Involvement of abscisic acid in modulating ascorbic acid synthesis and accumulation: responses under basal and high incident irradiance conditions

SENN MARIA EUGENIA; MAZORRA MORALES LM ; GERGOFF GROZEFF GUSTAVO; GALATRO A; DA CRUZ SARAIVA KD; PEREIRA DOS SANTOS C; COSTA JH; GONÇALVES DE OLIVEIRA J ; BARTOLI CARLOS GUILLERMO

Rosario

Congreso; XXXIV Reunión de la Sociedad Argentina de Fisiología Vegetal (SAB); 2023

Sociedad Argentina de Fisiología Vegetal

Ascorbic acid (AA) is the most abundant soluble ROS-processing metabolite found in various cell compartments. AA in conjunction with abscisic acid (ABA), are major players of signaling networks allowing the acclimation of plants to a challenging environment. It is known that gene expression of a key enzyme in AA synthesis is regulated by transcriptional factors linked to ABA metabolism and also environmental factors such as incident irradiance provokes changes in the accumulation of AA. In this work we hypothesized that ABA regulates AA accumulation in Arabidopsis thaliana rosettes and modulates the AA content responding to the incident irradiance. An approach using wild type Col-0 and ABA synthesis mutants (aba1-6: impaired in the conversion of zeaxanthin to violaxanthin; aba2-1: deficient in the conversion of xanthoxin to ABA-aldehyde; aba3-1: deficient in the conversion of ABA-aldehyde to ABA), was employed. Plants were grown for 5 weeks under controlled conditions, after which the irradiance was doubled and exogenous ABA treatments (0, 10 and 100 μM) were also applied 48h prior to harvesting. The total AA level was significantly higher in the three mutants studied as compared to Col-0 plants, with significant but minor differences after the incident irradiance doubling treatment, and decreased with the application of exogenous ABA. On the other hand, the increase in AA levels in response to the increase in incident irradiance (low irradiance-high irradiance AA ratio) observed in the wild type was markedly attenuated in the mutant genotypes (although ABA-deficient plants reached higher net AA content) and partially restored with ABA treatment in aba2 and aba3. The results suggest that i: ABA negatively modulates the accumulation of AA in arabidopsis leaf tissues; ii: ABA positively modulates the increase in AA accumulation in response to increased irradiance in terms of plasticity of the response. Possible mechanisms involved in this regulation are analyzed.