Effect of GDP‑L‑galactose phosphorylase deficiency in the expression of ascorbic acid biosynthetic and ethylene signaling genes in tomato leaves and fruits

ALEGRE, MATÍAS LEONEL; STEELHEART, CHARLOTTE; BALDET, PIERRE; ROTHAN, CHRISTOPHE; JUST, DANIEL; BRES, CECILE; GERGOFF GROZEFF, GUSTAVO ESTEBAN; BARTOLI, CARLOS G.

Congreso; XXXIII Argentinian meeting of plant Physiology; 2021

Sociedad Argentina de Fisiologia Vegetal

Ascorbic acid (AA) plays severalfunctions in plants. The Smirnoff-Wheeler pathway or galactose pathway is themain AA synthesis pathway both in tomato fruits and leaves. Besides, there is evidence indicating that AA may be synthesizedin fruits from metabolites derived from the degradation of pectin duringripening. This work explores the effect of the deficiency in GDP-L-galactose phosphorylase (GGP, the enzyme catalyzing the key regulatory reaction and the first exclusivelydedicated to AA synthesis) in the expression of genesassociated with AA biosynthesis and ethylene signaling. The study was performed with two Micro-Tom deficient lines in GGP1 (slggp1). Plants were grownhydroponically inside a greenhouse during spring-summer seasons under anirradiance of 700 µmol photons m-2 s-1 at midday and atemperature of 25±2 ºC. Leaf and fruit samples were collected and stored at -80°C until gene expression was analyzed by RT-PCR. The expression of genes encodingenzymes upstream and downstream GGP-catalyzedreaction for AA synthesis and recyclingascorbic acid from oxidized forms in leaves and in fruits along ripening in wtand both slggp1 was studied. Inaddition the synthesis ofother genes associated with the AA biosynthetic pathway such as those leadingto the formation of components of cell wall or pectin degradation and ethylenesignalling was also analysed. The results presented here showalterations in the expression of genes involved in AA and cell wall metabolismand ethylene perception as a consequence of GGP1 deficiency that would explainmodifications observed in slggp1 plants.