The effect of spermidine supplementation on polyamine metabolism and Fusarium infection in Linum usitatissimum

Abstract

Flax (Linum usitatissimum) is a valuable industrial crop in temperate climate zones. However, the prevalence of fungal diseases, particularly those caused by Fusarium oxysporum sp. linii, poses a substantial threat, leading to significant crop losses and diminished interest in flax cultivation. In this study, flax plants were treated with spermidine and subsequently infected with Fusarium oxysporum to investigate multiple aspects: (1) the uptake of exogenous spermidine by the plants, (2) the impact of this uptake on the levels of other polyamines and the expression of polyamine biosynthesis genes, and (3) the effects of fungal infection on these parameters. The results demonstrated that flax plants effectively absorb spermidine, leading to substantial changes in the levels of polyamines and the expression of related genes in both roots and shoots. Notably, spermidine treatment resulted in significant alterations in the levels of putrescine and spermine, as well as in the transcript levels of key genes involved in polyamine biosynthesis. Moreover, Fusarium oxysporum infection itself induced changes in polyamine content and gene expression, which varied between root and shoot tissues. When spermidine-treated plants were infected with Fusarium oxysporum, a more complex response was observed, characterized by modifications in polyamine levels and gene expression that suggest an enhanced defense mechanism against the pathogen. These findings indicate that polyamine treatment not only affects the infection process but also modulates the plant's internal polyamine metabolism and gene expression, contributing to an improved resistance to fungal attack. This study highlights the potential of spermidine as a protective agent in flax and provides a foundation for further exploration of polyamine-related defense mechanisms.