Genotype-specific and light dependence of polyamine uptake and metabolism in wheat plants

Information about genotype- or light-dependent differences in the dynamics of polyamine uptake and metabolism is limited in plants. In the present study, these differences were characterised in putrescine-treated three wheat genotypes grown on hydroponic solution in growth chamber. Putrescine treatment induced putrescine accumulation especially in the roots; however, distinct variations indicated different regulation strategies among the genotypes. In Mv Be<acute accent>res, decreased expression of polyamine synthesis and back-conversion-related genes was detected, which partly mitigated excessive putrescine build-up, reaching a 976% increase maximum after 13 h, compared to the 0-h-control. In Mv Emese, the putrescine synthesis and absorption decreased, the synthesis and back-conversion of higher polyamines were not, but the terminal catabolism was initiated, and after 5 h and 642% maximum increase resulted in successful catabolism of putrescine excess. In TC33 a lower, but persistent putrescine accumulation was found with 412, 359, 418 and 419% increases after 1, 3, 5 and 7 h, respectively. However, the illumination had less influence on the root polyamine-pools than the exogenous polyamine treatments. The effects of putrescine or spermidine treatments on polyamine homeostasis were also monitored under continuous light or dark in Mv Emese. In contrast to the roots, at least in a 24-h period, the circadian rhythm had a primary influence, rather than polyamine treatments or the absence of light in the leaves. Understanding how the genotype and light influence polyamine metabolism contributes to selecting genotypes with favourable polyamine regulatory mechanisms and optimising crop management strategies, leading to improved crop productivity.