Participation of polyamines in the resistance mechanism induced by phosphites against P. infestans in potato.

DALEO, G.R.; LOBATO, M. C.; ANDREU, A B.; OLIVIERI, F. P.

Salta

Congreso; . IV CONGRESO DE SOCIEDAD ARGENTINA DE INVESTIGACIONES BIOQUIMICAS (SAIB) Y XIV CONGRESO DE LA PAN-AMERICAN ASSOCIATION OF BIOCHEMISTRY AND MOLECULAR BIOLOGY (PABMB).; 2019

Sociedad Argentina de Investigaciones Bioquímicas

Potato is the main horticultural crop in Argentina. Late Blight, caused by the oomycete Phytophthora infestans, is the most important potato disease that seriously affects crop yield. A strategy to diminish the use of toxic agrochemicals is the use of biocompatible compounds. Phosphites are metallic salts of phosphorous acid (H3PO3) non toxic for the environment or human health. They are effective in increasing potato tolerance against various diseases, UV-B radiation, and also cause positive effects on physiological parameters related to crop quality and yield. These compounds would have a broad spectrum of action, however, their mode of action have not been completely elucidated yet. Previous results in our laboratory have shown that these compounds induce enzymes related to the antioxidant system and the reinforcement of the cell wall in potato. Polyamines (PAs) are aliphatic amines present in almost all organisms, including plants. Most common PAs in plants are: Putrescine (PUT), Spermidine (SPD) and Spermine (SPM). They are involved in many growth and development processes and also in the response to biotic and abiotic stresses. PAs can scavenge reactive oxygen species or directly modulate the activity antioxidant enzymes. In addition, the can also act as a source of hydrogen peroxide in response to stress through the activity of the catabolic enzymes such as diamino oxidases (DAO) and polyamino oxidases (PAO). The objective of the present work was to study the participation of PAs in the resistance mechanism induced by phosphites against P. infestans in potato plants. The results indicated that PAs differentially accumulate in potato leaves depending on the treatments. In the absence of infection, an increase in the content of SPD and SPM was observed in leaves 3 days after potassium phosphite (KPhi) treatment. Upon pathogen challenge, the content of PUT, SPD and SPM increased in KPhi treated leaves 48 h post-inoculation, compared to non treated inoculated leaves. The expression of different genes involved in PA metabolism showed that many of both biosynthetic and catabolic genes decreased in non treated inoculated leaves 48 hpi, compared to non treated and non inoculated leaves (control). However, this was not observed in KPhi treated and inoculated leaves, where an increase in the expression of various genes was observed. At this time, PAO enzymatic activity also increased in KPhi treated and inoculated leaves respect to the control. These results suggest that polyamine metabolism could be involved in the resistance mechanisms induced by phosphites in potato plants inoculated with P. infestans.