Brassica oleracea var. italica cultivar:BOP04-28-6 Raw sequence reads

Broccoli is one of the vegetable crops with excellent economic benefits and high dietary nutritional value among cruciferous plants. Broccoli contains a sulfur-containing secondary metabolite-sulforaphane, which has strong detoxification, antioxidant and anti-cancer effects. At the same time, broccoli has typical selenium-rich properties, which can catalyze the transformation of selenium in inorganic form into various organic selenides, of which methyl organoselenium compounds (Se-methylselenocysteine) have been proven to have anti-cancer and detoxification effects. The effective combination of sulfur-containing compounds and organic selenium-containing compounds makes broccoli have a more balanced dietary nutrition and health-promoting effects.In previous researches, we found that selenium metabolism pathway gene BoSMT might be involved in the sodium selenite-mediated sulforaphane biosynthesis pathway in broccoli. The results of phenotypic identification of BoSMT overexpression and knockdown expression broccoli lines have indicated that overexpression of BoSMT gene significantly increases Se-methylselenocysteine (SeMSC) content in broccoli florets, while suppression of BoSMT gene causes SeMSC content decreased. The GSLs and sulforaphane content were measured. It was found that GSLs and sulforaphane contents accumulated a higher level in florets of broccoli BoSMT-overexpressed lines, while GSLs and sulforaphane contents were significantly decreased in BoSMT knockdown lines. The BoSMTkd#10 line and wild-type plants were used to perform RNA-Seq analysis. A total of 1718 differentially expressed genes (DEGs) were identified, which were enriched in the glucosinolates (GSLs) biosynthesis, tryptophan metabolism, sulfur metabolism, starch and sucrose metabolism, and so on. RT-qPCR analysis showed that the expression levels of aliphatic GSLs regulator BoMYB28-2 and indole GSLs regulator BoMYB51 were significantly up-regulated in BoSMT-overexpressed broccoli lines, while BoMYB8-2 and BoMYB51 expression was down-regulated in BoSMT knockdown lines. In addition, overexpression of BoSMT can significantly increase the total sulfur and amino acid content in broccoli florets, while suppression of BoSMT can significantly reduce the accumulation of both. These findings suggest that BoSMT gene can affect SeMSC, GSLs and sulforaphane accumulation in broccoli.Exogenous sodium selenite can significantly increase SeMSC content in two BoSMT knockdown transgenic lines, and partially compensated for the phenotypes of GSLs and sulforaphane content loss, which indicates that the accumulation of endogenous SeMSC induced by sodium selenite treatment may positively regulate the synthesis of GSLs and sulforaphane.