Hydrogen peroxide generation rates of uninfected and infected leaves of two tomato (Lycopersicon esculentum) cultivars showing differential susceptibility to Botrytis cinerea were determined. The superoxide anion, hydroxyl radical, ascorbate contents and changes in NADH peroxidase, superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT) activities in the apoplast fraction were analysed. Infected leaves had an increased hydrogen peroxide level. It was greater and generally occurred earlier in plants of the less susceptible cv. Perkoz than in those of the more susceptible cv. Corindo. Induction of nitrotetrazolium blue reducing activity and SOD levels in apoplast were higher in cv. Perkoz 24 h after inoculation. In the controls, NADH peroxidase activity in apoplast was higher in the more susceptible cv. Corindo, but after infection it increased faster and to a higher level in the less susceptible cv. Perkoz. NADH oxidation was inhibited by only 15% by a specific inhibitor DPI (diphenylene‐iodonium) but was completely inhibited by KCN and NaN3. Similar increases in APX activity after 48 h and a small increase in catalase activities were observed in both cultivars soon after infection. These results indicate that resistance of tomato plants to infection by the necrotrophic fungus B. cinerea may result from early stimulation of hydrogen peroxide and superoxide radical generations by NADH peroxidase and SOD in apoplastic space, and they confirm the important role of their enhanced production in apoplastic spaces of plants.

The frequency of parasitism of the European mistletoe, Viscum album L. subsp. album, in the city of Lodz, a typical major city in Poland, was investigated. The infection prevalence and intensity of the mistletoe Viscum album subsp. album on its main host, Acer saccharinum as a function of host size was also investigated. The parasite showed a strong preference for alien, planted tree species (i.e. A. saccharinum, Populus×canadensis and Robinia pseudoacacia). In 2009-2011, V. album subsp. album was observed on 28 host taxa of trees and shrubs, which represents the highest diversity of host trees in a single locality in the Poland. Within the studied area 2147 trees were infested by mistletoe. The distribution of mistletoes (V. album subsp. album) among A. saccharinum hosts is significantly aggregated. The intensity of mistletoe infection in the silver maple trees was affected by the individual tree characteristics, such as the height of the tree. The overall level of aggregation as indicated by the variance to mean ratio of mistletoe numbers per host fell within the midrange of values found in other published studies of host-mistletoe interactions. The higher mistletoe infection prevalence in taller trees results from differential dispersal of mistletoe seeds to tall trees as well as differential survival of established mistletoes on tall trees. The incidence of mistletoe was higher in city centre (zone of high density development) than it was on the outskirts of a city (outer marginal zone). It was found that the abundant occurrence of mistletoe was recorded in the stands of increased nitrogen input, while other stands have little or no mistletoe infection present. Thus, this mistletoe species uses both passive and active uptake, which may be a selective advantage in a nutrient-poor environment or on a nutrient-deficient host species.

Phaseolus vulgaris cv. Korona plants were inoculated with the bacteria Pseudomonas syringae pv. phaseolicola (Psp), necrotrophic fungus Botrytis cinerea (Bc) or with both pathogens sequentially. The aim of the experiment was to determine how plants cope with multiple infection with pathogens having different attack strategy. Possible suppression of the non-specific infection with the necrotrophic fungus Bc by earlier Psp inoculation was examined. Concentration of reactive oxygen species (ROS), such as superoxide anion (O 2 -) and H 2 O 2 and activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) were determined 6, 12, 24 and 48 h after inoculation. The measurements were done for ROS cytosolic fraction and enzymatic cytosolic or apoplastic fraction. Infection with Psp caused significant increase in ROS levels since the beginning of experiment. Activity of the apoplastic enzymes also increased remarkably at the beginning of experiment in contrast to the cytosolic ones. Cytosolic SOD and guaiacol peroxidase (GPOD) activities achieved the maximum values 48 h after treatment. Additional forms of the examined enzymes after specific Psp infection were identified; however, they were not present after single Bc inoculation. Subsequent Bc infection resulted only in changes of H 2 O 2 and SOD that occurred to be especially important during plant-pathogen interaction. Cultivar Korona of common bean is considered to be resistant to Psp and mobilises its system upon infection with these bacteria. We put forward a hypothesis that the extent of defence reaction was so great that subsequent infection did not trigger significant additional response.

No abstract

Changes in O 1 − and H 1 O 1 generation as well as super! oxide dismutase\ catalase\ ascorbate peroxidase and guai! acol peroxidase activities were examined in fusaric acid! treated tomato leaves[ Fusaric acid application resulted in a lasting activation of O 1 − and H 1 O 1 production[ Within the _rst day after toxin application the H 1 O 1 scavenging enzymes] catalase and ascorbate peroxidase showed a strong activity decrease followed by a gradual recovery to the control level after 1 and 2 days[ By con! trast fusaric acid markedly stimulated peroxidase activity measured with guaiacol as well as ferulic and coumaric acids\ and syringaldazine[ The maximum activity increase\ coinciding with the highest H 1 O 1 level\ was about two!fold and 4[4!fold for phenolic acids and syr! ingaldazine\ respectively[ The results obtained are dis! cussed in the light of the data on the role of activated oxygen species and enzymes of their metabolism in plant defence[ U[ S[ Copyright Clearance Center Code Statement] 9820Ð0674:88:3697Ð9274 , 03[99:9 dazin gemessen wurde[ Der maximale Aktivita Ãtsanstieg _el mit dem ho à chsten H 1 O 1 !Wert zusammen und lag bei den Phenolsa Ãuren bei ungefa Ãhr dem 1!fachen und bei Syringaldazin beim 4\4!fachen[ Die Ergebnisse werden im Hinblick auf die Daten zur Rolle von aktivierten Sau! ersto}spezies und die fu à r ihren Sto}wechsel verantwortli! chen Enzyme in der Abwehrreaktion von P~anzen diskutiert[

Key words: an ti ox i dant en zymes, apoplast, Bo trytis cinerea, hy dro gen per ox ide, peroxidase. Ab stractThe aim of the re search was to es ti mate the sen si tiv ity of tomato tis sue and spore from necrotrophic iso late of B. cinerea on H 2 O 2 . The in flu ence of exo gen ic H 2 O 2 and B. cinerea on plant tis sue and on the ac tiv ity of peroxidases (PO), catalase (CAT) and superoxide dismutase (SOD) in apoplastic to mato leaves frac tion were in ves ti gated.It was proved that 40 mM H 2 O 2 dam aged the cells of a host, and in hib ited in vi tro ger mi na tion of B.cinerea spores. Complete in hi bi tion of ger mi na tion was ob served af ter the use 100 mM H 2 O 2 . In the pres ence of spores H 2 O 2 was de com posed to H 2 O and O 2 . Trace ac tiv ity of catalase was ob served in a so lution of spores used for in oc u la tion. Ne cro sis which ap peared on the leaves af ter 40 mM H 2 O 2 treat ment re sem bled hy persen si tive re sponse. On the leaves pretreated at this con cen tration the de vel op ment of in fec tion was ob served. The H 2 O 2 con cen tra tion harm ful for the tis sues, stim u lated the PO ac tivity mea sured with NADH -re spon si ble for gen er a tion of . O 2 -, as well as with syringaldazine (S) and ferulic acid (FA), substrates char ac ter is tic of forms lig ni fy ing and strength en ing the cell wall. Clear in crease in CAT ac tiv ity, re sult ing from in fection and early pre treat ment with H 2 O 2 was ob served in apoplast. No ef fect on SOD ac tiv ity was ob served.A hy poth e sis may be put for ward, that ger mi nat ing spores produce en zymes which al low them to de com pose H 2 O 2 gen erated in apoplast, so there is lit tle like li hood that B. cinerea can be di rectly in hib ited by re ac tive ox y gen forms (ROS) dur ing ini tial stages of in fec tion. Ne crotic le sions re sem bling HR gener ated by ex og e nous H 2 O 2 as well as in duc tion of ac tiv ity of apoplastic plant en zymes, par tic u larly PO con nected with strength en ing and lig ni fi ca tion of cell wall, were not suf fi cient fac tors to in hibit fun gal ex pan sion.List of ab bre vi a tions: ROS = re ac tive ox y gen species, CAT = catalase, PO = peroxidase, SOD = superoxide dismutase, TMB = tetramethylbenzidine , FA = ferulic acid, S = syringaldazine, MBTH = 3-methylbenzothiazoline hydrazone In tro duc tionMe chan i cal bar ri ers -cuticule and a cell wall, as well as, other bi o log i cal and mo lec u lar mech anisms pro tect plants from patho gen at tacks. Only a few patho gens are able to cause in fec tion of cho sen plant spe cies (com pat i ble re sponse), while most of po ten tial ag gres sors as well as fungi are rec og nized and blocked by plant de fense sys tems (in com pat ible re sponse). Dur ing in com pat i ble re ac tion in the cells sur round ing the sites of patho gen pen e tra tion hy per sen si tive re ac tion (HR) is ob served as well as genes syn the siz ing phytoalexins and other pathogenesis related proteins are en coded.Many au thors sug gest that in plants re ac tive ox yge...

Changes in O 1 − and H 1 O 1 generation as well as super! oxide dismutase\ catalase\ ascorbate peroxidase and guai! acol peroxidase activities were examined in fusaric acid! treated tomato leaves[ Fusaric acid application resulted in a lasting activation of O 1 − and H 1 O 1 production[ Within the _rst day after toxin application the H 1 O 1 scavenging enzymes] catalase and ascorbate peroxidase showed a strong activity decrease followed by a gradual recovery to the control level after 1 and 2 days[ By con! trast fusaric acid markedly stimulated peroxidase activity measured with guaiacol as well as ferulic and coumaric acids\ and syringaldazine[ The maximum activity increase\ coinciding with the highest H 1 O 1 level\ was about two!fold and 4[4!fold for phenolic acids and syr! ingaldazine\ respectively[ The results obtained are dis! cussed in the light of the data on the role of activated oxygen species and enzymes of their metabolism in plant defence[ U[ S[ Copyright Clearance Center Code Statement] 9820Ð0674:88:3697Ð9274 , 03[99:9 dazin gemessen wurde[ Der maximale Aktivita Ãtsanstieg _el mit dem ho à chsten H 1 O 1 !Wert zusammen und lag bei den Phenolsa Ãuren bei ungefa Ãhr dem 1!fachen und bei Syringaldazin beim 4\4!fachen[ Die Ergebnisse werden im Hinblick auf die Daten zur Rolle von aktivierten Sau! ersto}spezies und die fu à r ihren Sto}wechsel verantwortli! chen Enzyme in der Abwehrreaktion von P~anzen diskutiert[

Rumex confertus is a biennial species native to Eastern Europe and Asia, where it thrives on meadow-steppes and glades in forest-steppe. This species has increased its range rapidly within central Europe, yet its biology is not well understood, which has led to poorly timed management. Effects of temperature, light, sodium chloride (NaCl), hydrogen ion concentration (pH), potassium nitrate (KNO3), and polyethylene glycol 6000 on seed germination were examined. Seedling emergence was examined for seeds sown at different depths in sand-filled pots. Seeds of R. confertus were nondormant at maturity. The germination percentage and rate of germination were significantly higher in light than in darkness. Secondary dormancy was induced in these seeds by 12 weeks of dark incubation at 4°C. The seeds of R. confertus undergo a seasonal dormancy cycle with deep dormancy in winter and early spring and a low level of dormancy in early autumn. Germination decreased as soil salinity increased. NO3 − increased the percentage and rate of germination in the studied species. Decrease in seedling emergence from the seeds buried at >0.5 cm may be due to deficiency of light. From our experiments, we conclude that the weed R. confertus normally becomes established in vegetation gaps or due to disturbance of the uppermost soil layer during the growing season through the germination of seeds originating from a long-lived seed bank.