Field surveys conducted in two urban green spaces in Athens (Greece) revealed the presence of Phy... more Field surveys conducted in two urban green spaces in Athens (Greece) revealed the presence of Phytophthorarelated diseases on Platanus orientalis and P. x acerifolia trees. Declining trees showed a range of disease symptoms including root rot, stem bleeding cankers and extensive canopy dieback. Since there is little information about the etiology of these diseases, a study was conducted from 2016 to 2021 to define the main pathogens involved. A total of 71 Phytophthora isolates were obtained from bark tissues and rhizosphere samples collected from symptomatic plane trees. Based on morphological traits and DNA sequence data, Phytophthora isolates were identified as Ph. mediterranea (11 isolates) and Ph. nicotianae (60). Over a five-year period 41% of P. orientalis trees associated with Phytophthora infections died and were removed from the park. Pathogenicity tests confirmed that all Phytophthora species including Ph. cinnamomi used for comparison, are pathogenic on both P. orientalis and P. x acerifolia trees. Phytophthora cinnamomi was shown to be the most aggressive species on both P. orientalis and P. x acerifolia. Phytophthora nicotianae was the dominant species, whereas Ph. mediterranea was associated with a few trees. Our finding has contributed to expanding knowledge on the host and geographic range of Ph. mediterranea, an invasive pathogen with a high potential for diffusion in Mediterranean regions and highlights the importance of enhancing biosecurity measures to prevent and limit the spread of invasive pathogens in urban and natural ecosystems.
ABSTRACT Tamarix plants are resistant to abiotic stresses, as they thrive in zones where drought,... more ABSTRACT Tamarix plants are resistant to abiotic stresses, as they thrive in zones where drought, soil salinity, and high temperature areSpecial Abstracts / Journal of Biotechnology 150S (2010) S1–S576 S479 regular phenomena. Their survival capacity and genetic biodiversity can be harnessed to help sequester a significant part of the high atmospheric CO2 content, by increasing Tamarix plantation in marginal areas. The taxonomy of this genus is troublesome, as the species cannot be distinguished at vegetative status. Italian coastal zones could provide Tamarix germplasm adapted to stressing habitats, but there is not any information about its genetic structure. A good knowledge of the natural genetic resources and variability of Tamarix is the basis for the selection of tolerant genotypes for the recovery of degraded areas. The aim of this work is the genetic characterization of three populations of Tamarix spp. with SSR and EST-SSR markers, and the development of a new methodology for clarifying the taxonomy of this genus. Eight polymorphic microsatellites were selected and analysed on 163 plants from three populations from Southern Italy: Basento River (Basilicata), Simeto River (Sicily), and Crati River (Calabria). Each site is characterized by a wide variety of environments, and plant material was collected along altitudinal, water availability, and salinity gradient. Forty-nine plants were identified with Baum’s morphological keys, the speciesT. africana,T. gallica, andT. canariensiswere found; anyway, a large set of sampled plants remained unidentified. The set of EST-SSR and SSR were used as tool for species identification, comparing the unidentified samples to our identified samples. Both kinds of markers showed cross-species amplification, moreover, intraspecific and interspecific polymorphism was observed. Our results provide a first contribution to the genetic diversity of Italian species. Moreover, the amount and distribution of genetic variability of Tamarix plants will clarify their ecological role, and offer information about genetic basis of abiotic stress tolerance in Tamarix.
Tamarix L. plants are tolerant to extreme environmental conditions and represent a resource for t... more Tamarix L. plants are tolerant to extreme environmental conditions and represent a resource for the recovery of marginal areas. The aim of this study is to develop a molecular method for species assignment and to characterize the genetic differentiation of Italian Tamarix populations. Blind sampling was performed and individuals were gathered without any regard for species identity from seven sites in Italy. If possible, flowers for species identification were collected, but 60% of samples remained unidentified. The genotypic profile of 17 microsatellite markers and a Bayesian statistical approach allowed the individuals to split among genetic entities rather than by their species identity. A clear assignment of Tamarix africana Poir. individuals was found, but this was not the case for Tamarix gallica L. and Tamarix canariensis Willd., whose individuals were clustered in a unique group (T. gallica-like). In T. africana, the Bayesian analysis of the genetic structure pointed out the...
Page 1. ORIGINAL PAPER Functional characterisation of three Italian Populus alba L. genotypes und... more Page 1. ORIGINAL PAPER Functional characterisation of three Italian Populus alba L. genotypes under salinity stress Isacco Beritognolo Æ Moica Piazzai Æ Simona Benucci Æ Elena Kuzminsky Æ Maurizio Sabatti Æ Giuseppe Scarascia Mugnozza Æ Rosario Muleo ...
Quercus ilex L. seedlings were exposed in open-top chambers for one growing season to three level... more Quercus ilex L. seedlings were exposed in open-top chambers for one growing season to three levels of ozone (O3 ): charcoal filtered air, non-filtered air supplemented with +30% or +74% ambient air O3 . Key functional parameters related to photosynthetic performance and stomatal density were measured to evaluate the response mechanisms of Q. ilex to chronic O3 exposure, clarifying how ecophysiological traits are modulated during the season in an ozone-enriched environment. Dark respiration showed an early response to O3 exposure, increasing approximately 45% relative to charcoal-filtered air in both O3 enriched treatments. However, at the end of the growing season, maximum rate of assimilation (Amax ) and stomatal conductance (gs ) showed a decline (-13% and -36%, for Amax and gs , respectively) only in plants under higher O3 levels. Photosystem I functionality supported the capacity of Q. ilex to cope with oxidative stress by adjusting the energy flow partitioning inside the photosystems. The response to O3 was also characterised by increased stomatal density in both O3 enriched treatments relative to controls. Our results suggest that in order to improve the reliability of metrics for O3 risk assessment, the seasonal changes in the response of gs and photosynthetic machinery to O3 stress should be considered.
Soil salinity is an important limiting factor to tree growth and productivity. Populus alba L. is... more Soil salinity is an important limiting factor to tree growth and productivity. Populus alba L. is a moderately salt-tolerant species and its natural populations are adapted to contrasting environments, thus providing genetic resources to identify key genes for tolerance to abiotic stress, such as salinity. To elucidate the molecular and genetic basis of variation for salinity tolerance in P. alba, we analyzed the short-term ecophysiological and transcriptome response to salinity. Two contrasting genotypes, 6K3, salt sensitive, and 14P11, salt tolerant, originating from North and South Italy, respectively, were challenged with salt stress (200 mM NaCl). Sodium accumulated in the leaves of salt-treated plants and its concentration increased with time. The net photosynthesis was strongly reduced by salinity in both genotypes, with 6K3 being significantly more affected than 14P11. The transcriptional changes in leaves were analyzed using cDNA microarrays containing about 7000 stress-related poplar expressed sequence tags (EST). A microarray experiment based on RNA pooling showed a number of salinity--regulated transcripts that markedly increased from 3 h to 3 days of salinity treatment. Thus, a detailed analysis was performed on replicated plants collected at 3 days, when ~20% of transcripts showed significant change induced by salinity. In 6K3, there were more genes with decreased expression than genes with increased expression, whereas such a difference was not found in 14P11. Most transcripts with decreased expression were shared between the two genotypes, whereas transcripts with increased expression were mostly regulated in a genotype-specific manner. The commonly decreased transcripts (71 genes) were functionally related to carbohydrate metabolism, energy metabolism and photosynthesis. These biological processes were consistent with the strong inhibition of photosynthesis, caused by salinity. The commonly increased transcripts (13 genes) were functionally related to primary metabolism and biosynthesis of proteins and macromolecules. The salinity-increased transcripts discriminated the molecular response of the two genotypes. In 14P11, the 21 genes specifically salinity-induced were related to stress response, cell development, cell death and catabolism. In 6K3, the 15 genes with salinity-increased expression were involved in protein biosynthesis, metabolism of macromolecules and cell organization and biogenesis. The difference in transcriptome response between the two genotypes could address the molecular basis of intra-specific variation of salinity tolerance in P. alba.
Field surveys conducted in two urban green spaces in Athens (Greece) revealed the presence of Phy... more Field surveys conducted in two urban green spaces in Athens (Greece) revealed the presence of Phytophthorarelated diseases on Platanus orientalis and P. x acerifolia trees. Declining trees showed a range of disease symptoms including root rot, stem bleeding cankers and extensive canopy dieback. Since there is little information about the etiology of these diseases, a study was conducted from 2016 to 2021 to define the main pathogens involved. A total of 71 Phytophthora isolates were obtained from bark tissues and rhizosphere samples collected from symptomatic plane trees. Based on morphological traits and DNA sequence data, Phytophthora isolates were identified as Ph. mediterranea (11 isolates) and Ph. nicotianae (60). Over a five-year period 41% of P. orientalis trees associated with Phytophthora infections died and were removed from the park. Pathogenicity tests confirmed that all Phytophthora species including Ph. cinnamomi used for comparison, are pathogenic on both P. orientalis and P. x acerifolia trees. Phytophthora cinnamomi was shown to be the most aggressive species on both P. orientalis and P. x acerifolia. Phytophthora nicotianae was the dominant species, whereas Ph. mediterranea was associated with a few trees. Our finding has contributed to expanding knowledge on the host and geographic range of Ph. mediterranea, an invasive pathogen with a high potential for diffusion in Mediterranean regions and highlights the importance of enhancing biosecurity measures to prevent and limit the spread of invasive pathogens in urban and natural ecosystems.
ABSTRACT Tamarix plants are resistant to abiotic stresses, as they thrive in zones where drought,... more ABSTRACT Tamarix plants are resistant to abiotic stresses, as they thrive in zones where drought, soil salinity, and high temperature areSpecial Abstracts / Journal of Biotechnology 150S (2010) S1–S576 S479 regular phenomena. Their survival capacity and genetic biodiversity can be harnessed to help sequester a significant part of the high atmospheric CO2 content, by increasing Tamarix plantation in marginal areas. The taxonomy of this genus is troublesome, as the species cannot be distinguished at vegetative status. Italian coastal zones could provide Tamarix germplasm adapted to stressing habitats, but there is not any information about its genetic structure. A good knowledge of the natural genetic resources and variability of Tamarix is the basis for the selection of tolerant genotypes for the recovery of degraded areas. The aim of this work is the genetic characterization of three populations of Tamarix spp. with SSR and EST-SSR markers, and the development of a new methodology for clarifying the taxonomy of this genus. Eight polymorphic microsatellites were selected and analysed on 163 plants from three populations from Southern Italy: Basento River (Basilicata), Simeto River (Sicily), and Crati River (Calabria). Each site is characterized by a wide variety of environments, and plant material was collected along altitudinal, water availability, and salinity gradient. Forty-nine plants were identified with Baum’s morphological keys, the speciesT. africana,T. gallica, andT. canariensiswere found; anyway, a large set of sampled plants remained unidentified. The set of EST-SSR and SSR were used as tool for species identification, comparing the unidentified samples to our identified samples. Both kinds of markers showed cross-species amplification, moreover, intraspecific and interspecific polymorphism was observed. Our results provide a first contribution to the genetic diversity of Italian species. Moreover, the amount and distribution of genetic variability of Tamarix plants will clarify their ecological role, and offer information about genetic basis of abiotic stress tolerance in Tamarix.
Tamarix L. plants are tolerant to extreme environmental conditions and represent a resource for t... more Tamarix L. plants are tolerant to extreme environmental conditions and represent a resource for the recovery of marginal areas. The aim of this study is to develop a molecular method for species assignment and to characterize the genetic differentiation of Italian Tamarix populations. Blind sampling was performed and individuals were gathered without any regard for species identity from seven sites in Italy. If possible, flowers for species identification were collected, but 60% of samples remained unidentified. The genotypic profile of 17 microsatellite markers and a Bayesian statistical approach allowed the individuals to split among genetic entities rather than by their species identity. A clear assignment of Tamarix africana Poir. individuals was found, but this was not the case for Tamarix gallica L. and Tamarix canariensis Willd., whose individuals were clustered in a unique group (T. gallica-like). In T. africana, the Bayesian analysis of the genetic structure pointed out the...
Page 1. ORIGINAL PAPER Functional characterisation of three Italian Populus alba L. genotypes und... more Page 1. ORIGINAL PAPER Functional characterisation of three Italian Populus alba L. genotypes under salinity stress Isacco Beritognolo Æ Moica Piazzai Æ Simona Benucci Æ Elena Kuzminsky Æ Maurizio Sabatti Æ Giuseppe Scarascia Mugnozza Æ Rosario Muleo ...
Quercus ilex L. seedlings were exposed in open-top chambers for one growing season to three level... more Quercus ilex L. seedlings were exposed in open-top chambers for one growing season to three levels of ozone (O3 ): charcoal filtered air, non-filtered air supplemented with +30% or +74% ambient air O3 . Key functional parameters related to photosynthetic performance and stomatal density were measured to evaluate the response mechanisms of Q. ilex to chronic O3 exposure, clarifying how ecophysiological traits are modulated during the season in an ozone-enriched environment. Dark respiration showed an early response to O3 exposure, increasing approximately 45% relative to charcoal-filtered air in both O3 enriched treatments. However, at the end of the growing season, maximum rate of assimilation (Amax ) and stomatal conductance (gs ) showed a decline (-13% and -36%, for Amax and gs , respectively) only in plants under higher O3 levels. Photosystem I functionality supported the capacity of Q. ilex to cope with oxidative stress by adjusting the energy flow partitioning inside the photosystems. The response to O3 was also characterised by increased stomatal density in both O3 enriched treatments relative to controls. Our results suggest that in order to improve the reliability of metrics for O3 risk assessment, the seasonal changes in the response of gs and photosynthetic machinery to O3 stress should be considered.
Soil salinity is an important limiting factor to tree growth and productivity. Populus alba L. is... more Soil salinity is an important limiting factor to tree growth and productivity. Populus alba L. is a moderately salt-tolerant species and its natural populations are adapted to contrasting environments, thus providing genetic resources to identify key genes for tolerance to abiotic stress, such as salinity. To elucidate the molecular and genetic basis of variation for salinity tolerance in P. alba, we analyzed the short-term ecophysiological and transcriptome response to salinity. Two contrasting genotypes, 6K3, salt sensitive, and 14P11, salt tolerant, originating from North and South Italy, respectively, were challenged with salt stress (200 mM NaCl). Sodium accumulated in the leaves of salt-treated plants and its concentration increased with time. The net photosynthesis was strongly reduced by salinity in both genotypes, with 6K3 being significantly more affected than 14P11. The transcriptional changes in leaves were analyzed using cDNA microarrays containing about 7000 stress-related poplar expressed sequence tags (EST). A microarray experiment based on RNA pooling showed a number of salinity--regulated transcripts that markedly increased from 3 h to 3 days of salinity treatment. Thus, a detailed analysis was performed on replicated plants collected at 3 days, when ~20% of transcripts showed significant change induced by salinity. In 6K3, there were more genes with decreased expression than genes with increased expression, whereas such a difference was not found in 14P11. Most transcripts with decreased expression were shared between the two genotypes, whereas transcripts with increased expression were mostly regulated in a genotype-specific manner. The commonly decreased transcripts (71 genes) were functionally related to carbohydrate metabolism, energy metabolism and photosynthesis. These biological processes were consistent with the strong inhibition of photosynthesis, caused by salinity. The commonly increased transcripts (13 genes) were functionally related to primary metabolism and biosynthesis of proteins and macromolecules. The salinity-increased transcripts discriminated the molecular response of the two genotypes. In 14P11, the 21 genes specifically salinity-induced were related to stress response, cell development, cell death and catabolism. In 6K3, the 15 genes with salinity-increased expression were involved in protein biosynthesis, metabolism of macromolecules and cell organization and biogenesis. The difference in transcriptome response between the two genotypes could address the molecular basis of intra-specific variation of salinity tolerance in P. alba.
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