A plant-derived compound called ailanthone reduced HSV-1 replication in several cell models and eased corneal disease in a mouse model of herpes simplex keratitis, according to the study. The researchers found that ailanthone acted mainly after the virus entered cells and linked much of this effect to reduced expression of integrin beta 2, or ITGB2, a host protein that supports viral replication. The results identify ailanthone as a potential drug candidate, but the experiments do not establish that it is safe or effective in people.

The team began by screening natural compounds and testing ailanthone in African green monkey kidney Vero cells infected with HSV-1. Concentrations of 100 to 3,000 nanomolar reduced transcription of the viral immediate-early genes ICP0 and ICP4 and the late gene gD in a dose-dependent manner. The compound also reduced plaque formation and the concentration of progeny virus released into culture. Ailanthone had a half-maximal cytotoxic concentration above 10,000 nanomolar in these cells, while its half-maximal effective concentration against viral replication was 197.4 nanomolar, giving a selectivity index greater than 50. It also suppressed HSV-1-induced increases in the inflammatory cytokine genes IL-1B and TNF-α.

Antiviral activity was subsequently observed in human corneal epithelial cells, a model more directly relevant to the tissue affected by keratitis. Ailanthone concentrations of 100 to 500 nanomolar markedly reduced the cytopathic effects of HSV-1F, lowered expression of ICP0, ICP4 and gD, and reduced the viral induction of IL-1B and TNF-α. Its effective concentration in these cells was 50.16 nanomolar, with a cytotoxicity concentration above 10,000 nanomolar and a selectivity index greater than 100. The researchers also tested the compound in human retinal pigment epithelial ARPE-19 cells, where it reduced viral gene expression, plaque formation and progeny-virus titers while showing low cytotoxicity.

Activity was not restricted to the laboratory HSV-1F strain. In ARPE-19 cells, ailanthone concentration-dependently inhibited the late gD gene in the clinical acyclovir-resistant strain HSV-1/153, whereas 1,000 nanomolar acyclovir had little effect. The compound’s effective concentration was 35.05 nanomolar against HSV-1F and 227.4 nanomolar against HSV-1/153, with selectivity indices above 100 for both strains. A time-of-addition experiment indicated that ailanthone did not prevent attachment of HSV-1 to cells. It reduced entry under one experimental schedule and had its strongest effect on post-entry replication, where it lowered gD expression.

To investigate how the compound might work, the researchers combined computational target prediction with protein-interaction network analysis. They identified 36 targets shared by ailanthone and herpes simplex keratitis, then selected ITGB2 as a highly connected hub in the resulting network and as a top candidate in molecular docking. The predicted docking score for ailanthone and ITGB2 was −8.6 kcal per mole. Computational predictions alone cannot establish direct binding, so the team also performed a drug affinity responsive target stability assay in THP-1 cell lysates. Ailanthone protected ITGB2 from digestion by the protease pronase E in a dose-dependent manner, while acyclovir did not, providing biochemical evidence consistent with a direct interaction.

Functional experiments then tested whether ITGB2 was necessary for the antiviral effect. Three independent small interfering RNAs reduced ITGB2 messenger RNA and protein in THP-1 cells. Following HSV-1 infection, this knockdown lowered gD messenger RNA and protein and reduced the number of plaques produced when culture supernatants were transferred to fresh Vero cells. The converse pattern appeared when ITGB2 was overexpressed: elevated ITGB2 increased gD expression in infected cells, and it partially counteracted the reduction in gD protein caused by ailanthone in 293T and ARPE-19 cells. Together, these loss- and gain-of-function results support the conclusion that ailanthone’s antiviral activity is mediated at least partly by lowering ITGB2.

The researchers next tested ailanthone in an acute mouse model of HSV-1 keratitis. Six-week-old male BALB/c mice received a corneal scratch followed by application of HSV-1F, then received intraperitoneal ailanthone at 1 or 5 milligrams per kilogram or acyclovir at 5 milligrams per kilogram on days 1, 3 and 5 after infection. The methods section states that six animals were assigned to each group, although the discussion says five mice per group were used in the animal experiment. The 5-milligram-per-kilogram ailanthone treatment significantly reduced clinical disease scores, improved the appearance of the cornea under normal and cobalt-blue illumination, and lowered fluorescein staining scores on days 3 and 5. Hematoxylin and eosin staining at day 6 also indicated reduced corneal inflammation, and viral titers in ocular swabs were significantly lower than in infected mice given vehicle.

Analysis of mouse corneal tissue was consistent with the proposed mechanism. ITGB2 was upregulated in the corneas of infected animals, and ailanthone reduced its fluorescence intensity in a dose-dependent manner. Acyclovir did not significantly alter corneal ITGB2 levels. The investigators interpreted this as evidence that ailanthone differs from a direct viral DNA-replication inhibitor: the data are consistent with modulation of a host dependency factor rather than action solely through a viral enzyme. However, the study did not determine precisely how binding to ITGB2 leads to lower protein abundance. The authors note that transcriptional regulation, changes in messenger-RNA stability, or enhanced protein degradation could all be involved, and dedicated experiments would be required to distinguish among them.

Several limitations constrain how far the findings can be generalized. The cell experiments used established lines, including corneal epithelial and retinal pigment epithelial cells, rather than primary human corneal cells or an intact human immune system. The animal experiment examined acute primary infection in young male mice, whereas recurrent reactivation and the inflammation associated with repeated episodes are important features of human herpes simplex keratitis. Ailanthone was administered by intraperitoneal injection, but no topical ophthalmic formulation, corneal penetration, intraocular distribution, or optimized dosing regimen was evaluated. Long-term ocular toxicity and safety under repeated exposure also remain unknown. The natural compound may additionally affect multiple targets, and compensation among integrins could limit or alter its effects. The evidence therefore supports further preclinical investigation of ailanthone and ITGB2 as a host-directed antiviral strategy, not a clinical recommendation or a claim of human therapeutic benefit.

Subject of Research: Preclinical evaluation of ailanthone as a host-directed inhibitor of HSV-1 replication and herpes simplex keratitis.

Article Title: Natural compound ailanthone alleviates herpes simplex keratitis in mice by inhibiting HSV-1 replication

Article References: Chen, L., Yang, E., Zhang, X., Zhang, L., Wu, L., Chen, S., Jin, W., Qin, Q., Chen, R., Wu, J., & Chen, D. (2026). Natural compound ailanthone alleviates herpes simplex keratitis in mice by inhibiting HSV-1 replication. Frontiers in Pharmacology, 17, Article 1937590. https://doi.org/10.3389/fphar.2026.1937590

Image Credits: AI Generated

DOI: 10.3389/fphar.2026.1937590

Keywords: HSV-1, herpes simplex keratitis, ailanthone, ITGB2, host-directed antivirals, viral replication, corneal infection, mouse model, integrin beta 2, drug resistance, Natural, compound

The PLOS One editors have issued an expression of concern for a 2024 case study concerning the digital economy, innovation factor allocation and industrial structure transformation in China’s Yangtze River Delta city cluster. The notice, published on October 21, 2026, states that the article was identified as one of a series of submissions for which the journal has concerns about the integrity or reliability of the peer-review process. Readers are advised to interpret the original study with this issue in mind.

The notice does not report a new scientific finding, identify an error in the paper or evaluate the study’s scientific validity. According to the editors, PLOS did not assess the article’s integrity or scientific validity when following up on the matter. The expression of concern therefore records a concern about the circumstances surrounding peer review rather than announcing that the study’s data, methods or conclusions have been disproved. The editors also state that they have no concerns regarding the authors’ conduct during the peer-review process.

The affected article was published in PLOS One in 2024 under the title “Digital economy, innovation factor allocation and industrial structure transformation—A case study of the Yangtze River Delta city cluster in China.” The supplied notice does not provide the study’s findings, population details, analytical methods, model estimates, uncertainty measures or specific mechanisms linking the subjects named in the title. As a result, the notice does not support conclusions about the relationship between digital-economy development, innovation factors and industrial structure in the region, nor does it establish whether any reported association or causal effect is reliable.

For the wider research record, the immediate effect is that the 2024 article is accompanied by an editorial notice questioning the integrity or reliability of its peer-review process. The notice does not provide details about the submissions or explain the specific basis for the journal’s concerns. It also does not announce a correction, replacement analysis or revised conclusion. The central status of the paper’s scientific validity remains unevaluated in the supplied material, while the issue is sufficiently significant for PLOS One to advise readers to consider it when interpreting the study.

Subject of Research: A PLOS One expression of concern concerning peer-review reliability in a Yangtze River Delta regional-economy case study.

Article Title: Expression of Concern: Digital economy, innovation factor allocation and industrial structure transformation—A case study of the Yangtze River Delta city cluster in China

Article References: The PLOS One Editors (2026). Expression of Concern: Digital economy, innovation factor allocation and industrial structure transformation—A case study of the Yangtze River Delta city cluster in China. PLOS One, 21(10), e0360867. https://doi.org/10.1371/journal.pone.0360867

Image Credits: AI Generated

DOI: 10.1371/journal.pone.0360867

Keywords: PLOS One, expression of concern, peer review, research integrity, digital economy, innovation factors, industrial structure, Yangtze River Delta, China, Expression, Concern, Digital

A retrospective study of 1,307 patients undergoing elective percutaneous vertebroplasty for osteoporotic vertebral compression fractures found that 136, or 10.4%, had a puncture-site wound event within two weeks of surgery. The composite outcome included erythema or swelling, bleeding or exudate, subcutaneous hematoma, and infection. After adjustment for patient and procedural factors, suture closure was associated with more than twice the risk of the composite outcome, while diabetes, mildly elevated international normalized ratio, and multilevel treatment were also associated with higher risk.

The findings come from consecutive patients treated at Ningde Municipal Hospital in China between January 2022 and June 2026. Patients were excluded if they underwent surgery for a new fracture, had uncontrolled coagulation disorders, received concomitant open spinal surgery, required an intraoperative incision at the puncture site, had malignant tumors or abnormal immune status, or lacked key clinical or follow-up information. The analysis therefore describes elective vertebroplasty performed within one hospital system, rather than all fracture patients or all puncture wounds treated after other forms of spine surgery.

Researchers extracted information from electronic medical records, operative and anesthesia records, laboratory reports, dressing-change notes, wound-clinic assessments, and documented telephone follow-up. All puncture sites were covered with waterproof dressings and assessed within two weeks through inpatient observation, clinical review, or telephone follow-up. A wound event was counted only when explicitly documented in the records. Erythema, swelling, bleeding, exudate, hematoma, and infection were combined into one patient-level outcome, counted once even if a patient experienced several types of event, while individual components were also summarized separately.

Closure was not assigned through a randomized comparison. The operating physician selected nonsuture or suture closure according to intraoperative bleeding, exudation, skin condition, wound tension, and routine practice. Sutured wounds were typically closed with one 3-0 Vicryl Rapide stitch. Among the 1,307 patients, 774 received nonsuture closure and 533 received sutures. An early event was recorded in 53 nonsuture cases, or 6.8%, and in 83 sutured cases, or 15.6%. The crude risk ratio for any event was 2.27, with a 95% confidence interval of 1.64 to 3.15 and a P value below 0.001.

After the researchers adjusted for closure method, diabetes, INR above 1.2, age, sex, body mass index, and multilevel treatment, the association with suturing remained. The adjusted risk ratio was 2.24, with a 95% confidence interval of 1.59 to 3.16 and P below 0.001. Diabetes was associated with an adjusted risk ratio of 1.57, with a 95% confidence interval of 1.11 to 2.21 and P equal to 0.010. An INR above 1.2, defined using the hospital laboratory’s upper reference limit, was associated with an adjusted risk ratio of 1.66, with a 95% confidence interval of 1.08 to 2.57 and P equal to 0.022. Multilevel treatment had an adjusted risk ratio of 1.73, with a 95% confidence interval of 1.03 to 2.89 and P equal to 0.038.

The component findings were concentrated in relatively common superficial manifestations rather than infection. Erythema or swelling occurred in 4.1% of patients with nonsuture closure and 10.9% of those with sutures, producing a crude risk ratio of 2.63, with a 95% confidence interval of 1.73 to 3.99. Bleeding or exudate occurred in 2.7% and 5.8% of the respective groups, with a crude risk ratio of 2.14 and a 95% confidence interval of 1.25 to 3.69. Subcutaneous hematoma was uncommon, affecting two nonsuture cases and three sutured cases, and its wide confidence interval included no difference. Infection was documented in one nonsuture case and no sutured cases, too few events to model infection separately.

Age, sex, and body mass index were not independently associated with the composite outcome in the primary adjusted model. Each additional decade of age had an adjusted risk ratio of 1.15, with a 95% confidence interval of 0.94 to 1.41 and P equal to 0.186. Female sex had an adjusted risk ratio of 0.96, with a 95% confidence interval of 0.66 to 1.39 and P equal to 0.829, while each 1 kg/m² increase in body mass index had an adjusted risk ratio of 1.07, with a 95% confidence interval of 0.99 to 1.17 and P equal to 0.091. These estimates mean that the study did not find clear independent associations for those demographic and anthropometric measures, not that they have no relationship to wound events in every clinical setting.

The suture result is particularly notable because the design cannot establish that suturing caused the additional events. The authors excluded several conditions that could make closure decisions unusual, including uncontrolled coagulation disorders, concomitant open surgery, and wounds requiring an intraoperative incision. Even so, surgeons may have selected sutures for locally difficult wounds, bleeding, exudation, poor skin condition, or excessive tension. Those unrecorded features could confound the comparison, while the fact that sutured patients may have had more wound checks or suture-removal visits could also increase the likelihood that mild redness or exudate was noticed and recorded. The finding should therefore be interpreted as an adjusted observational association rather than proof that sutures themselves produce wound inflammation or other complications.

Several other constraints limit what the study can establish. Follow-up was retrospective and varied among inpatient observation, wound-clinic examination, and telephone reporting, so assessment intensity and recording thresholds were not standardized. Very mild redness or transient bleeding may have been missed, and the records did not consistently capture event duration, patient discomfort, additional care, revisits, or hospitalization. The composite endpoint improved capture of local findings but combined conditions with different causes and severities. Only one infection occurred within two weeks, preventing meaningful analysis of surgical-site infection or later infections. The single-center design and the selected elective population also limit generalizability to open spine surgery, malignant disease, immunosuppression, or puncture sites requiring remedial closure.

Overall, the study identifies four factors associated with the short-term local wound status after elective vertebroplasty: suture closure, diabetes, elevated INR, and multilevel treatment. Its practical signal is that early observation may be especially relevant for patients with these characteristics, although the findings do not establish a clinical rule or a preferred closure technique. Because closure was clinician-selected, follow-up was not standardized, and the endpoint combined mild events with rare infection, the results point to priorities for further prospective research rather than definitive guidance. Within those limits, the observed 15.6% event rate after suturing compared with 6.8% after nonsuture closure provides the clearest signal in the cohort, while the observational design makes the mechanism unresolved.

Subject of Research: Factors associated with early puncture-site wound events after percutaneous vertebroplasty for osteoporotic vertebral compression fractures

Article Title: Factors associated with early puncture-site wound events after percutaneous vertebroplasty for osteoporotic vertebral compression fractures: a retrospective cohort study

Article References: He, X., Huang, C., Zheng, B., Wu, X., Huang, C., Lu, S., Huang, Y., Chen, J., Huang, J., & Li, B. (2026). Factors associated with early puncture-site wound events after percutaneous vertebroplasty for osteoporotic vertebral compression fractures: a retrospective cohort study. Frontiers in Medicine, 13, Article 1988843. https://doi.org/10.3389/fmed.2026.1988843

Image Credits: AI Generated

DOI: 10.3389/fmed.2026.1988843

Keywords: Percutaneous vertebroplasty, Osteoporotic fractures, Puncture-site wounds, Suture closure, Diabetes, Coagulation, Multilevel treatment, Retrospective cohort, Postoperative care, Factors, associated, early

Cardiovascular magnetic resonance measurements identified a hemodynamic pattern associated with death or heart-transplant referral or listing in people with Fontan circulation, according to a retrospective study of 182 patients followed at a moderate-altitude center. Patients who later experienced the composite outcome had a lower superior vena cava flow index than those who did not. In time-to-event analysis, each 0.1-liter-per-minute-per-square-meter increase in the indexed flow was associated with a 30% lower hazard of the outcome.

The association remained in an exploratory model that also included ventricular ejection fraction, but the researchers said the estimate requires prospective, multicenter validation before clinical application. The cohort comprised people who had undergone Fontan palliation between 1999 and 2021 at a tertiary institution approximately 5,118 feet above sea level. Fontan circulation passively directs systemic venous blood into the pulmonary arteries without the support of a sub-pulmonary ventricle.

Eligible participants had a clinically indicated CMR examination at least five years after Fontan completion, a threshold selected to match the center’s routine surveillance practice. For patients with multiple examinations, investigators used the last CMR obtained before an outcome or censoring. Most participants, 173 of 182, or 95%, had an extracardiac conduit Fontan circulation, and 76, or 42%, underwent a Damus–Kaye–Stansel anastomosis.

At CMR, the median body surface area was 1.43 square meters, with an interquartile range of 1.16 to 1.69 square meters. The median age at Fontan completion was 3.2 years, and the median interval between surgery and imaging was 10.9 years. Median follow-up after CMR was 4.7 years, while participants’ median home elevation was 5,221 feet above sea level.

Hypoplastic left heart syndrome was the most common underlying diagnosis, accounting for 35% of the cohort, followed by tricuspid atresia at 30%. The systemic ventricle was left-dominant in 53% and right-dominant in 47%. Magnetic resonance examinations were performed on 1.5- or 3.0-tesla scanners, with cine imaging used to assess ventricular function and phase-contrast sequences used to measure blood flow.

The primary endpoint combined death with referral or listing for heart transplantation. Fourteen patients, or 7.7% of the cohort, met that endpoint during follow-up: two died and 12 were referred or listed for transplantation. Among patients who experienced the outcome, the median time from CMR to the first qualifying event was 1.2 years, with an interquartile range of 0.5 to 2.5 years.

The median superior vena cava flow index was 0.54 liters per minute per square meter among patients with the primary outcome, compared with 0.82 liters per minute per square meter among those without it; the difference was statistically significant, with a p-value of 0.011. The superior vena cava-to-ascending-aorta flow ratio was also lower in the event group, with medians of 0.22 and 0.30, respectively. Several other CMR flow measures did not differ significantly between patients with and without the primary outcome.

These included flow indices in the ascending aorta, right pulmonary artery, left pulmonary artery and inferior vena cava, as well as calculated systemic-to-pulmonary collateral flow. Receiver operating characteristic analysis indicated that superior vena cava flow index discriminated between patients who met the endpoint and those who did not with an area under the curve of 0.74 and a 95% confidence interval of 0.56 to 0.92. A data-derived threshold of 0.66 liters per minute per square meter, selected using the Youden index, yielded 70% sensitivity and 75% specificity.

Kaplan–Meier curves showed significantly poorer event-free survival among patients below that threshold. Because the threshold and discrimination measures came from the same cohort, they are exploratory rather than externally validated clinical cutoffs. Univariable Cox proportional hazards regression found a hazard ratio of 0.70 for each 0.1-liter-per-minute-per-square-meter increase in superior vena cava flow index, with a 95% confidence interval of 0.50 to 0.92 and a p-value of 0.008.

Right-dominant ventricular morphology was also associated with a higher hazard than left-ventricular dominance, with a hazard ratio of 3.21, a 95% confidence interval of 1.00 to 10.29 and a p-value of 0.049. The investigators constructed a two-variable Cox model containing superior vena cava flow index and ejection fraction. Each one-percentage-point increase in ejection fraction was associated with an adjusted hazard ratio of 0.92, with a 95% confidence interval of 0.86 to 0.97.

Because only 14 primary events occurred, the multivariable analysis was deliberately restricted and was intended to test whether the flow association persisted beyond ventricular function rather than develop a full prediction model. Internal bootstrap analysis using 2,500 resamples produced a median hazard ratio of 0.71 for superior vena cava flow index and 0.92 for ejection fraction, close to the original adjusted estimates. Collinearity between the two variables was negligible, with a Spearman absolute correlation below 0.1, an R-squared value of 0.008 and a variance inflation factor of 1.01.

Tests did not indicate violation of the proportional-hazards assumption. Ventricular measures also differed according to morphology: in the right-dominant subgroup, patients with events had larger indexed ventricular volumes and lower ejection fraction than those without events, whereas comparable differences were not statistically significant in the smaller left-dominant event subgroup. The study does not establish why lower superior vena cava flow was associated with poorer outcomes.

One proposed explanation is that chronic hypobaric exposure at moderate altitude promotes pulmonary vasoconstriction and raises pulmonary vascular resistance, potentially restricting passive flow through the Fontan pathway. However, pulmonary vascular resistance was not directly measured, and the cohort included no sea-level comparator, so the study cannot determine whether altitude caused the observed hemodynamic pattern. Other possible contributors include anatomical differences in the superior vena cava, systemic venovenous collateral vessels that divert blood around the pulmonary vascular bed, and differences in preload or single-ventricle filling.

The findings therefore associate reduced indexed flow with an unfavorable hemodynamic state rather than demonstrate a specific underlying mechanism. Important limitations constrain the results. The retrospective, single-center design creates the possibility of selection bias, and clinically performed CMR examinations were not acquired at standardized surveillance intervals.

Selecting the last scan before an outcome or censoring may introduce reverse-causation bias because patients approaching clinical deterioration could have been imaged nearer the event. Clinically relevant potential confounders—including functional class, cardiopulmonary exercise capacity, resting oxygen saturation, natriuretic peptide levels, catheterization-derived Fontan pressure and pulmonary vascular resistance, pulmonary vasodilator therapy, arrhythmia burden and the severity of liver disease—were unavailable or not incorporated. The small number of events also leaves the multivariable estimates vulnerable to overfitting despite the deliberately parsimonious model and bootstrap resampling.

Furthermore, the predominance of fenestrated extracardiac conduit Fontan circulation limits generalizability to other surgical configurations. The results position superior vena cava flow index as a candidate prognostic marker that may complement ventricular size and ejection fraction in longitudinal assessment of Fontan circulation, but they do not establish a clinical measurement rule or treatment strategy. Prospective, multicenter studies comparing cohorts across elevations would be needed to test the temporal relationship, determine whether altitude modifies the association, and establish external validity.

The authors also identified four-dimensional flow CMR as a possible tool for characterizing three-dimensional flow patterns and energy loss within the Fontan pathway. Further work could compare imaging signatures with exercise physiology, biomarkers of end-organ dysfunction and pulmonary vascular imaging. Until those studies are completed, the association between reduced superior vena cava flow and adverse outcomes should be regarded as an exploratory finding that requires independent validation.

Subject of Research: Association between CMR-derived blood flow and adverse outcomes in people with Fontan circulation

Article Title: Cardiovascular magnetic resonance–derived hemodynamics predict adverse outcomes after Fontan palliation

Article References: Platnick, C., Frank, B., Romanowicz, J., Gonzalez De Alba, C., Chase, M., Umer, A., Chaudhuri, N. R., Awori, J., Chauhan, D., Mascio, C. E., Udassi, J. P., & Hedjazi Moghari, M. (2026). Cardiovascular magnetic resonance–derived hemodynamics predict adverse outcomes after Fontan palliation. Frontiers in Cardiovascular Medicine, 13, Article 1937933. https://doi.org/10.3389/fcvm.2026.1937933

Image Credits: AI Generated

DOI: 10.3389/fcvm.2026.1937933

Keywords: Fontan circulation, cardiovascular magnetic resonance, superior vena cava flow, heart transplantation, congenital heart disease, risk stratification, ventricular function, moderate altitude, flow quantification, retrospective cohort, Cardiovascular, magnetic

In hot weather, trees “sweat” to cool down by releasing water from their leaves or needles and then replacing it with water from the soil. But during long periods of high temperatures, trees may release more water than they can replace. To strengthen forests against heat stress and other environmental hazards, scientists have suggested adding fungi to the soil. 

Soil fungi living on tree roots are called ectomycorrhizal fungi. They help trees absorb water by expanding their root networks, and trees help the fungi by providing them with sugars for energy. This beneficial partnership is known as symbiosis. Scientists at Fujian Agriculture and Forestry University in China tested whether symbiosis with ectomycorrhizal fungi could help the pine trees Pinus massoniana survive warmer temperatures. 

For their experiment, the researchers grew pine seedlings with and without ectomycorrhizal fungi in a greenhouse under different temperature conditions. First, they grew fungi called Cenococcum geophilum for 45 days on a gel-like substance called agar. At the same time, they grew the pine seedlings for 30 days, then transferred them into pots with natural soil. 

After 15 days in the pots, the researchers spread the gel-like agar containing the fungi over small 1 x 1 centimeter (cm) areas of the pine root tips to introduce the fungi to the seedlings, a process called inoculation. They assumed that the fungal network would expand from the starting area to colonize new root tips as the seedlings grew. The team’s inoculations included 6 different C. geophilum strains and 1 fungi-free control. To simulate heat stress, the researchers replicated each of the 7 inoculations at 25°C (77°F) and 35°C (95°F). They repeated each inoculation condition in 3 pots with 3 seedlings, for a total of 126 seedlings. 

After 60 days, the researchers harvested the pine seedlings and used a microscope to count how many of their root tips had fungi. They divided the number of root tips with fungi by the total number of root tips to calculate a colonization rate. They considered seedlings with a colonization rate of 80% or higher to have successfully formed a symbiotic relationship with the fungi. Then, the researchers analyzed seedlings with an 80% colonization rate to investigate their symbiotic partnerships.

The team observed that pine seedlings grown under heat stress at 35°C were 24% to 59% smaller than those grown at 25°C, and their needles were yellow instead of a healthy green. However, the seedlings that formed a symbiotic relationship with the ectomycorrhizal fungi were greener and 80% heavier than the control seedlings. 

Investigating the trees further, the team measured 3 chemical compounds related to plant stress, including malondialdehyde (MDA), proline, and nitric oxide. Plants release MDA when damaged, so high MDA levels mean a plant is struggling. In contrast, plants release proline and nitric oxide to repair cells or hold water, so high amounts of these compounds mean a plant is healing.

To measure MDA and proline levels in the pine needles, the researchers mixed them with different acids that change color depending on the sample’s MDA or proline content. To measure nitric oxide, the researchers mixed the needles with a protein that converts the compound into a chemical that changes color. They found that inoculated seedlings at 35°C had about 30% to 40% less MDA, 15% to 30% more proline, and 150% more nitric oxide in their roots than the control seedlings. 

Finally, the researchers measured changes in gene activity in the inoculated pine seedlings. They identified active genes by analyzing RNA molecules from the pine seedling roots with a process called RNA sequencing or transcriptomics. They found that inoculating the seedlings with ectomycorrhizal fungi activated more genes related to root strength, water retention, cell defense, and general plant protection than were activated in the control seedlings. 

By combining chemical analyses with growth measurements, the team concluded that a symbiotic partnership with the ectomycorrhizal fungi helped the pine seedlings survive heat stress. They demonstrated that through prolonged heat, inoculated seedlings maintained greener needles and lower levels of stress chemicals. They suggested that ectomycorrhizal fungi could be an ecological tool to help trees stay hydrated in a warming world. They recommended that future researchers conduct field trials with inoculated trees to translate these findings into forest management strategies. 

The post Fungi help pine trees survive heat stress appeared first on Sciworthy.