Secretory structures in plants: lessons from the Plumbaginaceae on their origin, evolution and roles in stress tolerance

Special IssueThe Plumbaginaceae (non-core Caryophyllales) is a family well known for species adapted to a wide range of arid and saline habitats. Of its salt-tolerant species, at least 45 are in the genus Limonium; two in each of Aegialitis, Limoniastrum and Myriolimon, and one each in Psylliostachys, Armeria, Ceratostigma, Goniolimon and Plumbago. All the halophytic members of the family have salt glands, which are also common in the closely related Tamaricaceae and Frankeniaceae. The halophytic species of the three families can secrete a range of ions (Na+, K+, Ca2+, Mg2+, Cl−, HCO3 −, SO4 2-) and other elements (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn). Salt glands are, however, absent in salt-tolerant members of the sister family Polygonaceae. We describe the structure of the salt glands in the three families and consider whether glands might have arisen as a means to avoid the toxicity of Na+ and/or Cl− or to regulate Ca2+ concentrations within the leaves. We conclude that the establishment of lineages with salt glands took place after the split between the Polygonaceae and its sister group the Plumbaginaceaeinfo:eu-repo/semantics/publishedVersio

Toxic effects of Pb2+ on the growth and mineral nutrition of signal grass (Brachiaria decumbens) and Rhodes grass (Chloris gayana)

Although grasses are commonly used to revegetate sites contaminated with lead (Pb), little is known regarding the Pb-tolerance of many of these species. Using dilute solution culture to mimic the soil solution, the growth of signal grass (Brachiaria decumbens Stapf cv. Basilisk) and Rhodes grass (Chloris gayana Kunth cv. Pioneer) was related to the mean activity of Pb2+ {Pb2+} in solution. There was a 50% reduction in fresh mass of signal grass shoots at 5 mu M {Pb2+} and at 3 mu M {Pb2+} for the roots. Rhodes grass was considerably more sensitive to Pb in solution, with shoot and root fresh mass being reduced by 50% at 0.5 mu M {Pb2+}. The higher tolerance of signal grass to Pb appeared to result from the internal detoxification of Pb, rather than from the exclusion of Pb from the root. At toxic {Pb2+}, an interveinal chlorosis developed in the shoots of signal grass (possibly a Pb-induced Mn deficiency), whilst in Rhodes grass, Pb2+ caused a bending of the root tips and the formation of a swelling immediately behind some of the root apices. Root hair growth did not appear to be reduced by Pb2+ in solution, being prolific at all {Pb2+} in both species

The Growth Rate and Age of Tree Fern Trunks in Relation to Habitats

Volume: 85Start Page: 37End Page: 4

Iconic relationships in some halophytic Iranian Chenopodiaceae and their rhizospheres

Matinzadeh Z, Breckle S-W, Mirmassoumi M, Akhani H. Iconic relationships in some halophytic Iranian Chenopodiaceae and their rhizospheres. Plant And Soil. 2013;372(1-2):523-539.Previous studies on the identification of ion relations in halophytes have revealed that many members of Chenopodiaceae accumulate high amounts of sodium and chloride even in soils with low salinity, indicating a typical pattern which is genetically fixed. In this study, we followed up with the question of ion relations in different halophyte species with different photosynthetic pathways and different salt tolerance strategies over a complete growing season. Soil and plant samples from five species Climacoptera turcomanica (Litv.) Botsch. (leaf succulent-C-4), Salicornia persica Akhani subsp. rudshurensis Akhani (stem succulent-C-3), Halimocnemis pilifera Moq. (leaf succulent-C-4), Petrosimonia glauca (Pall.) Bunge (leaf succulent-C-4) and Atriplex verrucifera M. Bieb. (recreto-halophyte-C-3) were collected over a complete growing season from a salt flat 60 km W of Tehran. The contents of main cations (Na+, K+, Ca2+, and Mg2+) and chloride were determined in plant and soil samples. Na+ and Cl- concentration in the shoots of two hygro-halophytes Climacoptera turcomanica and Salicornia persica subsp. rudshurensis were constant over the period of the growing season. In contrast, sodium and chloride in the shoots of Halimocnemis pilifera and Petrosimonia glauca showed respectively an increasing and, in the shoots of Atriplex verrucifera, a decreasing, trend. We did not notice any decreasing trend of K+ together with increasing trend of Na+ in the shoots of the studied species; however K+ in the shoots of all examined species was considerably lower than Na+ and Cl-. It was observed that Climacoptera and Salicornia could absorb and retain calcium even in high salinity conditions, while Halimocnemis and Petrosimonia could not. Na+, K+, Cl-, Ca2+, and Mg2+ contents in the shoots of different types of halophytes (stem-succulent, leaf-succulent and excreting halophyte) or different type of photosynthesis (C-3, C-4) are independent of those in their rhizosphere. We concluded that it is controlled by the genetic characteristic of the specific taxon rather than by the environment