Phytochemical profiles and antifungal activity of extracts from Prunus persica leaves inoculated with Taphrina deformans

BUTASSI, ESTEFANIA; CASTELLI, MARIA VICTORIA; LOPEZ, SILVIA NOELI; VALENTINI, GABRIEL; DRINCOVICH, MARÍA FABIANA; LARA, MARÍA VALERIA

Congreso; LVI SAIB Meeting - XV SAMIGE Meeting ? SAIB-SAMIGE Joint Meeting 2020 on line; 2020

SAIB-SAMIGE

Taphrina deformans is a dimorphic fungus that causes the ?leaf curl disease? in peach trees (Prunus persica) around the world.This fungus is responsible for premature leaf drop, and a severe defoliation leads to lower fruit production, higher vulnerabilityto frost and opportunistic pathogens, leading to very important economic problems. In order to understand the plant metabolicchanges upon fungal infection, the secondary metabolite profile of different P. persica extracts obtained from leaves ofsusceptible and resistant genotypes before and after fungal infection was studied. For this purpose, leaves of P. persicasusceptible (DS and FL) and resistant (DR) genotypes were inoculated with the fungus and collected at 0 (control) and 96 hpi(hours post inoculation). Then, dried leaves were extracted by maceration using hexane, chloroform, ethyl acetate andmethanol (MeOH). Solutions were filtered and evaporated in vacuum, obtaining the control (FL0, DS0 and DR0) andinoculated (FL96, DS96, and DR96) extracts. Extracts were analyzed using Thin Layer Chromatography (TLC) in automatedequipment CAMAG. Plates were revealed with UV light (254 and 366 nm) and 10% (v/v) H2SO4. Flavonoids were detectedusing NP-PEG reagent (Natural Products-polyethylenglycol). TLC analysis of extracts shows that there is no difference in thechromatographic profiles neither among genotypes nor inoculation status. However, some compounds were observed as moreintense bands in the DR96 MeOH extract. This is interesting since, although the induction of new metabolites is not observedupon infection, an increase in the synthesis of some of them could be involved in the tolerance of the resistant genotype DRagainst the attack of the pathogen. In addition, chlorogenic acid was detected in all MeOH extracts, and flavonoids analysisallowed to detect rutin and quercitrin in MeOH extracts, and quercetin and kaempferol in hydrolyzed MeOH extracts. Theantifungal activity of extracts against T. deformans was studied using the broth microdilution technique in 96-well microplates.Results show that MeOH extracts were active, reaching an inhibition between 75?80% of the fungal growth at 500 µg/mL.The antifungal activity was the same for the inoculated and un-inoculated extracts within the same genotype, and the sameamong the different genotypes studied. In addition, different flavonoids identified in the extracts and chlorogenic were alsotested for their antifungal activity. Besides, these metabolites showed activity against the pathogen, the mixtures of chlorogenicacid with rutin, quercitrin or kaempferol were more active than individual components. Therefore, in vivo antifungal activitywould rely on the combination of different metabolites which act additively to fight the fungus. Even though the samemetabolite profile was detected at 0 and 96 hpi by this technique, the further induction of new compounds at later times cannotbe ruled out and should be tested.