The enzyme polyphenol oxidase (PPO) catalyzes the oxidation of phenolic compounds into highly reactive quinones. Polymerization of PPO-derived quinones causes the postharvest browning of cut or ...bruised fruit, but the native physiological functions of PPOs in undamaged, intact plant cells are not well understood. Walnut (Juglans regia) produces a rich array of phenolic compounds and possesses a single PPO enzyme, rendering it an ideal model to study PPO. We generated a series of PPO-silenced transgenic walnut lines that display less than 5% of wild-type PPO activity. Strikingly, the PPO-silenced plants developed spontaneous necrotic lesions on their leaves in the absence of pathogen challenge (i.e. a lesion mimic phenotype). To gain a clearer perspective on the potential functions of PPO and its possible connection to cell death, we compared the leaf transcriptomes and metabolomes of wild-type and PPO-silenced plants. Silencing of PPO caused major alterations in the metabolism of phenolic compounds and their derivatives (e.g. coumaric acid and catechin) and in the expression of phenylpropanoid pathway genes. Several observed metabolic changes point to a direct role for PPO in the metabolism of tyrosine and in the biosynthesis of the hydroxycoumarin esculetin in vivo. In addition, PPOsilenced plants displayed massive (9-fold) increases in the tyrosine-derived metabolite tyramine, whose exogenous application elicits cell death in walnut and several other plant species. Overall, these results suggest that PPO plays a novel and fundamental role in secondary metabolism and acts as an indirect regulator of cell death in walnut.
Phenolic compounds in apple leaves after infection with apple scab Mikulic Petkovsek, M., University of Ljubljana (Slovenia). Agronomy Dept; Slatnar, A., University of Ljubljana (Slovenia). Agronomy Dept; Stampar, F., University of Ljubljana (Slovenia). Agronomy Dept ...
Biologia plantarum,
12/2011, Letnik:
55, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Leaves of the scab-susceptible apple cultivar Golden Delicious were harvested from May to August 2008 and 2009. Some leaves were healthy and some infected with Venturia inaequalis. The phenolic ...compounds were analysed in healthy leaves, infected leaves and in the scab spot tissue. In comparison with healthy leaves, the infected leaves showed higher concentrations of hydroxycinnamic acid, flavanols and phloridzin, and lower concentrations of procyanidins, quercetins and phloretin. The total amount of phenolic compounds in the infected tissue was 10 to 20 % higher than in the healthy leaves. Accumulation of phenolic compounds is a post-infection response.
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•High-speed camera recordings used for polymer gear tooth deflection analysis.•Digital image correlation enables deflection analysis on the gear's side surface.•Edge displacement ...detection method provides accurate flank profile deflection results.•Edge displacement detection opens new possibilities for in-situ wear evaluation.
The engineering characteristics of polymer gears, such as wear and fatigue resistance, are dictated by the underlying processes that take place during the gear meshing phase. These are in turn dependent on the running load, speed, temperature, lubrication regime and other parameters. So far, the structural response of a meshing gear could only be analysed using numerical approaches, typically involving the finite element method. In this study, an optical experimental analysis approach is proposed to evaluate the in-mesh gear tooth deflection based on high-speed camera recordings. For this purpose, two image processing methods were implemented, namely the well-known Digital image correlation method and a newly proposed Edge displacement detection method.
Using an experimental setup with a camera resolution of 1024×1024px, an exposure time of 40 μs, a frame rate of 2·104fps and a 2000 lm focused light source, a measurement accuracy of ±5μm could be achieved. A good correlation between both methods and finite element analysis results was confirmed. Furthermore, the newly proposed Edge displacement detection method offers high potential for experimental analysis of long-term wear and strain accumulation processes.
Background and Aims
Bois noir (BN) is developing into one of the most serious phytosanitary problems in global viticulture. The aim of this work was to study the phenolic substances in incompletely ...lignified shoots/canes from BN‐infected vines.
Methods and Results
The study was conducted on 25‐year‐old BN‐infected and BN‐free vines of Vitis vinifera cv. Chardonnay. Shoots and canes were sampled at three key phenological stages (BBCH 89 – berries ripe for harvest; BBCH 91 – after harvest, end of wood maturation; BBCH 97 – end of leaf‐fall), cut into three sections (base, middle and apex) and stored at −80°C until analysis. Phenolic substances were identified and quantified with a liquid chromatography‐mass spectrometry system with a reverse phase column. The BN infection affects the synthesis of ellagic acid derivatives, flavonoids and stilbenoids, especially in the earlier phenological stages of shoot/cane lignification. Modulation of the phenylpropanoid pathway occurred in canes from BN‐infected vines, leading to a significantly higher concentration of ferulate, 5‐hydroxyconiferyl aldehyde and eriodictyol‐5‐rhamnoside, quercetins, resveratrol trimers 1, 3, 4, vitisins, piceatannol and ε‐viniferins during shoot lignification (BBCH 89).
Conclusions
The study demonstrated that incomplete cane lignification caused by phytoplasma affected many phenolic substances, especially individual flavonoids and stilbenoids in earlier phenological stages of cane lignification. Moreover, the significantly higher concentration of identified hydroxycinnamic acid and monolignol derivatives and flavanone in canes from BN‐infected vines suggested an alteration of the monolignol pathway and may be responsible for the lack of cane maturation.
Significance of the Study
To our knowledge, this is the first paper that has reported a modulation of phenylpropanoid pathway in 1‐year‐old canes with incomplete lignification caused by phytoplasma.
•Developed thermo-mechanical model produces results consistent with exp. measurements.•Model enables the consideration of any type of spur gear tooth profile.•High-speed thermography offers detailed ...insight into thermal response of polymer gears.•Tooth flash temperature gradient quickly dissipates after meshing cycle completion.•Geometric tolerance deviations influence the temperature rise on a given tooth pair.
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The presented work is focused on the development of a comprehensive thermo-mechanical model for predicting the temperature rise in thermoplastic polymer spur gears with any desired profile geometry while running. The specific constitutional behavior of thermoplastics influences the gear-meshing pattern, which can deviate substantially from ideal gear meshing, as typically exhibited by metal gears in moderate-loading conditions. Taking this aspect into account is of paramount importance if realistic temperature-rise predictions are to be made. The thermal response of the considered gear pair is studied thoroughly from both the analytical and experimental standpoints. Good agreement was found between the results of the model and the experimental measurements performed using a high-speed thermal imaging infrared camera, although it was also observed that the real-life temperature rise can increase noticeably if large geometric tolerance deviations from the ideal profile geometry are present. The presented experimental approach also offers the possibility to observe the temperature rise inside and outside the meshing cycle.
: In this study, we evaluated the changes in apple fruit quality during shelf life. After a month of cold storage, apples of cultivars “Jonagold” and “Golden Delicious” were exposed to ambient ...temperatures for 21 d, with subsequent sampling every 3 or 4 d. Fruit firmness, changes in amounts of sugars, malic acid, and phenolics were observed during shelf life. Chemical analyses were done with HPLC‐PDA system. An interchange between various sugars was noticed, but in general, the sum of sugars remained at the same level. The content of malic acid remained stable or dropped, resulting in sweeter fruit. Levels of phenolics were more constant in the pulp of both cultivars analyzed, while in the peel, the changes were more pronounced. In the pulp, a peak in the content of hydroxycinnamic acids and flavanols was noticed on the 2nd or 3rd sampling and afterwards, the amounts remained constant. In the peel an initial decrease of all analyzed phenolic groups was observed in both cultivars, however it was more pronounced in “Jonagold.” It can be concluded that changes in primary and secondary metabolites are not the main reason for the lower quality of fruit exposed to ambient temperatures. On the other hand, fruit firmness might be the limiting factor for shelf life duration.
Practical Application: In our study, we were able to show that various quality parameters react uniquely to exposure to ambient temperatures. The most dramatic change was noticed in fruit firmness, which might be the limiting factor for the practical duration of shelf life. On the other hand phenolics, as the health‐beneficial constituents in the flesh and peel of apples, did not change dramatically during shelf life. This information is important for nutritionists as well as for the consumers and specialists in fruit storage and handling.
The phenolic profile of healthy and infected raspberry canes was investigated in three raspberry cultivars: Autumn Bliss, Himbo Top and Polka. The content of total phenols and tannins was determined ...using spectrophotometric methods, whilst individual phenolic acids, flavan‐3‐ols, ellagic acid derivatives and glycosides of quercetin were analysed using HPLC/MS analysis. The content of secondary metabolites varied considerably among the analysed raspberry cultivars. Moreover, Didymella applanata and Leptosphaeria coniothyrium infection significantly altered the metabolism of phenolic compounds. Flavanols represented the greatest share of all identified phenolics in raspberry canes (90%), followed by glycosides of quercetin (6%), derivatives of ellagic acid (3%) and traces of hydroxycinnamic acid derivatives. Spur and cane blight diseases caused an increase of flavan‐3‐ols and tannins but the levels of hydroxycinnamic acid derivatives, conjugates of ellagic acid and quercetin glycosides were significantly reduced. Cultivars Himbo Top and Polka contained higher levels of hydroxycinnamic acid and ellagic acid derivatives in healthy and infected canes compared to cv. Autumn Bliss. Cultivar Polka also contained the highest level of flavanols and tannins. However, despite high levels of flavanols and total phenols measured in cv. Polka, the canes were highly diseased following infection with D. applanata and L. coniothyrium. The results of the study provide evidence that the level of phenolic compounds in the canes could be causally linked to the differences in disease susceptibility.
The research dealt with phenolics in healthy versus scab infected apple leaves and fruits. The leaf samples were picked in the period from May to September and the fruit samples at technological ...maturity. Infection with the
Venturia inaequalis fungus enhanced the metabolism of phenolics at the infected sites, especially in the boundary tissue. Tissue infected with
Venturia inaequalis showed in comparison to the healthy tissue up to 7.6 times more hydroxycinnamic acids, up to 2.6 times more flavan-3-ols and up to 2.9 times higher values of flavanols. The content level of total phenolics in the infected tissue was 1.3–2.4 times higher than in the healthy leaves and fruit.
Bradyrhizobium japonicum bacteria on the intensity of nodulation during nine phenophases (R1-R7) in relation to the isoflavone content in soybean seeds. Nine domestic soybean varieties were sown in ...three replicates, with Bradyrhizobium japonicum inoculated and non-inoculated seeds. The different morphological characteristics of nodules, the number and mass of nodules were studied during plants’ ontogenesis. The content of individual isoflavones in the sowing seed material was determined using high performance liquid chromatography mass spectrometry (HPLC-MS). The most abundant isoflavone was acetylgenistin in the variety Galeb (2741.4 μg/g), and the highest content of all isoflavones was recorded in the variety Gorštak (8117.7 μg/g). The variety Sava of the inoculated treatment exhibited the highest average values of the nodule mass (21.1 mg) and the highest number of nodules (23.3) in the phenophase, in which 10% of pods reached full length (R4). The average values of mass and number of nodules were calculated for the entire vegetation period, being higher in the inoculated treatment. There was no positive correlation between the content of isoflavones in seeds and the number and mass of nodules. The impact of quantity of isoflavone on nodulation intensity in soybeans was not significant,, which could be related to already saturated soil with nitrogen-fixing bacteria.
An increasing body of research has linked the geographic distribution of lead with various indicators of criminal and antisocial behavior.
The current study, using data from an ongoing project ...related to lead exposure in St. Louis City, MO, analyzed the association between aggregate blood lead levels and specific indicators violent crime within the city.
Ecological study.
St. Louis, Missouri.
Blood lead levels.
Official reports of violent crimes were categorized as 1) crimes involving a firearm (yes/no), 2) assault crimes (with or without a firearm), 3) robbery crimes (with or without a firearm), 4) homicides and 5) rape.
With the exception of rape, aggregate blood-lead levels were statistically significant predictors of violent crime at the census tract level. The risk ratios for each of the outcome measures were as follows: firearm crimes 1.03 (1.03-1.04), assault crimes 1.03 (1.02-1.03), robbery crimes 1.03 (1.02-1.04), homicide 1.03 (1.01, 1.04), and rape 1.01 (0.99-1.03).
Extending prior research in St. Louis, results suggest that aggregated lead exposure at the census tract level predicted crime outcomes, even after accounting for important sociological variables. Moving forward, a more developed understanding of aggregate level crime may necessitate a shift toward studying the synergy between sociological and biological risk factors such as lead exposure.
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