Polyamines inhibit root elongation in wheat plants by modulating reactive oxygen species and nitric oxide formation.

RECALDE L, ; VÁZQUEZ A, ; GROPPA MD; BENAVIDES MP.

Congreso; 11th International Plant Molecular Biology Congress. IPMB 2015; 2015

Reactive oxygen (ROS) and nitric oxide (NO) are now considered beneficial molecules for plant growth and essential in intracellular signaling. Polyamines (PAs), nitrogen compounds involved in plant development, are able to generate ROS (during normal catabolism) or NO, by still unknown processes. In the present work, we examined if ROS or NO are involved in exogenous PAs-induced root growth inhibition. Triticum aestivum L. seeds were germinated and seedlings were then transferred to a hydroponic system with Hoagland solution containing: 0.1 mM of the NO-donor SNP, 1 mM putrescine (Put), spermidine (Spd) or spermine (Spm). A similar degree of root growth inhibition was detected after treating wheat seedlings with Spm or SNP for 5 d (around 75 %), while Spd and Put inhibited root growth to a lesser extent (from 61% to 35 %, respectively). The NO trapping agent cPTIO partially reversed root growth inhibition, suggesting that NO was involved in this response. Spermine and SNP both reduced O2.- but increased H2O2 in roots. Nitric oxide formation, detected in the apical primary roots, revealed that the three PAs increased NO formation more than SNP. Spermine and SNP increased proline content by 91% or 160% in leaves and 233% or 194% in roots, respectively, while nitrate reductase, one of the NO recognized producers, was severely inhibited by SNP and Spm. These results suggest that polyamines-induced inhibition of root growth was probably mediated by mechanisms involving NO and ROS, either by regulating NR-dependent NO synthesis or by modulating redox signaling through NADPH oxidase or PAs catabolism