Combining QTL Mapping with Genome Resequencing Identifies an Indel in an R Gene that is Associated with Variation in Leaf Rust Disease Resistance in Poplar.

Poplar trees (Populus spp.) are important and are widely grown worldwide. However, the extensive occurrence of leaf rust disease caused by Melampsora spp. seriously inhibits their growth and reduces their biomass. In our previous study, a high-quality genetic map was constructed for the poplar F1 population I-69 × XYY by using next-generation sequencing-based genotyping-by-sequencing. Here, we collected phenotypic data on leaf rust disease resistance on three different dates for all 300 progenies of the F1 population. Combining a high-quality genetic map and phenotypic data, we were able to detect 11 major quantitative trait loci (QTLs) for leaf rust disease resistance. Among these 11 QTLs, two pairs were detected on at least two dates. In the corresponding genomic sequence, we found that resistance (R) gene clusters were located in these two QTL regions. By using genome resequencing, PCR confirmation and statistical analysis, a 611-bp deletion within an R gene in one QTL region was found to be associated with variation in leaf rust disease resistance. A PCR-based examination of this 611-bp deletion was performed. This 611-bp deletion was also found to affect mRNA splicing and form a new protein with the loss of some key protein domains. Based on this study, we were able to determine the genetic architecture of variation in poplar leaf rust disease resistance, and the 611-bp deletion in the R gene could be used as a diagnostic marker for future poplar molecular breeding.

Comprehensive analysis of dynamic gene expression and investigation of the roles of hydrogen peroxide during adventitious rooting in poplar.

BACKGROUND: Adventitious roots (ARs) are roots that are generated from nonrooting tissues. ARs are usually produced both during normal development and in response to stress conditions, such as flooding, nutrient deprivation, heavy metal stress and wounding. The ability of plants to form ARs is a key trait that enables plant propagation, especially for most tree species. RESULTS: Here, the kinetics of AR formation in a tissue culture of a hybrid variety of poplar were investigated. AR formation mainly occurred during the first 8 days and both pre- and newly- formed primordia contributed to AR formation in poplar by histological study. RNA-Seq-based transcriptome analysis was performed for stem bases collected at 0, 2, 4, 6 and 8 days after excision (DAE). Based on the data, the expression patterns of 8 phytohormone-related genes were investigated, and their influences on AR formation were considered. Subsequent gene expression cluster analysis showed a number of biological processes involved in AR formation. Among these biological pathways, genes involved in H2O2 homeostasis showed enrichment in one cluster that was highly upregulated from DAE0 to DAE8. Pharmacological assay confirmed that an appropriate content of H2O2 in stem bases could accelerate the formation of ARs in poplar. CONCLUSIONS: Based on the results of this study, we were able to predict a regulatory network for 7 phytohormones that are involved in poplar AR formation. The influence of H2O2 on AR formation was also confirmed. These results enhance our understanding of the regulation of AR formation in tree species.

Integrated Transcriptome Analysis Reveals Plant Hormones Jasmonic Acid and Salicylic Acid Coordinate Growth and Defense Responses upon Fungal Infection in Poplar.

Plants have evolved a sophisticated system to respond to various stresses. Fungal attack or infection is one of the most important biotic stresses for most plants. During the defense response to fungal infection, the plant hormones jasmonic acid (JA) and salicylic acid (SA) play critical roles. Here, gene expression data on JA/SA treatments and Melampsora larici-populina (MLP) infection were generated. Integrated transcriptome analyses of these data were performed, and 943 genes in total were identified as common responsive genes (CRG). Gene ontology (GO) term analysis revealed that the genes from CRG are generally involved in the processes of stress responses, metabolism, and growth and development. The further cluster analysis of the CRG identified a set of core genes that are involved in the JA/SA-mediated response to fungal defense with distinct gene expression profiles upon JA/SA treatment, which highlighted the different effects of these two hormones on plant fungal defenses. The modifications of several pathways relative to metabolism, biotic stress, and plant hormone signal pathways suggest the possible roles of JA/SA on the regulation of growth and defense responses. Co-expression modules (CMs) were also constructed using the poplar expression data on JA, SA, M. larici-populina, Septoria musiva, and Marssonina brunnea treatment or infection. A total of 23 CMs were constructed, and different CMs clearly exhibited distinct biological functions, which conformably regulated the concerted processes in response to fungal defense. Furthermore, the GO term analysis of different CMs confirmed the roles of JA and SA in regulating growth and defense responses, and their expression profiles suggested that the growth ability was reduced when poplar deployed defense responses. Several transcription factors (TFs) among the CRG in the co-expression network were proposed as hub genes in regulating these processes. According to this study, our data finely uncovered the possible roles of JA/SA in regulating the balance between growth and defense responses by integrating multiple hormone signaling pathways. We were also able to provide more knowledge on how the plant hormones JA/SA are involved in the regulation of the balance between growth and plant defense.

Construction of a high-density genetic map and its application for leaf shape QTL mapping in poplar.

MAIN CONCLUSION: High-quality and dense genetic maps were constructed, and leaf shape variation was dissected by QTL mapping in poplar. Species in the genus Populus, also known as poplars, are important woody species and considered model plants for perennial trees. High-density genetic maps are valuable genomic resources for population genetics. Here, we generated a high-quality and dense genetic map for an F1 poplar population using high-throughput NGS-based genotyping. A total of 92,097 high-quality SNP markers were developed by stringent filtering and identification. In total, 889 and 1650 SNPs formed the female and male genetic maps, respectively. To test the application of the genetic maps, QTL mapping of leaf shape was conducted for this F1 population. A total of nine parameters were scored for leaf shape variation in three different environments. Combining genetic maps and measurements of the nine leaf shape parameters, we mapped a total of 42 significant QTLs. The highest LOD score of all QTLs was 9.2, and that QTL explained the most (15.13%) trait variation. A total of nine QTLs could be detected in at least two environments, and they were located in two genomic regions. Within these two QTL regions, some candidate genes for regulating leaf shape were predicted through functional annotation. The successful mapping of leaf shape QTLs demonstrated the utility of our genetic maps. According to the performance of this study, we were able to provide high-quality and dense genetic maps and dissect the leaf shape variation in poplar.

Identification of TIFY Family Genes and Analysis of Their Expression Profiles in Response to Phytohormone Treatments and Melampsora larici-populina Infection in Poplar.

The TIFY domain contains approximately 36 conserved amino acids that form the core motif TIF[F/Y]XG, and they were reported to play important roles in plant growth, tissue development and defense regulation. Moreover, more and more evidence has shown that some members of the TIFY gene family perform their functions by modulating plant hormone signaling pathways. Poplar trees are found worldwide, and they comprise approximately 30 species. Benefit from the importance of poplar and its advanced platform, this tree is considered to be the model perennial plant. Here, we conducted a genome-wide identification of TIFY genes in poplar, and 24 TIFY genes were found. These 24 TIFY genes were assigned to different subfamilies according to the presence or absence of domains and motifs that they harbored. Careful analyses of their locations, structures, evolution and duplication patterns revealed an overview of this gene family in poplar. The expression profiles of these 24 TIFY genes were then analyzed in different tissues using publicly available expression data; their expression profiles following different JA/SA treatments and infection with leaf rust pathogen were also carefully examined by qRT-PCR assays. Based on their expression profiles, the functions of a number of TIFY genes could be predicted. By performing this study, we have provided valuable information for further functional characterisation of TIFY genes in poplar and candidate genes for the improvement of poplar disease resistance.

Synthesis, structures and properties of two metal-organic coordination polymers derived from manganese(ΙΙ), thiabendazole and polydentate carboxylic acids.

Two novel binuclear Mn(II) metal-organic coordination complexes [Mn2(TBZ)2(CDC)(C2O4)]n (1), {[Mn2(TBZ)2(BDC)(0.5)(BTC)(H2O)2]·ET}n (2), (where TBZ = thiabendazole, H2CDC = trans-1,4-cyclohexanedicarboxylic acid, H2C2O4 = oxalic acid, H3BTC = 1,3,5-benzenetricarboxylic acid, ET = ethanol, H2BDC = 1,4-benzenedicarboxylate) have been hydrothermally synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, electrochemical analysis and single crystal X-ray diffraction. The X-ray structure analysis reveals that 1 is s two-dimensional layer and 2 is s one-dimensional chain. In complex 1, it reveals 2-D layers composed of multi-(bidentate) bridging ligands (CDC and C2O4), and in 2, the coordinated BTC ligands adopt a monodentate mode and with BDC ligands adopt alternately chelating Mn1 and Mn2 bridges into 1-D chains. The 3-D structures of the two complexes are stabilized by π-π stacking interactions and hydrogen bonds.

[Study on the efficacy and safety of ultrasound ablation in treatment of uterine fibroids].

OBJECTIVE: To investigate the safety and efficacy of ultrasound ablation in treatment of uterine fibroids. METHODS: Ninety-nine patients with 117 leiomyomas in total treated by Haifu JC focused ultrasound tumor therapeutic system were enrolled in prospective and non-randomized clinical trial in First Affiliated Hospital of Chongqing Medical University and Academy of Military Medical Sciences. Ultrasound ablation was performed guided by real-time ultrasonography under conscious sedation for single session. All patients were followed up at 6 months after treatment. On the day of treatment and after 1 month, patients were given by magnetic resonance imaging (MRI) exam to evaluate the effect of fibroids ablation. At 3 and 6 months after treatment, the ratio of ablated area and volume reduction of fibroids more than 50% were evaluated by MRI exam again. The symptoms improvements were evaluated by uterine fibroid symptom (UFS) and complications were analyzed by guideline of society of international radiation (SIR). RESULTS: The average ablated area ratio of the target fibroid was (76 ± 24)%. The average reduction in fibroid volume determined by MRI at 3 and 6 months after treatment was (45 ± 21)% and (59 ± 26)%. Which were significantly decreased than those before treatment (P < 0.05). At 6 months after treatment, 84.6% (99/117) of patients showed more than 50% volume reduction, the rate of improved symptom score was 92% (66/72). All patients could resume normal daily activities at 2 hours after treatment. The adverse reactions of SIR C-D included delayed hospitalization, repeat treatment and increased level of nursing. E-F included permanent sequelae and death. In this study, no adverse reactions of C-F were recorded. Common complications (SIR A-B, only observation or simple management without sequelae) were 35% (35/99). Four cases with adverse reactions B of SIR were found, including 2 cases with skin burning of degree II and 2 cases with febrile, they were administered by symptomatic therapy and changing dressing. The other adverse reaction A of SIR included sorness of buttock, vaginal discharge, dysuria and painful urination, they were only suggested by follow-up. CONCLUSION: It was efficacy and safe that ultrasound ablation as a single strategy were used in treatment of uterine fibroids.

[Analysis of complications of high intensity focused ultrasound in treatment of uterine leiomyoma].

OBJECTIVE: To analysis complications and its associated risk factors of high intensity focused ultrasound (HIFU) in treatment of uterine leiomyoma for selecting rationale indicated patients and reducing complications. METHODS: Medical documents of 171 patients with 231 leiomyomas in total treated by HIFU were studied retrospectively. Common complications were categorized and analyzed, the relationship between risk factors and complications were studied. RESULTS: Common complications in treatment of uterine leiomyomas by HIFU were 71.9% (123/171) of abdominal pain, 17.5% (30/171) of vaginal bloody discharge, 8.2% (14/171) of sacroiliac or buttock pain, 7.6% (13/171) of skin blister, 4.7% (8/171) of leg pain, 2.9% (5/171) of hematuria and 1.8% (3/171) of febrile. By logistic regression analysis, the factor correlated with abdominal pain included diameter of uterine leiomyomas, sonication time and average power (P < 0.05). The factor correlated with sacroiliac or buttock pain was uterine leiomyomas located in posteriors of uterine wall (P < 0.05); the factors correlated with vaginal bloody discharge were sonication time and type of uterine leiomyomas (submucous > intramural > subserous, P < 0.05); the factors correlated with skin blister was sonication time (P < 0.05). There were no statistical relationship between multiple factors and leg pain, hematuria, febrile (P > 0.05). CONCLUSION: The modality of high-power and short-term treatment might reduce complications of HIFU ablation.