A review on the genetic resources, domestication and breeding history of spinach (Spinacia oleracea L.)

Abstract

This paper addresses the genetic resources, domestication and breeding history of spinach as a comprehensive review of these crop aspects is currently unavailable. It is shown that the availability of genetic resources of wild relatives belonging to the primary gene pool is currently very limited, which hampers breeding and research activities. Therefore, new collecting expeditions are clearly warranted. The domestication of spinach is discussed on the basis of its presumed migration routes and the traits that were probably involved in the domestication syndrome. Spinach is thought to have domesticated in former Persia. Migration then occurred eastwards to China and westwards to Europe, but additional genetic data are needed to reveal the most likely migration routes. Morphological changes in pistillate flowers and loss of dormancy are identified as the main traits involved in the domestication syndrome of spinach. To a large extent we could reconstruct the relationships between spinach cultivars that were developed until the 1950s, but this appeared difficult for the more recent cultivars due to intellectual property protection by breeding companies. Resistance against downy mildew has been the main breeding target in spinach. The introgression of NBS-LRR resistance genes from wild relatives is the major strategy to develop downy mildew resistant cultivars. However, the use of lossof-function alleles of susceptibility genes may provide a more durable strategy to develop resistant cultivars. So far, abiotic resistance and quality traits have received minor attention in spinach research and breeding. This is expected to change considering the potential effects of climate change on these traits.

On the origin and dispersal of cultivated spinach (Spinacia oleracea L.)

“…Bold identifiers are used for the accessions from Iran, where spinach presumably has been domesticated the Western Asian landraces from the Caucasus. The genetic relationships between the reference cultivars are in line with their breeding history as Resistoflay has been developed from Viroflay by introgression of a downy mildew resistance, whereas Viking has resulted from a cross between Viroflay and the old European cultivar King of Denmark (Ribera et al 2020).…”

“…Despite their large similarity, the two wild species differ in inflorescence characteristics. Additionally, S. tetrandra male plants are considerably smaller than females, while this sexual dimorphism is not as pronounced in S. turkestanica (Ribera et al 2020). It has been suggested that one or both of these two species may have been ancestor of cultivated spinach (Andersen and Torp 2011).…”

RxLR and CRN effectors of the spinach downy mildew Peronospora effusa and their interacting plant proteins

“…Individual effectors are usually not crucial for survival and there is redundancy in effector repertoires [200,309]. In Pfs, these dynamics lead to the continuous emergence of new races that break R-gene mediated resistance of newly bred spinach varieties [30,32]. The identification of Arabidopsis proteins that interact with Pfs effectors supports the idea of conserved plant targets across species (Chapter 3).…”

“…Peronospora effusa (Pfs) is an obligate biotrophic oomycete that causes downy mildew on spinach and is a major threat to spinach production worldwide [30,32]. Its hyphae can penetrate the leaf tissue and grow between plant cells, which they invaginate to form haustoria, the sites of interaction between the oomycete and plant cells [37].…”

“…Downy mildew is a major disease in commercial spinach fields worldwide and restrains both crop quality and quantity [30]. Pfs was first reported in 1824 [31] and, following the introduction of resistant spinach cultivars, new isolates evolved rapidly over the last two decades [23,32].…”