MicroRNAs (miRNAs) are small, non-coding RNAs that play essential roles in plant growth, development, and stress response. Populus euphratica is a typical abiotic stress-resistant woody species. This ...study presents an efficient method for genome-wide discovery of new drought stress responsive miRNAs in P. euphratica. High-throughput sequencing of P. euphratica leaves found 197 conserved miRNAs between P. euphratica and Populus trichocarpa. Meanwhile, 58 new miRNAs belonging to 38 families were identified, an increase in the number of P. euphratica miRNAs. Twenty-six new and 21 conserved miRNA targets were verified by degradome sequencing, and target annotation showed that these targets were involved in multiple biological processes, including transcriptional regulation and response to stimulus. Furthermore, comparison of high-throughput sequencing with miRNA microarray profiling data indicated that 104 miRNA sequences were up-regulated, whereas 27 were down-regulated under drought stress. This preliminary characterization provides a framework for future analysis of miRNA genes and their roles in key poplar traits such as stress resistance, and could be useful for plant breeding and environmental protection
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Degumming bast fibers by organic solvents has been a promising method in recent years due to easy recovery and reuse of organic solvents. In this research, the possibility of ramie fiber degumming by ...glycol and a combination of acetic acid with glycol was studied, in which two steps were involved in the degumming process: distilled water boiling pretreatment and organosolv treatment by a combination of glycol/acetic acid (100/0, 90/10, 80/20, 70/30, 60/40, 50/50). Results displayed that the pretreatment could remove 6.99% of hemicellulose, 0.59% of lignin and 36.26% of other gums compared with raw ramie. While with organosolv treatment (130 °C, 6 h), fibers treated by glycol/acetic acid (50/50) had the best effect of removing gums. The hemicellulose and lignin content of fibers reduced by 44.81% and 54.12%, respectively (compared with raw ramie), while the residual gum content still failed to meet the requirements of spinning process. Besides, the tenacity of glycol/acetic acid treated fibers was lower than that of only glycol treated fibers (4.67 cN/dtex). Considering that the addition of acid could cause a decrease in fiber tenacity, the step of organosolv (only glycol) treatment was optimized by altering the degumming condition. The tenacity, linear density, non-cellulosic component ratio of fibers treated with the optimized condition (200 °C, 80 min) were 6.53 cN/dtex, 6.06 dtex, 5.78%, respectively, which met the needs of industrial production. Compared with the organosolv treated fibers, these properties of fibers with traditional alkaline treatment were better, but the yield (62.4%) was much lower than that of fibers treated with glycol in two degumming condition (77–82%). Considering impressive properties of the treated ramie, the method of organosolv degumming with high degumming efficiency and environmental protection would bring an innovative thought for natural fiber isolation.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A total of 2 542 lincRNAs were identified from Populus trichocarpa and some of them play key roles in drought stress tolerance or regulate microRNA through target mimicry patterns.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Water deficiency is a critical environmental condition that is seriously reducing global plant production. Improved water‐use efficiency (WUE) and drought tolerance are effective strategies to ...address this problem. In this study, PdEPF1, a member of the EPIDERMAL PATTERNING FACTOR (EPF) family, was isolated from the fast‐growing poplar clone NE‐19 Populus nigra × (Populus deltoides × Populus nigra). Significantly, higher PdEPF1 levels were detected after induction by dehydration and abscisic acid. To explore the biological functions of PdEPF1, transgenic triploid white poplars (Populus tomentosa ‘YiXianCiZhu B385’) overexpressing PdEPF1 were constructed. PdEPF1 overexpression resulted in increased water deficit tolerance and greater WUE. We confirmed that the transgenic lines with greater instantaneous WUE had approximately 30% lower transpiration but equivalent CO₂ assimilation. Lower transpiration was associated with a 28% reduction in abaxial stomatal density. PdEPF1 overexpression not only strongly enhanced WUE, but also greatly improved drought tolerance, as measured by the leaf relative water content and water potential, under limited water conditions. In addition, the growth of these oxPdEPF1 plants was less adversely affected by reduced water availability than plants with a higher stomatal density, indicating that plants with a low stomatal density may be well suited to grow in water‐scarce environments. Taken together, our data suggest that PdEPF1 improves WUE and confers drought tolerance in poplar; thus, it could be used to breed drought‐tolerant plants with increased production under conditions of water deficiency.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Nuclear Factor-Y (NF-Y), composed of three subunits NF-YA, NF-YB and NF-YC, exists in most of the eukaryotes and is relatively conservative in evolution. As compared to animals and fungi, the number ...of NF-Y subunits has significantly expanded in higher plants. The NF-Y complex regulates the expression of target genes by directly binding the promoter
box or by physical interaction and mediating the binding of a transcriptional activator or inhibitor. NF-Y plays an important role at various stages of plant growth and development, especially in response to stress, which attracted many researchers to explore. Herein, we have reviewed the structural characteristics and mechanism of function of NF-Y subunits, summarized the latest research on NF-Y involved in the response to abiotic stresses, including drought, salt, nutrient and temperature, and elaborated the critical role of NF-Y in these different abiotic stresses. Based on the summary above, we have prospected the potential research on NF-Y in response to plant abiotic stresses and discussed the difficulties that may be faced in order to provide a reference for the in-depth analysis of the function of NF-Y transcription factors and an in-depth study of plant responses to abiotic stress.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
To survive in stressful conditions, plants have developed multiple strategies to relieve damage. One of the strategies is to clear the damaged protein and organelles. Autophagy is a highly ...conservative degradation process, which refers to the recycling of damaged protein and organelles. Over the past decades, increasing evidence has revealed the important roles of autophagy in response to stress conditions, and many factors have been revealed involved in the sophisticated regulation of the autophagy signaling pathway. However, the accurate regulation pathway of the autophagy pathway is largely unknown. The current review proposes how stress-response factors respond to stress conditions involved in regulating the autophagy signaling pathway. In short, clarifying the regulating pathway of autophagy in response to stress conditions is beneficial to plant breeding.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Quantifying intra-specific variation in leaf functional traits along environmental gradients is important for understanding species' responses to climate change. In this study, we assessed the degree ...of among and within populations variation in leaf functional traits and explored leaf response to geographic and climate change using Caryopteris mongholica as material, which has a wide range of distribution environments.
We selected 40 natural populations of C. mongholica, measured 8 leaf functional traits, analyzed the extent of trait variation among and within populations, and developed geographic and climatic models to explain trait variation between populations. Our results showed that the variation in leaf functional traits of C. mongholica was primarily lower within populations compared to among populations. Specifically, the leaf area (LA) exhibited higher variability both among and within populations, whereas leaf carbon content (LC) exhibited lower variation within populations but greater variation among populations. We observed a specific covariation pattern among traits and a strong linkage between morphological, economic, and mechanical traits. Increasing minimum temperature, precipitation of month, and seasonal precipitation differences all limited the growth and development of C. mongholica. However, it was observed that an increase in mean annual precipitation positively influenced the morphological development of its leaf.
These results demonstrate the response of intra-specific trait variation to the environment and provide valuable insights into the adaptation of intra-specific leaf functional traits under changing climatic conditions.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Ammopiptanthus mongolicus (Maxim. ex Kom.) Cheng f., an evergreen broadleaf legume shrub, is distributed in Mid-Asia where the temperature can be as low as -30°C during the winter. Although A. ...mongolicus is an ideal model to study the plant response to cold stress, insufficient genomic resources for this species are available in public databases. To identify genes involved in cold acclimation (a phenomenon experienced by plants after low temperature stress), a high-throughput sequencing technology was applied.
We sequenced cold-treated and control (untreated) samples of A. mongolicus, and obtained 65,075,656 and 67,287,120 high quality reads, respectively. After de novo assembly and quantitative assessment, 82795 all-unigenes were finally generated with an average length of 816 bp. We then obtained functional annotations by aligning all-unigenes with public protein databases including NR, SwissProt, KEGG and COG. Differentially expressed genes (DEGs) were investigated using the RPKM method. Overall, 9309 up-regulated genes and 23419 down-regulated genes were identified. To increase our understanding of these DEGs, we performed GO enrichment and metabolic pathway enrichment analyses. Based on these results, a series of candidate genes involved in cold responsive pathways were selected and discussed. Moreover, we analyzed transcription factors, and found 720 of them are differentially expressed. Finally, 20 of the candidate genes that were up-regulated and known to be associated with cold stress were examined using qRT-PCR.
In this study, we identified a large set of cDNA unigenes from A. mongolicus. This is the first transcriptome sequencing of this non-model species under cold-acclimation using Illumina/Solexa, a next-generation sequencing technology. We sequenced cold-treated and control (untreated) samples of A. mongolicus and obtained large numbers of unigenes annotated to public databases. Studies of differentially expressed genes involved in cold-related metabolic pathways and transcription factors facilitate the discovery of cold-resistance genes.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Plant miR164 family is highly conserved and miR164 members regulate conserved targets belonging to NAC transcription factors. Our previous studies have revealed that peu-miR164a–e and its target gene ...POPTR_0007s08420 participate in abiotic stress response in Populus euphratica according to deep sequencing and degradome sequencing. In this study, miR164 family comprises six members that generate two mature products (miR164a–e and miR164f) and target seven NAC genes in P. euphratica. Co-expression in Nicotiana benthamiana and 5′ RACE confirmed that peu-miR164 directs PeNAC070, PeNAC012 and PeNAC028 mRNAs cleavage. Expression profiles of primary peu-miR164 a/b/c/d/e bear similarity to those of peu-miR164a–e, whereas PeNAC070 and PeNAC081 showed inverse expression patterns with peu-miR164a–e under abiotic stresses. Existence of cis-acting elements in PeNAC070 promoter (ABRE,MBs, Box-W1, GC-motif, and W-box) and in peu-MIR164b promoter (HSE) further confirmed different responses of peu-miR164 and PeNAC070 to abiotic stresses. Histochemical β-glucuronidase (GUS) staining revealed that GUS activities increased when ProPeNAC070::GUS transgenic Arabidopsis plants were exposed to NaCl, mannitol and abscisic acid (ABA), whereas GUS activity of Propeu-MIR164b::GUS plants decreased under ABA treatment. Subcellular localization and transactivation assays showed that PeNAC070 protein was localized to the nucleus and exhibited transactivation activity at the C-terminal. Overexpression of PeNAC070 in Arabidopsis promoted lateral root development, delayed stem elongation, and increased sensitivity of transgenic plants to drought and salt stresses. This study aids in understanding the adaptability of P. euphratica to extreme drought and salt environment by analysing tissue-specific expression patterns of miR164-regulated and specific promoter-regulated PeNAC genes.
•Six peu-miR164 members and seven target NAC genes were identified from Populus euphratica.•Peu-miR164 directs PeNAC070, PeNAC012 and PeNAC028 mRNAs cleavage were confirmed.•Peu-miR164 and its targets showed diverse expression patterns under abiotic stresses.•More stress response cis-elements in the promoter of PeNAC070 than that of PNAC070.•Overexpression of PeNAC070 in Arabidopsis reduced drought and salt resistance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Populus euphratica is the only arboreal species that is established in the world's largest shifting‐sand desert in China and is well‐adapted to the extreme desert environment, so it is widely ...considered a model system for researching into abiotic stress resistance of woody plants. However, few P. euphratica reference genes (RGs) have been identified for quantitative real‐time polymerase chain reaction (qRT‐PCR) until now. Validation of suitable RGs is essential for gene expression normalization research. In this study, we screened 16 endogenous candidate RGs in P. euphratica leaves in six abiotic stress treatments, including abscisic acid (ABA), cold, dehydration, drought, short‐duration salt (SS) and long‐duration salt (LS) treatments, each with 6 treatment gradients. After calculation of PCR efficiencies, three different software tools, NormFinder, geNorm and BestKeeper, were employed to analyze the qRT‐PCR data systematically, and the outputs were merged by means of a non‐weighted unsupervised rank aggregation method. The genes selected as optimal for gene expression analysis of the six treatments were RPL17 (ribosomal protein L17) in ABA, EF1α (elongation factor‐1 alpha) in cold, HIS (histone superfamily protein H3) in dehydration, GIIα in drought and SS, and TUB (tubulin) in LS. The expression of 60S (the 60S ribosomal protein) varied the least during all treatments. To illustrate the suitability of these RGs, the relative quantifications of three stress‐inducible genes, PePYL1, PeSCOF‐1 and PeSCL7 were investigated with different RGs. The results, calculated using qBasePlus software, showed that compared with the least‐appropriate RGs, the expression profiles normalized by the recommended RGs were closer to expectations. Our study provided an important RG application guideline for P. euphratica gene expression characterization.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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