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Native-Invasive Plants vs. Halophytes in Mediterranean Salt Marshes: Stress Tolerance Mechanisms in Two Related Species.

Al Hassan M, Chaura J, López-Gresa MP, Borsai O, Daniso E, Donat-Torres MP, Mayoral O, Vicente O, Boscaiu M - Front Plant Sci (2016)

Bottom Line: This explains the (slightly) higher stress tolerance of I. crithmoides, as compared to D. viscosa, established from growth inhibition measurements and their distribution in nature.Oxidative stress level-estimated from malondialdehyde accumulation-was higher in the less tolerant D. viscosa, which consequently activated antioxidant responses as a defense mechanism against stress; these responses were weaker or absent in the more tolerant I. crithmoides.Based on these results, we concluded that although D. viscosa cannot directly compete with true halophytes in highly saline environments, it is nevertheless quite stress tolerant and therefore represents a threat for the vegetation located on the salt marshes borders, where several endemic and threatened species are found in the area of study.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Biología Molecular y Celular de Plantas, (UPV-CSIC), Universitat Politècnica de València Valencia, Spain.

ABSTRACT
Dittrichia viscosa is a Mediterranean ruderal species that over the last decades has expanded into new habitats, including coastal salt marshes, ecosystems that are per se fragile and threatened by human activities. To assess the potential risk that this native-invasive species represents for the genuine salt marsh vegetation, we compared its distribution with that of Inula crithmoides, a taxonomically related halophyte, in three salt marshes located in "La Albufera" Natural Park, near the city of Valencia (East Spain). The presence of D. viscosa was restricted to areas of low and moderate salinity, while I. crithmoides was also present in the most saline zones of the salt marshes. Analyses of the responses of the two species to salt and water stress treatments in controlled experiments revealed that both activate the same physiological stress tolerance mechanisms, based essentially on the transport of toxic ions to the leaves-where they are presumably compartmentalized in vacuoles-and the accumulation of specific osmolytes for osmotic adjustment. The two species differ in the efficiency of those mechanisms: salt-induced increases in Na(+) and Cl(-) contents were higher in I. crithmoides than in D. viscosa, and the osmolytes (especially glycine betaine, but also arabinose, fructose and glucose) accumulated at higher levels in the former species. This explains the (slightly) higher stress tolerance of I. crithmoides, as compared to D. viscosa, established from growth inhibition measurements and their distribution in nature. The possible activation of K(+) transport to the leaves under high salinity conditions may also contribute to salt tolerance in I. crithmoides. Oxidative stress level-estimated from malondialdehyde accumulation-was higher in the less tolerant D. viscosa, which consequently activated antioxidant responses as a defense mechanism against stress; these responses were weaker or absent in the more tolerant I. crithmoides. Based on these results, we concluded that although D. viscosa cannot directly compete with true halophytes in highly saline environments, it is nevertheless quite stress tolerant and therefore represents a threat for the vegetation located on the salt marshes borders, where several endemic and threatened species are found in the area of study.

No MeSH data available.


Related in: MedlinePlus

Principal Component Analysis (PCA). Site score plots of the studied variables on the two principal components (1 and 2) for D. viscosa(A,C) and I. crithmoides(B,D) plants, after 3 weeks (A,B) and 6 weeks (C,D) of salt treatments. PCAs included, as the analyzed variables: electrical conductivity of the substrate at the end of the salt treatments (EC), fresh weight percentage (FW%), water content percentage (WC%), chlorophyll a (Chl a), chlorophyll b (Chl b), total carotenoids (Caro), sodium ions (Na+), potassium ions (K+), chloride ions (Cl−), glycine-betaine (GB), proline (Pro), arabinose (Ara), fructose (Fru), glucose (Glu), malondialdehyde (MDA), total antioxidant activity—DPPH scavenging activity—(DPPH), total flavonoids (TF), total phenolic compounds (TPC), and specific activity of catalase (CAT), glutathione reductase (GR), and superoxide dismutase (SOD). Values of the different parameters were obtained from the experiments shown in Figures 3–6 and Tables 1–4, and in “Supplementary Material” Table S1.
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Figure 8: Principal Component Analysis (PCA). Site score plots of the studied variables on the two principal components (1 and 2) for D. viscosa(A,C) and I. crithmoides(B,D) plants, after 3 weeks (A,B) and 6 weeks (C,D) of salt treatments. PCAs included, as the analyzed variables: electrical conductivity of the substrate at the end of the salt treatments (EC), fresh weight percentage (FW%), water content percentage (WC%), chlorophyll a (Chl a), chlorophyll b (Chl b), total carotenoids (Caro), sodium ions (Na+), potassium ions (K+), chloride ions (Cl−), glycine-betaine (GB), proline (Pro), arabinose (Ara), fructose (Fru), glucose (Glu), malondialdehyde (MDA), total antioxidant activity—DPPH scavenging activity—(DPPH), total flavonoids (TF), total phenolic compounds (TPC), and specific activity of catalase (CAT), glutathione reductase (GR), and superoxide dismutase (SOD). Values of the different parameters were obtained from the experiments shown in Figures 3–6 and Tables 1–4, and in “Supplementary Material” Table S1.

Mentions: Principal component analyses (PCAs) were performed independently for D. viscosa and I. crithmoides, and for the 3-week and 6-week salt treatments, and included all measured parameters (Figure 8). In the four PCAs shown, two components with an Eigenvalue equal to or greater than 1 explained a cumulative percentage of variance of more than 80%. The first component (X-axis) was determined by the electrical conductivity of the substrates (shown as Supplementary Material in Table S1), and was found to be strongly correlated, negatively, with growth parameters (FW%, WC%) and contents of photosynthetic pigments (Chl a, Chl b, and Caro), and positively with toxic ions (Na+ and Cl−) levels, osmolyte (GB, Pro, Glu, Fru, Ara) contents, MDA, total antioxidant activity (DPPH), non-enzymatic antioxidants (TPC and TF), or SOD activity. Although similar correlation patterns were observed for each species, regardless of the duration of the treatment, the variation explained by the first component increased from about 67% at 3 weeks to 79% at 6 weeks, in both D. viscosa and I. crithmoides. This is in agreement with the fact that, in general, the loading vectors of the analyzed variables presented smaller angles with the X-axis—that is, higher correlation with salinity—in the PCAs corresponding the 6 weeks of treatment, due to the prolonged salt stress effects. The joint analysis of all variables indicated that the responses of the two species to salt stress are the same or very similar, qualitatively, and that quantitative differences are most clearly manifested after a longer treatment.


Native-Invasive Plants vs. Halophytes in Mediterranean Salt Marshes: Stress Tolerance Mechanisms in Two Related Species.

Al Hassan M, Chaura J, López-Gresa MP, Borsai O, Daniso E, Donat-Torres MP, Mayoral O, Vicente O, Boscaiu M - Front Plant Sci (2016)

Principal Component Analysis (PCA). Site score plots of the studied variables on the two principal components (1 and 2) for D. viscosa(A,C) and I. crithmoides(B,D) plants, after 3 weeks (A,B) and 6 weeks (C,D) of salt treatments. PCAs included, as the analyzed variables: electrical conductivity of the substrate at the end of the salt treatments (EC), fresh weight percentage (FW%), water content percentage (WC%), chlorophyll a (Chl a), chlorophyll b (Chl b), total carotenoids (Caro), sodium ions (Na+), potassium ions (K+), chloride ions (Cl−), glycine-betaine (GB), proline (Pro), arabinose (Ara), fructose (Fru), glucose (Glu), malondialdehyde (MDA), total antioxidant activity—DPPH scavenging activity—(DPPH), total flavonoids (TF), total phenolic compounds (TPC), and specific activity of catalase (CAT), glutathione reductase (GR), and superoxide dismutase (SOD). Values of the different parameters were obtained from the experiments shown in Figures 3–6 and Tables 1–4, and in “Supplementary Material” Table S1.
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4834351&req=5

Figure 8: Principal Component Analysis (PCA). Site score plots of the studied variables on the two principal components (1 and 2) for D. viscosa(A,C) and I. crithmoides(B,D) plants, after 3 weeks (A,B) and 6 weeks (C,D) of salt treatments. PCAs included, as the analyzed variables: electrical conductivity of the substrate at the end of the salt treatments (EC), fresh weight percentage (FW%), water content percentage (WC%), chlorophyll a (Chl a), chlorophyll b (Chl b), total carotenoids (Caro), sodium ions (Na+), potassium ions (K+), chloride ions (Cl−), glycine-betaine (GB), proline (Pro), arabinose (Ara), fructose (Fru), glucose (Glu), malondialdehyde (MDA), total antioxidant activity—DPPH scavenging activity—(DPPH), total flavonoids (TF), total phenolic compounds (TPC), and specific activity of catalase (CAT), glutathione reductase (GR), and superoxide dismutase (SOD). Values of the different parameters were obtained from the experiments shown in Figures 3–6 and Tables 1–4, and in “Supplementary Material” Table S1.
Mentions: Principal component analyses (PCAs) were performed independently for D. viscosa and I. crithmoides, and for the 3-week and 6-week salt treatments, and included all measured parameters (Figure 8). In the four PCAs shown, two components with an Eigenvalue equal to or greater than 1 explained a cumulative percentage of variance of more than 80%. The first component (X-axis) was determined by the electrical conductivity of the substrates (shown as Supplementary Material in Table S1), and was found to be strongly correlated, negatively, with growth parameters (FW%, WC%) and contents of photosynthetic pigments (Chl a, Chl b, and Caro), and positively with toxic ions (Na+ and Cl−) levels, osmolyte (GB, Pro, Glu, Fru, Ara) contents, MDA, total antioxidant activity (DPPH), non-enzymatic antioxidants (TPC and TF), or SOD activity. Although similar correlation patterns were observed for each species, regardless of the duration of the treatment, the variation explained by the first component increased from about 67% at 3 weeks to 79% at 6 weeks, in both D. viscosa and I. crithmoides. This is in agreement with the fact that, in general, the loading vectors of the analyzed variables presented smaller angles with the X-axis—that is, higher correlation with salinity—in the PCAs corresponding the 6 weeks of treatment, due to the prolonged salt stress effects. The joint analysis of all variables indicated that the responses of the two species to salt stress are the same or very similar, qualitatively, and that quantitative differences are most clearly manifested after a longer treatment.

Bottom Line: This explains the (slightly) higher stress tolerance of I. crithmoides, as compared to D. viscosa, established from growth inhibition measurements and their distribution in nature.Oxidative stress level-estimated from malondialdehyde accumulation-was higher in the less tolerant D. viscosa, which consequently activated antioxidant responses as a defense mechanism against stress; these responses were weaker or absent in the more tolerant I. crithmoides.Based on these results, we concluded that although D. viscosa cannot directly compete with true halophytes in highly saline environments, it is nevertheless quite stress tolerant and therefore represents a threat for the vegetation located on the salt marshes borders, where several endemic and threatened species are found in the area of study.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Biología Molecular y Celular de Plantas, (UPV-CSIC), Universitat Politècnica de València Valencia, Spain.

ABSTRACT
Dittrichia viscosa is a Mediterranean ruderal species that over the last decades has expanded into new habitats, including coastal salt marshes, ecosystems that are per se fragile and threatened by human activities. To assess the potential risk that this native-invasive species represents for the genuine salt marsh vegetation, we compared its distribution with that of Inula crithmoides, a taxonomically related halophyte, in three salt marshes located in "La Albufera" Natural Park, near the city of Valencia (East Spain). The presence of D. viscosa was restricted to areas of low and moderate salinity, while I. crithmoides was also present in the most saline zones of the salt marshes. Analyses of the responses of the two species to salt and water stress treatments in controlled experiments revealed that both activate the same physiological stress tolerance mechanisms, based essentially on the transport of toxic ions to the leaves-where they are presumably compartmentalized in vacuoles-and the accumulation of specific osmolytes for osmotic adjustment. The two species differ in the efficiency of those mechanisms: salt-induced increases in Na(+) and Cl(-) contents were higher in I. crithmoides than in D. viscosa, and the osmolytes (especially glycine betaine, but also arabinose, fructose and glucose) accumulated at higher levels in the former species. This explains the (slightly) higher stress tolerance of I. crithmoides, as compared to D. viscosa, established from growth inhibition measurements and their distribution in nature. The possible activation of K(+) transport to the leaves under high salinity conditions may also contribute to salt tolerance in I. crithmoides. Oxidative stress level-estimated from malondialdehyde accumulation-was higher in the less tolerant D. viscosa, which consequently activated antioxidant responses as a defense mechanism against stress; these responses were weaker or absent in the more tolerant I. crithmoides. Based on these results, we concluded that although D. viscosa cannot directly compete with true halophytes in highly saline environments, it is nevertheless quite stress tolerant and therefore represents a threat for the vegetation located on the salt marshes borders, where several endemic and threatened species are found in the area of study.

No MeSH data available.


Related in: MedlinePlus