Outbreak of Alternaria Black Spot of Pomegranate (Punica granatum L.) in Italy as a Consequence of Unusual Climatic Conditions.

Alternaria black spot of pomegranate (Punica granatum) was reported for the first time in Italy. In spring 2023, an outbreak of this disease was noticed in commercial pomegranate 'Wonderful' orchards of the municipality of Misterbianco (Sicily), following an unusually rainy period. A total of 30 randomly selected Alternaria isolates recovered from typical necrotic spots of leaves and fruits were characterized. Based on the colony morphology on solid agar media (PDA and MEA), isolates were separated into three distinct morphotypes (1, 2, and 3). The first two morphotypes comprised only isolates from fruits, while morphotype 3 comprised only isolates from leaves. Multigene phylogenetic analysis of four DNA regions, including internal transcribed spacer (ITS), translation elongation factor 1-α (EF-1α), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and a SCAR marker (OPA10-2), identified the isolates of morphotypes 1 and 2 as Alternaria alternata and morphotype 3 isolates as A. arborescens. In pathogenicity tests on unwounded leaves and fruit, the isolates of all three morphotypes produced symptoms on the leaves of three pomegranate cultivars, 'Acco', 'Wonderful', and 'Etna'. The symptoms on 'Acco' leaves were the least severe. Conversely, the fruits of 'Acco' were the most susceptible. The isolates of morphotypes 2 and 3 were not pathogenic on the fruits of 'Wonderful' and 'Etna'. This is the first report of Alternaria black spot in Italy and of A. arborescens associated with Alternaria black spot of pomegranate worldwide.

Chitosan-based films grafted with citrus waste-derived antifungal agents: An innovative and sustainable approach to enhance post-harvest preservation of citrus fruit.

This paper reports the synthesis, characterization, and properties of chitosan films (CHI) grafted with a natural antifungal agent with the aim of developing active films of natural origin to prevent post-harvest losses of citrus fruit. The antifungal agent was prepared by fermentation using lemon peel (AntiFun-LM), a citrus waste, and grafted on chitosan using different coupling agents (CHI/AntiFun-LM). Bioactive films were prepared by solvent casting. FTIR-ATR and ToF-SIMS analyses provided compelling evidence of the successful grafting process. TGA-DSC demonstrated that the films are stable after grafting. SEM studies showed the continuous and compact surface of the films. WCA measurements proved that CHI/AntiFun-LM films are more hydrophilic than CHI films. Moreover, the CHI/AntiFun-LM films showed stronger UV shielding effect when compared to CHI. The biological evaluation demonstrated that CHI/AntiFun-LM films gained considerable antifungal properties against most fungi responsible for post-harvest decay. Cytotoxicity tests showed that CHI/AntiFun-LM films did not cause any toxic effect against L929 fibroblasts. This study highlights the great potential of chemical grafting of antifungal agents produced from citrus waste to chitosan and preparation of natural-based films to act as a powerful alternative in post-harvest protection of citrus fruit in a perspective of circular economy.

Phytophthora pseudocryptogea, P. nicotianae and P. multivora Associated to Cycas revoluta: First Report Worldwide.

A dieback was observed on three-year-old pot-grown plants of Cycas revoluta in Sicily (Italy). Symptoms, including stunting, yellowing and blight of the leaf crown, root rot and internal browning and decay of the basal stem, closely resembled the Phytophthora root and crown rot syndrome, common in other ornamentals. Isolations from rotten stem and roots, using a selective medium, and from rhizosphere soil of symptomatic plants, using leaf baiting, yielded three Phytophthora species, P. multivora, P. nicotianae and P. pseudocryptogea, were obtained. Isolates were identified by both morphological characters and DNA barcoding analysis, using three gene regions: ITS, ß-tub and COI. Phytophthora pseudocryptogea was the sole species isolated directly from the stem and roots. The pathogenicity of the isolates of the three Phytophthora species was tested on one-year-old potted plants of C. revoluta, using both stem inoculation by wounding, and root inoculation through infested soil. Phytophthora pseudocryptogea was the most virulent and, like P. nicotianae, reproduced all the symptoms of natural infections, while P. multivora was the least virulent and induced solely very mild symptoms. Phytophthora pseudocryptogea was identified as the causal agent of the decline of C. revoluta, as it was re-isolated from both the roots and stems of artificially infected symptomatic plants, thus fulfilling Koch's postulates.

A super absorbent polymer containing copper to control Plenodomus tracheiphilus the causative agent of mal secco disease of lemon.

The aim of this study was to determine the effectiveness of a Super absorbent polymer (SAP) containing copper (SAP-Cu) in controlling mal secco disease (MSD) of lemon caused by the fungus Plenodomus tracheiphilus. Super absorbent polymer containing copper was characterized by atomic absorption spectrometry (AAS) and UV-VIS spectroscopy. In vitro tests were performed to determine the inhibitory effects of SAP-Cu against the pathogen on both potato-dextrose-agar medium and naturally infected lemon cuttings. Super absorbent polymer was able to absorb up to about 200 and 30 times its weight of ionized water and copper (II) sulfate solution (Cu2+ ions at the concentration 236 mM), respectively. The distribution of copper released on twigs after 24 h of contact with SAP-Cu was determined by secondary ion mass spectrometry with time-of-flight analyzer (ToF-SIMS). Super absorbent polymer containing copper significantly inhibited the viability of P. tracheiphilus in lemon twigs. Overall, the results of this study showed that the SAP could be a suitable carrier of antifungal compounds.

Phytophthora × cambivora as a Major Factor Inciting the Decline of European Beech in a Stand within the Southernmost Limit of Its Natural Range in Europe.

The objective of this study was to investigate the role of the oomycete Phytophthora× cambivora in the decline affecting European beech (Fagus sylvatica) in the Nebrodi Regional Park (Sicily, southern Italy). In a survey of a beech forest stand in the heart of the park, Phytophthora× cambivora was the sole Phytophthora species recovered from the rhizosphere soil and fine roots of trees. Both A1 and A2 mating type isolates were found. Direct isolation from the stem bark of trees showing severe decline symptoms and bleeding stem cankers yielded exclusively P. gonapodyides, usually considered as an opportunistic pathogen. The mean inoculum density of P.× cambivora in the rhizosphere soil, as determined using the soil dilution plating method and expressed in terms of colony forming units (cfus) per gm of soil, the isolation frequency using leaf baiting, and the percentage of infected fibrous roots from 20 randomly selected beech trees with severe decline symptoms (50 to 100 foliage transparency classes) were 31.7 cfus, 80%, and 48.6%, respectively. These were significantly higher than the corresponding mean values of 20 asymptomatic or slightly declining trees, suggesting P.× cambivora is a major factor responsible for the decline in the surveyed stand.

DNA Metabarcoding and Isolation by Baiting Complement Each Other in Revealing Phytophthora Diversity in Anthropized and Natural Ecosystems.

Isolation techniques supplemented by sequencing of DNA from axenic cultures have provided a robust methodology for the study of Phytophthora communities in agricultural and natural ecosystems. Recently, metabarcoding approaches have emerged as new paradigms for the detection of Phytophthora species in environmental samples. In this study, Illumina DNA metabarcoding and a conventional leaf baiting isolation technique were compared to unravel the variability of Phytophthora communities in different environments. Overall, 39 rhizosphere soil samples from a natural, a semi-natural and a horticultural small-scale ecosystem, respectively, were processed by both baiting and metabarcoding. Using both detection techniques, 28 out of 39 samples tested positive for Phytophthora. Overall, 1,406,613 Phytophthora internal transcribed spacer 1 (ITS1) sequences and 155 Phytophthora isolates were obtained, which grouped into 21 taxa, five retrieved exclusively by baiting (P. bilorbang; P. cryptogea; P. gonapodyides; P. parvispora and P. pseudocryptogea), 12 exclusively by metabarcoding (P. asparagi; P. occultans; P. psycrophila; P. syringae; P. aleatoria/P. cactorum; P. castanetorum/P. quercina; P. iranica-like; P. unknown sp. 1; P. unknown sp. 2; P. unknown sp. 3; P. unknown sp. 4; P. unknown sp. 5) and four with both techniques (P. citrophthora, P. multivora, P. nicotianae and P. plurivora). Both techniques complemented each other in describing the variability of Phytophthora communities from natural and managed ecosystems and revealing the presence of rare or undescribed Phytophthora taxa.

Inhibitory Activity of Shrimp Waste Extracts on Fungal and Oomycete Plant Pathogens.

(1) Background: This study was aimed at determining the in vitro inhibitory effect of new natural substances obtained by minimal processing from shrimp wastes on fungi and oomycetes in the genera Alternaria, Colletotrichum, Fusarium, Penicillium, Plenodomus and Phytophthora; the effectiveness of the substance with the highest in vitro activity in preventing citrus and apple fruit rot incited by P. digitatum and P. expansum, respectively, was also evaluated. (2) Methods: The four tested substances, water-extract, EtOAc-extract, MetOH-extract and nitric-extract, were analyzed by HPLC-ESI-MS-TOF; in vitro preliminary tests were carried out to determine the minimal inhibitory/fungicidal concentrations (MIC and MFC, respectively) of the raw dry powder, EtOAc-extract, MetOH-extract and nitric-extract for each pathogen. (3) Results: in the agar-diffusion-assay, nitric-extract showed an inhibitory effect on all pathogens, at all concentrations tested (100, 75, 50 and 25%); the maximum activity was on Plenodomus tracheiphilus, C. gloeosporioides and Ph. nicotianae; the diameters of inhibition halos were directly proportional to the extract concentration; values of MIC and MFC of this extract for all pathogens ranged from 2 to 3.5%; the highest concentrations (50 to 100%) tested in vivo were effective in preventing citrus and apple fruit molds. (4) Conclusions: This study contributes to the search for natural and ecofriendly substances for the control of pre- and post-harvest plant pathogens.

Natural Biostimulants Elicit Plant Immune System in an Integrated Management Strategy of the Postharvest Green Mold of Orange Fruits Incited by Penicillium digitatum.

This study was aimed at testing the integrated use of a natural biostimulant based on seaweed (Ascophyllum nodosum) and plant (alfalfa and sugarcane) extracts and reduced dosages of the conventional synthetic fungicide Imazalil (IMZ) to manage postharvest rots of orange fruits. The following aspects were investigated: (i) the effectiveness of postharvest treatment with natural biostimulant alone or in mixture with IMZ at a reduced dose against green mold caused by Penicillium digitatum; (ii) the differential expression of defense genes in orange fruits treated with the natural biostimulant both alone and in combination with a reduced dose of IMZ; (iii) the persistence of the inhibitory activity of both biostimulant and the mixture biostimulant/IMZ against green mold; and (iv) the residue level of fungicide in citrus peel when applied alone or in combination with the biostimulant. Treatments with the chemical plant resistance-inducer potassium phosphite, alone or with a reduced dose of IMZ, were included for comparison. The mixture of natural biostimulant and IMZ at a low dose consistently reduced the incidence and severity of fruit green mold and induced a significant increase of the expression level of ß-1,3-glucanase-, peroxidase (PEROX)-, and phenylalanine ammonia-lyase (PAL)-encoding genes in fruit peel, suggesting that the natural biostimulant elicits a long-lasting resistance of citrus fruits to infections by P. digitatum. Interestingly, the residual concentration of IMZ in fruits treated with the biostimulant/fungicide mixture was significantly lower than that of IMZ in fruits treated only with the fungicide at the same dose and by far below the threshold values set by the European Union. This study laid the foundations for (i) conceiving a practical and more eco-friendly alternative to the conventional postharvest management of green mold of citrus fruits, based almost exclusively on the use of synthetic fungicide IMZ, alone or mixed with potassium phosphite and (ii) providing a better insight into the mechanisms of disease resistance induction by biostimulants.

Bot Gummosis of Lemon (Citrus × limon) Caused by Neofusicoccum parvum.

Neofusicoccum parvum, in the family Botryosphaeriaceae, was identified as the causal agent of bot gummosis of lemon (Citrus × limon) trees, in the two major lemon-producing regions in Italy. Gummy cankers on trunk and scaffold branches of mature trees were the most typical disease symptoms. Neofusicoccum parvum was the sole fungus constantly and consistently isolated from the canker bark of symptomatic lemon trees. It was identified on the basis of morphological characters and the phylogenetic analysis of three loci, i.e., the internal transcribed spacer of nuclear ribosomal DNA (ITS) as well as the translation elongation factor 1-alpha (TEF1) and ß-tubulin (TUB2) genes. The pathogenicity of N. parvum was demonstrated by wound inoculating two lemon cultivars, 'Femminello 2kr' and 'Monachello', as well as citrange (C. sinensis × Poncirus trifoliata) 'Carrizo' rootstock. In artificial inoculations, the fungus was very aggressive on lemons and weakly virulent on citrange, consistently with symptoms observed in the field as a consequence of natural infections. This is the first report of N. parvum, both in a wide and in a strict taxonomic sense, as a pathogen of lemon in Italy.

Twig and Shoot Dieback of Citrus, a New Disease Caused by Colletotrichum Species.

(1) Background: This study was aimed at identifying the Colletotrichum species associated with twig and shoot dieback of citrus, a new syndrome occurring in the Mediterranean region and also reported as emerging in California. (2) Methods: Overall, 119 Colletotrichum isolates were characterized. They were recovered from symptomatic trees of sweet orange, mandarin and mandarin-like fruits during a survey of citrus groves in Albania and Sicily (southern Italy). (3) Results: The isolates were grouped into two distinct morphotypes. The grouping of isolates was supported by phylogenetic sequence analysis of two genetic markers, the internal transcribed spacer regions of rDNA (ITS) and ß-tubulin (TUB2). The groups were identified as Colletotrichum gloeosporioides and C. karstii, respectively. The former accounted for more than 91% of isolates, while the latter was retrieved only occasionally in Sicily. Both species induced symptoms on artificially wound inoculated twigs. C. gloeosporioides was more aggressive than of C. karstii. Winds and prolonged drought were the factor predisposing to Colletotrichum twig and shoot dieback. (4) Conclusions: This is the first report of C. gloeosporioides and C. karstii as causal agents of twig and shoot dieback disease in the Mediterranean region and the first report of C. gloeosporioides as a citrus pathogen in Albania.

Characterization of Alternaria Species Associated with Heart Rot of Pomegranate Fruit.

This study was aimed at identifying Alternaria species associated with heart rot disease of pomegranate fruit in southern Italy and characterizing their mycotoxigenic profile. A total of 42 Alternaria isolates were characterized. They were obtained from pomegranate fruits with symptoms of heart rot sampled in Apulia and Sicily and grouped into six distinct morphotypes based on macro- and microscopic features. According to multigene phylogenetic analysis, including internal transcribed spacer (ITS), translation elongation factor 1-α (EF-1α), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and a SCAR marker (OPA10-2), 38 isolates of morphotypes 1 to 5 were identified as Alternaria alternata, while isolates of morphotype 6, all from Sicily, clustered within the Alternaria arborescens species complex. In particular, isolates of morphotype 1, the most numerous, clustered with the ex-type isolate of A. alternata, proving to belong to A. alternata. No difference in pathogenicity on pomegranate fruits was found between isolates of A. alternata and A. arborescens and among A. alternata isolates of different morphotypes. The toxigenic profile of isolates varied greatly: in vitro, all 42 isolates produced tenuazonic acid and most of them other mycotoxins, including alternariol, alternariol monomethyl ether, altenuene and tentoxin.

In Vitro and In Vivo Biological Activity of Berberine Chloride against Uropathogenic E. coli Strains Using Galleria mellonella as a Host Model.

Berberine is an alkaloid of the protoberberine type used in traditional oriental medicine. Its biological activities include documented antibacterial properties against a wide variety of microorganisms; nonetheless, its use against Escherichia coli strains isolated from urinary infections has not yet been widely investigated in vivo. The emergence of antimicrobial resistance requires new therapeutic approaches to ensure the continued effectiveness of antibiotics for the treatment and prevention of urinary infections. Moreover, uropathogenic Escherichia coli (UPEC) has developed several virulence factors and resistance to routine antibiotic therapy. To this end, several in vitro and in vivo tests were conducted to assess the activity of berberine on uropathogenic E. coli strains. Galleria mellonella as an infection model was employed to confirm the in vivo translatability of in vitro data on berberine activity and its influence on adhesion and invasion proprieties of E. coli on human bladder cells. In vitro pre-treatment with berberine was able to decrease the adhesive and invasive UPEC ability. In vivo treatment increased the larvae survival infected with UPEC strains and reduced the number of circulating pathogens in larvae hemolymph. These preliminary findings demonstrated the efficacy and reliability of G. mellonella as in vivo model for pre-clinical studies of natural substances.

Trichoderma Counteracts the Challenge of Phytophthora nicotianae Infections on Tomato by Modulating Plant Defense Mechanisms and the Expression of Crinkler, Necrosis-Inducing Phytophthora Protein 1, and Cellulose-Binding Elicitor Lectin Pathogenic Effectors.

Decoding the mechanisms of plant defense against plant pathogens in a scenario where antagonistic activity and the plant growth-promoting effects of useful organisms intervene simultaneously is a new frontier of plant pathology. Here, we demonstrated that (i) two selected strains of Trichoderma asperellum and Trichoderma atroviride promoted tomato (Solanum lycopersicum) growth and reduced the severity of disease caused by the oomycete Phytophthora nicotianae and (ii) the genetic patterns of the components of the experimental model system tomato-Trichoderma spp.-P. nicotianae were differentially expressed. The beneficial effects in both the promotion of the growth of host plant and the biological control of the pathogen by two selected strains of different Trichoderma species were tested both in planta and in vitro. In both respects, T. atroviride demonstrated to be more effective than T. asperellum. Additionally, the simultaneous transcriptional reprogramming of several plant defense-related genes, pathogen effectors, and mycoparasitism-related genes in tomato, P. nicotianae, and Trichoderma spp., respectively, was evaluated during the three-component interaction. Results support the hypothesis that Trichoderma spp. elicit the expression of plant defense-related genes. As expected, a mycoparasitism-related gene was significantly up-regulated in Trichoderma-colonizing tomato plants infected by P. nicotianae. Finally, a marked up-regulation of the genes encoding two necrosis-inducing effectors was observed in P. nicotianae infecting tomato plants colonized by Trichoderma. In conclusion, this study is a contribution toward understanding the genetic pathways related with the ability of Trichoderma spp. to counteract the challenge of P. nicotianae infections on tomato. Additionally, the experiments revealed the beneficial effects in the tomato growth promotion of a new T. atroviride strain and its good antagonistic effectiveness in the biological control of root and crown rot incited by P. nicotianae, confirming that Trichoderma spp. can be a powerful tool in integrated pest management strategies of Phytophthora diseases of horticultural crops.

First Report of Root Rot Caused by Phytophthora bilorbang on Olea europaea in Italy.

Leaf chlorosis, severe defoliation and wilt associated with root rot were observed on mature olive trees cv. Nera di Gonnos in an experimental orchard at Mirto Crosia (Calabria, southern Italy). An oomycete was consistently isolated from rotten roots of symptomatic olive trees. It was identified as Phytophthora bilorbang by morphological characters and sequencing of Internal Transcribed Spacer (ITS) regions of ribosomal DNA (rDNA). Pathogenicity was verified by inoculating potted two-month-old rooted cuttings of Olea europaea var. Nera di Gonnos in a soil infestation trial. P. bilorbang was re-isolated from roots of symptomatic, artificially inoculated olive cuttings to fulfill Koch's postulates. This is the first report of P. bilorbang on O. europaea L. and on a species of the Oleaceae family worldwide.

Characterization of Colletotrichum ocimi Population Associated with Black Spot of Sweet Basil (Ocimum basilicum) in Northern Italy.

Black spot is a major foliar disease of sweet basil (Ocimum basilicum) present in a typical cultivation area of northern Italy, including the Liguria and southern Piedmont regions, where this aromatic herb is an economically important crop. In this study, 15 Colletotrichum isolates obtained from sweet basil plants with symptoms of black spot sampled in this area were characterized morphologically and by nuclear DNA analysis using internal transcribed spacers (ITS) and intervening 5.8S nrDNA as well as part of the ß-tubulin gene (TUB2) regions as barcode markers. Analysis revealed all but one isolate belonged to the recently described species C. ocimi of the C. destructivum species complex. Only one isolate was identified as C. destructivum sensu stricto (s.s.). In pathogenicity tests on sweet basil, both C. ocimi and C. destructivum s.s. isolates incited typical symptoms of black spot, showing that although C. ocimi prevails in this basil production area, it is not the sole causal agent of black spot in northern Italy. While no other hosts of C. ocimi are known worldwide, the close related species C. destructivum has a broad host range, suggesting a speciation process of C. ocimi within this species complex driven by adaptation to the host.

Multiple new cryptic pathogenic Phytophthora species from Fagaceae forests in Austria, Italy and Portugal.

During surveys of Phytophthora diversity in natural and semi-natural Fagaceae forests in Austria, Italy and Portugal, four new cryptic species were isolated from rhizosphere soil samples. Multigene phylogeny based on nuclear ITS, ß-tubulin and HSP90 and mitochondrial cox1 and NADH1 gene sequences demonstrated that two species, P. tyrrhenica and P. vulcanica spp. nov., belong to phylogenetic Clade 7a, while the other two species, P. castanetorum and P. tubulina spp. nov., clustered together with P. quercina forming a new clade, named here as Clade 12. All four new species are homothallic and have low optimum and maximum temperatures for growth and very slow growth rates at their respective optimum temperature. They differed from each other and from related species by a unique combination of morphological characters, cardinal temperatures, and growth rates. Pathogenicity of all Phytophthora species to the root system of their respective host species was demonstrated in soil infestation trials.

Characterization of Phytophthora infestans populations in northwestern Algeria during 2008-2014.

A total of 161 Phytophthora infestans isolates, collected from infected potato and tomato plants during 2008-2014, were characterized based on mating type, metalaxyl sensitivity and polymorphism at 12 simple sequence repeat (SSR) loci, in order to investigate the population of P. infestans in the north-west of Algeria, an emerging potato production region. The majority of isolates were of A2 mating type (112 isolates). A high percentage (89 %) of resistance to metalaxyl among isolates was detected. The metalaxyl resistant phenotype was present in both mating types with a higher percentage in A2 mating type isolates. SSR-based genotypic analysis of P. infestans population showed a low diversity. Genotype 13_A2 was the predominant in the population with a frequency of 67 % followed by 2_A1 (21 %) and 23_A1 (5 %). Genotype 23_A1 was detected only in tomato and potato isolates collected in 2013 and 2014.

Two previously unknown Phytophthora species associated with brown rot of Pomelo (Citrus grandis) fruits in Vietnam.

Two distinct Phytophthora taxa were found to be associated with brown rot of pomelo (Citrus grandis), a new disease of this ancestral Citrus species, in the Vinh Long province, Mekong River Delta area, southern Vietnam. On the basis of morphological characters and using the ITS1-5.8S-ITS2 region of the rDNA and the cytochrome oxidase subunit 1 (COI) as barcode genes, one of the two taxa was provisionally named as Phytophthora sp. prodigiosa, being closely related to but distinct from P. insolita, a species in Phytophthora Clade 9, while the other one, was closely related to but distinct from the Clade 2 species P. meadii and was informally designated as Phytophthora sp. mekongensis. Isolates of P. sp. prodigiosa and P. sp. mekongensis were also obtained from necrotic fibrous roots of Volkamer lemon (C. volkameriana) rootstocks grafted with 'King' mandarin (Citrus nobilis) and from trees of pomelo, respectively, in other provinces of the Mekong River Delta, indicating a widespread occurrence of both Phytophthora species in this citrus-growing area. Koch's postulates were fulfilled via pathogenicity tests on fruits of various Citrus species, including pomelo, grapefruit (Citrus x paradisi), sweet orange (Citrus x sinensis) and bergamot (Citrus x bergamia) as well as on the rootstock of 2-year-old trees of pomelo and sweet orange on 'Carrizo' citrange (C. sinensis 'Washington Navel' x Poncirus trifoliata). This is the first report of a Phytophthora species from Clade 2 other than P. citricola and P. citrophthora as causal agent of fruit brown rot of Citrus worldwide and the first report of P. insolita complex in Vietnam. Results indicate that likely Vietnam is still an unexplored reservoir of Phytophthora diversity.

Cadmium induces cadmium-tolerant gene expression in the filamentous fungus Trichoderma harzianum.

The filamentous fungus Trichoderma harzianum, strain IMI 393899, was able to grow in the presence of the heavy metals cadmium and mercury. The main objective of this research was to study the molecular mechanisms underlying the tolerance of the fungus T. harzianum to cadmium. The suppression subtractive hybridization (SSH) method was used for the characterization of the genes of T. harzianum implicated in cadmium tolerance compared with those expressed in the response to the stress induced by mercury. Finally, the effects of cadmium exposure were also validated by measuring the expression levels of the putative genes coding for a glucose transporter, a plasma membrane ATPase, a Cd(2+)/Zn(2+) transporter protein and a two-component system sensor histidine kinase YcbA, by real-time-PCR. By using the aforementioned SSH strategy, it was possible to identify 108 differentially expressed genes of the strain IMI 393899 of T. harzianum grown in a mineral substrate with the addition of cadmium. The expressed sequence tags identified by SSH technique were encoding different genes that may be involved in different biological processes, including those associated to primary and secondary metabolism, intracellular transport, transcription factors, cell defence, signal transduction, DNA metabolism, cell growth and protein synthesis. Finally, the results show that in the mechanism of tolerance to cadmium a possible signal transduction pathway could activate a Cd(2+)/Zn(2+) transporter protein and/or a plasma membrane ATPase that could be involved in the compartmentalization of cadmium inside the cell.

Phytophthora niederhauserii sp. nov., a polyphagous species associated with ornamentals, fruit trees and native plants in 13 countries.

A non-papillate, heterothallic Phytophthora species first isolated in 2001 and subsequently from symptomatic roots, crowns and stems of 33 plant species in 25 unrelated botanical families from 13 countries is formally described here as a new species. Symptoms on various hosts included crown and stem rot, chlorosis, wilting, leaf blight, cankers and gumming. This species was isolated from Australia, Hungary, Israel, Italy, Japan, the Netherlands, Norway, South Africa, Spain, Taiwan, Turkey, the United Kingdom and United States in association with shrubs and herbaceous ornamentals grown mainly in greenhouses. The most prevalent hosts are English ivy (Hedera helix) and Cistus (Cistus salvifolius). The association of the species with acorn banksia (Banksia prionotes) plants in natural ecosystems in Australia, in affected vineyards (Vitis vinifera) in South Africa and almond (Prunus dulcis) trees in Spain and Turkey in addition to infection of shrubs and herbaceous ornamentals in a broad range of unrelated families are a sign of a wide ecological adaptation of the species and its potential threat to agricultural and natural ecosystems. The morphology of the persistent non-papillate ellipsoid sporangia, unique toruloid lobate hyphal swellings and amphigynous antheridia does not match any of the described species. Phylogenetic analysis based on sequences of the ITS rDNA, EF-1α, and ß-tub supported that this organism is a hitherto unknown species. It is closely related to species in ITS clade 7b with the most closely related species being P. sojae. The name Phytophthora niederhauserii has been used in previous studies without the formal description of the holotype. This name is validated in this manuscript with the formal description of Phytophthora niederhauserii Z.G. Abad et J.A. Abad, sp. nov. The name is coined to honor Dr John S. Niederhauser, a notable plant pathologist and the 1990 World Food Prize laureate.