Polyamine content and regulation during pre-penetration and penetration resistance events in oat against crown rust (Puccinia coronata f. sp. avenae)

Trabajo presentado en el X Congreso de Biotecnología Vegetal y Agricultura (BIOVEG 2015), celebrado en Cuba del 11 al 15 de mayo de 2015.During recent years a wealth of studies has focused on the role of polyamines in plant-environmental stress interaction, but less is known about the role of these compounds in plant disease resistance, and most of this knowledge is specifically related to the hypersensitive response. We examined the involvement of polyamines in the oat-crown rust interaction focusing in the mesophyll cell pre-penetration and penetration resistance mechanisms. For this, we used two different oat cultivars: one resistant to crown rust (cv. Saia) and other susceptible to the fungal infection (cv. Araceli). Differential increases in polyamine levels between the resistant and susceptible oat cultivars upon rust inoculation were observed and as sociated with increased pre/penetration resistance. Elevated levels of spermidine and spermine, together with increases of the cell wall bound diamine-and polyamine oxidase activities, and concomitant increases of the polyamine oxidation product DAP, were observed in the resistant cultivar at early stages of the infection process. This suggests an involvement of polyamines and derived H2O2 during penetration resistance responses. The putative role of polyamines in oat resistance to crown rust is supported by the increased resistance observed in the susceptible cultivar Araceli, as a result of reduced appressorium formation, after treatment with exogenous polyamines. Since ADC has been reported as a key polyamine biosynthesis enzyme in plants exposed to stress, the ADC transcript levels and enzyme activity have also been evaluated in order to determine ADC involvement in the resistance response.This work was supported by the Spanish Ministry of Economy and Competitivity [AGL2013-48687-R], the European Regional Development Funds, a JAE fellowship from CSIC to GMB.N