Is the Tolerance of Commercial Peach Cultivars to Brown Rot Caused by Monilinia laxa Modulated by its Antioxidant Content?

Vitus I Obi,Yolanda Gogorcena,Fayza Saidani,Christophe Aubert,Juan J Barriuso,Joaquín Montenegro

doi:10.3390/plants9050589

Abstract

Brown rot, caused by Monilinia spp., provokes pre- and post-harvest damage in peach (Prunus persica (L.) Batsch), which causes an economic impact in the industry. With a view to breeding for increased tolerance to this disease, a screening test based upon artificial fruit inoculation was validated on several parental lines of a peach breeding program during the two-period harvest. In addition, cultivars with different total phenolic contents were included in the two-year study. All physicochemical fruit traits recorded at harvest showed differences among all cultivars. The antioxidant compound content determined using spectrophotometry (to measure ascorbic acid and antioxidant capacity) and UPLC-MS (to measure and identify phenolic compounds) also revealed important differences among all genotypes. The rate of brown rot lesion following fruit inoculation varied widely among cultivars, and it was possible to discriminate between highly and less susceptible cultivars. Cultivars with minimal development of damage were identified as germplasm with the desirable allele combination to increase brown rot tolerance in peach breeding programs. Finally, Pearson’s correlation coefficients (r) between pairs of variables were calculated, searching for any biochemical candidate conferring tolerance. The correlation of phytopathological traits with the antioxidant composition, concerning contents of ascorbic, neochlorogenic, and chlorogenic acids and total polyphenols in fruit, is discussed.

Highlights

One of the most important stone fruit crops in Spain is peaches (Prunus persica (L.) Batsch) with a production of 903,809 tons in 2018 [1], though this crop is often hindered by the activities of pathogenic fungi
We studied eight commercial peach cultivars with different fruit characteristics and tested their tolerance to brown rot caused by Monilinia laxa after artificial inoculation
The content of ascorbic acid can only partially explain the tolerance/susceptibility observed, indicating that other factors are probably involved in the response

Summary

Introduction

One of the most important stone fruit crops in Spain is peaches (Prunus persica (L.) Batsch) with a production of 903,809 tons in 2018 [1], though this crop is often hindered by the activities of pathogenic fungi. The most important fungal disease agent of peaches and nectarines in Spain is Monilinia spp. The most extended species with the greatest degree of damage is Monilinia laxa (Aderhold and Ruhland) Honey, the occurrence of which is currently at the same relative frequency as M. fructicola Winter) Honey [2,3,4,5]. Both species have been associated with about 85%–90% of brown rot (BR) incidence in Spanish peach commodities [2]. Yield losses have been recorded, especially after harvest, reaching 80%–85% depending on the meteorological conditions [6,7], obviously posing a great threat for sustainable production of crops

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