Brassica oleracea var. italica Raw sequence reads. Brassica oleracea var. italica

Broccoli (Brassica oleracea var. italica, 2n=2x=18) is an important vegetable crops, whose flower head is rich in vitamins, minerals and secondary metabolites such as glucosinolates glucoraphanin (GR) (Natella et al., 2016; Bjorkman et al., 2011; Sarvan et al., 2017). In the past decades, breeders have acquired high-yield broccoli commercial cultivars by traditional breeding methods. During 2010-2014, global production and cultivation area of broccoli were both increasing from ~21.07 million tonnes to ~24.2 million tonnes, from ~1.21 million to ~1.38 million hectares (the data were combined with cauliflowers), respectively (http://www.fao.org/faostat/en/#data/QC). It is very important to breed new varieties with high GR or resistance to abiotic and biotic stresses and high yield in broccoli’s industry. Classical breeding methods have constraints and it is time-consuming and difficult to obtain such varieties. Modern breeding technology including molecular marker assisted selection (MAS) can overcome the shortage of conventional breeding methods. High-density genetic maps are important foundation to analyze complex trait for breeders and foundation for MAS.