. The total genome sequence of S. matsudana was 655.72 Mb in size, with repeated sequences accounting for 45.97% of the total length. In total, 531.43 Mb of the genome sequence could be mapped onto 38 chromosomes using the published genetic map as a reference. The genome of S. matsudana could be divided into two groups, the A and B genomes, through homology analysis with the genome of Populus trichocarpa, and the A and B genomes contained 23,985 and 25,107 genes, respectively. 4DTv combined transposon analysis predicted that allotetraploidy in S. matsudana appeared ~4 million years ago. The results from this study will help reveal the evolutionary history of S. matsudana and lay a genetic basis for its breeding.

Over-expression of PttEXPA8 gene showed various resistances to diverse stresses.

Expansins play a pivotal role in plant adaptation to environmental stress via cell wall loosening. To evaluate the roles of expansin in response to different environmental stress conditions, the expansin gene PttEXPA8 from Populus tomentosa was transformed into tobacco. Analysis of physiological indices demonstrated the transgenic plants with improved resistance to heat, drought, salt, cold, and cadmium stress but to different extents. In mature plants, PttEXPA8 exerted the greatest effect on heat stress, with a response index value of 137.46%, followed by drought, cadmium, cold, and salt stress with response index values of 101.04%, 70.61%, 69.95%, and 54.68%, respectively. Over-expression of PttEXPA8 resulted in differential responses in physiological indices to the stresses. Soluble sugar content showed the highest response to the stresses, with an average response index value of 29.29%, whereas the absolute response index value for malondialdehyde content, relative electrolyte leakage, chlorophyll content, and superoxide dismutase activity ranged from 11.01% to 19.21%. The present results provide insight into the roles of expansin in stress resistance in Populus.