The recretohalophyte swith specialized process, salt secreting structure, salt glands or salt bladders, can secrete salt from thier bodies, and they can easily adapt themselves to many kinds of salt habitats. Recretohalophyte resources are rich in China, and they can be widely used with great value. This paper describes the species, geographical distribution and utilization of recretohalophytes in China and summarizes the advance of study on salt secreting structure and mechanism of the recretohalophytes. Futher researches are also proposed in this paper. Fig 4, Ref
Glycine soja Sieb. et Zucc. plants living in saline soil in three provinces of China were treated with different salinity concentrations under different laboratory culture conditions (including solution, sand and field cultivation). The attachment shape and distribution on the surface of stalk and leaf of G. soja plants were observed with scanning electron microscopy (SEM), and the ultrastructure of glandular hair with transmission electron microscopy (TEM). Na+ and Cl- contents in the secretion of the leaf surface and inside the leaf of G. soja subjected to different treatments were measured. The Na+ relative contents in glandular cells, epidermal cells and mesophyllous cells of leaves under different salinities were determined by X-ray microanalysis. Results show that only glandular and epidermal hair exist on the surface attachments of leaves and stalks of G. soja plants. These glandular hair were similar in shape to some salt glands of Gramineae halophytes, and they attached to the vein on the leaf surface. The cell structure of the glandular hair showed the characteristics of common salt glands, such as big vacuoles, dense cytoplasm, a great deal of mitochondria, chloroplast, plasmodesmata and thicker cell walls, etc. The results of Na+ and Cl- contents in the leaf secretion and inside the leaf showed that the glandular hair executed the function of salt-secretion, and when treated with the salt gland inhibitor the salt-secretion process was inhibited. As a result, Na+ and Cl- were mainly accumulated inside G. soja leaves. The results of Na+ X-ray microanalysis under different salinities proved that the three cells of the glandular hair, especially the top cell, possessed strong competence for Na+ accumulation. Above all, the glandular hair were the salt gland, and no other kind of salt glands were found on G. soja plants. The secreting mechanism of the salt gland was also discussed.
