2019 ASHS Annual Conference

Genetic male sterility in squash (Cucurbita pepo L.) is controlled by a single recessive gene designated ms-2. The phenotype is characterized by shriveling and browning of the androecium. Deployment of ms-2 in commercial production of hybrid seeds would eliminate the need for emasculation or defloration. However, its application is limited due to inability to easily distinguish male fertile from male infertile plants in the field. Availability of DNA markers linked to ms-2 gene would allow marker-assisted selection (MAS) for male sterile plants prior to sowing through a seed-based genotyping system (seed chip technology). However, no information is currently available on the genetic loci underlying ms-2 in C. pepo. The goal of the current study was to identify the chromosomal location for ms-2 using an F₂ population segregating for male sterility (TQ x #181761-36P). The F₂ population was phenotyped at flowering stage in the greenhouse, while SNP genotyping was performed using a seqSNP platform (LGC genomics). Approximately 60% of the SNPs assayed were polymorphic between the parents, and were used to generate a linkage map spanning 20 C. pepo linkage groups. A major QTL explaining 50% of the phenotypic variation observed in the F₂ was mapped on LG 4 in a region containing a candidate gene involved in male sterility across many plant species. Several SNPs adjacent to this QTL are good candidate for MAS for male sterility in C. pepo. Further work is underway to validate CAPS markers targeting these SNPs.