Functional analysis of the Solanum lycopersicum GDHB1 promoter

GISELA FERRARO Y ESTELA VALLE

San Miguel de Tucumán

Congreso; XLV Reunión Anual de SAIB; 2009

SAIB

Glutamate dehydrogenase (GDH) catalyses the reversible amination of 2-oxoglutarate to form glutamate, using ammonium as a substrate. Although GDH is ubiquitous in plant tissues, itsphysiological role is a subject of controversy particularly in non photosynthetic tissues such as ripening fruits. In ripening tomato fruits a strong induction of NAD(H)- GDH paralleled the increase of glutamate concentration. A full-length gene encoding the alfa-subunit of GDH and its corresponding promoter were isolated in our lab. In silico analysis of this putative promoter revealed two groups of motif, one associated with physiological growing conditions such as ripening, nitrogen and carbon metabolisms, and another group associated with stress processes like drought and pathogen infection. We cloned 900pb of GDH promoter upstream of the alfa-glucuronidase (GUS) reporter gene in order to test the in vivo response of this promoter in Arabidopsis and tomato (cv. Micro-tom) plants. Transgenic plants were subjected to severaltreatments including ABA, SA, carbon and nitrogen sources. We found that the GDH promoter responded differently to the assayed conditions, corroborating some of the predictive cis-actingelements. In addition we found, for the first time, regulation of GDH by intermediates of the TCA cycle