Photosynthetic response dynamics in the invasive species Tithonia diversifolia and two co-occurring native shrub species under fluctuating light conditions

To determine the invasiveness of invasive plants,many studies have compared photosynthetic traits or strategies between invasive and native species.However,few studies have compared the photosynthetic dynamics between invasive and native species during light fluctuations.We compared photosynthetic induction,relaxation dynamics and leaf traits between the invasive species,Tithonia diversifolia and two native species,Clerodendrum bungei and Blumea balsamifera,in full-sun and shady habitats.The photosynthetic dynamics and leaf traits differed among species.T.diversifolia showed a slower induction speed and stomatal opening response but had higher average intrinsic water-use efficiency than the two native species in full-sun habitats.Thus,the slow induction response may be attributed to the longer stomatal length in T.diversifolia.Habitat had a significant effect on photosynthetic dynamics in T.diversifolia and B.balsamifera but not in C.bungei.In shady habitat,T.diversifolia had a faster photosynthetic induction response than in full-sun habitat,leading to a higher average stomatal conductance during photosynthetic induction in T.diversifolia than in the two native species.In contrast,B.balsamifera had a larger stomatal length and slower photosynthetic induction and relaxation response in shady habitat than in full-sun habitat,resulting in higher carbon gain during photosynthetic relaxation.Nevertheless,in both habitats,T.diversifolia had an overall higher carbon gain during light fluctuations than the two native species.Our results indicated that T.diversifolia can adopt more effective response strategies under fluctuating light environments to maximize carbon gain,which may contribute to its successful invasion.

Hydraulic properties and drought response of a tropical bamboo (Cephalostachyum pergracile)

Bamboo plants are an essential component of tropical ecosystems,yet their vulnerability to climate extremes,such as drought,is poorly understood due to limited knowledge of their hydraulic properties.Cephalostachyum pergracile,a commonly used tropical bamboo species,exhibited a substantially higher mortality rate than other co-occurring bamboos during a severe drought event in 2019,but the underlying mechanisms remain unclear.This study investigated the leaf and stem hydraulic traits related to drought responses,including leaf-stem embolism resistance(P50leaf;P50stem) estimated using optical and X-ray microtomography methods,leaf pressure-volume and water-releasing curves.Additionally,we investigated the seasonal water potentials,native embolism level(PLC) and xylem water source using stable isotope.We found that C.pergracile exhibited strong resistance to embolism,showing low P50leaf,P50stem,and turgor loss point,despite its rapid leaf water loss.Interestingly,its leaves displayed greater resistance to embolism than its stem,suggesting a lack of effective hydraulic vulnerability segmentation(HVS) to protect the stem from excessive xylem tension.During the dry season,approximately 49% of the water was absorbed from the upper 20-cm-deep soil layer.Consequently,significant diurnal variation in leaf water potentials and an increase in midday PLC from 5.87±2.33% in the wet season to 12.87±4.09%in the dry season were observed.In summary,this study demonstrated that the rapid leaf water loss,high reliance on surface water,and a lack of effective HVS in C.pergracile accelerated water depletion and increased xylem embolism even in the typical dry season,which may explain its high mortality rate during extreme drought events in 2019.

Portal vein thrombosis in a noncirrhotic patient after hemihepatectomy:A case report and review of literature

BACKGROUND Portal vein thrombosis(PVT)is a condition caused by hemodynamic disorders.It may be noted in the portal vein system when there is an inflammatory stimulus in the abdominal cavity.However,PVT is rarely reported after hepatectomy.At present,related guidelines and major expert opinions tend to consider vitamin K antagonists or low-molecular weight heparin(LMWH)as the standard treatment.But based on research,direct oral anticoagulants may be more effective and safe for noncirrhotic PVT and are also beneficial by reducing the recurrence rate of PVT.CASE SUMMARY A 51-year-old woman without any history of disease felt discomfort in her right upper abdomen for 20 d,with worsening for 7 d.Contrast-enhanced computed tomography(CECT)of the upper abdomen showed right liver intrahepatic cholangiocarcinoma with multiple intrahepatic metastases but not to the left liver.Therefore,she underwent right hepatic and caudate lobectomy.One week after surgery,the patient underwent a CECT scan,due to nausea,vomiting,and abdominal distension.Thrombosis in the left branch and main trunk of the portal vein and near the confluence of the splenic vein was found.After using LMWH for 22 d,CECT showed no filling defect in the portal vein system.CONCLUSION Although PVT after hepatectomy is rare,it needs to be prevented during the perioperative period.