Lotus tenuis plants overexpressing oatADC positively regulates NCED gene in response to salinity.

ESPASANDÍN, F.; CALZADILLA, P.; RUIZ, O.; SANSBERRO, P.

Congreso; International Congress of Plant Molecular Biology, ICPB 2015.; 2015

To study how the steady-state content of free polyamines (PAs) can be influenced by the stress-inducible overexpression of arginine decarboxylase (ADC), we constructed transgenic plants via Agrobacterium tumefaciens-mediated transformation. The binary vector contained the RD29A osmotic stress-inducible promoter from Arabidopsis and the ADC gene from oat (pBiRD29:ADC). The responses to osmotic stress from RD29A:oatADC (Lt19) and the wild type (wt) were analysed at the molecular, physiological and biochemical level. Stress generating plants were irrigated every five days with a solution of increasing concentration of NaCl starting from 50 mM up to 300 mM (30 days). The expression of oatADC gene from Lt19 line was up-regulated by the stress (31,1±17,1). Consequently, the enzymatic activity increased 3-fold in the leaves and stems respect to the unstressed treatment. In contrast, neither the relative gene expression nor the activity of related enzyme showed no significant variation in wt. Functional analysis from Lt19 line determined a significant increase of K+ in roots and high accumulation of Na+ in leaves probably through compartmentalization of Na+ in vacuoles. Additionally, we observed a redistribution of photoassimilates by promoting root growth in response to stress concomitantly with a decrease of leaf abscission (1.3 and 3.2 folds, Lt19 and wt, respectively). Finally, we observed a positive correlation (p= 0.00009) between the expression of oatADC and NCED genes. Since NCED gene encoded the enzyme 9-cis-epoxicarotenoide dioxygenase that regulates the biosynthesis of ABA under stress conditions, our results would suggest a possible link between PAs and ABA in such circumstances.