Generation of Se‐fortified broccoli as functional food: impact of Se fertilization on S metabolism

Abstract

Selenium (Se)-fortified broccoli (Brassica oleracea var. italica) has been proposed as a functional food for cancer prevention, based on its high glucosinolate (GSL) content and capacity for Se accumulation. However, as selenate and sulphate share the initial assimilation route, Se fertilization could interfere with sulphur metabolism and plant growth. Consequently, GSL accumulation could be compromised. To evaluate these potentially adverse effects of Se fertilization, we performed a comprehensive study on sand-grown young broccoli plants (weekly selenate applications of 0.8 mmol plant -1 via the root) and field-grown adult broccoli plants during head formation (single foliar selenate application: 25.3 or 253 mmol plant -1 ). The results show that under these conditions, Se application does not affect plant growth, contents of cysteine, glutathione, total GSL, glucoraphanin (major aliphatic GSL) or the expression of BoMYB28 (encoding a functionally confirmed master regulator for aliphatic GSL biosynthesis). Conversely, due to the changed expression of sulphate transporters (BoSULTR1;1, 1;2, 2;1, and 2;2), sulphate and total S contents increased in the shoot of young plants while decreasing in the root. We conclude that broccoli can be fertilized with Se without reduction in GSL content, even with Se accumulation exceeding the level recommended for human consumption.

The potential role of nutritional genomics tools in validating high health foods for cancer control: Broccoli as example

“…Thus, broccoli is a good vegetable source of major mineral elements such as sodium, potassium, calcium, magnesium, chlorine, potassium and sulphur, and trace elements such as iron, zinc, copper, manganese and selenium (Se). Indeed, broccoli has the ability to accumulate high levels of Se with the majority of the seleno amino acids in the form of Se-methylselenocysteine, and this may also be an important factor in chemoprevention [25][26][27]. Health benefits of broccoli may also be enhanced due to the presence of proteins containing the essential amino acids isoleucine, leucine, lysine phenylalanine, tryptophan, methionine, valine and threonine, as well as beneficial fatty acids [28].…”

Applied Cell Biology of Sulphur and Selenium in Plants

“…The high-affinity sulphate transporter Sultr1;2 has been identified in Arabidopsis using selenate as analogue of sulphate (Shibagaki et al 2002) and has been shown to be a major contributor in the acquisition of selenate (El Kassis et al 2007). A selenate-induced expression of sulphate transporters has been reported in several studies (Hsu et al 2011;Takahashi et al 2000;Van Hoewyk et al 2008;Yoshimoto et al 2002).…”

Effect of Se treatment on glucosinolate metabolism and health-promoting compounds in the broccoli sprouts of three cultivars

“…Extraction and quantitative analyses of the total GSL were performed following the method described by Hsu et al (2011) with minor modifications. Freeze-dried sample (0.05 g) was pulverized in a mortar, until a homogeneous meal was obtained.…”