Interaction of ascorbic acid and gibberellins in the establishment of tomato fruits

ALEGRE, MATÍAS LEONEL; BALDET, PIERRE; ROTHAN, CHRISTOPHE; BRES, CECILE; JUST, DANIEL; OKABE, YOSHIHIRO; EZURA, HIROSHI; GERGOFF GROZEFF, GUSTAVO E.; BARTOLI CARLOS GUILLERMO

Rosario

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

Sociedad Argentina de Fisiología Vegetal

Tomato fruit have a great economic and nutritional importance for human beings. Thenumber of fruits per plant is the most important factor determining the yield of tomatocrops. This factor depends on the efficiency of fruit set and is a consequence ofsuccessful pollination and fertilization. Gibberellins (GA) have been found to play a veryimportant role in promoting pollen tube growth and the onset of fruit growth. Tomatomutants (slggp1) deficient in GDP-L-galactose phosphorylase activity, a key enzyme inthe ascorbic acid (AA) synthesis pathway, have lower GA concentrations in the flowersand a lower percentage of fruit set. AA plays a central role in the antioxidant defense ofplants and numerous other functions, among which we will highlight its role as anenzymatic cofactor in the synthesis of GA and its participation in the regulation of celldivision and expansion. To determine the mechanisms and signals triggered by GA andAA in fruit set and pollen grain growth, slggp1 mutants deficient in AA and a wild typewere used. These plants were periodically sprayed with GA3 and paclobutrazol (PBZ,an inhibitor of GA synthesis). The PBZ treatment decreased the percentage of fruit setin the mutant genotypes but not in the wild type plants and the GA treatment increasedthe percentage of fruit set, similar in both mutant and wild type. The pollen tubes of themutant genotypes have a lower in vitro growth rate. The GA content (GA1, GA3, GA4 yGA8) as well as the expression of key genes in the gibberellin synthesis, degradationand signaling mechanism were analyzed in gynoecia of pre-anthesis, anthesis flowers,and 2-4 mm fruits. From these preliminary results, it can be assumed that there is aninteraction between a signaling molecule such as GA with AA levels, which could be anew contribution to the complex signaling process involved in the establishment andinitiation of fruit growth.