Climatic signals of tree-ring in Quercus gussonei (Borz\uec) Brullo in the Mediterranean region

Change in growth is among the primary response of trees to environmental variation. Tree-rings contain a wealth of information related to the climatic conditions. A dendroclimatic study on Quercus gussonei (Borz\uec) Brullo was carried out in the Nature Reserve of \u201cBosco della Ficuzza, Rocca Busambra, Bosco Del Cappelliere, Gorgo Del Drago\u201d (southern Italy). Q. gussonei is an endemic deciduous oak and thermophilous form of Quercus cerris L. that is found only in Sicily, although with clear sign of decline. The knowledge of ecology of this species should help to establish criteria for forest conservation in the Mediterranean region. For definining the ecological character and understanding the potential causes of the oak decline, we collected cores from ten trees with an increment borer. Precipitation and temperature data were obtained from a meteorological station located nearby from the stand. Annual ring widths, earlywood and latewood analyses were used in order to investigate and better understand the climatic dynamics influencing the oaks\u2019 growth. We determined the stable isotope discrimination of carbon (D13C) in the wood in order to investigate wateruse efficiency variations and the expression of possible plant adaptive traits. Climate-growth relationship, for the chronology 1951-2008, were analyzed using response, correlation and moving correlation functions. Our finding mostly highlight relationships between tree-rings width and climate data. Furthermore, D13C in treerings was used to identify long-term adjustments in water-use efficiency

Temperature responses of Rubisco from Paniceae grasses provide opportunities for improving C3 photosynthesis.

Enhancing the catalytic properties of the CO2-fixing enzyme Rubisco is a target for improving agricultural crop productivity. Here, we reveal extensive diversity in the kinetic response between 10 and 37 °C by Rubisco from C3 and C4 species within the grass tribe Paniceae. The CO2 fixation rate (kcatc) for Rubisco from the C4 grasses with nicotinamide adenine dinucleotide (NAD) phosphate malic enzyme (NADP-ME) and phosphoenolpyruvate carboxykinase (PCK) photosynthetic pathways was twofold greater than the kcatc of Rubisco from NAD-ME species across all temperatures. The declining response of CO2/O2 specificity with increasing temperature was less pronounced for PCK and NADP-ME Rubisco, which would be advantageous in warmer climates relative to the NAD-ME grasses. Modelled variation in the temperature kinetics of Paniceae C3 Rubisco and PCK Rubisco differentially stimulated C3 photosynthesis relative to tobacco above and below 25 °C under current and elevated CO2. Amino acid substitutions in the large subunit that could account for the catalytic variation among Paniceae Rubisco are identified; however, incompatibilities with Paniceae Rubisco biogenesis in tobacco hindered their mutagenic testing by chloroplast transformation. Circumventing these bioengineering limitations is critical to tailoring the properties of crop Rubisco to suit future climates

Laparoscopic right hemicolectomy: a SICE (Società Italiana di Chirurgia Endoscopica e Nuove tecnologie) network prospective study on the approach to right colon lymphadenectomy in Italy: is there a standard?—CoDIG 2 (ColonDx Italian Group)

Background: Colon cancer is a disease with a worldwide spread. Surgery is the best option for the treatment of advanced colon cancer, but some aspects are still debated, such as the extent of lymphadenectomy. In Japanese guidelines, the gold standard was D3 dissection to remove the central lymph nodes (203, 213, and 223), but in 2009, Hoenberger et al. introduced the concept of complete mesocolic excision, in which surgical dissection follows the embryological planes to remove the mesentery entirely to prevent leakage of cancer cells and collect more lymph nodes. Our study describes how lymphadenectomy is currently performed in major Italian centers with an unclear indication on the type of lymphadenectomy that should be performed during right hemicolectomy (RH). Methods: CoDIG 2 is an observational multicenter national study that involves 76 Italian general surgery wards highly specialized in colorectal surgery. Each center was asked not to modify their usual surgical and clinical practices. The aim of the study was to assess the preference of Italian surgeons on the type of lymphadenectomy to perform during RH and the rise of any new trends or modifications in habits compared to the findings of the CoDIG 1 study conducted 4 years ago. Results: A total of 788 patients were enrolled. The most commonly used surgical technique was laparoscopic (82.1%) with intracorporeal (73.4%), side-to-side (98.7%), or isoperistaltic (96.0%) anastomosis. The lymph nodes at the origin of the vessels were harvested in an inferior number of cases (203, 213, and 223: 42.4%, 31.1%, and 20.3%, respectively). A comparison between CoDIG 1 and CoDIG 2 showed a stable trend in surgical techniques and complications, with an increase in the robotic approach (7.7% vs. 12.3%). Conclusions: This analysis shows how lymphadenectomy is performed in Italy to achieve oncological outcomes in RH, although the technique to achieve a higher lymph node count has not yet been standardized. Trial registration (ClinicalTrials.gov) ID: NCT05943951

Influence of diurnal variation in mesophyll conductance on modelled 13C discrimination: results from a field study

Mesophyll conductance to CO2 (gm) limits carbon assimilation and influences carbon isotope discrimination (Δ) under most environmental conditions. Current work is elucidating the environmental regulation of gm, but the influence of gm on model predictions of Δ remains poorly understood. In this study, field measurements of Δ and gm were obtained using a tunable diode laser spectroscope coupled to portable photosynthesis systems. These data were used to test the importance of gm in predicting Δ using the comprehensive Farquhar model of Δ (Δcomp), where gm was parameterized using three methods based on: (i) mean gm; (ii) the relationship between stomatal conductance (gs) and gm; and (iii) the relationship between time of day (TOD) and gm. Incorporating mean gm, gs-based gm, and TOD-based gm did not consistently improve Δcomp predictions of field-grown juniper compared with the simple model of Δ (Δsimple) that omits fractionation factors associated with gm and decarboxylation. Sensitivity tests suggest that b, the fractionation due to carboxylation, was lower (25‰) than the value commonly used in Δcomp (29‰) and Δsimple (27‰). These results demonstrate the limits of all tested models in predicting observed juniper Δ, largely due to unexplained offsets between predicted and observed values that were not reconciled in sensitivity tests of variability in gm, b, or e, the day respiratory fractionation

Photosynthesis-nitrogen relationships: interpretation of different patterns between Pseudotsuga menziesii and Populus x euroamericana in a mini-stand experiment

We compared photosynthesis–nitrogen relationships of one broad-leaved (poplar; Populus × euroamericana (Dole) Guinier) and one conifer (Douglas-fir; Pseudotsuga menziesii (Mirb.) Franco) species. Plants were grown in large pots to allow free root development and were kept well watered. We determined effects of low, intermediate and high nitrogen supply rates on area-based leaf nitrogen (Na) and chlorophyll concentrations, leaf mass per area (LMA), light-saturated photosynthesis (Amax), maximum carboxylation (Vcmax) and electron transport rate (Jmax), photosynthetic nitrogen-use efficiency (PNUE), and proportions of leaf N in active Rubisco (PR), bioenergetic pools (PB) and the light-harvesting complex (PLH). Nitrogen supply significantly affected leaf Na. Leaf mass per area did not differ between species and was unaffected by the N treatments. In both species, there was a positive correlation between leaf Na and chlorophyll concentration, and between leaf Na and the photosynthetic parameters Amax, Jmax and Vcmax. At comparable leaf Na, however, poplar showed twofold higher PNUE and a threefold steeper slope of the Amax– nitrogen relationship than Douglas-fir. Leaf Na was negatively correlated with PNUE in Douglas-fir but not in poplar. Leaf Na was also negatively correlated with PR, PB and PLH in Douglas-fir, whereas in poplar, a negative correlation was found only for PLH. Parameter PR was significantly higher in poplar than in Douglas-fir. The ratio of CO2 concentration in the intercellular space to that in ambient air was higher in poplar than in Douglas-fir. Overall, our data suggest that differences in the photosynthesis–nitrogen relationship and PNUE between Douglas-fir and poplar primarily reflect a different investment of N to active Rubisco, and possibly a different constraint to CO2 diffusion

Variation in nitrogen supply changes the water use efficiency of Pseudotsuga menziesii and Populus x euroamericana; a comparison of three different approaches to determine water-use efficiency

We studied the effects of three nitrogen (N) supply rates (low, intermediate and high) on Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings and poplar clone “I-214” (Populus × euroamericana (Dole) Guinier) cuttings growing in mini-stands. Our specific objectives were to: (1) evaluate the effects ofNsupply onwater-use efficiency (WUE) and biomass production; (2) determine if N affects WUE through control of carbon assimilation rates or through stomatal control of water loss; and (3) compare three methods of estimating WUE: one short-term method (WUEi, based on gas exchange measurements) and two long-term methods (WUET, based on the ratio between biomass production and transpired water, and Δ, based on leaf carbon isotope discrimination tested as a proxy of WUE). In both species, biomass production, WUEi andWUET increased with increasing Nsupply, but there was no effect of N supply on either transpiration or stomatal conductance and Δ was negatively related to leaf N concentration. Plots of Δ versus both WUEi and WUET revealed negative trends, but the regression betweenWUEi and Δ was significant only for Douglas-fir, and the regression between WUET and Δ was significant only for poplar. Thus, the mechanisms underlying the response of WUE to N supply were mainly related to a positive effect of N supply on photosynthetic rates. The data confirm that carbon isotope discrimination may be a useful proxy of WUE. The finding that N availability enhances both biomass production and WUE may have practical implications in regions where these factors impose constraints on forest productivity

Climate-growth relationships of Quercus gussonei (Borz\uec) Brullo in the Mediterranean region: adaptive traits and water use efficiency.

Due to their marginal distribution, peripheral tree populations are highly vulnerable and are more likely to be influenced by extreme climate conditions. This occurrence is known to cause dieback in many species at their Mediterranean margins. Quercus gussonei (Borz\uec) Brullo is a deciduous oak endemic of Sicily. It is a thermophilous, peripheral form of Quercus cerris L. which is showing an incipient but ongoing decline. A deeper ecophysiological knowledge is urgently needed on this species in order to plan proper conservation actions and reduce the risk of its extinction. In the aim to understand at what extent changes in environmental conditions could be responsible for Q. gussonei decline, we carried out dendrochronological and water-use efficiency investigations. Annual ring widths, earlywood and latewood analyses were accomplished in order to assess the climatic factors influencing the growth of Q. gussonei. In addition, we determined the carbon isotope discrimination (\u394 13C) in tree rings, allowing to evaluate WUE variations and the expression of possible plant adaptive traits. Climate-growth relationship were analyzed using response functions. Our findings highlight significant relationships between tree-rings width and climate data. The dendrochronological analysis of Q. gussonei showed a rather good adaptation of this species to the typical Mediterranean climate and oak trees seem to retain a certain resilience to efficiently face 14 less favorable environmental conditions. Furthermore \u394 13C indicates a long-term adjustment in water-use efficiency and the increase of WUE could be interpreted as a fair adaptation of this species to drought-prone environments