Modification of photosynthetic regulation in tomato overexpressing glutathione peroxidase

Selenite transiently represses transcription of photosynthesis-related genes in potato leaves

“…Accordingly, it seems that selenite triggers a selective transient transcriptional shutdown of genes coding for photosynthetic functions. This observation is, at our knowledge, unprecedented: a partial down regulation of photosynthetic systems components has been previously observed at the protein level in transgenic tomato plants over expressing glutathione peroxidase (Herbette et al 2005). The gene coding for this enzyme, but also the one coding for GST, have been shown to be transcriptionally modulated by selenium in other biological systems (Xiao and Parkin 2006;'t Hoen et al 2002); moreover, both GST and GPX have been correlated with stress responses following mechanical stimulation, salt and chilling stress (Holland et al1993;Depege et al 1998;Rodriguez Milla et al 2003;Gechev et al 2003).…”

“…The gene coding for this enzyme, but also the one coding for GST, have been shown to be transcriptionally modulated by selenium in other biological systems (Xiao and Parkin 2006;'t Hoen et al 2002); moreover, both GST and GPX have been correlated with stress responses following mechanical stimulation, salt and chilling stress (Holland et al1993;Depege et al 1998;Rodriguez Milla et al 2003;Gechev et al 2003). These enzymes are supposed to modulate H 2 O 2 -mediated signal transduction pathways (Herbette et al 2005). As a matter of fact, one of the major effects of selenite is to stimulate H 2 O 2 production (Stadman 1990) and we indeed observe a net transcriptional induction of two genes coding for GST activities ( Table 2).…”

“…Thus the induction of these genes immediately precedes the peak of transient repression of photosynthetic components and could therefore be involved in their down regulation. Otherwise, it is possible that GST over expression, as it has been suggested for GPX (Herbette et al 2005), or selenite itself, interfere with ferredoxin-thioredoxin system which is known to regulate several enzymes of the Calvin cycle (Shurmann and Jaquot 2000). Nevertheless, our data ( Fig.…”

Effect of chilling on photosynthesis and antioxidant enzymes in Hevea brasiliensis Muell. Arg.

“…The increases in GR and DHAR activities and transcripts strongly suggest a response to cope with an accumulation of ROS. The increase in GPX transcript level at 96 h confirms its important role in defense against membrane lipid peroxidation (Yoshimura et al 2004;Herbette et al 2005Herbette et al , 2007.…”

“…Total conductivity (C2) was obtained after autoclaving of the flasks (120°C, 30 min). The relative electrolyte leakage was calculated as (C1/C2)% (Herbette et al 2005).…”