Genome-Wide Association Study of Brown Rot (Monilinia spp.) Tolerance in Peach.

Wanfang Fu,Cassia da Silva Linge,Ksenija Gasic

doi:10.3389/fpls.2021.635914

Abstract

Brown rot, caused by Monilinia spp., is one of the most important diseases on stone fruit worldwide. Severe yield loss can be caused by pre- and post-harvest fruit decay. Although some degree of tolerance has been reported in peach and almond, the genetic resistance in peach cultivars is still lacking. To date, only few genomic regions associated with brown rot response in fruit skin and flesh have been detected in peach. Previous studies suggested brown rot tolerance in peach being a polygenic quantitative trait. More information is needed to uncover the genetics behind brown rot tolerance in peach. To identify the genomic regions in peach associated with this trait, 26 cultivars and progeny from 9 crosses with ‘Bolinha’ sources of tolerance, were phenotyped across two seasons (2015 and 2016) for brown rot disease severity index in wounded and non-wounded fruits and genotyped using a newly developed 9+9K peach SNP array. Genome wide association study using single- and multi-locus methods by GAPIT version 3, mrMLM 4.0, GAPIT and G Model, revealed 14 reliable SNPs significantly associated with brown rot infection responses in peach skin (10) and flesh (4) across whole genome except for chromosome 3. Candidate gene analysis within the haplotype regions of the detected markers identified 25 predicted genes associated with pathogen infection response/resistance. Results presented here facilitate further understanding of genetics behind brown rot tolerance in peach and provide an important foundation for DNA-assisted breeding.

Highlights

Brown rot, caused by Monilinia spp., is one of the most economically important diseases in stone fruits (Van Leeuwen et al, 2002)
Since most of the accessions showed no signs of infection or very low level of infection after the inoculation, the disease severity index (DSI) distribution of NW treatment was skewed toward low DSI
The correlations between NW and W DSI observed in our study are in agreement with the results reported by Pacheco et al (2014) in peach and Walter et al (2004) in apricot but were in contrast with Pascal et al (1994) study in several Prunus cultivars

Summary

Introduction

Brown rot, caused by Monilinia spp., is one of the most economically important diseases in stone fruits (Van Leeuwen et al, 2002). This worldwide disease favors warm and humid growing conditions (Bernat et al, 2017) and can lead to severe yield losses in both pre- and post-harvest stages. In the United States, M. fructicola is the predominate species that causes brown rot in peach while M. laxa and M. fructigena are causative fungi in Europe (Byrde and Willetts, 1977; Lino et al, 2016). Monilinia can affect the peaches at two growth stages: blossom and twig blight caused by ascospores and conidia in the early spring and pre- and post-harvest fruit decay caused by conidia infection in the late spring and summer (Zehr, 1982; Tate and Wood, 2000; Luo et al, 2005; Lino et al, 2016).

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