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

SENN, MARÍA EUGENIA; MAZORRA MORALES, LUIS M; GERGOFF GROZEFF, GUSTAVO E.; GALATRO, ANDREA; DA CRUZ SARAIVA, KATIA; PEREIRA DOS SANTOS, CLESIVAN; COSTA, JOSE H; GONCALVES DE OLIVEIRA, JURANDI; BARTOLI CARLOS GUILLERMO

Rosario

Congreso; XXXIV Reunión de la Sociedad Argentina de Fisiología Vegetal; 2023

Sociedad Argentina de Fisiología Vegetal

Ascorbicacid (AA) is the most abundant soluble ROS-processing metabolite found invarious cell compartments. AA in conjunction with abscisic acid (ABA), aremajor players of signaling networks allowing the acclimation of plants to achallenging environment. It is known that gene expression of a key enzyme in AAsynthesis is regulated by transcriptional factors linked to ABA metabolism and alsoenvironmental factors such as incident irradiance provokes changes in theaccumulation of AA. In this work we hypothesized that ABA regulates AAaccumulation in Arabidopsis thalianarosettes and modulates the AA content responding to the incident irradiance. Anapproach 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 ofxanthoxin to ABA-aldehyde; aba3-1:deficient in the conversion of ABA-aldehyde to ABA), was employed. Plants were grownfor 5 weeks under controlled conditions, after which the irradiance was doubledand exogenous ABA treatments (0, 10 and 100 μM) were also applied 48h prior to harvesting.  The total AA level was significantly higher inthe three mutants studied as compared to Col-0 plants, with significant butminor differences after the incident irradiance doubling treatment, and decreasedwith the application of exogenous ABA. Onthe other hand, the increase in AA levels in response to the increase in incidentirradiance (low irradiance-high irradiance AA ratio) observed in the wild typewas markedly attenuated in the mutant genotypes (although ABA-deficient plants reachedhigher net AA content) and partially restored with ABA treatment in aba2 and aba3. The results suggest that i: ABA negatively modulates theaccumulation of AA in arabidopsis leaf tissues; ii: ABA positively modulatesthe increase in AA accumulation in response to increased irradiance in terms ofplasticity of the response. Possible mechanisms involved in this regulation areanalyzed.