Quantitative trait loci controlling Phytophthora cactorum resistance in the cultivated octoploid strawberry (Fragaria × ananassa)

Abstract

The cultivated strawberry, Fragaria × ananassa ( Fragaria spp.) is the most economically important global soft fruit. Phytophthora cactorum , a water-borne oomycete causes economic losses in strawberry production globally. A bi-parental cross of octoploid cultivated strawberry segregating for resistance to P . cactorum , the causative agent of crown rot disease, was screened using artificial inoculation. Multiple putative resistance quantitative trait loci (QTL) were identified and mapped. Three major effect QTL ( FaRPc6C , FaRPc6D and FaRPc7D ) explained 37% of the variation observed. There were no epistatic interactions detected between the three major QTLs. Testing a subset of the mapping population progeny against a range of P. cactorum isolates revealed no significant interaction ( p = 0.0593). However, some lines showed higher susceptibility than predicted, indicating that additional undetected factors may affect the expression of some quantitative resistance loci. Using historic crown rot disease score data from strawberry accessions, a preliminary genome-wide association study (GWAS) of 114 individuals revealed an additional locus associated with resistance to P . cactorum . Mining of the Fragaria vesca Hawaii 4 v1.1 genome revealed candidate resistance genes in the QTL regions.

How Do Trichoderma Genus Fungi Win a Nutritional Competition Battle against Soft Fruit Pathogens? A Report on Niche Overlap Nutritional Potentiates

“…and Botrytis sp., the causal actors of anthracnose and gray mould, respectively, require effective management strategies to combat them [ 8 ]. The Verticillium genus representatives, which cause wilt, are also critical from an economic point of view [ 9 , 10 ]. Phytophthora species are responsible for many losses in all of the production areas of the world [ 11 ].…”

Disease Resistance Genetics and Genomics in Octoploid Strawberry

“…An analysis of diploid R-genes across the Rosaceae genus was previously conducted (Arya et al 2014). New genetic resources for high-resolution genotyping in octoploid strawberry have resulted in the recent identification of several disease resistance loci (Mangandi et al 2017; Nellist et al 2019; Cockerton et al 2018; Pincot et al 2018; Salinas et al 2018; Anciro et al 2018; Roach et al 2016; Verma et al 2018). However, the specific genes mediating resistance in these QTL intervals typically remain unresolved, as genomic resources for octoploid strawberry have not kept pace with genetic mapping.…”

A roadmap for research in octoploid strawberry

“…Many resistances appear to be primarily conferred by one or two major loci or large-effect QTL, including to Phytophthora fragariae 141 , Xanthomonas fragariae 57 , Phytophthora cactorum 60 , Fusarium oxysporum f.sp fragariae 142 , Colletotrichum gloeosporoides 58 , and Colletotrichum acutatum 59,143 . For P. cactorum, additional minor loci have recently been identified 144 . On the other hand, resistances to Verticillium dahaliae 145 and Podosphaera aphanis 146 appear to be quite complex, with no major loci identified to date.…”