INFIVE   05416
INSTITUTO DE FISIOLOGIA VEGETAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
NITRIC OXIDE GENERATION IN SOYBEAN COTYLEDONS IS DEPENDENT ON CHLOROPLAST FUNCTION
Autor/es:
GALATRO A; PUNTARULO S; SIMONTACCHI M
Lugar:
Mar del Plata
Reunión:
Congreso; XXIX Reunión Argentina de Fisiología vegetal; 2012
Institución organizadora:
Sociedad Argentina de Fisiología Vegetal (SAFV)
Resumen:
NO is a key signaling molecule which plays crucial physiological roles throughout the lifespan of a plant. Several pathways have been proposed for NO synthesis in plants, however, the understanding of the mechanisms underlying the biosynthesis of NO is still incomplete and controversial. The specific aims of this study were to identify the sub-cellular localization of NO generation in soybean cotyledons, and to investigate the relationship between NO synthesis and in vivo chloroplast performance. Fluorescence microscopy, employing 4-aminomethyl-2´,7´-difluorofluorescein diacetate (DAF-FM DA), showed a strongly punctuated fluorescence in mesophyll cells. The co-localization of DAF-FM and chlorophyll fluorescence, in confocal laser microscopy images indicated the presence of NO in chloroplasts. NO visualization was dependent on light irradiance, seedling age, and chloroplast function throughout cotyledons lifespan. The addition of herbicides with action in chloroplasts (DCMU and paraquat) dramatically affected the quantum yield of photosystem II (PSII), and lead to images with absence of punctuated green fluorescence. Moreover, lower electronic paramagnetic resonance signals corresponding to NO-spin trap adduct were observed in herbicide treated cotyledons, as compared to controls. Finally, NO generation was evaluated in cotyledons from plants growing in the presence of ammonium as the only nitrogen source. In that condition, plants were able to produce levels of NO similar to control cotyledons (growing in the presence of nitrate), implying that different pathways are operative in vivo. Our data indicate that chloroplasts are organelles that contribute to NO synthesis in vivo, and their proper functionality is essential for maintaining NO levels in soybean cotyledons. This study was supported by grants from the Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT), UBACyT (UBA) and CONICET.