Analysis of some nutritional parameters in green asparagus spears (asparagus officinalis) - lack of chemical and physical treatments post-harvest in green asparagus causes physiological and morphological changes after packaging and during storage. our aim was to monitor some nutritional parameters in the apical and basal portions of spear of the edible part (corresponding to 15 cm). after 9 days in the dark at 4 °c, there is an huge and slight decrease in ascorbate total content and soluble sugars, respectively. total chlorophyll and carotenoid levels decrease but the anthocyanins content not changes. Higher lignin level is mostly present in apical than basal portion.

I meccanismi coinvolti nell’interazione pianta-agente fitopatogeno, e in particolare le risposte di difesa dell’ospite e i processi coinvolti nella patogenesi e nella induzione/manifestazione dei sintomi costituiscono una delle aree di ricerca più interessanti della fitovirologia moderna. L’interazione di una pianta ospite con un patogeno, quale può essere un virus, può innescare due possibili tipologie di risposta: resistenza della pianta alla malattia, nel caso di un’interazione geneticamente incompatibile; suscettibilità e quindi insorgenza della malattia, nel caso di un’interazione geneticamente compatibile (gReenbeRg, yao, 2004). i percorsi che si sviluppano nei due tipi di interazione, incompatibile e non, si sovrappongono e seguono alcune tappe fondamentali, come la produzione di specie reattive dell’ossigeno (RoS) e l’attivazione di sistemi di detossificazione intenti a regolare i livelli di tali molecole all’interno della cellula vegetale, l’induzione di cascate di trasmissione del segnale mediate da specifiche chinasi e ormoni vegetali, l’induzione di geni coinvolti nella risposta di difesa, l’innesco di fenomeni di morte cellulare programmata e/o risposta ipersensibile. e’ ampiamente riconosciuto che le RoS siano cruciali sia per lo sviluppo della pianta che per la sua difesa da aggressioni di varia natura (boLweLL, 1999; foyeR, noctoR, 2005): se da un lato le piante utilizzano le RoS come messaggeri in cascate di trasduzione del segnale, che regolano diversi processi come mitosi e tropismi, dall’altro la loro natura chimica le rende potenzialmente pericolose per le cellule vegetali. infatti l’incremento di perossido di idrogeno (H2o2) e anione superossido che si osserva nelle cellule a seguito dell’interazione con un patogeno, oltre una certa soglia di concentrazione, risulta tossico. Le cellule, tuttavia, possiedono sistemi di detossificazione di natura enzimatica e non enzimatica. nel presente lavoro sono stati studiati alcuni enzimi quali ascorbato perossidasi (aPx), catalasi (cat), perossidasi generiche (Pod) e superossido dismutasi (Sod), e metaboliti quali acido ascorbico, aventi un ruolo chiave nei processi di detossificazione da H2o2 e anione superossido (tommaSi et al., 1998; conkLin, baRtH, 2004), utilizzando come modello sperimentale il pomodoro (Solanum lycopersicum cv uc82) e Cucumber mosaic virus (cmV, virus del mosaico del cetriolo). in particolare, in piante di pomodoro inoculate con il ceppo cmV-fny (f), che mostrano sintomi di riduzione di crescita e malformazioni fogliari ma non di morte cellulare, e in piante inoculate con lo stesso ceppo in combinazione con la sua variante di Rna satellite necrogenica (fn), che incorrono in una necrosi letale, sono stati confrontati i valori relativi ad attività enzimatica e livelli di espressione di geni coinvolti nella detossificazione delle RoS, nonché di altri geni coinvolti nelle risposte di difesa ai patogeni. i risultati ottenuti su campioni di Rna ed estratti proteici a 9 giorni dopo l’inoculazione mostrano un aumento dell’espressione genica per aPx, in entrambi i campioni f ed fn, e per cat , solo nei campioni f, rispetto al controllo (piante di pomodoro sane). Si osserva, poi, un incremento dell’attività enzimatica dei loro prodotti in entrambi i campioni rispetto al controllo. inoltre, sia il livello di espressione dei trascritti che l’attività enzimatica risulta minore nei campioni fn rispetto ai campioni f. La misura del contenuto di acido ascorbico mostra un incremento nei campioni f ed fn, (maggiore in f) rispetto al controllo. L’incremento osservato riflette il suo ruolo di molecola antiossidante. il dato ottenuto, oltre a indicare il coinvolgimento dell’acido ascorbico nelle risposte antiossidanti di difesa, conferma l’esistenza di una relazione di proporzionalità diretta tra

During their life cycle, plants can undergo simultaneous attack by different pathogens that produce various toxins. It is well known that in some plant-fungal interactions, mycotoxins play an important role in pathogenesis and induce a reactive oxygen species (ROS) increase. Plants counteract the over-accumulation of ROS by reinforcing the defence systems. T-2 toxin (T-2) and beauvericin (BEA) mycotoxins are produced by some Fusarium species and have different chemical structures, mechanisms of action and biological activities. In this study, the individual and combined effects of the two toxins on defence systems such as the ascorbate-glutathione cycle and peroxidases were evaluated in cherry tomato shoots. Hydrogen peroxide content as an index of oxidative stress was also measured. Inhibitory effects on ascorbate peroxidase, dehydroascorbate reductase and ascorbate, and stimulatory effects on glutathione reductase, monodehydroascorbate reductase and reduced glutathione were observed when tomato plants were simultaneously treated with BEA and T-2. The trends of these biochemical parameters highlight the presence of a range of defence mechanisms activated by plants in response to mycotoxins. The interaction between BEA and T-2 resulting in synergistic and/or antagonistic effects on the studied defence systems is also discussed. It is concluded that the effects of these mycotoxins alone are not predictive of their combined effects.

Developing kernels of resistant and susceptible maize genotypes were inoculated with Fusarium proliferatum, F. subglutinans, and Aspergillus flavus. Selected defense systems were investigated using real-time reverse transcription-polymerase chain reaction to monitor the expression of pathogenesis-related (PR) genes (PR1, PR5, PRm3, PRm6) and genes protective from oxidative stress (peroxidase, catalase, superoxide dismutase and ascorbate peroxidase) at 72 h postinoculation. The study was also extended to the analysis of the ascorbate-glutathione cycle and catalase, superoxide dismutase, and cytosolic and wall peroxidases enzymes. Furthermore, the hydrogen peroxide and malondialdehyde contents were studied to evaluate the oxidation level. Higher gene expression and enzymatic activities were observed in uninoculated kernels of resistant line, conferring a major readiness to the pathogen attack. Moreover expression values of PR genes remained higher in the resistant line after inoculation, demonstrating a potentiated response to the pathogen invasions. In contrast, reactive oxygen species-scavenging genes were strongly induced in the susceptible line only after pathogen inoculation, although their enzymatic activity was higher in the resistant line. Our data provide an important basis for further investigation of defense gene functions in developing kernels in order to improve resistance to fungal pathogens. Maize genotypes with overexpressed resistance traits could be profitably utilized in breeding programs focused on resistance to pathogens and grain safety.

We attempt to identify genes involved in Fusarium ear rot resistance using resistant and susceptible maize genotypes. Gene expression data were obtained from microarray hybridizations using seeds inoculated at 15 days after silking. At 48 hours after infection, differentially expressed sequences were identified and classified into 11 functional categories, principally assigned to the category cell rescue, defence and virulence in both lines. These genes encode for PR proteins, detoxification enzymes and beta-glucosidases. The differentialy expressed genes were validated in qPCR, also performed in silks 12, 24, 48 and 72 h after F. verticillioides infection. Parallel, we have studied the detoxifying enzymes ascorbate peroxidase (APX), catalase (CAT), total peroxidase (POD) and superoxide dismutase (SOD) in seedlings, before and at five days after F. verticillioides infection. In resistant seedlings, before infection, the defence genes, APX and SOD enzymatic activities were higher than in the susceptible ones while, after treatment, they remained unchanged. On the other hand, in susceptible seedlings, except for SOD, all enzymes and defence genes were activated by the pathogen.

Fusarium ear rot is one of the most important diseases of maize, that is of concern because Fusarium verticillioides produces the mycotoxins known as fumonisins. F. verticillioides can be transmitted either through infected silks or seed-to-kernel. In order to better understand the virulence of F. verticillioides, the effect of the fungus on the defense systems was investigated both in immature kernels and in seedlings. The molecular mechanisms involved in compatible and incompatible responses were also studied. Gene expression data were obtained from microarray hybridizations, comparing healthy and infected kernels of resistant and susceptible maize inbreds 48 h after infection with a fumonisin-producing strain of F. verticillioides. A total of 739 transcripts were differentially expressed between the two inbred lines at one time point after infection. Among all the differentially regulated genes, 7.3% of encoded proteins play a role in cell rescue and defense. The qRT-PCR analysis confirmed that most of the defense genes had already been transcribed before infection occurred in the maize-resistant line. The study was extended to the analysis of enzymes involved in removing reactive oxygen species, namely ascorbate peroxidase, catalase, total peroxidase and superoxide dismutase. In resistant seedlings, before infection, ascorbate peroxidase and superoxide dismutase enzyme activities were higher than in the susceptible ones and, five days after treatment, they remained unchanged. On the other hand, in the susceptible seedlings, except for superoxide dismutase, all enzymes assayed were activated after pathogen attack. These results support our previous findings of a basal defense response provided by maize genotypes resistant against F. verticillioides infection, both in kernels and seedlings

Selenate and selenite are the most prevalent bioavailable selenium (Se) forms and most easily taken up by plants. Some studies indicate that they are differently absorbed and accumulated in plants and that selenium is toxic if accumulated at high concentrations. Toxicity is due to substitution of sulphur by selenium in cysteine and methionine aminoacids with alteration of the tertiary structure and catalytic activity of proteins and with inhibition of enzymes involved in chlorophyll biosynthesis. Moreover, the interaction between Se and thiol groups induces loss of efficiency of plant defence systems and increases the reactive oxygen species (ROS) production thus enhancing the oxidative stress. To further elucidate the role of Se in higher plants, in this study the antioxidative response to the phytotoxicity of selenite and selenate in Senecio scandens L. was evaluated. The data indicate that while selenite induces oxidative stress enhancing ROS production, lipid peroxidation and the oxidised forms of ascorbate and glutathione, selenate does not significantly affect the analysed pathways. This article outlines that the synergistic action of different antioxidant components is necessary to overcome the phytotoxicity of selenium in Senecio.

Powdery mildew (PM), caused by the fungus Erysiphe necator, is one of the most widespread fungal disease of grape and may cause extensive openings on the berry surface during the infection.We evaluated the effect of damage caused by PMin grape berries on the growth of and mycotoxin production by Aspergillus and on the oxidative stress in infected berries. Berries of Vitis vinifera L. cv. Negroamaro with sound skin (SS) and those naturally infected by PM were surface sterilized and inoculated with either fumonisin B2 (FB2)-producing strains of Aspergillus niger or ochratoxin A (OTA)-producing strains of Aspergillus carbonarius and incubated at 20 and 30uC. The PM berries were significantly more susceptible to both Aspergillus colonization (5 to 15 times more susceptible) and OTA and FB2 contamination (2 to 9 times more susceptible) than were SS berries. The highest toxin concentration was detected in inoculated PM berries both for OTA (9 ng/g) at 20uC and for FB2 (687 ng/g) at 30uC. In inoculated SS and PM berries, although malondialdehyde and hydrogen peroxide concentrations did not increase, the two black Aspergillus species caused a significant decrease in ascorbate content, thus inducing a pro-oxidant effect. These results indicate that grape berries affected by PM are more susceptible to black Aspergillus growth and to production and/or accumulation of FB2 and OTA. Thus, preventive control of E. necator on grape berries could reduce the mycotoxicological risk from black Aspergillus infection.

L’ozono (O3) è una specie chimica altamente reattiva composta da tre atomi di ossigeno. come forte ossidante (o come generatore di radicali liberi) a livello fogliare esso può causare differenti sintomi inclusi clorosi e necrosi, che possono portare a seri problemi per la sopravvivenza della pianta. Questo succede quando la capacità di detossificazione biochimica cellulare non riesce a prevenire le ossidazioni o3-indotte. l’ozono, infatti, si decompone rapidamente nella fase acquosa della matrice apoplastica originando specie reattive dell’ossigeno (RoS). tuttavia, grazie alla presenza a livello apoplastico di acido ascorbico e altri scavengers di RoS, la maggior parte dell’ozono con cui la pianta viene a contatto è distrutto preservando così l’integrità della membrana plasmatica (chameideS, 1989; conklin, BaRth, 2004). le RoS sono considerate, tuttavia, anche molecole segnali che inducono il potenziamento dei sistemi antiossidanti nei processi di detossificazione cellulare (Bolwell, 1999; foyeR, noctoR, 2005). Per contro è stato riportato che l’acqua ozonata è di utile impiego per il suo potere antibatterico e antivirale. Pertanto sulla base di ciò, attraverso approcci biochimici e fitopatologici, sono state condotte indagini preliminari per accertare se applicazioni limitate di acqua ozonata su piantine di melone (Cucumis melo l.) possono potenziare i meccanismi di difesa nella pianta quando questa è attaccata da funghi fitopatogeni quali Sphaerotheca fusca (Schlecht. ex fr.) Poll. in particolare è stata studiata l’attività degli enzimi “sensori” dello stress ossidativo quali ascorbato perossidasi, perossidasi generiche, superossido dismutasi e catalasi (tommaSi et al., 1998) in radici di piantine di melone dopo trattamento con acqua ozonata e trasferimento delle piantine stesse in terreno ed in vermiculite. le analisi condotte hanno evidenziato una differente situazione nelle risposte dell’ apparato radicale in relazione al substrato considerato (terreno o vermiculite). in particolare è risultato che nel terreno l’attività della catalasi è maggiormente potenziata dopo il trattamento con acqua ozonata, mentre l’attività degli altri enzimi antiossidanti rimane invariata. in vermiculite invece l’attività degli enzimi studiati dopo il trattamento con acqua ozonata diminuisce fino a scomparire del tutto.

The karyotype structures and the composition and distribution of the heterochromatin in Glebionis coronaria and Glebionis segetum using Giemsa and fluorescent banding techniques were analysed. The species studied are diploids with 2n = 2x = 18 chromosomes. G. coronaria possesses the most symmetrical karyotype, comprising mainly metacentric chromosomes. G. segetum, with formula 12 m + 6 sm, showed a slightly less symmetrical karyotype. Giemsa C-banding revealed little constitutive heterochromatin in both species. The presence of telomeric bands was restricted to two chromosome pairs. After staining with chromomycin A3, the chromosomes of G. coronaria and G. segetum revealed bright fluorescence at the telomeric regions of two chromosomes. No 4-6-diamidino-2-phenyl-indole bright blocks were observed. To estimate genetic variability in the species under consideration, genotypic expression was also determined through isozyme electrophoresis of cytosolic ascorbate peroxidase, considered a genetic marker in the study of plant phylogenetics. The relationships between G. coronaria and G. segetum are discussed. Abbreviations: ASC, ascorbate; BSA, bovine serum albumin; cAPX, cytosolic ascorbate peroxidase; CMA, chromomycin A3; DAPI, 4-6-diamidino-2-phenyl-indole; EDTA, ethylenediaminetetraacetic acid; PAGE, polyacrylamide gel electrophoresis.

In this work, we studied the mechanism of light influence on AsA pool size in Avena sativa L. under the effects of low intensity light at different wavelengths. Exposure to low intensity light of oat leaf segments incubated in water or in l-galactono-1,4-lactone (GL), resulted in an increase in AsA content compared with the dark control. This increase was due to modulation of l-galactono-1,4-lactone dehydrogenase (GLDH; EC 1.3.2.3) light-dependent activity and was dependent on the size of the endogenous GL pool. Both blue and red light were effective in increasing AsA, and this increase depended on both exposure time and light intensity. Protein biosynthesis, photosynthesis and calcium were involved in controlling the level of light-dependent AsA. We suggest that multiple checkpoints correlated to the presence of light underlie the ascorbate pool size. The presence of a light-activated switch for the maintenance of an adequate AsA level seems to be necessary for the various tasks of scavenging reactive oxygen species, in response to the dark-light cycle which plants experience under natural conditions.

In this work the authors analyzed sixty italian strains of the edible mushroom “cardoncello” (Pleurotus eryngii) belonging to the varieties eryngii and ferulae by sequencing two housekeeping genes (ef1-a and rpb2) and evaluating the activity of peroxidase, superoxide dis- mutase and catalase, in order to find some molecular markers for the traceability of “cardoncello”. Sequence analysis showed the presence of Snps variety-specific (eryngii and ferulae) in both genes useful for the development of molecular identification tools. none correlation between enzymatic analysis and analyzed varieties was observed.

The Pleurotus eryngii species complex is an economically important group which includes several closely related varieties, whose genetic discrimination is still not clear. One hundred and ten Italian strains of Pleurotus eryngii belonging to the varieties elaeoselini, eryngii, ferulae and thapsiae and P. nebrodensis were analysed by sequencing two housekeeping genes (ef1-a and rpb2), in order to find molecular markers for the identification of different varieties. Sequence analysis of partial ef1-a and rpb2 genes, allowed identification of some conserved nucleotide positions within each variety but variable among var. elaeoselini, var. eryngii, var. ferulae var. thapsiae and P. nebrodensis, allowing their discrimination. Phylogenetic analysis from the data of the two genes data set showed that var. elaeoselini, var. thapsiae, var. ferulae and var. eryngii are closely related to each other, and confirm P. nebrodensis as a separate clade.