Fructose-2,6-bisphosphate contents were increased in response to salt, water and osmotic stress in leaves of Bruguiera gymnorrhiza by differential changes in the activity of the bifunctional enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphate 2-phosphatase

Abstract

The steady-state level of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphate 2-phosphatase (F6P2K/F26BPase) transcript has been found to be raised in the mangrove Bruguiera gymnorrhiza treated with 500 mM NaCl for 6 h. In the present study, we assayed both F6P2K/F26BPase activity and fructose-2,6-bisphosphate (F26BP) contents in leaves of salt- and water-stressed B. gymnorrhiza. In the plants treated with 500 mM NaCl, no increase in transcript level was observed after 1 day of treatment, while both the ratio between F6P2K and F26BPase activity (K/P ratio) and leaf F26BP level were about two-fold higher than in control plants. Several water stress-associated treatments, including 500 mM NaCl treatment for 6 h, 1 M mannitol treatment for 6 h and dehydration treatment, resulted in increases in leaf F26BP level as compared with water-grown plants. The raised levels of F26BP in osmotically stressed plants treated with NaCl and mannitol were accompanied with increased transcript levels and subsequent increases in both F6P2K and F26BPase activities, while the increase in F26BP levels in dehydrated plants was attributed to an increase in K/P ratio without an increase in transcript levels. These results suggest that, although both treatments resulted in increases in F26BP levels, B. gymnorrhiza differentially responds to osmotic stress and water stress.

Salt tolerance mechanisms in mangroves: a review

“…It was supposed to act in osmotic regulation process by controlling the content of Fru-2, 6-P 2 Banzai et al (2002Banzai et al ( , 2003 Cytosolic Cytosolic Cu/Zn superoxide dismutase-High salinity, mannitol and ABA induced accumulation Takemura et al (2002) Cu/Zn SOD Of its transcripts in leaves; Transcript was induced by high salinity in young and mature leaves rather than in old leaves Cytosolic CAT (partial)…”

Transcriptional and physiological study of the response of Burma mangrove (Bruguiera gymnorhiza) to salt and osmotic stress

“…The leaves were sampled at three time points: 0 h (just before the stress treatments; control condition), 6 h, and 24 h after salt (500 mM) and sorbitol (1 M) treatment, respectively. The time points 6 and 24 h were adopted based on a previous study (Banzai et al 2003). All leaves were entirely wilted within 6 h after 500 mM NaCl treatment and recovered by 24 h, indicating that the plants had suffered severe stress at about 6 h but overcame it by 24 h (Banzai et al 2003).…”

“…The time points 6 and 24 h were adopted based on a previous study (Banzai et al 2003). All leaves were entirely wilted within 6 h after 500 mM NaCl treatment and recovered by 24 h, indicating that the plants had suffered severe stress at about 6 h but overcame it by 24 h (Banzai et al 2003). At each time point, three leaves were sampled from each tree under each stress treatment as biological replicates.…”

Adaptation to salinity in mangroves: Implication on the evolution of salt-tolerance

“…It was supposed to act in osmotic regulation process by controlling the content of Fru-2, 6-P 2 [39,41] Cytosolic Cu/Zn SOD cytosolic Cu/Zn superoxide dismutase High salinity, mannitol and ABA induced accumulation of its transcripts in leaves; Transcript was induced by high salinity in young and mature leaves rather than in old leaves [42] Bruguiera gymnorrhiza Cytosolic CAT partial catalase No significant change occurred in the expression of this gene during the treatment with NaCl, mannitol and ABA, but CEPA (2-chloroethylphosphonic acid) can increase its transcript level [42] Bruguiera sexangula CCTĮ Į subunit of CCT complex Transgenic E. coli with one domain of this subunit displayed enhanced tolerance to high salinity [43] Mangrin partially homologous to gene encoding Allene Oxide Cyclase (AOC) It was upregulated by high salinity and its overexpression enhanced salt tolerance of transgenic yeast and tobacco cell [43] tially isolated and its corresponding gene was also obtained [36] . OEE1 encoded the precursor of OEE1, which contained 322 amino acids.…”