Involvement of abscisic acid in the high irradiance induced accumulation of ascorbic acid in Arabidopsis thaliana

SENN, MARÍA EUGENIA; MAZORRA, LUIS MIGUEL; GONCALVES DE OLIVEIRA, JURANDI; BARTOLI, CARLOS GUILLERMO

Mar del Plata

Congreso; XV Congreso Latinoamericano y XXX Reunión Argentina de Fisiología Vegetal; 2014

Asociación Sociedad Argentina de Fisiología Vegetal

The final step of the ascorbic acid (AA) biosynthesis pathway involves the oxidation of the precursor L-galactono-1,4-lactone (L-GalL) to ascorbic acid (AA). This reaction occurs in the mitochondrial inner membrane catalyzed by the L-GalL dehydrogenase. The accumulation of AA in leaf is light-dependent, suggesting a linkage between the AA accumulation and photosynthesis. However, the mechanisms by which light regulates AA synthesis are unknown. To explore if the hormone abscisic acid (ABA) could be implicated in this regulatory process, the total AA level of ABA-deficient (aba1-6) and insensitive (abi1-1 and abi2-1) mutant seedlings was measured in response to high irradiance (HI). As expected, AA accumulation increased in wild type seedlings grown at 120 µmol m-2 s-1 (10/14hr light/dark) when exposed to HI (250 µmol m-2 s-1 over 48 hours). However, mutant seedlings showed a reduced AA accumulation (~40-65% lower) in response to HI. In addition, treatments of seedlings with ABA (10 and 100 µM) recovered the AA accumulation of the aba1-6 mutant seedlings to the level of wild type ones. Changes in the rates of photosynthesis and respiration of these mutant seedlings are also presented. Taken together, evidences suggest that ABA participates in the regulation of leaf AA accumulation.