Induction of Resistance in Mandarin Fruits Against Penicillium digitatum, the Causative Agent of Green Mold Infection

Abstract

This study was conducted at the College of Agricultural Engineering Sciences / University of Baghdad during 2021-2022. This work aimed to evaluate the efficiency of Sodium Bicarbonate(SB) and Phylex to protect and induce mandarin fruits’ resistance against the green mold pathogen, Penicillium digitatum at 4ºCstorage conditions. The molecular diagnosis by PCR technology using the primers ITS1 and ITS4, confirmed the identification of P. digitatum. The genetic tree showed that the two Iraqi isolates(K1andK2) were belonging to one group, matched by 98% with the universal isolates registered in the GenBank of China (MZ8819 and MT448740.1) and Portugal(OK0949001). The best treatment method was when the wounded fruits were immersed in Phylex at 4ml/ liter for an hour, then inoculated with a drop of fungal spore’s suspension (103 spores.ml-1). In this treatment, no fungal infection was observed on the fruits after 42days compared to the Inoculation with P.digitatum(15.27%) under refrigerated condition(4ºC). The highest rate of peroxidase (POX) and Phenylalanine ammonia-lyase (PAL) activity was reported 194.22, unite (estimated based on the changes of spectrophotometer OD / minute / gram fresh weight) and 26.33 µg cinnamic acid / hour / gram fresh weight respectively. The above results indicated that the Phylex was more efficient to induce fruit’s resistance against P.