“…Common PAs putrescine (Put), spermidine (Spd) and spermine (Spm) are the most abundant in the plant cells and have been proposed as a new category of plant growth regulators involved in a variety of physiological processes such as cell division and elongation, root growth, flower and fruit development and membrane stabilization among others (Bais and Ravishankar, 2002;Liu et al, 2007;Kusano et al, 2008;Zhao and Yang, 2008). PAs are also implicated in the protection against of a wide variety of environmental stresses including salinity (Shevyakova et al, 2013) due to their capacity to stabilize macromolecules such as RNA, DNA, proteins and phospholipids, and to their free radical scavenging activity (Groppa and Benavides, 2008;Hussain et al, 2011). In plant cells, PAs occur as free bases but may also be covalently liked to small molecules such as hydroxycinnamic acids to form soluble conjugated PAs.…”