The polyamine uptake transporters PUT2/LAT4 and PUT5/LAT5 contribute to Arabidopsis defense response against Botrytis cinerea.

Under biotic stress, plant polyamine metabolism undergoes significant changes, including increased biosynthesis and catabolism, which lead to hydrogen peroxide production. However, the roles of polyamine mobilization and transport across membranes remain elusive. Arabidopsis thaliana encodes five Polyamine Uptake Transporters (PUT1-PUT5). In this study, we investigated the role of polyamine transport in Arabidopsis during its interaction with the necrotrophic fungus Botrytis cinerea (Bc). Fungal inoculation induced the expression of all PUT/LAT genes at different times throughout disease progression. To assess their contribution to defense, we challenged five homozygous put mutants (put1-1 to put5-1) with Bc. Notably, put2-1 and put5-1 exhibited increased susceptibility to Bc, which was further exacerbated in the put2-1 put5-1 double mutant. Spermidine supplementation had a reduced effect on enhancing Bc resistance in put mutants, while it increased resistance in the 35S::PUT2 overexpression lines, suggesting that spermidine transport contributes to plant defense. Consistently, spermidine treatment elevated endogenous spermidine levels in WT but had minimal effect on put2-1, put5-1, or the double mutant. In contrast, spermine supplementation raised endogenous spermine levels in all genotypes, even under infection. Under mock conditions, catalase and ascorbate peroxidase activities were elevated in put mutants, while polyamine oxidase activity remained unchanged. These antioxidant enzymes and polyamine oxidase activity were induced upon Bc infection in WT but not in put mutants. Thus, disruptions in polyamine transport may affect their catabolism and the plant antioxidant response. This research emphasizes the importance of PUT-mediated polyamine transport in the plant's defense response to Bc.

Supplementary information: The online version contains supplementary material available at 10.1007/s12298-025-01630-1.