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

ALEGRE, MATÍAS L.; STEELHEART, CHARLOTTE; BALDET, PIERRE; ROTHAN, CHRISTOPHE; JUST, DANIEL; BRES, CECILE; GERGOFF GROZEFF, GUSTAVO E.; BARTOLI CARLOS GUILLERMO

Santa Fé

Congreso; XXXIII Argentinian meeting of Plant Physiology; 2021

Sociedad Argentina de Fisiología 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 indicatingthat AA may be synthesizedin fruits from metabolites derived from the degradation of pectin during ripening.This work explores the effect of the deficiency in GDP-L-galactosephosphorylase (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. Theexpression of genes encodingenzymesupstream and downstreamGGP-catalyzed reaction forAA synthesis and recycling ascorbic acid from oxidized formsin leavesand in fruits along ripening in wild type and both slggp1 was studied.In addition the synthesis of other genes associatedwith the AA biosynthetic pathway such as those leading to the formation of componentsof cell wall or pectin degradation and ethylene signalling was also analysed. The results presentedhere show alterations in the expression of genes involved inAA and cell wallmetabolism and ethylene perception as a consequence of GGP1 deficiency thatwould explain modifications observedin slggp1plants.