Functional analysis of the Solanum lycopersicum gdhB1 promoter

GISELA FERRARO; ESTELA M. VALLE

San Miguel de Tucumán

Congreso; XLV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB).; 2009

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

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, its physiological role is a subject of controversy particularly in non photosynthetic tissues such as ripening fruits. In ripening tomato fruits a strong induction of NADH- GDH paralleled the increase of glutamate concentration. A full-length gene encoding the β-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 β-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 several treatments 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-acting elements. In addition we found, for the first time, regulation of gdh by intermediates of the TCA cycle