Publications by authors named "Erika Sabella"

23 Publications

  • Page 1 of 1

Screening of Olive Biodiversity Defines Genotypes Potentially Resistant to .

Front Plant Sci 2021 16;12:723879. Epub 2021 Aug 16.

Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy.

The recent outbreak of the Olive Quick Decline Syndrome (OQDS), caused by subsp. (), is dramatically altering ecosystem services in the peninsula of Salento (Apulia Region, southeastern Italy). Here we report the accomplishment of several exploratory missions in the Salento area, resulting in the identification of thirty paucisymptomatic or asymptomatic plants in olive orchards severely affected by the OQDS. The genetic profiles of such putatively resistant plants (PRPs), assessed by a selection of ten simple sequence repeat (SSR) markers, were compared with those of 141 Mediterranean cultivars. Most (23) PRPs formed a genetic cluster (K1) with 22 Italian cultivars, including 'Leccino' and 'FS17', previously reported as resistant to . The remaining PRPs displayed relatedness with genetically differentiated germplasm, including a cluster of Tunisian cultivars. Markedly lower colonization levels were observed in PRPs of the cluster K1 with respect to control plants. Field evaluation of four cultivars related to PRPs allowed the definition of partial resistance in the genotypes 'Frantoio' and 'Nocellara Messinese'. Some of the PRPs identified in this study might be exploited in cultivation, or as parental clones of breeding programs. In addition, our results indicate the possibility to characterize resistance to in cultivars genetically related to PRPs.
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http://dx.doi.org/10.3389/fpls.2021.723879DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8415753PMC
August 2021

Molecular Responses to Cadmium Exposure in Two Contrasting Durum Wheat Genotypes.

Int J Mol Sci 2021 Jul 8;22(14). Epub 2021 Jul 8.

Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100 Lecce, Italy.

Cadmium is a heavy metal that can be easily accumulated in durum wheat kernels and enter the human food chain. Two near-isogenic lines (NILs) with contrasting cadmium accumulation in grains, High-Cd or Low-Cd (H-Cd NIL and L-Cd NIL, respectively), were used to understand the Cd accumulation and transport mechanisms in durum wheat roots. Plants were cultivated in hydroponic solution, and cadmium concentrations in roots, shoots and grains were quantified. To evaluate the molecular mechanism activated in the two NILs, the transcriptomes of roots were analyzed. The observed response is complex and involves many genes and molecular mechanisms. We found that the gene sequences of two basic helix-loop-helix (bHLH) transcription factors (bHLH29 and bHLH38) differ between the two genotypes. In addition, the transporter Heavy Metal Tolerance 1 (HMT-1) is expressed only in the low-Cd genotype and many peroxidase genes are up-regulated only in the L-Cd NIL, suggesting ROS scavenging and root lignification as active responses to cadmium presence. Finally, we hypothesize that some aquaporins could enhance the Cd translocation from roots to shoots. The response to cadmium in durum wheat is therefore extremely complex and involves transcription factors, chelators, heavy metal transporters, peroxidases and aquaporins. All these new findings could help to elucidate the cadmium tolerance in wheat and address future breeding programs.
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http://dx.doi.org/10.3390/ijms22147343DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8306872PMC
July 2021

Advances in Plant Disease Detection and Monitoring: From Traditional Assays to In-Field Diagnostics.

Sensors (Basel) 2021 Mar 18;21(6). Epub 2021 Mar 18.

Omnics Research Group, Department of Mathematics and Physics "Ennio De Giorgi", University of Salento, Via per Monteroni, 73100 Lecce, Italy.

Human activities significantly contribute to worldwide spread of phytopathological adversities. Pathogen-related food losses are today responsible for a reduction in quantity and quality of yield and decrease value and financial returns. As a result, "early detection" in combination with "fast, accurate, and cheap" diagnostics have also become the new mantra in plant pathology, especially for emerging diseases or challenging pathogens that spread thanks to asymptomatic individuals with subtle initial symptoms but are then difficult to face. Furthermore, in a globalized market sensitive to epidemics, innovative tools suitable for field-use represent the new frontier with respect to diagnostic laboratories, ensuring that the instruments and techniques used are suitable for the operational contexts. In this framework, portable systems and interconnection with Internet of Things (IoT) play a pivotal role. Here we review innovative diagnostic methods based on nanotechnologies and new perspectives concerning information and communication technology (ICT) in agriculture, resulting in an improvement in agricultural and rural development and in the ability to revolutionize the concept of "preventive actions", making the difference in fighting against phytopathogens, all over the world.
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http://dx.doi.org/10.3390/s21062129DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8003093PMC
March 2021

Secondary Metabolites in -Plant Interaction.

Pathogens 2020 Aug 20;9(9). Epub 2020 Aug 20.

Department of Biological and Environmental Sciences and Technologies, University of Salento, 73100 Lecce, Italy.

During their evolutionary history, plants have evolved the ability to synthesize and accumulate small molecules known as secondary metabolites. These compounds are not essential in the primary cell functions but play a significant role in the plants' adaptation to environmental changes and in overcoming stress. Their high concentrations may contribute to the resistance of the plants to the bacterium , which has recently re-emerged as a plant pathogen of global importance. Although it is established in several areas globally and is considered one of the most dangerous plant pathogens, no cure has been developed due to the lack of effective bactericides and the difficulties in accessing the xylem vessels where the pathogen grows and produces cell aggregates and biofilm. This review highlights the role of secondary metabolites in the defense of the main economic hosts of and identifies how knowledge about biosynthetic pathways could improve our understanding of disease resistance. In addition, current developments in non-invasive techniques and strategies of combining molecular and physiological techniques are examined, in an attempt to identify new metabolic engineering options for plant defense.
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http://dx.doi.org/10.3390/pathogens9090675DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7559865PMC
August 2020

Increase in ring width, vessel number and δ18O in olive trees infected with Xylella fastidiosa.

Tree Physiol 2020 10;40(11):1583-1594

WSL Swiss Federal Institute for Forest, Snow and Landscape Research, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland.

Xylella fastidiosa (Xf) Wells, Raju et al., 1986 is a bacterium that causes plant diseases in the Americas. In Europe, it was first detected on the Salento Peninsula (Italy), where it was found to be associated with the olive quick decline syndrome. Here, we present the results of the first tree-ring study of infected and uninfected olive trees (Olea europaea L.) of two different cultivars, one resistant and one susceptible, to establish the effects induced by the spread of the pathogen inside the tree. Changes in wood anatomical characteristics, such as an increase in the number of vessels and in ring width, were observed in the infected plants of both the cultivars Cellina di Nardò (susceptible to Xf infection) and Leccino (resistant to Xf infection). Thus, whether infection affects the mortality of the tree or not, the tree shows a reaction to it. The presence of occlusions was detected in the wood of both 4-year-old branches and the tree stem core. As expected, the percentage of occluded vessels in the Xf-susceptible cultivar Cellina di Nardò was significantly higher than in the Xf-resistant cultivar Leccino. The δ 18O of the 4-year-old branches was significantly higher in infected trees of both cultivars than in noninfected trees, while no variations in δ 13C were observed. This suggests a reduction in leaf transpiration rates during infection and seems to be related to the occlusions observed in rings of the 4-year-old branches. Such occlusions can determine effects at leaf level that could influence stomatal activity. On the other hand, the significant increase in the number of vessels in infected trees could be related to the tree's attempt to enhance water conductivity in response to the pathogen-induced vessel occlusions.
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http://dx.doi.org/10.1093/treephys/tpaa095DOI Listing
October 2020

Biochemical Changes in Leaves of cv. Sangiovese Infected by Bois Noir Phytoplasma.

Pathogens 2020 Apr 7;9(4). Epub 2020 Apr 7.

Department of Biological and Environmental Sciences and Technologies, University of Salento, 73100 Lecce, Italy.

Bois noir is a disease associated with the presence of phytoplasma ' Phytoplasma solani' belonging to the Stolbur group (subgroup 16SrXII-A), which has a heavy economic impact on grapevines. This study focused on the changes induced by phytoplasma in terms of the profile and amount of secondary metabolites synthesized in the phenylpropanoid pathway in leaves of L. red-berried cultivar Sangiovese. Metabolic alterations were assessed according to the disease progression through measurements of soluble sugars, chlorophyll, and phenolic compounds produced by plant hosts, in response to disease on symptomatic and asymptomatic Bois noir-positive plants. Significant differences were revealed in the amount of soluble sugars, chlorophyll, and accumulation/reduction of some compounds synthesized in the phenylpropanoid pathway of Bois noir-positive and negative grapevine leaves. Our results showed a marked increase in phenolic and flavonoid production and a parallel decrease in lignin content in Bois noir-positive compared to negative leaves. Interestingly, some parameters (chlorophyll , soluble sugars, total phenolic or flavonoids content, proanthocyanidins, quercetin) differed between Bois noir-positive and negative leaves regardless of symptoms, indicating measurable biochemical changes in asymptomatic leaves. Our grapevine cultivar Sangiovese results highlighted an extensive modulation of the phenylpropanoid biosynthetic pathway as a defense mechanism activated by the host plant in response to Bois noir disease.
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http://dx.doi.org/10.3390/pathogens9040269DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7238227PMC
April 2020

The -Resistant Olive Cultivar "Leccino" Has Stable Endophytic Microbiota during the Olive Quick Decline Syndrome (OQDS).

Pathogens 2019 Dec 31;9(1). Epub 2019 Dec 31.

Department of Biological and Environmental Sciences and Technologies, University of Salento, Via Prov. le Monteroni, I-73100 Lecce, Italy.

is a highly virulent pathogen that causes Olive Quick Decline Syndrome (OQDS), which is currently devastating olive plantations in the Salento region (Apulia, Southern Italy). We explored the microbiome associated with -infected (-infected) and -uninfected (-uninfected) olive trees in Salento, to assess the level of dysbiosis and to get first insights into the potential role of microbial endophytes in protecting the host from the disease. The resistant cultivar "Leccino" was compared to the susceptible cultivar "Cellina di Nardò", in order to identify microbial taxa and parameters potentially involved in resistance mechanisms. Metabarcoding of 16S rRNA genes and fungal ITS2 was used to characterize both total and endophytic microbiota in olive branches and leaves. "Cellina di Nardò" showed a drastic dysbiosis after infection, while "Leccino" (both infected and uninfected) maintained a similar microbiota. The genus dominated all "Leccino" and -uninfected "Cellina di Nardò" trees, whereas prevailed in infected "Cellina di Nardò". Diversity of microbiota in -uninfected "Leccino" was higher than in -uninfected "Cellina di Nardò". Several bacterial taxa specifically associated with "Leccino" showed potential interactions with . The maintenance of a healthy microbiota with higher diversity and the presence of cultivar-specific microbes might support the resistance of "Leccino" to . Such beneficial bacteria might be isolated in the future for biological treatment of the OQDS.
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http://dx.doi.org/10.3390/pathogens9010035DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7168594PMC
December 2019

Combined Effect of Cadmium and Lead on Durum Wheat.

Int J Mol Sci 2019 Nov 24;20(23). Epub 2019 Nov 24.

Department of Biological and Environmental Sciences and Technologies (DiSTeBA), Salento University, Via Prov. le Lecce-Monteroni, 73100 Lecce, Italy.

Cadmium (Cd) and lead (Pb) are two toxic heavy metals (HMs) whose presence in soil is generally low. However, industrial and agricultural activities in recent years have significantly raised their levels, causing progressive accumulations in plant edible tissues, and stimulating research in this field. Studies on toxic metals are commonly focused on a single metal, but toxic metals occur simultaneously. The understanding of the mechanisms of interaction between HMs during uptake is important to design agronomic or genetic strategies to limit contamination of crops. To study the single and combined effect of Cd and Pb on durum wheat, a hydroponic experiment was established to examine the accumulation of the two HMs. Moreover, the molecular mechanisms activated in the roots were investigated paying attention to transcription factors (bHLH family), heavy metal transporters and genes involved in the biosynthesis of metal chelators (nicotianamine and mugineic acid). Cd and Pb are accumulated following different molecular strategies by durum wheat plants, even if the two metals interact with each other influencing their respective uptake and translocation. Finally, we demonstrated that some genes ( and ) were induced in the durum wheat roots only in response to Cd.
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http://dx.doi.org/10.3390/ijms20235891DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6929116PMC
November 2019

Molecular Effects of and Drought Combined Stress in Olive Trees.

Plants (Basel) 2019 Oct 23;8(11). Epub 2019 Oct 23.

Department of Biological and Environmental Sciences and Technologies, University of Salento, 73100 Lecce, Italy.

Due to global climate change, complex combinations of stresses are expected to occur, among which the interaction between pathogens and drought stress may have a significant effect on growth and yield. In this study, the ()-resistant Leccino and the susceptible one Cellina di Nardò were subjected to (a) individual drought stress, (b) infection and (c) combination of both stress conditions. Here we report the physiological response to stresses in water content in leaves and the modulation in the expression level of seven genes responsive to plant water status and pathogen infection. In -resistant plants, higher expression levels are reported for genes belonging to ROS-scavenging systems and for genes involved in pathogen stress (pathogenesis-related, , and leucine-rich repeat genes, ). However, and were not further induced by water deficit. Interestingly, the genes related to drought response (aquaporin, , dehydration responsive element binding, , and dehydrin, ), which induction was higher in Cellina di Nardò compared to Leccino during drought stress, was poorly induced in -susceptible plants when occur. Conversely, was induced by presence in Leccino. These results were consistent with observations on water content. Indeed, response was similar in Leccino regardless kind of stress or combination, whereas a strong reduction was observed in -susceptible plants infected by or in presence of combined stresses. Thus, the reported findings indicate that resistance of Leccino to could be linked to its lower resistance to water stress, probably leading to the activation of alternative defense pathways that support the plant in response.
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http://dx.doi.org/10.3390/plants8110437DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6918294PMC
October 2019

Xylem cavitation susceptibility and refilling mechanisms in olive trees infected by Xylella fastidiosa.

Sci Rep 2019 07 3;9(1):9602. Epub 2019 Jul 3.

Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100, Lecce, Italy.

In olive trees, Xylella fastidiosa colonizes xylem vessels and compromises water transport causing the olive quick decline syndrome (OQDS). The loss of hydraulic conductivity could be attributed to vessel occlusions induced both by the bacteria biofilm and by plant responses (tyloses, gums, etc.) that could trigger embolism. The ability of the infected plants to detect embolism and to respond, by activating mechanisms to restore the hydraulic conductivity, can influence the severity of the disease symptomatology. In order to investigate these mechanisms in the X. fastidiosa-resistant olive cultivar Leccino and in the susceptible Cellina di Nardò, sections of healthy olive stems were analysed by laser scanning microscope to calculate the cavitation vulnerability index. Findings indicated that the cultivar Leccino seems to be constitutively less susceptible to cavitation than the susceptible one. Among the vascular refilling mechanisms, starch hydrolysis is a well-known strategy to refill xylem vessels that suffered cavitation and it is characterized by a dense accumulation of starch grains in the xylem parenchima; SEM-EDX analysis of stem cross-sections of infected plants revealed an aggregation of starch grains in the Leccino xylem vessels. These observations could indicate that this cultivar, as well as being anatomically less susceptible to cavitation, it also could be able to activate more efficient refilling mechanisms, restoring vessel's hydraulic conductivity. In order to verify this hypothesis, we analysed the expression levels of some genes belonging to families involved in embolism sensing and refilling mechanisms: aquaporins, sucrose transporters, carbohydrate metabolism and enzymes related to starch breakdown, alpha and beta-amylase. The obtained genes expression patterns suggested that the infected plants of the cultivar Leccino strongly modulates the genes involved in embolism sensing and refilling.
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http://dx.doi.org/10.1038/s41598-019-46092-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6610111PMC
July 2019

Phenolic Profile and Antioxidant Activity of Italian Monovarietal Extra Virgin Olive Oils.

Antioxidants (Basel) 2019 Jun 5;8(6). Epub 2019 Jun 5.

Department of Biological and Environmental Sciences and Technologies (DiSTeBA), Salento University, Via Prov. le Lecce-Monteroni, 73100 Lecce, Italy.

In the last years, the interest in Italian monovarietal oils has increased due to their specific organoleptic qualities. Extra virgin olive oils (EVOOs) are rich in phenolic compounds, secondary metabolites well known and studied for their nutraceutical properties. However, among EVOOs, there is great variability in phenolic composition due to the origin, the production technique, and mainly, the genotype. The aim of this work was to evaluate the different phenolic profiles and the antioxidant activities of monovarietal oils. The results confirm this variability. In fact, the overall content of oleuropein varies up to four times between the different genotypes (from 33.80 to 152.32 mg/kg oil), while the oleocanthal content is significant only in two oils. The antioxidant activity, determined with 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and oxygen radical absorbance capacity (ORAC) assays, is correlated with the content of total phenolic substances, with half maximal inhibitory concentration (IC) values for the DPPH test ranging from 160 to 91 mg of oil, while the ORAC test shows values between 5.45 and 8.03 μmol Trolox equivalent (TE)/g oil.
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http://dx.doi.org/10.3390/antiox8060161DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6617199PMC
June 2019

Evaluation of Phytochemical and Antioxidant Properties of 15 Italian L. Cultivar Leaves.

Molecules 2019 May 24;24(10). Epub 2019 May 24.

Department of Biological and Environmental Sciences and Technologies, University of Salento, 73100 Lecce, Italy.

Olive leaf extracts are of special interest due to their proven therapeutic effects. However, they are still considered a by-product of the table olive and the oil industries. In order to learn possible ways of exploiting this waste for health purposes, we investigated the phytochemical profiles and antioxidant activities in the leaves of 15 Italian L. cultivars grown in the same pedoclimatic conditions. The phenolic profiles and amounts of their seven representative compounds were analyzed using HPLC ESI/MS-TOF. The antioxidant activities were determined using three different antioxidant assays (DPPH, ORAC, and superoxide anion scavenging assay). Wide ranges of total phenolic content (11.39-48.62 g GAE kg dry weight) and antioxidant activities (DPPH values: 8.67-29.89 µmol TE mg dry weight, ORAC values: 0.81-4.25 µmol TE mg dry weight, superoxide anion scavenging activity values: 27.66-48.92 µmol TE mg dry weight) were found in the cultivars. In particular, the cultivars Itrana, Apollo, and Maurino, showed a high amount of total phenols and antioxidant activity, and therefore represent a suitable natural source of biological compounds for use in terms of health benefits.
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http://dx.doi.org/10.3390/molecules24101998DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6572269PMC
May 2019

Antioxidant Activity and Anthocyanin Contents in Olives ( Cellina di Nardò) during Ripening and after Fermentation.

Antioxidants (Basel) 2019 May 18;8(5). Epub 2019 May 18.

Department of Biological and Environmental Sciences and Technologies (DiSTeBA), Salento University, Via Prov. le Lecce-Monteroni, 73100 Lecce, Italy.

The olive tree "Cellina di Nardò" (CdN) is one of the most widespread cultivars in Southern Italy, mainly grown in the Provinces of Lecce, Taranto, and Brindisi over a total of about 60,000 hectares. Although this cultivar is mainly used for oil production, the drupes are also suitable and potentially marketable as table olives. When used for this purpose, olives are harvested after complete maturation, which gives to them a naturally black color due to anthocyanin accumulation. This survey reports for the first time on the total phenolic content (TPC), anthocyanin characterization, and antioxidant activity of CdN olive fruits during ripening and after fermentation. The antioxidant activity (AA) was determined using three different methods. Data showed that TPC increased during maturation, reaching values two times higher in completely ripened olives. Anthocyanins were found only in mature olives and the concentrations reached up to 5.3 g/kg dry weight. AA was determined for the four ripening stages, and was particularly high in the totally black olive fruit, in accordance with TPC and anthocyanin amounts. Moreover, the CdN olives showed a higher TPC and a greater AA compared to other black table olives produced by cultivars commonly grown for this purpose. These data demonstrate the great potential of black table CdN olives, a product that combines exceptional organoleptic properties with a remarkable antioxidant capacity.
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http://dx.doi.org/10.3390/antiox8050138DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6562514PMC
May 2019

Accumulation of Azelaic Acid in Xylella fastidiosa-Infected Olive Trees: A Mobile Metabolite for Health Screening.

Phytopathology 2019 Feb 19;109(2):318-325. Epub 2018 Dec 19.

Department of Biological and Environmental Sciences and Technologies, University of Salento, Lecce, Italy.

Monitoring Xylella fastidiosa is critical for eradicating or at least containing this harmful pathogen. New low-cost and rapid methods for early detection capability are very much needed. Metabolomics may play a key role in diagnosis; in fact, mobile metabolites could avoid errors in sampling due to erratically distributed pathogens. Of the various different mobile signals, we studied dicarboxylic azelaic acid (AzA) which is a key molecule for biotic stress plant response but has not yet been associated with pathogens in olive trees. We found that infected Olea europaea L. plants of cultivars Cellina di Nardò (susceptible to X. fastidiosa) and Leccino (resistant to the pathogen) showed an increase in AzA accumulation in leaf petioles and in sprigs by approximately seven- and sixfold, respectively, compared with plants negative to X. fastidiosa or affected by other pathogens. No statistically significant variation was found between the X. fastidiosa population level and the amount of AzA in either of the plant tissues, suggesting that AzA accumulation was almost independent of the amount of pathogen in the sample. Furthermore, the association of AzA with X. fastidiosa seemed to be reliable for samples judged as potentially false-negative by quantitative polymerase chain reaction (cycle threshold [C] > 33), considering both the absolute value of AzA concentration and the values normalized on negative samples, which diverged significantly from control plants. The accumulation of AzA in infected plants was partially supported by the differential expression of two genes (named OeLTP1 and OeLTP2) encoding lipid transport proteins (LTPs), which shared a specific domain with the LTPs involved in AzA activity in systemic acquired resistance in other plant species. The expression level of OeLTP1 and OeLTP2 in petiole samples showed significant upregulation in samples positive to X. fastidiosa of both cultivars, with higher expression levels in positive samples of Cellina di Nardò compared with Leccino, whereas the two transcripts had a low expression level (C > 40) in negative samples of the susceptible cultivar. Although the results derived from the quantification of AzA cannot confirm the presence of the erratically distributed X. fastidiosa, which can be definitively assessed by traditional methods, we believe they represent a fast and cheap screening method for large-scale monitoring.
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http://dx.doi.org/10.1094/PHYTO-07-18-0236-FIDOI Listing
February 2019

Activation of a gene network in durum wheat roots exposed to cadmium.

BMC Plant Biol 2018 Oct 16;18(1):238. Epub 2018 Oct 16.

Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100, Lecce, Italy.

Background: Among cereals, durum wheat (Triticum turgidum L. subsp. durum) accumulates cadmium (Cd) at higher concentration if grown in Cd-polluted soils. Since cadmium accumulation is a risk for human health, the international trade organizations have limited the acceptable concentration of Cd in edible crops. Therefore, durum wheat cultivars accumulating low cadmium in grains should be preferred by farmers and consumers. To identify the response of durum wheat to the presence of Cd, the transcriptomes of roots and shoots of Creso and Svevo cultivars were sequenced after a 50-day exposure to 0.5 μM Cd in hydroponic solution.

Results: No phytotoxic effects or biomass reduction was observed in Creso and Svevo plants at this Cd concentration. Despite this null effect, cadmium was accumulated in root tissues, in shoots and in grains suggesting a good cadmium translocation rate among tissues. The mRNA sequencing revealed a general transcriptome rearrangement after Cd treatment and more than 7000 genes were found differentially expressed in root and shoot tissues. Among these, the up-regulated genes in roots showed a clear correlation with cadmium uptake and detoxification. In particular, about three hundred genes were commonly up-regulated in Creso and Svevo roots suggesting a well defined molecular strategy characterized by the transcriptomic activation of several transcription factors mainly belonging to bHLH and WRKY families. bHLHs are probably the activators of the strong up-regulation of three NAS genes, responsible for the synthesis of the phytosiderophore nicotianamine (NA). Moreover, we found the overall up-regulation of the methionine salvage pathway that is tightly connected with NA synthesis and supply the S-adenosyl methionine necessary for NA biosynthesis. Finally, several vacuolar NA chelating heavy metal transporters were vigorously activated.

Conclusions: In conclusion, the exposure of durum wheat to cadmium activates in roots a complex gene network involved in cadmium translocation and detoxification from heavy metals. These findings are confident with a role of nicotianamine and methionine salvage pathway in the accumulation of cadmium in durum wheat.
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http://dx.doi.org/10.1186/s12870-018-1473-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6192290PMC
October 2018

Phylogenetic analysis of viruses in Tuscan Vitis vinifera sylvestris (Gmeli) Hegi.

PLoS One 2018 18;13(7):e0200875. Epub 2018 Jul 18.

Department of Agriculture, Food and Environment, University of Pisa, Via del Borghetto, Pisa, Italy.

The health status of the native grapevine Vitis vinifera subsp. sylvestris (Gmeli) Hegi in natural areas in Europe has received little attention. A survey was carried out on wild grapevines in Tuscany (Italy), where isolates of the Grapevine rupestris stem pitting virus (GRSPaV), Grapevine leafroll-associated virus 1 and 3 (GLRaV-1 and GLRaV-3) and Grapevine virus A (GVA) were detected. The complete coat protein (CP) region of these isolates was sequenced to investigate the relationship of the viral variants from Tuscan wild grapevines with isolates from different geographical origins. According to the phylogenetic analyses, GLRaV-1 and GLRaV-3 isolates from Tuscan wild grapevines clustered with isolates from cultivated grapevines with nucleotide sequence identities ranging from 66% to 87% and from 72.5% to 99% respectively, without any correlation between the distribution and geographical origin. Conversely, GRSPaV and GVA isolates clustered together with other Italian isolates from V. vinifera with nucleotide sequence identities ranging from 71.14% to 96.12% and from 73.5% to 92%, respectively. Our analysis of the whole amino acid sequences revealed a high conservation level for the studied proteins explained by a selective pressure on this genomic region, probably due to functional constraints imposed on CP, such as specific interactions with cellular receptors in the insect vectors necessary for successful transmission. In addition, analyses of genetic recombination suggest no significant point mutations that might play a significant role in genetic diversification. The dN/dS ratio also estimated a low number of non-silent mutations, highlighting the purifying selective pressure. The widespread distribution of the Rugose wood complex (GRSPaV and GVA associated disease) in comparison with the Grapevine Leafroll associated viruses (GLRaV-1 and -3) could explain the major geographical correlation found for the viral variants detected in Tuscany.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0200875PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6051638PMC
January 2019

Development of a lab-on-a-chip method for rapid assay of Xylella fastidiosa subsp. pauca strain CoDiRO.

Sci Rep 2018 05 9;8(1):7376. Epub 2018 May 9.

CNR NANOTEC Institute of Nanotechnology, via Monteroni, Lecce, 73100, Italy.

Xylella fastidiosa subsp. pauca strain CoDiRO, a pathogen responsible for Olive Quick Decline Syndrome (OQDS), is strongly threatening the agricultural-based economy of South Italy and making its typical landscape collapse. The bacteria can also infect more than other twenty woody or shrub species and quarantine programs are carried out in Italy. Since symptoms of OQDS like leaf scorching and wilting of canopy may appear several months after infection and some hosts are asymptomatic, a tool for the rapid and early screening of plants is desirable, in order to plan a sudden control strategy and apply programs for pest management. X. fastidiosa detection is usually performed by ELISA and PCR methods. In this work, the two standard methods are compared with an innovative on-chip detection strategy for X. fastidiosa assay from leaves samples, based on an electrochemical transduction method. The realized lab-on-chip includes also a microfluidic module and its performances are competitive with conventional diagnostic methods in terms of reliability, but with further advantages of portability, low-costs and ease of use. Thus, the proposed technology has the potential to provide a useful assay method for large-scale monitoring programs.
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http://dx.doi.org/10.1038/s41598-018-25747-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5943246PMC
May 2018

Specific Fluorescence Hybridization (FISH) Test to Highlight Colonization of Xylem Vessels by in Naturally Infected Olive Trees ( L.).

Front Plant Sci 2018 6;9:431. Epub 2018 Apr 6.

WSL Swiss Federal Research Institute, Birmensdorf, Switzerland.

The colonization behavior of the strain CoDiRO, the causal agent of olive quick decline syndrome (OQDS), within the xylem of L. is still quite controversial. As previous literature suggests, even if xylem vessel occlusions in naturally infected olive plants were observed, cell aggregation in the formation of occlusions had a minimal role. This observation left some open questions about the whole behavior of the CoDiRO strain and its actual role in OQDS pathogenesis. In order to evaluate the extent of bacterial infection in olive trees and the role of bacterial aggregates in vessel occlusions, we tested a specific fluorescence hybridization (FISH) probe (KO 210) for and quantified the level of infection and vessel occlusion in both petioles and branches of naturally infected and non-infected olive trees. All symptomatic petioles showed colonization by , especially in the larger innermost vessels. In several cases, the vessels appeared completely occluded by a biofilm containing bacterial cells and extracellular matrix and the frequent colonization of adjacent vessels suggested a horizontal movement of the bacteria. Infected symptomatic trees had 21.6 ± 10.7% of petiole vessels colonized by the pathogen, indicating an irregular distribution in olive tree xylem. Thus, our observations point out the primary role of the pathogen in olive vessel occlusions. Furthermore, our findings indicate that the KO 210 FISH probe is suitable for the specific detection of .
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http://dx.doi.org/10.3389/fpls.2018.00431DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5897508PMC
April 2018

Salvia clandestina L.: unexploited source of danshensu.

Nat Prod Res 2019 Feb 19;33(3):439-442. Epub 2018 Mar 19.

a Department of Biological and Environmental Sciences and Technologies, University of Salento , Lecce , Italy.

We report the characterisation of Salvia clandestina L. shoots and roots aqueous extract using HPLC-ESI/MS-TOF. Among the 29 compounds detected, we observed the presence of danshensu (3-(3,4-dihydroxy-phenyl) 2-hydroxy-propinic acid), a powerful antioxidant and a cardio-protective agent. The danshensu content found in the shoots of S. clandestina was considerable (4.96 mg g DW) if compared with previous studies on S. miltiorrhiza Bunge, the main source of this compound. We also determined the total phenolic concentration and we evaluated their antioxidant activity by ABTS, FRAP and Superoxide anion scavenging methods. All the three assays confirmed a greater antioxidant activity for the shoots in comparison to roots. S. clandestina shoots may represent a valuable and natural unexploited source of danshensu and other phenolic compounds, so that it may be useful for future applications in functional foods and pharmaceutical industries.
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http://dx.doi.org/10.1080/14786419.2018.1452015DOI Listing
February 2019

Xylella fastidiosa induces differential expression of lignification related-genes and lignin accumulation in tolerant olive trees cv. Leccino.

J Plant Physiol 2018 Jan 10;220:60-68. Epub 2017 Nov 10.

Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov.le Monteroni 165, 73100 Lecce, Italy.

Recently, Xylella fastidiosa was reported in Italy, associated with the "Olive Quick Decline Syndrome". The cv. Leccino exhibits an evident tolerance with a slow disease progression compared with the other cultivars. Between the mechanisms proposed to explain the putative tolerance of some hosts to X. fastidiosa diseases, lignin deposition plays an important role. Analysis of phenolic compounds in healthy and infected Leccino and Cellina di Nardò leaves showed, in the two cultivars, a reduction of hydroxytyrosol glucoside (usually associated with drought and cold stress) and, only in Leccino, an increase of quinic acid, precursor of lignin. To determine if lignin biosynthesis is involved in defence response, we investigated the expression of genes coding for entry-point enzymes in different branches of the phenylpropanoid pathway. In stems of Cellina di Nardò infected plants, Cinnamate-4-Hydroxylase (C4H) and 4-Coumarate:CoA Ligase (4CL) resulted strongly down-regulated, indicating a plant disease response since the inhibition of C4H is reported to promote the accumulation of benzoic acid and salicylic acid as defence signals. Instead, in the cv. Leccino, Cinnamoyl-CoA Reductase (CCR, reported to be strongly induced during the formation of lignin defence response associated) was up-regulated in the stem of infected plants; moreover, Polyphenol oxidase (PPO), coding for an enzyme involved in the hydroxytyrosol biosynthesis, was down-regulated. The quantification of lignin in healthy and infected branches of both cultivars, showed a significant increase of total lignin in infected Leccino compared with the sensitive cultivar; moreover, histochemical observations of stem sections exhibited a different lignin distribution in the sclerenchyma and in the xylem tissue of infected Leccino plants compared to sections of healthy ones. Results suggest a critical role for lignin in X. fastidiosa tolerance of cv. Leccino.
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http://dx.doi.org/10.1016/j.jplph.2017.10.007DOI Listing
January 2018

Cadmium Concentration in Grains of Durum Wheat (Triticum turgidum L. subsp. durum).

J Agric Food Chem 2017 Aug 19;65(30):6240-6246. Epub 2017 Jul 19.

Department of Biological and Environmental Sciences and Technologies, University of Salento , via Prov.le Monteroni 165, 73100 Lecce, Italy.

Heavy metal excess in soil represents a critical problem for crop productivity. Among these pollutants, cadmium (Cd) is one of the most dangerous in terms of food-chain contamination. Two durum wheat near-isogenic lines (NILs) and 12 commercial varieties (cultivars Arcangelo, Aureo, Aziziah, Cappelli, Cirillo, Creso, Iride, Maestrale, Parsifal, Russello, Strongfield, and Svevo) of durum wheat were exposed to a nontoxic level of Cd to evaluate its concentration in grains, roots, and shoots, as well as effects on biomass production. Cultivar Iride showed the most interesting behavior because it stored large amounts of Cd in the roots, preventing its translocation to grains. On the contrary, Cirillo and Svevo genotypes were characterized by a high Cd concentration in the grains. Furthermore, a molecular characterization employing the ScOPC20 marker associated with the Cd uptake locus has shown the absence of the expected fragment in the Iride variety and in other varieties characterized by low Cd concentration, as well as the presence of it in high Cd-accumulating cultivars.
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http://dx.doi.org/10.1021/acs.jafc.7b01946DOI Listing
August 2017

Glutathione S-transferase related detoxification processes are correlated with receptor-mediated vacuolar sorting mechanisms.

Plant Cell Rep 2017 Sep 2;36(9):1361-1373. Epub 2017 Jun 2.

DISTEBA, Department of Biological and Environmental Sciences and Technologies, University of Salento, via Prov. le Lecce-Monteroni, 73100, Lecce, Italy.

Key Message: Triticum durum Glutathione S-transferase Z1 is specifically responsive to glyphosate. Its expression influences the receptor-mediated vacuolar sorting mechanisms involved in tolerance mechanisms. A zeta subfamily glutathione S-transferase gene from Triticum durum (cv Cappelli) (TdGSTZ1) was characterized as part of a complex detoxification mechanism. The effect of different abiotic stresses on TdGSTZ1 revealed that the gene is unexpectedly responsive to glyphosate (GLY) herbicide despite it should not be part of tolerance mechanisms. Its role in the non-target-site mechanism of GLY resistance was then investigated. To analyze the GLY and the TdGSTZ1 overexpression effects on vacuolar sorting mechanisms, we performed transient transformation experiments in Nicotiana tabacum protoplasts using two vacuolar markers, AleuGFPgl133 and GFPgl133Chi, labeling the Sar1 dependent or independent sorting, respectively. We observed that the adaptive reaction of tobacco protoplasts vacuolar system to the treatment with GLY could be partially mimicked by the overexpression of TdGSTZ1 gene. To confirm the influence of GLY on the two vacuolar markers accumulation and the potential involvement of the secretion pathway activity in detoxification events, Arabidopsis thaliana transgenic plants overexpressing the non-glycosylated versions of the two markers were analyzed. The results suggested that GLY treatment specifically altered different vacuolar sorting characteristics, suggesting an involvement of the receptor-mediated AleuGFP sorting mechanism in GLY resistance. Finally, the expression analysis of selected genes confirmed that the non-target-site GLY resistance mechanisms are related to vacuolar sorting.
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http://dx.doi.org/10.1007/s00299-017-2159-3DOI Listing
September 2017

Drought and Heat Differentially Affect XTH Expression and XET Activity and Action in 3-Day-Old Seedlings of Durum Wheat Cultivars with Different Stress Susceptibility.

Front Plant Sci 2016 10;7:1686. Epub 2016 Nov 10.

Dipartimento di Scienze e Tecnologie Biologiche ed Ambientali, Università del Salento Lecce, Italy.

Heat and drought stress have emerged as major constraints for durum wheat production. In the Mediterranean area, their negative effect on crop productivity is expected to be exacerbated by the occurring climate change. Xyloglucan endotransglucosylase/hydrolases (XTHs) are chief enzymes in cell wall remodeling, whose relevance in cell expansion and morphogenesis suggests a central role in stress responses. In this work the potential role of XTHs in abiotic stress tolerance was investigated in durum wheat. The separate effects of dehydration and heat exposure on XTH expression and its endotransglucosylase (XET) activity and action have been monitored, up to 24 h, in the apical and sub-apical root regions and shoots excised from 3-day-old seedlings of durum wheat cultivars differing in stress susceptibility/tolerance. Dehydration and heat stress differentially influence the XTH expression profiles and the activity and action of XET in the wheat seedlings, depending on the degree of susceptibility/tolerance of the cultivars, the organ, the topological region of the root and, within the root, on the gradient of cell differentiation. The root apical region was the zone mainly affected by both treatments in all assayed cultivars, while no change in XET activity was observed at shoot level, irrespective of susceptibility/tolerance, confirming the pivotal role of the root in stress perception, signaling, and response. Conflicting effects were observed depending on stress type: dehydration evoked an overall increase, at least in the apical region of the root, of XET activity and action, while a significant inhibition was caused by heat treatment in most cultivars. The data suggest that differential changes in XET action in defined portions of the root of young durum wheat seedlings may have a role as a response to drought and heat stress, thus contributing to seedling survival and crop establishment. A thorough understanding of the mechanisms underlying these variations could represent the theoretical basis for implementing breeding strategies to develop new highly productive hybrids adapted to future climate scenarios.
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http://dx.doi.org/10.3389/fpls.2016.01686DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5102909PMC
November 2016
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