Common reed produces starch granules at the shoot base in response to salt stress

Abstract

Summary• Common reed ( Phragmites australis ) is a well known salt-tolerant plant and it is suggested that reeds recover Na + in the xylem sap of the shoot base (basal part of the shoot), store it temporarily in the shoot base, release it into the phloem sap, and then retranslocate it to the roots.• To investigate whether Na + is retained in the shoot base of reeds, confocal laser scanning microscope (CLSM) observations were conducted using an intracellular Na + -specific fluorescent probe. The CLSM observations revealed that reeds produced a large number of the starch granules at the shoot base when salt-stressed, and that the fluorescence indicating the location of intracellular free Na + was observed in the same position as the starch granules.• The Na content of starch granules was considerably greater than that of the shoot base, whereas the potassium (K) contents of the granules was only slightly greater than that of the shoot base.• Reeds produced Na + -binding starch granules in the parenchyma cells of the shoot base when salt-stressed; these starch granules may decrease intracellular free Na + . It is proposed that the site-specific production of Na + -binding starch granules constitutes a novel salt tolerance mechanism.

Canola seed germination and seedling initial growth under conditions of salinity

“…(GEISSLER et al, 2009) and these are the major reserves sources in canola seeds, because typically canola seed has an oil content ranging from 35-45% and a minimum of 35% protein (AOF, 2007), probably, this cause negative effects on seedling growth because the energy available for this process is reduced. Is important also to highlight that in plant cells, toxicity is resolved by vacuolar compartmentalization (QIU et al, 2007), and recent reports suggest that Na + can be bound in starch granules (KANAI et al, 2007), although, this compartmentalization would be energy intensive, while binding sodium to starch would prevent the starch from being used to provide energy for germination (ZHANG et al, 2010) as for seedling growth.…”

Transcriptional regulations of the genes of starch metabolism and physiological changes in response to salt stress rice (Oryza sativa L.) seedlings

“…In Pokkali, soluble starch increased early during the salt exposure period (1-4 d), then dropped. The functional role of soluble sugar in the salt defense mechanism is as an osmoregulation system, controlling the osmotic pressure in the plant cells in Na + -enriched conditions (Cha-um et al 2009), and starch content may perform as a chelating agent, namely "Na + -starch granule bound" (Kanai et al 2007). In the present study, novel transcriptional genes involved in starch metabolism, in both salt-tolerant and salt-sensitive genotypes of rice, were discovered in seedlings grown in salt-stress conditions.…”

“…Starch is the principle carbon reserve for energy preservation in higher plants. Also, starch may play a critical role as a Na + -starch binding granule, detoxifying toxic ions (Kanai et al 2007). The chloroplast organelle, especially in the endosperm of cereals, is the origin of starch biosynthesis, forming complex polysaccharides, including linear and branched molecules of glucose polymer, amylose and amylopectin, by ADP-glucose pyrophosphorylase (ADP-AGPase), starch synthase (SS) and starch branching enzymes (SBE).…”

Effect of temperature and salinity on germination ofRuta graveolensL.

“…Despite the importance of seed germination under salt stress (Ungar, 1995), the mechanism of salt tolerance in seeds is relatively poorly understood, especially when compared with the amount of information currently available about salt tolerance physiology and biochemistry in vegetative plants (Garthwaite et al, 2005;Hu et al, 2005;Ren et al, 2005;Kanai et al, 2007). Salinity affects seed germination through osmotic effects (Bliss et al, 1986), ion toxicity (Hampson & Simpson, 1990) or a combination of the two (Huang & Redmann, 1995).…”