Exploitation of crop wild relatives for more sustainable and healthier spinach
Spinach (Spinacia oleracea L.) is an economically important crop and one of the most nutritious vegetables in the human diet. Spinach has been domesticated from one of its related wild relatives S. tetrandra and S. turkestanica. Both wild species are sexually compatible with cultivated spinach and therefore are important genetic resources in the breeding of improved spinach varieties. In this project, our overall aim is to explore genetic variation in S. turkestanica and S. tetrandra by elucidating the genomic structure of spinach in the unique CGN collection, which will facilitate maximum use of genetic diversity in breeding for traits related to productivity, adaption and human health.
In 2017, an assembly of the spinach genome was published, which is available from SpinachBase. The spinach genome has an estimated size of ~1000 Mb, containing 74.4% of repetitive sequences and an approximate number of 25,500 protein-coding genes. Previous research revealed a total of 93 genomic regions associated with wild introgressions that are potentially related with spinach domestication and breeding.
Until recently the availability of wild spinach accessions in genetic resources collections worldwide has been poor which limited the breeding of spinach considerably. Therefore the Centre for Genetic Resources, the Netherlands (CGN), in close collaboration with spinach breeding companies unified within the organisation Plantum, collected in the centres of origin of spinach 66 accessions of S. turkestanica in Central Asia (2008) and 36 accessions of S. tetrandra in the Trans Caucasus (https://missions.cgn.wur.nl). To elucidate the genomic variation in the CGN collection, three objectives are defined in this project:
- de novo sequencing of two wild accessions; one from S. turkestanica and the other from S. tetrandra.
- re-sequencing about 100 spinach genotypes including the CGN accessions and landraces/cultivars that have contributed to the breeding of spinach cultivars.
- setting up a core-collection that represents the genetic diversity of spinach by screening the differences in genome structure, heterozygosity and allelic variation among the CGN collection.
The availability of genome assemblies for S. turkestanica and S. tetrandra would greatly facilitate the exploitation of the genetic diversity of these species in spinach breeding for new robust varieties, which fit into the newly developed cultivation systems with a high resistance to pests and diseases (biotic stress) as well as to environmental influences (abiotic stress and climate change). This type of research remains a constant point of attention in circular agriculture, which is restarted annually from healthy and adapted plant materials.