Tulip transcription factor TgWRKY75 activates salicylic acid and abscisic acid biosynthesis to synergistically promote petal senescence.

WRKY transcription factors play a central role in controlling plant organ senescence; however, it is unclear whether and how they regulate petal senescence in the widely grown ornamental plant tulip (Tulipa gesneriana). In this study, we report that TgWRKY75 promotes petal senescence by enhancing the synthesis of both abscisic acid (ABA) and salicylic acid (SA) in tulip and in transgenic Arabidopsis. The expression level of TgWRKY75 was up-regulated in senescent petals, and exogenous ABA or SA treatment induced its expression. The endogenous contents of ABA and SA significantly increased during petal senescence and in response to TgWRKY75 overexpression. Two SA synthesis-related genes, TgICS1 and TgPAL1, were identified as direct targets of TgWRKY75, which binds to their promoters. In parallel, TgWRKY75 activated the expression of the ABA biosynthesis-related gene TgNCED3 via directly binding to its promoter region. Site mutation of the W-box core motif located in the promoters of TgICS1, TgPAL1, and TgNCED3 eliminated their interactions with TgWRKY75. In summary, our study demonstrates a dual regulation of ABA and SA biosynthesis by TgWRKY75, revealing a synergistic process of tulip petal senescence through feedback regulation between TgWRKY75 and the accumulation of ABA and SA.

The R2R3-MYB Transcriptional Repressor TgMYB4 Negatively Regulates Anthocyanin Biosynthesis in Tulips (Tulipa gesneriana L.).

Anthocyanins play a paramount role in color variation and significantly contribute to the economic value of ornamental plants. The conserved activation complex MYB-bHLH-WD40 (MBW; MYB: v-myb avian myeloblastosis viral oncogene homolog; bHLH: basic helix-loop-helix protein; WD40:WD-repeat protein) involved in anthocyanin biosynthesis has been thoroughly researched, but there have been limited investigations into the function of repressor factors. In this study, we characterized TgMYB4, an R2R3-MYB transcriptional repressor which is highly expressed during petal coloration in red petal cultivars. TgMYB4-overexpressing tobaccos exhibited white or light pink petals with less anthocyanin accumulation compared to control plants. TgMYB4 was found to inhibit the transcription of ANTHOCYANIDIN SYNTHASE (TfANS1) and DIHYDRO-FLAVONOL-4-REDUCTASE (AtDFR), although it did not bind to their promoters. Moreover, the TgMYB4 protein was able to compete with the MYB activator to bind to the :bHLHprotein, thereby suppressing the function of the activator MBW complex. These findings demonstrate that TgMYB4 plays a suppressive role in the regulation of anthocyanin synthesis during flower pigmentation.

Lupus low disease activity state attainment in the phase 3 TULIP trials of anifrolumab in active systemic lupus erythematosus.

OBJECTIVES: In patients with systemic lupus erythematosus (SLE), lupus low disease activity state (LLDAS) attainment is associated with improved outcomes. We investigated LLDAS attainment in anifrolumab-treated patients. METHODS: We performed post hoc analysis of pooled Treatment of Uncontrolled Lupus via the Interferon Pathway (TULIP-1) (NCT02446912) and TULIP-2 (NCT02446899) anifrolumab phase 3 trial data in patients with moderate to severe SLE receiving standard therapy. LLDAS was defined as: SLE Disease Activity Index 2000 ≤4 without major organ activity, no new disease activity, Physician's Global Assessment ≤1, prednisone ≤7.5 mg/day and no non-standard immunosuppressant dosing. Time to first LLDAS attainment was compared between groups using Cox regression modelling; responses were compared using logistic regression. RESULTS: Agnostic to treatment, 205/819 (25.0%) patients attained LLDAS at week 52; 186/205 (90.7%) were also British Isles Lupus Assessment Group-based Composite Lupus Assessment (BICLA)-responders. Among BICLA-responders at week 52, 186/318 (58.5%) attained LLDAS; 203/380 (53.4%) SLE Responder Index-4 (SRI(4)) responders attained LLDAS. Improvements from baseline in patient global assessment scores at week 52 were threefold greater in LLDAS-attainers. At week 52, 30.0% of anifrolumab-treated patients and 19.6% of placebo were in LLDAS (OR 1.8, 95% CI 1.3 to 2.5, p=0.0011). Compared with placebo, anifrolumab treatment was associated with earlier LLDAS attainment (time to first LLDAS, HR 1.76, 95% CI 1.35 to 2.30, p<0.0001), increased cumulative time in LLDAS (p<0.0001) and higher likelihood of sustained LLDAS (p<0.001). Anifrolumab treatment was also associated with higher rates of Definition of Remission in SLE remission at week 52 (15.3% vs 7.6%; OR 2.2, 95% CI 1.4 to 3.6, p=0.0013). CONCLUSIONS: LLDAS attainment was highly associated with, but more stringent than, BICLA and SRI(4) responses. Compared with placebo, anifrolumab treatment was associated with earlier, more frequent, and more prolonged and sustained LLDAS. TRIAL REGISTRATION NUMBERS: NCT02446912 and NCT02446899.

Sustained glucocorticoid tapering in the phase 3 trials of anifrolumab: a post hoc analysis of the TULIP-1 and TULIP-2 trials.

OBJECTIVES: Glucocorticoid sparing is a key priority for SLE management. We evaluated the effects of sustained glucocorticoid tapering in patients with SLE. MATERIAL AND METHODS: This was a post hoc analysis of the randomized, placebo-controlled, 52-week phase 3 Treatment of Uncontrolled Lupus via the Interferon Pathway (TULIP)-1 and TULIP-2 trials of anifrolumab (300 mg i.v. once every 4 weeks for 48 weeks) plus standard therapy in patients with moderate to severe SLE. In a cohort of patients receiving glucocorticoids (prednisone or equivalent) 10 mg or more per day at baseline, we assessed changes in glucocorticoid dosage, patient-reported outcomes (PROs) and safety. Outcome measures were compared between sustained glucocorticoid taper responders (7.5 mg or less per day by week 40 sustained through week 52) and non-responders, regardless of treatment group, and between patients receiving anifrolumab or placebo. RESULTS: Among the 726 patients in the TULIP trials, 375 patients received glucocorticoids 10 mg or more per day at baseline, and of these, 155 (41%) patients were sustained glucocorticoid taper responders. Compared with non-responders (n = 220), sustained glucocorticoid taper responders reduced their mean cumulative glucocorticoid dose by 32%, improved PRO scores, reduced blood pressure and experienced fewer serious adverse events. Sustained glucocorticoid tapering was achieved by 51% (96/190) of patients receiving anifrolumab vs 32% (59/185) receiving placebo. Compared with placebo, more anifrolumab-treated patients achieved both sustained glucocorticoid taper and reduced overall disease activity [38% (72/190) vs 23% (43/185)]. CONCLUSIONS: Sustained glucocorticoid tapering is associated with clinical benefits. Anifrolumab treatment has potential to reduce disease activity and glucocorticoid exposure, a key goal of SLE management. STUDY REGISTRATION: ClinicalTrials.gov identifier: NCT02446912 and NCT02446899.

NAC transcription factor TgNAP promotes tulip petal senescence.

Petal senescence is a crucial determinant for ornamental quality and economic value of floral crops. Salicylic acid (SA) and reactive oxygen species (ROS) are two prominent factors involved in plant senescence regulation. In this study, tulip TgNAP (NAC-like, activated by APETALA3/PISTILLATA) was characterized as positively regulating tulip petal senescence through dually regulating SA biosynthesis and ROS detoxification pathways. TgNAP was upregulated in senescing petals of tulip while exogenous SA and H2O2 treatments substantially promoted petal senescence in tulip. Silencing of TgNAP by VIGS assay delayed SA and H2O2-induced petal senescence in tulip, whereas overexpression of TgNAP promoted the senescence process in Arabidopsis (Arabidopsis thaliana) plants. Additionally, inhibition of SA biosynthesis prolonged the lifespan of TgNAP-silenced petal discs. Further evidence indicated that TgNAP activates the transcriptions of two key SA biosynthetic genes ISOCHORISMATE SYNTHASE 1 (TgICS1) and PHENYLALANINE AMMONIA-LYASE 1 (TgPAL1) through directly binding to their promoter regions. Meanwhile, TgNAP repressed ROS scavenging by directly inhibiting PEROXIDASE 12 (POD12) and POD17 expression. Taken together, these results indicate that TgNAP enhances SA biosynthesis and ROS accumulation to positively regulate petal senescence in tulip.

The Uniform grading tooL for flexIble ureterorenoscoPes (TULIP-tool): a Delphi consensus project on standardised evaluation of flexible ureterorenoscopes.

OBJECTIVE: To develop a standardised tool to evaluate flexible ureterorenoscopes (fURS). MATERIALS AND METHODS: A three-stage consensus building approach based on the modified Delphi technique was performed under guidance of a steering group. First, scope- and user-related parameters used to evaluate fURS were identified through a systematic scoping review. Then, the main categories and subcategories were defined, and the expert panel was selected. Finally, a two-step modified Delphi consensus project was conducted to firstly obtain consensus on the relevance and exact definition of each (sub)category necessary to evaluate fURS, and secondly on the evaluation method (setting, used tools and unit of outcome) of those (sub)categories. Consensus was reached at a predefined threshold of 80% high agreement. RESULTS: The panel consisted of 30 experts in the field of endourology. The first step of the modified Delphi consensus project consisted of two questionnaires with a response rate of 97% (n = 29) for both. Consensus was reached for the relevance and definition of six main categories and 12 subcategories. The second step consisted of three questionnaires (response rate of 90%, 97% and 100%, respectively). Consensus was reached on the method of measurement for all (sub)categories. CONCLUSION: This modified Delphi consensus project reached consensus on a standardised grading tool for the evaluation of fURS - The Uniform grading tooL for flexIble ureterorenoscoPes (TULIP) tool. This is a first step in creating uniformity in this field of research to facilitate future comparison of outcomes of the functionality and handling of fURS.

Gunther Tulip Filter Strut Penetration: Benign Long-Term Follow-up.

PURPOSE: To describe the natural history of Gunther Tulip filter (GTF) strut penetration based on the computed tomography (CT)-documented distance penetrated over time and any clinical manifestations. MATERIALS AND METHODS: The records of 203 patients (mean age, 59.1 years; 59.4% men) who had had an infrarenal GTF placed for venous thromboembolism (84.2%) with contraindications to anticoagulation (95.1%) and had CT follow-up were reviewed retrospectively for clinical or imaging evidence of complications. Filter strut penetration was measured on axial images from the outer caval wall to the inner edge of the distal end of each strut. Filter strut behavior over time was modeled using a linear mixed model. RESULTS: The extent of penetration correlated positively with filter dwell time (P < .001) but plateaued at 3.3 mm at 10-year follow-up. At median 4.7-year follow-up 79.3% of patients had at least 1 strut that was >0.2 mm and 31% had a strut >3 mm from the inferior vena caval wall. The extent of strut penetration was greater at all time points for women (P = .002). Abutment or entry into an adjacent structure was identified in 183 struts of 105 (52.7%) filters; of the 80 filters with CT follow-up, 47% showed progression and 19% regressed. There were no symptoms referable to filter strut penetration. CONCLUSIONS: GTF struts often penetrate the inferior vena cava progressively; however, this tends to plateau by 10 years. The limited long-term progression and a very low incidence of symptomatic complications together support a noninterventional approach to the finding of an asymptomatic GTF strut penetration.

Transcription factors TgbHLH42-1 and TgbHLH42-2 positively regulate anthocyanin biosynthesis in Tulip (Tulipa gesneriana L.).

The floral coloration of tulip flowers is one of the most prominent traits contributing to its high ornamental value. The molecular mechanisms of petal coloration remain elusive in tulip species. In this study, we performed comparative metabolome and transcriptome analyses using four tulip cultivars with distinguished petal colors. Four types of anthocyanins were identified, including cyanidin derivatives and pelargonidin derivatives. Comparative transcriptome analysis identified 22,303 differential expressed genes (DEGs) from the four cultivars, and 2589 DEGs were commonly regulated in three comparison groups (colored vs. white cultivar), including anthocyanins biosynthesis-related genes and regulatory transcription factors. Two basic helix-loop-helix (bHLH) transcription factors, TgbHLH42-1 and TgbHLH42-2, with differential expression levels among cultivars and petal developmental stages, have high homology to TRANSPARENT TESTA 8 (AtTT8) of Arabidopsis. The anthocyanins accumulation in TgbHLH42-1 overexpressing (OE) seedlings was markedly greater than that in wild-type seedlings in the presence of methyl jasmonate (MeJA), but not for TgbHLH42-2 OE seedlings. Both TgbHLH42-1 and TgbHLH42-2 restored pigmentation defects in tt8 mutant seeds after complementation assay. TgbHLH42-1 could interact with MYB protein AtPAP1 to synergistically activate the transcription of AtDFR, whereas TgbHLH42-2 failed to. Silencing TgbHLH42-1 or TgbHLH42-2 individually could not, but simultaneously silencing both TgbHLH42 could reduce the anthocyanin in tulip petals. These results indicate that TgbHLH42-1 and TgbHLH42-2 function partially redundantly to positively regulate anthocyanin biosynthesis during tulip petal coloration.

Bilateral sacroiliac joint fusion in long constructs using self-harvesting porous S2-alar iliac screws with an integrated tulip: technical considerations and early clinical and radiographic experience.

OBJECTIVE: The incidence of sacroiliac joint (SIJ) dysfunction after lumbosacral fusion is high. Upfront bilateral SIJ fusion using novel fenestrated self-harvesting porous S2-alar iliac (S2AI) screws could reduce the incidence of SIJ dysfunction and need for subsequent SIJ fusion. In this study, the authors report their early clinical and radiographic results of SIJ fusion using this novel screw. METHODS: The authors began using self-harvesting porous screws in July 2022. This is a retrospective review of consecutive patients at a single institution who underwent long thoracolumbar surgery with extension to the pelvis using this porous screw. Radiographic parameters of regional and global alignment were collected preoperatively and at the time of last follow-up. The incidence of intraoperative complications and need for revision were collected. The incidences of mechanical complications, including screw breakage, implant loosening/pullout, and screw cap dislocation at the time of last follow-up were also collected. RESULTS: Ten patients with a mean age of 67 years were included, 6 of whom were male. Seven patients had a thoracolumbar construct with extension to the pelvis. Three patients had upper instrumented vertebrae at the proximal lumbar spine. Intraoperative breach was not encountered in any of the patients (0%). Postoperatively, 1 patient (10%) had screw breakage at the neck of the tulip of the modified iliac screw discovered at routine follow-up without clinical sequalae. CONCLUSIONS: Use of self-harvesting porous S2AI screws incorporated into long thoracolumbar constructs was safe and feasible, demanding unique technical considerations. Long-term clinical and radiographic follow-up with a large patient cohort is necessary to determine their durability and efficacy to achieve SIJ arthrodesis and prevent SIJ dysfunction.

A practical method for the retrieval of tulip-head polyaxial pedicle screw by reusing the rod in revision and implants removal surgery: introduction of technique and evaluation of clinical outcomes.

BACKGROUND: The removal of spinal implants is needed in revision surgery or in some cases whose fracture had healed or fusion had occurred. The slip of polyaxial screw or mismatch of instruments would make this simple procedure intractable. Here we introduce a simple and practical method to address this clinical dilemma. METHODS: This is a retrospective study. The patients underwent new technique for retrieving the implants from July 2019 to July 2022 were labeled as group A, while the patients underwent traditional implants retrieval technique from January 2017 to January 2020 were labeled as group B. Patients in each group were subdivided into revision surgery group (r group) and simple implants removal group (s group) according to the surgery fashion. For the new technique, the retrieved rod was cut off to a proper length which was matched with the size of tulip head, and was replaced into the tulip head. After tightened with nut, a monoaxial screw-rod "construct" was formed. Then the "construct" can be retrieved by a counter torque. The operation duration, intraoperative blood loss, post-operative bacteria culture, hospital stay and costs were analyzed. RESULTS: A total of 116 polyaxial screws with difficult retrieval (43 screws in group A, 73 screws in group B) in 78 patients were recorded, in which 115 screws were successfully retrieved. Significant differences were found in the mean operation duration, intraoperative blood loss when comparing the r group in group A and B, as well as the s group in group A and B (P < 0.05). There were no significant differences in hospital stay and costs between group A and B. Three patients were found positive bacteria culture of drainage tube/tape in group A (3/30), while 7 patients in group B (7/48). The most prevalent bacteria was Propionibacterium acnes. CONCLUSION: This technique is practical and safe in retrieving tulip head poly-axial screw. Reduced operation duration and intraoperative bloods loss may potentially alleviate the hospitalization burden of patients. Positive bacterial cultivation results are common after implants removal surgery, but they rarely represent an organized infection. A positive culture with P. acnes or S. epidermidis should be interpreted with caution.

Assessment of heavy metal stress in the adaptation strategies of Tulipa luanica growing on serpentine soil through some biomarkers in comparison to Tulipa kosovarica.

The aim of this study was to gain a better understanding of how Tulipa luanica adapts to growth in soil with higher concentrations of heavy metals and to assess potential toxic effects using various biomarkers, in comparison to Tulipa kosovarica, a typical serpentine species. For this purpose, we analyzed the concentrations of Al, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb, and Zn in the soil, as well as their accumulation in plants and their associated stress effects. The results indicate that, despite the presence of some metals in very high concentrations in the soil (Al, Fe, Mn, and Ni), they are translocated in minimal amounts within plant organs, particularly in T. luanica. Nearly all metals exhibited significantly higher concentrations in T. kosovarica when compared to T. luanica. Based on the analysis of biomarkers, it is apparent that T. luanica shows greater sensitivity to these conditions. This is evident through the decreased activity of δ-aminolevulinic acid dehydratase and levels of δ-aminolevulinic acid, malondialdehyde, and glutathione observed in T. luanica. It appears that T. luanica effectively restricts the absorption of metals in serpentine soils; however, it experiences oxidative stress induced by these metals, setting it apart from the more resilient T. kosovarica.

The efficacy and safety of anifrolumab in Japanese patients with systemic lupus erythematosus: TULIP-2 subanalysis.

OBJECTIVES: Evaluate the efficacy and safety of anifrolumab in the subpopulation of Japanese patients with systemic lupus erythematosus (SLE) in phase 3 TULIP-2 trial. METHODS: TULIP-2 was a 52-week randomized placebo-controlled trial (N = 362) that evaluated efficacy and safety of anifrolumab 300 mg IV every 4 weeks vs. placebo in patients with moderate to severe SLE who were receiving standard therapy. We performed a post hoc analysis of the primary and key secondary endpoints, and safety, of TULIP-2 in the Japanese subpopulation. RESULTS: In the Japanese subpopulation (anifrolumab, n = 24; placebo, n = 19), the proportion of patients who achieved a British Isles Lupus Assessment Group-based Composite Lupus Assessment response at Week 52 (primary endpoint) was greater in the anifrolumab group vs. placebo [50.0% (12/24) vs. 15.8% (3/19); treatment difference: 34.2%, 95% confidence interval 6.9, 61.5; nominal p = .014]. Improvement in skin activity and flare rates (key secondary endpoints) were favourable for anifrolumab vs. placebo. Consistent with the overall population, anifrolumab had an acceptable safety and tolerability profile. CONCLUSIONS: The efficacy and safety of anifrolumab 300 mg in Japanese patients with SLE was consistent with the demonstrated clinical profile of anifrolumab for the overall TULIP-2 population.

Pharmacokinetics of glaucine after intravenous and oral administrations and detection of systemic aporphine alkaloids after ingestion of tulip poplar shavings in horses.

Glaucine, an aporphine alkaloid with anti-tussive, anti-inflammatory, and anti-nociceptive properties, has been identified in post-race samples from racehorses. To investigate pharmacokinetics of glaucine in horses, a three-way crossover study of intravenous and oral glaucine (0.1 mg/kg) and orally administered tulip poplar shavings (50 g shavings = 0.001 mg/kg glaucine) was performed in six horses. A two-compartment model best described IV administration with alpha ( t 1 / 2 α ) and beta ( t 1 / 2 ß ) half-life lives of 0.3 (0.1-0.7) and 3.1 (2.4-7.8) h, respectively. The area under the curve ( AUC 0 ∞ iv ) was 45.4 (34.7-52.3) h*ng/ml, and the volume of distribution of the central (Vdc ) and peripheral (Vdp ) compartments was 2.7 (1.3-4.6) and 4.9 (4.3-8.2) L/kg, respectively. A one compartment model best described the oral administration of glaucine with absorption ( t 1 / 2 ka ) and elimination ( t 1 / 2 kel ) half-lives of 0.09 (0.05-0.15) and 0.7 (0.6-0.8) h, respectively. The area under the curve ( AUC 0 ∞ PO ) was 15.1 (8.0-19.5) h·ng/ml. Bioavailability following oral administration was 17%-48%. Following ingestion of shavings, glaucine and liriodenine were detectable in plasma for up to 16 and 48 h, respectively. Glaucine was quantifiable briefly in the urine from two horses. Liriodenine was quantifiable in urine for 12-20 h in four horses and for 48 h in two horses. The presence of liriodenine indicates ingestion of tulip poplar tree parts, however, does not rule out co-administration of purified glaucine in horses.

Characterization of tulip streak virus, a novel virus associated with the family Phenuiviridae.

In Japan, tulip-growing areas have been plagued by viral diseases for decades, but the viruses causing the damage remain undescribed. In this study, Nicotiana benthamiana and Chenopodium quinoa plants mechanically inoculated with crude sap from a symptomatic tulip flower exhibited necrosis symptoms. Additionally, flexuous and filamentous virus particles were detected by electron microscopy analysis. Moreover, we determined the complete sequences of two genomic segments of the tulip streak virus (TuSV), which is a new virus associated with streaking symptoms, on the basis of a next-generation sequencing analysis. Homology analyses of the amino acid sequence of RNA-dependent RNA polymerase and the terminal sequence of the genomic RNA indicated that TuSV is associated with viruses in the family Phenuiviridae, but differs substantially from other reported viruses.

One year later: The effect of changing azole-treated bulbs for organic tulips bulbs in hospital environment on the azole-resistant Aspergillus fumigatus rate.

Azole-treated plant bulbs have already been evoked as a potential explanation of the worldwide spread of azole-resistant Aspergillus fumigatus (ARAf). We previously pointed out the presence of a high rate of ARAf (71% of A. fumigatus detected on azole-supplemented media) in flower beds containing azole-treated bulbs at the hospital's surroundings. We show here that planting organic bulbs can be a solution to reduce ARAf burden (from 71% rate to below 3%). The results suggest that replacing treated bulbs with organic bulbs may be sufficient to regain a population that is predominantly susceptible in just 1 year. LAY SUMMARY: Antifungal resistance is increasingly observed in fungal pathogens. This study argues that planting organic bulbs in hospitals' outdoor surroundings could be a good alternative to continue to beautify green spaces, without the risk of dissipating antifungal-resistant fungal pathogens.

The effects of single and a combination of determinants of anaemia in the very old: results from the TULIPS consortium.

BACKGROUND AND OBJECTIVES: Nutritional deficiencies, renal impairment and chronic inflammation are commonly mentioned determinants of anaemia. The aim of this study was to investigate the effects of these determinants, singly and in combination, on anaemia in the very old. METHOD: The TULIPS Consortium consists of four population-based studies in oldest-old individuals: Leiden 85-plus Study, LiLACS NZ, Newcastle 85+ study, and TOOTH. Five selected determinants (iron, vitamin B12, and folate deficiency; low estimated glomerular filtration rate (eGFR); and high C-reactive protein (CRP)) were summed. This sum score was used to investigate the association with the presence and onset of anaemia (WHO definition). The individual study results were pooled using random-effects models. RESULTS: In the 2216 participants (59% female, 30% anaemia) at baseline, iron deficiency, low eGFR and high CRP were individually associated with the presence of anaemia. Low eGFR and high CRP were individually associated with the onset of anaemia. In the cross-sectional analyses, an increase per additional determinant (adjusted OR 2.10 (95% CI 1.85-2.38)) and a combination of ≥2 determinants (OR 3.44 (95% CI 2.70-4.38)) were associated with the presence of anaemia. In the prospective analyses, an increase per additional determinant (adjusted HR 1.46 (95% CI 1.24-1.71)) and the presence of ≥2 determinants (HR 1.95 (95% CI 1.40-2.71)) were associated with the onset of anaemia. CONCLUSION: Very old adults with a combination of determinants of anaemia have a higher risk of having, and of developing, anaemia. Further research is recommended to explore causality and clinical relevance.

Content of Phenolic Compounds and Organic Acids in the Flowers of Selected Tulipa gesneriana Cultivars.

The study focused on the determination of phenolic acids, flavonoids and organic acids in five tulip cultivars 'Barcelona', 'Columbus', 'Strong Gold', 'Super Parrot' and 'Tropicana'. The cultivars grown in field and in a greenhouse were exposed after cutting to different times of storage (0, 3 and 6 days). The phenolic profile contained 4-hydroxybenzoic, 2,5-dihydroxybenzoic, gallic, vanillic, syringic, salicylic, protocatechuic, trans-cinnamic, p-coumaric, caffeic, ferulic, chlorogenic and sinapic acids, as well as quercetin, rutin, luteonin, catechin and vitexin. The mean phenolic acid content was in the following order: 'Columbus' and 'Tropicana' > 'Barcelona' > 'Strong Gold' > 'Super Parrot', while the levels of flavonoids were as follows: 'Strong Gold' > 'Barcelona' > 'Tropicana' > 'Columbus' > 'Super Parrot'. The highest content of phenolic acids was confirmed for Columbus and Tropicana, while the lowest was for Super Parrot. However total phenolic content was very similar, observed between the place of cultivation, time of storage and cultivars. Malonic, succinic, acetic and citric acids were the major organic acid components in tulip petals. More organic acids (except malonic) were accumulated in tulip petals from fields than those from the greenhouse, while changes during storage were strictly correlated with cultivars.

Comparative physiological and metabolomic analyses reveal natural variations of tulip in response to storage temperatures.

MAIN CONCLUSION: Three tulip cultivars were screened out with successful bloom after a short-term cold treatment, and the differential responses to postharvest cold treatment were analyzed between two contrasting tulip cultivars. Tulip is one of the most important ornamental bulbous plants in the world. A precious precooling treatment during bulb postharvest is required for optimal floral stalk elongation and flower development in tulip. In this study, the naturally growing and flowering variations of tulip to storage temperatures were analyzed after long-term cold (LTC) and short-term cold (STC) treatments. Three cultivars were screened out with successful blooming after STC, which included 'Dow Jones' (DJ), 'Van Eijk' (VE) and 'World's Favourite' (WF) (5 °C for 2 weeks). Comparative analysis revealed that DJ cultivar maintained normal and intact reproductive organs under STC condition, while the 'Orange Emperor' (OE) cultivar, which failed blooming after STC treatment, showed gradually destroyed reproductive organs under STC condition. In addition, the DJ cultivar accumulated lower ROS levels and higher antioxidant enzyme activities, as well as significantly higher contents of total primary metabolites than OE to maintain normal shoot growth and floral organ development under STC condition. The relative expression levels of genes involved in vernalization and/or flower time regulation in DJ were significantly higher than those in OE after STC treatment. This study provides new insights into understanding the underlying mechanism of natural variation of tulip cultivars during postharvest storage treatment.

Tulipa gesneriana and Lilium longiflorum PEBP Genes and Their Putative Roles in Flowering Time Control.

Floral induction in Tulipa gesneriana and Lilium longiflorum is triggered by contrasting temperature conditions, high and low temperature, respectively. In Arabidopsis, the floral integrator FLOWERING LOCUS T (FT), a member of the PEBP (phosphatidyl ethanolamine-binding protein) gene family, is a key player in flowering time control. In this study, one PEBP gene was identified and characterized in lily (LlFT) and three PEBP genes were isolated from tulip (TgFT1, TgFT2 and TgFT3). Overexpression of these genes in Arabidopsis thaliana resulted in an early flowering phenotype for LlFT and TgFT2, but a late flowering phenotype for TgFT1 and TgFT3. Overexpression of LlFT in L. longiflorum also resulted in an early flowering phenotype, confirming its proposed role as a flowering time-controlling gene. The tulip PEBP genes TgFT2 and TgFT3 have a similar expression pattern in tulip, but show opposite effects on the timing of flowering in Arabidopsis. Therefore, the difference between these two proteins was further investigated by interchanging amino acids thought to be important for the FT function. This resulted in the conversion of phenotypes in Arabidopsis upon overexpressing the substituted TgFT2 and TgFT3 genes, revealing the importance of these interchanged amino acid residues. Based on all obtained results, we hypothesize that LlFT is involved in creating meristem competence to flowering-related cues in lily, and TgFT2 is considered to act as a florigen involved in the floral induction in tulip. The function of TgFT3 remains unclear, but, based on our observations and phylogenetic analysis, we propose a bulb-specific function for this gene.

Molecular Regulation of Temperature-Dependent Floral Induction in Tulipa gesneriana.

The vegetative-to-reproductive phase change in tulip (Tulipa gesneriana) is promoted by increasing temperatures during spring. The warm winters of recent years interfere with this process and are calling for new adapted cultivars. A better understanding of the underlying molecular mechanisms would be of help, but unlike the model plant Arabidopsis (Arabidopsis thaliana), very little is known about floral induction in tulip. To shed light on the gene regulatory network controlling flowering in tulip, RNA sequencing was performed on meristem-enriched tissue collected under two contrasting temperature conditions, low and high. The start of reproductive development correlated with rounding of the shoot apical meristem and induction of TGSQA expression, a tulip gene with a high similarity to Arabidopsis APETALA1 Gene Ontology enrichment analysis of differentially expressed genes showed the overrepresentation of genes potentially involved in floral induction, bulb maturation, and dormancy establishment. Expression analysis revealed that TERMINAL FLOWER1 (TgTFL1) and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1-like1 (TgSOC1-like1) might be repressors, whereas TgSOC1-like2 likely is an activator, of flowering. Subsequently, the flowering time-associated expression of eight potential flowering time genes was confirmed in three tulip cultivars grown in the field. Additionally, heterologous functional analyses in Arabidopsis resulted in flowering time phenotypes in line with TgTFL1 being a floral repressor and TgSOC1-like2 being a floral activator in tulip. Taken together, we have shown that long before morphological changes occur in the shoot apical meristem, the expression of floral repressors in tulip is suppressed by increased ambient temperatures, leading either directly or indirectly to the activation of potential flowering activators shortly before the commencement of the phase change.