Salt stress is a global environmental problem that affects plant growth and development. Paulownia fortunei is an adaptable and fast-growing deciduous tree native to China that is environmentally and ...economically important. MicroRNAs (miRNAs) play important regulatory roles in growth, development, and stress responses in plants. MiRNAs that respond to biotic stresses have been identified; however, how miRNAs in P. fortunei respond to salt stress has not yet been reported. To identify salt-stress-responsive miRNAs and predict their target genes, four small RNA and four degradome libraries were constructed from NaCl-treated and NaCl-free leaves of P. fortunei seedlings. The results indicated that salt stress had different physiological effects on diploid and tetraploid P. fortunei. We detected 53 conserved miRNAs belonging to 17 miRNA families and 134 novel miRNAs in P. fortunei. Comparing their expression levels in diploid and tetraploid P. fortunei, we found 10 conserved and 10 novel miRNAs that were significantly differentially expressed under salt treatment, among them eight were identified as miRNAs probably associated with higher salt tolerance in tetraploid P. fortunei than in diploid P. fortunei. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses were performed to predict the functions of the target genes of the conserved and novel miRNAs. The expressions of 10 differentially expressed miRNAs were validated by quantitative real-time polymerase chain reaction (qRT-PCR). This is the first report on P. fortunei miRNAs and their target genes under salt stress. The results provided information at the physiological and molecular levels for further research into the response mechanisms of P. fortunei to salt stress.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Paulownia witches' broom (PaWB) caused by phytoplasma might result in devastating damage to the growth and wood production of Paulownia. To study the effect of phytoplasma on DNA sequence and to ...discover the genes related to PaWB occurrence, DNA polymorphisms and DNA methylation levels and patterns in PaWB seedlings, the ones treated with various concentration of methyl methane sulfonate (MMS) and healthy seedlings were investigated with amplified fragment length polymorphism (AFLP) and methylation-sensitive amplification polymorphism (MSAP). Our results indicated that PaWB seedlings recovered a normal morphology, similar to healthy seedlings, after treatment with more than 20 mg.L-1 MMS; Phytoplasma infection did not change the Paulownia genomic DNA sequence at AFLP level, but changed the global DNA methylation levels and patterns; Genes related to PaWB were discovered through MSAP and validated using quantitative real-time PCR (qRT-PCR). These results implied that changes of DNA methylation levels and patterns were closely related to the morphological changes of seedlings infected with phytoplasmas.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
MicroRNAs (miRNAs) are involved in plant growth, development, and response to biotic and abiotic stresses. Most of the miRNAs that have been identified in model plants are well characterized, but ...till now, no reports have previously been published concerning miRNAs in Paulownia australis. In order to investigate miRNA-guided transcript target regulation in P. australis, small RNA libraries from two P. australis (diploids, PA2; and autotetraploids, PA4) genotypes were subjected to Solexa sequencing. As a result, 10,691,271 (PA2) and 10,712,733 (PA4) clean reads were obtained, and 45 conserved miRNAs belonging to 15 families, and 31 potential novel miRNAs candidates were identified. Compared with their expression levels in the PA2 plants, 26 miRNAs were up-regulated and 15 miRNAs were down-regulated in the PA4 plants. The relative expressions of 12 miRNAs were validated by quantitative real-time polymerase chain reaction. Using the degradome approach, 53 transcript targets were identified and annotated based on Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis. These targets were associated with development, stimulus response, metabolism, signaling transduction and biological regulation. Among them, 11 targets, including TCP transcription factors, auxin response factors, squamosa promoter-binding-like proteins, scarecrow-like proteins, L-type lectin-domain containing receptor kinases and zinc finger CCCH domain-containing protein, cleaved by four known miRNA family and two potentially novel miRNAs were found to be involved in regulating plant development, biotic and abiotic stresses. The findings will be helpful to facilitate studies on the functions of miRNAs and their transcript targets in Paulownia.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Stem tips and nodal explants of Paulownia elongata plants grown at controlled conditions were cultured on Murashige and Skoog medium (MS) supplemented with NAA and BAP. Medium containing 2 mg/L BAP ...and 0.05 mg/L NAA gave the best shoot production and maximum number of shoots from nodal explant (8.2). The results indicated that P. elongata has a great potential for vegetative buds formation as the answer strongly related to the composition of medium and culture conditions. The described protocol allows the establishment of numerous cloned elite plants from selected genotypes of P. е longatа ..
Polyploidization is an important feature of speciation that results from genome doubling. Tetraploid plants often have better physical characteristics than their diploid counterparts, and
Paulownia
...is no exception. In our previous studies, several genes related to timber quality and abiotic stress resistance were identified in
Paulownia tomentosa
and
Paulownia fortunei
. However, the genes related to disease resistance and high biomass were not confirmed. In this study, small RNA and transcriptome sequencing were performed to analyze changes in microRNA (miRNA) and mRNA expression levels in tetraploid
Paulownia tomentosa
×
Paulownia fortunei
and
Paulownia australis
and their diploid counterparts. A total of 930 common differentially expressed genes and 66 (19 known and 47 novel) common differentially expressed miRNAs were detected in the two tetraploid
vs.
diploid comparisons. Twenty-two miRNA target genes were predicted, and the regulatory functions of the miRNA–target gene pairs were analyzed, of which the novel miR327- SGT1 HOMOLOG PROTEIN At5g65490 (PAU019930.1) and pau-miR2111a-MYB-RELATED TRANSCRIPTION FACTOR (PAU011118.1) interacting pairs were predicted to co-regulate disease resistance in tetraploid
Paulownia
. The pau-miR157i-SQUAMOSA PROMOTER-BINDING PROTEIN-LIKE 15 (PAU009402.1) and novel miR10-PUTATIVE PENTATRICOPEPTIDE REPEAT-CONTAINING PROTEIN At5g65820 (PAU012281.1) interacting pairs were predicted to co-regulate high biomass in tetraploid
Paulownia
. The expression trends of the miRNA and candidate target genes were validated by qRT-PCR. The results will help to accelerate genetic gain in
Paulownia
breeding programs to develop superior varieties.
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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
Paulownia witches' broom (PaWB) is a devastating disease of Paulownia spp. caused by phytoplasma infection. To reveal the reason for the absence of morphological changes at the early stage of ...phytoplasma infection, in this study, a combination of second-and third-generation sequencing (single-molecule real-time long-read isoform) and liquid chromatography tandem mass spectrometry were performed to analyse the changes of full-length transcripts and metabolites at the early stage of phytoplasma infection. A total of 140,528 non-redundant full-length transcripts, 597 transcription factors, 1,658 long non-coding RNAs, and 645 metabolites were identified. The third-generation sequencing improved the annotation of the reference Paulownia fortunei (Seem.) Hemsl. genome by 8.86%. Combination analysis of the full-length transcriptome and metabolome revealed that phenolics and phenylalanine ammonia-lyase synthesis related genes were significantly up-regulated in the early stage of phytoplasma-infected P. fortunei. Based on the results of full-length transcriptome and metabolome integrative analysis, we constructed an early defence model diagram of PaWB disease. Our results provide powerful insights into the reason for absence of morphological at the early stage of phytoplasma infection.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
In Ecuador, the reduction of forests is evident, so it is necessary to evaluate fast-growing forest species that can meet growing demands, avoiding deforestation in areas where forests of the region ...are still maintained. The objective was to evaluate the growth of three species of the genus Paulownia in three localities of the Ecuadorian Coast as a medium-term alternative for productive and afforestation purposes. Diameter, height and volume were evaluated in three locations with two planting frames for three Paulownia species (Paulownia fortunei Hemsl; Paulownia elongata SYHu; Paulownia hibrido and a control (Gmelina arborea Roxb) with three replications. Data were recorded in the second year of planting. The Paulownia species were surpassed by G. arborea in the evaluated variables. In the humid tropics localities, there was no statistical difference between Paulownia species contrasting with the dry tropics locality in which P. eloganta in the 3 x 3 m plantation frame that presented the best values. Paulownia species did not exceed the control. The best results were achieved in the localities of Los Ríos and Santo Domingo; however, they should not be considered an alternative for productive purposes and afforestation in the humid tropics of Ecuador.
Paulownias are among the fastest growing trees in the world, but they often suffer tremendous loss of wood production due to infection by Paulownia witches' broom (PaWB) phytoplasmas. In this study, ...we have sequenced and assembled a high-quality nuclear genome of Paulownia fortunei, a commonly cultivated paulownia species. The assembled genome of P. fortunei is 511.6 Mb in size, with 93.2% of its sequences anchored to 20 pseudo-chromosomes, and it contains 31 985 protein-coding genes. Phylogenomic analyses show that the family Paulowniaceae is sister to a clade composed of Phrymaceae and Orobanchaceae. Higher photosynthetic efficiency is achieved by integrating C3 photosynthesis and the crassulacean acid metabolism pathway, which may contribute to the extremely fast growth habit of paulownia trees. Comparative transcriptome analyses reveal modules related to cambial growth and development, photosynthesis, and defense responses. Additional genome sequencing of PaWB phytoplasma, combined with functional analyses, indicates that the effector PaWB-SAP54 interacts directly with Paulownia PfSPLa, which in turn causes the degradation of PfSPLa by the ubiquitin-mediated pathway and leads to the formation of witches' broom. Taken together, these results provide significant insights into the biology of paulownias and the regulatory mechanism for the formation of PaWB.
The genome sequences of Paulownia fortunei and Paulownia witches' broom phytoplasma are reported. Genome-based analyses and additional genetic and molecular experiments provide new insights into the mechanisms underlying the fast growth of paulownias and the formation of Paulownia witches' broom.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The effects of soil salinity on the functional activity of photosynthetic apparatus and pigment composition of two Paulownia lines (Paulownia tomentosa x fortunei and Paulownia elongata x elongata) ...were investigated. PAM chlorophyll fluorescence measurements revealed that salinity leads to: (i) an increase of the photochemical quenching coefficient (qP) and the linear electron transport rate (ETR) in both lines of Paulownia, while the maximum quantum yield of the primary photochemistry of PSII in the dark adapted state (Fv/Fm) was unaffected; (ii) improved the efficiency of the photochemical energy conversion (ФPSII); (iii) an impact on the chlorophyll fluorescence decrease ratio (RFd), which correlates to the net CO2 assimilation rate; (iv) an impact on QA− reoxidation. The analysis of the kinetics of P700+ reduction upon turning off far-red irradiation revealed that salinization lead to a delay of the cyclic electron transport around PSI in both studied lines as the effect on this process is more pronounced in P. tomentosa x fortunei than in (in comparison with) P. elongata x elongata. The present experimental results suggested high salt tolerance of the studied lines Paulownia, but P. tomentosa x fortunei is more tolerant to salinity than P. elongata x elongata. Molecular mechanisms involved in the Paulownia response to the soil salinity are discussed.
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•The studied Paulownia lines can be used for remediation of saline soils.•Data revealed an impact on QA− reoxidation in saline soils.•Up regulation of PSII activity in saline soils.•Different influence on PSI in stroma lamellae and grana margin.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The aim of this research is the characterization of physical and mechanical properties of Paulownia sawn wood from three plantation sites in Europe, namely Spain, Bulgaria and Serbia. As a ...fast-growing wood species, Paulownia has a significant positive forecast for the European markets and a wide range of possible applications that still need to be explored. For this purpose, Paulownia tomentosa(Tunb.) x elongata(S.Y. Hu) wood species was investigated. Sorption behaviour, Brinell hardness, 3-point bending strength, flexural modulus of elasticity, tensile strength, compressive strength and screw withdrawal resistance were examined in detail. The samples from Spain have the higher average bulk density (266 kg/m3), 3-point flexural strength (~40 N/mm2), 3-point flexural modulus of elasticity (~4900 N/mm2), compressive strength (~23 N/mm2), tensile strength (~44 N/mm2) and screw withdrawal resistance (~56 N/mm). The plantation wood from Bulgaria has the highest average of annual ring width (46 mm). Paulownia wood has potential in lightweight applications and can replace successfully expensive tropical species as Balsa.
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