ASR1 MEDIATES GLUCOSE-HORMONE CROSSTALK BY AFFECTING SUGAR TRAFFICKING IN TOBACCO PLANTS

DOMINGUEZ PIA GUADALUPE; FRANKEL, NICOLÁS; JEANNINE MAZUCH; ILSE BALBO; NORBERTO IUSEM; ALISDAIR R. FERNIE; CARRARI F

PLANT PHYSIOLOGY.

AMER SOC PLANT BIOLOGISTS

Lugar: Rockville; Año: 2013 p. 1486 - 1500

0032-0889

Asr (for ABA, stress, ripening) genes are exclusively found in the genomes of higher plants and the encoded proteins have been found localized both to the nucleus and cytoplasm, suggesting a dual function. However, before the mechanisms underlying the dual activity of ASR proteins can be determined, the role of these proteins in planta should be deciphered. Results from the present study suggest that ASR is positioned within the signaling cascade of interactions among glucose, abscisic acid and gibberellins. Nicotiana tabacum transgenic lines with reduced levels of ASR protein showed impaired glucose assimilation and altered abscisic acid and gibberellin levels. These changes were associated with dwarfism, reduced CO2 assimilation and accelerated leaf senescence as a consequence of a fine regulation exerted by ASR to the glucose influx into the cells. This regulation resulted in an impact on glucose signaling mediated by hexokinase1 and SnRk1 (for Snf1-related kinase) which subsequently affected photosynthesis, leaf senescence and hormone levels. It thus can be postulated that ASR is not only involved in the control of hexose uptake in heterotrophic organs, as we have previously reported, but also in the control of carbon fixation by the leaves mediated by the same mechanism.