First Insights into the Role of Polyamines in Biotic Stress Resistance Induced by Potassium Phosphite in Potato

LOBATO MC; FELDMAN M.L.; MACHINANDIARENA MF; OLIVIERI, FLORENCIA PÍA

Potato Research

Springer-Nature

Año: 2023

0014-3065

Phosphites (Phi) are inorganic salts widely used to protect plants from pathogens,especially oomycetes, on a wide range of horticultural crops. They were studied atthe molecular level in different pathosystems; however, their mode of action is notcompletely understood. In this work, we investigate the participation of polyamine(PA) metabolism in the defence mechanism induced by Phi. To this aim, potatoplants were treated with potassium phosphite (KPhi), and 3 days later, leaves wereinoculated with Phytophthora infestans (P. infestans). The content of free PAs wasanalysed and showed that KPhi induced the accumulation of spermine (Spm), sper-midine (Spd) and putrescine (Put). However, when treated leaves were detached andinoculated with P. infestans, their accumulation was even higher. In addition, theexpression of genes implicated in PA synthesis and degradation was measured. Mostof the genes involved in PA biosynthesis showed no changes in their expressionupon KPhi treatment, except for those involved in Spm synthesis: Spm synthase andS-adenosyl-L-methionine decarboxylase (SPMS and SAMDC, respectively). On theother hand, the catabolism genes: diamine oxidase (DAO), and polyamine oxidasesPAO1, PAO2 and PAO5, but not PAO4, decreased their expression after inoculationwith P. infestans, and this was reverted by KPhi pretreatment. To investigate thiseffect, assays were carried out using a PA oxidase inhibitor showing that defenceresponses induced by KPhi do not require products of PA catabolism. Additionally,we analysed in silico phytohormone and stress-responsive cis-elements in PAO genepromoters, which might explain, at least in part, the different behaviour of PAO4.