Mapping Cucumber Vein Yellowing Virus Resistance in Cucumber (Cucumis sativus L.) by Using BSA-seq Analysis

Abstract

Cucumber vein yellowing virus (CVYV) causes severe yield losses in cucurbit crops across Mediterranean countries. The control of this virus is based on cultural practices to prevent the presence of its vector (Bemisia tabaci) and breeding for natural resistance, which requires the identification of the loci involved and the development of molecular markers for linkage analysis. In this work, we mapped a monogenic locus for resistance to CVYV in cucumber by using a Bulked Segregant Analysis (BSA) strategy coupled with whole-genome resequencing. We phenotyped 135 F3 families from a segregating population between a susceptible pickling cucumber and a resistant Long Dutch type cucumber for CVYV resistance. Phenotypic analysis determined the monogenic and incomplete dominance inheritance of the resistance. We named the locus CsCvy-1. For mapping this locus, 15 resistant and 15 susceptible homozygous F2 individuals were selected for whole genome resequencing. By using a customized bioinformatics pipeline, we identified a unique region in chromosome 5 associated to resistance to CVYV, explaining more than 80% of the variability. The resequencing data provided us with additional SNP markers to decrease the interval of CsCvy-1 to 625 kb, containing 24 annotated genes. Markers flanking CsCvy-1 in a 5.3 cM interval were developed for marker-assisted selection (MAS) in breeding programs and will be useful for the identification of the target gene in future studies.

A Historical Account of Viruses in Intensive Horticultural Crops in the Spanish Mediterranean Arc: New Challenges for a Sustainable Agriculture

“…In addition, the introgression of a resistance gene in cucumber has been shown to be efficient in reducing susceptibility to mild variants of the virus, but not to severe ones that are not currently present in the area [70][71][72]. The resistance to CVYV in cucumber has been recently mapped in a locus called CsCvy-1 [73]. In melon, there are some advances in the mapping and introgression of the resistance, due to the fact that it is more complex than in cucumber, because three loci have been found to be controlling resistance and symptom severity [74].…”

Mapping a Partial Andromonoecy Locus in Citrullus lanatus Using BSA-Seq and GWAS Approaches

“…BSA-seq ( Takagi et al, 2013 ) is a helpful alternative to the conventional gene mapping approach. It has been very successfully used for mapping several agronomic traits in differing plant species, including cucurbit species such as cucumber and melon ( Pujol et al, 2019 ; Zhang T. et al, 2019 ), and watermelon ( Dou et al, 2018a ; Dou et al, 2018b ; Guo et al, 2019 ; Oren et al, 2019 ; Zhu et al, 2019 ; Gebremeskel et al, 2020 ). Utilising an F2 segregating population and a BSA-seq approach, we were also able to quickly map the locus pa on a single genomic region of chromosome 1.…”

Genomic-Assisted Marker Development Suitable for CsCvy-1 Selection in Cucumber Breeding

“…Sequences were aligned using Progressive Mauve (Darling et al, 2004). ***These markers were from Pujol et al (2019). ****The phenotype was not confirmed by using offspring to determine whether it is homozygous or heterozygous.…”

“…Cucumber hybrid lines resistant to CVYV exist in the commercial market; however, currently all the work for selecting resistant lines relies on traditional pathotesting efforts. Recently, Pujol et al ( 2019 ) described their elegant study on the resistant accession CE0749, a CVYV-resistant long Dutch-type cucumber. They used genomics and bulked segregant analysis (BSA) (Michelmore et al, 1991 ) and fine-mapped a locus containing the gene CsCvy-1 locus in a 625 kb region with 24 candidate genes (Pujol et al, 2019 ).…”

“…Recently, Pujol et al ( 2019 ) described their elegant study on the resistant accession CE0749, a CVYV-resistant long Dutch-type cucumber. They used genomics and bulked segregant analysis (BSA) (Michelmore et al, 1991 ) and fine-mapped a locus containing the gene CsCvy-1 locus in a 625 kb region with 24 candidate genes (Pujol et al, 2019 ).…”