The Over-expression of the Plastidial Transglutaminase from Maize in Arabidopsis Increases the Activation Threshold of Photoprotection.

Plastidial transglutaminase is one of the most promising enzymes in chloroplast bioenergetics due to its link with polyamine pathways and the cross talk with signals such as Ca(2+) and GTP. Here, we show the effect of the increase of transglutaminase activity in Arabidopsis by using genetic transformation techniques. These lines fulfill their biological cycle normally (normal growth in soil, production of viable seeds) and show a relatively mild increase in transglutaminase activity (127%).

Role of plastid transglutaminase in LHCII polyamination and thylakoid electron and proton flow.

Transglutaminases function as biological glues in animal cells, plant cells and microbes. In energy producing organelles such as chloroplasts the presence of transglutaminases was recently confirmed. Furthermore, a plastidial transglutaminase has been cloned from maize and the first plants overexpressing tgz are available (Nicotiana tabacum TGZ OE).

Amyloid-like protein inclusions in tobacco transgenic plants.

The formation of insoluble protein deposits in human tissues is linked to the onset of more than 40 different disorders, ranging from dementia to diabetes. In these diseases, the proteins usually self-assemble into ordered β-sheet enriched aggregates known as amyloid fibrils. Here we study the structure of the inclusions formed by maize transglutaminase (TGZ) in the chloroplasts of tobacco transplastomic plants and demonstrate that they have an amyloid-like nature.

Response of transglutaminase activity and bound putrescine to changes in light intensity under natural or controlled conditions in Quercus ilex leaves.

In order to further study a previously observed relationship between polyamine (PA) content and changes in irradiation, we examined the level of free and bound PAs, the activity of transglutaminase (TGase, EC 2.3.2.

Effect of end-of-day irradiations on polyamine accumulation in petal cultures of Araujia sericifera.

We have studied photoperiodic control and the effect of phytochrome photoconversion at the end-of-day (EOD) on polyamine (PA) accumulation in petal explants of Araujia sericifera. Petals from immature flowers were cultured under long (LD) and short (SD) days. Light was provided by Gro-lux fluorescent lamps (90-100 &mgr;mol m-2 s-1).

Effects of light quality on somatic embryogenesis in Araujia sericifera.

The effects of photoperiod, light quality and end-of-day (EOD) phytochrome photoconversion on somatic embryogenesis (SE) of Araujia sericifera petals have been studied. Petals from immature flowers were cultured under 8- and 16-h photoperiods using Gro-lux fluorescent lamps. The photon fluence rate was 90-100 µmol m-2 s-1 and the red (R):far-red (FR) ratio was 98.