| Abstract |
Polyamines (PAs) are essential molecules for differentiation and development of plant cells, and there is an increasing body of evidence correlating PAs and stresses. The most abundant PAs in eukaryots is Put, Spd and Spm, which occur as Soluble (S-PAs), Soluble Hydrolyzed (SH-PAs) and Pellet Hydrolyzed (PH-PAs). The titers of PAs within cells depend on a fine regulation based on their uptake, biosynthesis, transport and catabolism. The catabolism of PAs is mediated by Diamine oxidase (DAO) with main substrate Put, and Polyamine oxidase (PAO) with main substrates Spd and Spm. The role of this pathway is elusive, whereas it seems likely that PA catabolism contributes to the overall plant development, either through its products such as H2O2, or through PAs depletion. To unravel the role of the catabolic pathway, and more specifically that of PAO, Nicotiana tabacum cv Xanthi transgenic plants were developed, overexpressing PAO or downregulated. Transgenic plants overexpressing PAO exhibited high levels of pao transcript, protein and activity, suggesting that regulation of PAO is exerted at the transcriptional level. On the contrary, transgenic plants with PAO downregulated, exhibited high levels of the antisense transcript, and low levels of both protein and activity levels. Transgenic plants overexpressing PAO exhibited low titers of PAs and more profoundly of Spd and Spm, irrespectively of the fraction and the tissue examined, whereas transgenic plants with PAO downregulated did not exhibit significant differences of the respective levels. Moreover, the transgenic plants overexpressing PAO showed shorter internodes.
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Μοριακή και βιοχημική ανάλυση ΓΤ Φυτών που υπερ- και υπο-εκφράζουν το γονίδιο pao
