Ricerc@Sapienza

We recently showed that proline affects root meristem size, and in turn, root growth, in Arabidopsis (Biancucci et al., 2015). The effect of this amino acid on meristem size turned out to be uncoupled from the expression of genes controlling cell differentiation at the transition zone, and independent from the action of auxin, cytokinin and gibberellic acid. On the contrary, proline was found able to affect cell division activity in early stages of postembryonic root development, as shown by the proline-dependent expression of the G2/M-specific CYCLINB1;1 (CYCB1;1) gene (Biancucci et al., 2015). Overall, proline control over cell division altered the ratio between cell division and cell differentiation leading, in turn, to root elongation.
A similar effect on root meristem size has been ascribed to some reactve oxygen species (ROS), as reported by Dunand et al. (2007) and Tsukagoshi et al. (2010), who showed that the ratio between superoxide anion (O2-) and hydrogen peroxide can affect root meristem growth in a hormone-independent manner. Moreover, proline has been long proposed as an effective ROS scavenger (Smirnoff and Curves, 1998), although the molecular mechanism underlying this function is not yet clearly understood and the question whether proline exerts a direct or indirect effect on ROS detoxification is still an open question. This proposal aims at investigating a possible relationship between proline and ROS in the control of root meristem size.