Manipulating the metabolic composition of halophytes to increase their cultural and economic value through saline cultivation

[no abstract

The North American toxic fungal pathogen G3 Claviceps purpurea (Fries) Tulasne is established in the German Wadden Sea.

Three lineages (G1, G2 and G3) within the toxic invasive ergot fungus Claviceps purpurea (Fries) Tulasne are known; these should be recognized as unique species, or at least as varieties. On 2 November 2011, a very dense, well established population of G3 C. purpurea was found on the common cord-grass Spartina anglica C.E. Hubbard at two localities on the German North Sea coast in the Wadden Sea (Caciliengroden and Hooksiel). It is most likely that G3 C. purpurea has a North American origin and entered German coastal waters by floating sclerotia from Irish, British, or Benelux waters, where it was previously found. However, introduction via ships’ ballast water coming from their native or introduced ranges is also plausible. Furthermore imports of G3 sclerotia via seed mussels collected from wild subtidal banks in Irish, British and Dutch coastal waters and released into the German Wadden Sea can currently not be excluded. Risks from this highly toxic fungus for human, grazing animals and the marine environment have been identified but not yet quantified in terms of impact. A suitable monitoring programme should be implemented to detect any unwanted impacts caused by G3 C. purpurea in German salt marshes at an early phase

Manipulating the antioxidant capacity of halophytes to increase their cultural and economic value through saline cultivation

Halophytes, salt-tolerant plants, are a source of valuable secondary metabolites with potential economic value. The steady-state pools of many stress-related metabolites are already enhanced in halophytes when compared with glycophytes, but growth under conditions away from the optimum can induce stress and consequently result in changes to secondary metabolites such as antioxidants. However, direct evidence for increasing the concentration of valuable secondary metabolites as a consequence of altering the salinity of the growing environment still remains equivocal. To address this, we analysed a range of metabolites with antioxidant capacity (including total phenols, flavonoids, ascorbate, reduced/oxidized glutathione and reactive oxygen species scavenging enzymes) in seedlings and plants from different families (Amaranthaceae, Brassicaceae, Plantaginaceae and Rhizophoraceae) and habitats grown under different salt concentrations. We show that it is possible to manipulate the antioxidant capacity of plants and seedlings by altering the saline growing environment, the length of time under saline cultivation and the developmental stage. Among the species studied, the halophytes Tripolium pannonicum, Plantago coronopus, Lepidium latifolium and Salicornia europaea demonstrated the most potential as functional foods or nutraceuticals.Deutsche Bundesstiftung Umwelt/AZ/27708COST/STSM/FA/0901-041011-011415DEFR

<i>Halimione portulacoides</i> plants were set in containers, after an acclimatization time of one week, eight week old plants were exposed to salinity ranging in 5 PSU steps from 0 till 15 PSU.

<p>Fresh material (n = 4) was harvested at the indicated time. The mean biomass production (A), ORAC value (B), total ascorbate concentration (C) and proline concentration (D) for each salinity is plotted against the time. For better visibility the time is not true to scale. Different capital letters above the standard deviation indicate significant differences (<i>p</i> < 0.05) between points of time among a PSU value. Different lower letters indicate significant differences (<i>p</i> < 0.05) within one point of time between different PSU values.</p

Times for the different nursing steps of the plant species used in the experiments and their origin are shown.

<p>Times for the different nursing steps of the plant species used in the experiments and their origin are shown.</p

<i>Triglochin maritima</i> plants were set in containers, after an acclimatization time of one week, ten week old plants were exposed to salinity ranging in 5 PSU steps from 0 till 15 PSU.

<p>Fresh material (n = 4) was harvested at the indicated time. The mean biomass production (A), ORAC value (B), total ascorbate concentration (C) and proline concentration (D) for each salinity is plotted against the time. For better visibility the time is true to scale. Different capital letters above the standard deviation indicate significant differences (<i>p</i> < 0.05) between points of time among a PSU value. Different lower letters indicate significant differences (<i>p</i> < 0.05) within one point of time between different PSU values.</p

Changes in secondary metabolites in the halophytic putative crop species <i>Crithmum maritimum</i> L., <i>Triglochin maritima</i> L. and <i>Halimione portulacoides</i> (L.) Aellen as reaction to mild salinity - Fig 4

<p>Principal components for individual measurements of ORAC, phenol, flavonoid and proline concentration in <i>C</i>. <i>maritimum</i> (A), <i>T</i>. <i>maritima</i> (B) and <i>H</i>. <i>portulacoides</i>. The different salinities are indicated by different colours and the different points of time by different symbols.</p

Analysis of variance of the parameters measured at the different species.

<p>Analysis of variance of the parameters measured at the different species.</p

Changes in secondary metabolites in the halophytic putative crop species <i>Crithmum maritimum</i> L., <i>Triglochin maritima</i> L. and <i>Halimione portulacoides</i> (L.) Aellen as reaction to mild salinity

<div><p>It is assumed that salinity enhances the concentration of valuable metabolites in halophytes. The objective was to find a salt concentration and a point in time at which the yield for the valuable metabolites was maximal. Therefore, three different halophyte species were grown under different salinities and harvested over a period from shortly after stress induction up to three weeks. Various reaction patterns were found in the metabolite composition of the analyzed plant material. <i>Halimione portulacoides</i> showed a “short term response”, indicated by an increase in all metabolites analyzed after a few hours, whereas <i>Crithmum maritimum</i> showed a “long term response” through accumulation of proline starting after days. <i>Triglochin maritima</i> did not change in metabolite concentration, but like the other plant species the biomass was reduced by salinity. Generally, a higher production in secondary metabolites by higher salinity was outbalanced by a reduction in biomass production. Concentrations of analyzed antioxidants showed a similar reaction and correlated with each other.</p></div

Elemental composition of the plant material at selected points of time.

<p>Elemental composition of the plant material at selected points of time.</p