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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

Malondialdehyde (MDA) accumulation and DPPH scavenging activity (DPPH), in leaves of D. viscosa and I. crithmoides stressed plants. MDA (A–C) and DPPH (D–F) after 3 weeks (A,D) and 6 weeks (B,E) of treatment with the indicated NaCl concentrations, or after 3 weeks of water stress (C,F). Values shown are means ± SD (n = 5). Different letters (lowercase for D. viscosa and capital letters for I. crithmoides) over the bars indicate significant differences between treatments for each species according to Tukey test (α = 0.05). Asterisks (*) indicate significant differences between the two species for the same treatment. (N.D. stands for “not detectable”).
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Figure 6: Malondialdehyde (MDA) accumulation and DPPH scavenging activity (DPPH), in leaves of D. viscosa and I. crithmoides stressed plants. MDA (A–C) and DPPH (D–F) after 3 weeks (A,D) and 6 weeks (B,E) of treatment with the indicated NaCl concentrations, or after 3 weeks of water stress (C,F). Values shown are means ± SD (n = 5). Different letters (lowercase for D. viscosa and capital letters for I. crithmoides) over the bars indicate significant differences between treatments for each species according to Tukey test (α = 0.05). Asterisks (*) indicate significant differences between the two species for the same treatment. (N.D. stands for “not detectable”).

Mentions: Oxidative stress is usually associated to salt and water stress, through the generation of excess reactive oxygen species (ROS), toxic compounds that oxidize amino acid residues in proteins, unsaturated fatty acids in cell membranes, and DNA molecules, thus causing cellular damage (Halliwell, 2006). Malondialdehyde (MDA) is a product of membrane lipid peroxidation, considered an excellent marker of oxidative stress (Del Rio et al., 2005). MDA was found to increase moderately in plants of both species after 3 weeks of salt treatment, although significant differences with the corresponding controls were observed only in the presence of 600 mM NaCl (Figure 6A); prolonged treatments (6 weeks) led to a similar pattern of MDA accumulation in I. crithmoides, whereas significant differences with the control were already detected at 300 mM external NaCl concentration in D. viscosa plants (Figure 6B). Water stress also induced an increase of MDA levels in D. viscosa, but not in I. crithmoides (Figure 6C).


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)

Malondialdehyde (MDA) accumulation and DPPH scavenging activity (DPPH), in leaves of D. viscosa and I. crithmoides stressed plants. MDA (A–C) and DPPH (D–F) after 3 weeks (A,D) and 6 weeks (B,E) of treatment with the indicated NaCl concentrations, or after 3 weeks of water stress (C,F). Values shown are means ± SD (n = 5). Different letters (lowercase for D. viscosa and capital letters for I. crithmoides) over the bars indicate significant differences between treatments for each species according to Tukey test (α = 0.05). Asterisks (*) indicate significant differences between the two species for the same treatment. (N.D. stands for “not detectable”).
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4834351&req=5

Figure 6: Malondialdehyde (MDA) accumulation and DPPH scavenging activity (DPPH), in leaves of D. viscosa and I. crithmoides stressed plants. MDA (A–C) and DPPH (D–F) after 3 weeks (A,D) and 6 weeks (B,E) of treatment with the indicated NaCl concentrations, or after 3 weeks of water stress (C,F). Values shown are means ± SD (n = 5). Different letters (lowercase for D. viscosa and capital letters for I. crithmoides) over the bars indicate significant differences between treatments for each species according to Tukey test (α = 0.05). Asterisks (*) indicate significant differences between the two species for the same treatment. (N.D. stands for “not detectable”).
Mentions: Oxidative stress is usually associated to salt and water stress, through the generation of excess reactive oxygen species (ROS), toxic compounds that oxidize amino acid residues in proteins, unsaturated fatty acids in cell membranes, and DNA molecules, thus causing cellular damage (Halliwell, 2006). Malondialdehyde (MDA) is a product of membrane lipid peroxidation, considered an excellent marker of oxidative stress (Del Rio et al., 2005). MDA was found to increase moderately in plants of both species after 3 weeks of salt treatment, although significant differences with the corresponding controls were observed only in the presence of 600 mM NaCl (Figure 6A); prolonged treatments (6 weeks) led to a similar pattern of MDA accumulation in I. crithmoides, whereas significant differences with the control were already detected at 300 mM external NaCl concentration in D. viscosa plants (Figure 6B). Water stress also induced an increase of MDA levels in D. viscosa, but not in I. crithmoides (Figure 6C).

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