ARS | Publication request: Evaluation of genotypic variation of broccoli (brassica oleracea var. italic) in response to selenium treatment

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 2, 2011
Publication Date: May 3, 2011
Citation: Ramos, S., Yuan, Y., Faquin, V., Guilherme, L., Li, L. 2011. Evaluation of genotypic variation of broccoli (brassica oleracea var. italic) in response to selenium treatment. Journal of Agricultural and Food Chemistry. 59(8):3657-65.

Interpretive Summary: Selenium is an essential micronutrient and has been implicated as a cancer preventative agent. Foods fortified with selenium have been advocated as functional foods. Thus, increasing selenium content in food crops can have a positive impact on improving human nutrition and health. Exploiting genotypic variation is likely to be effective in providing information for breeding varieties with high levels of selenium along with other health beneficial compounds. However, only few studies have investigated the genotypic variation of crop species in accumulating selenium and its effect on other metabolite accumulation. In this manuscript, we evaluated thirty eight accessions of broccoli germplasm for their capacity to accumulate selenium and for their responses to selenate treatment in terms of organic selenium species production, essential micronutrient accumulation, glucosinolate synthesis, total antioxidant content, and selenium/sulfur gene expression. Our results provide new information for the effects of selenate treatment on selenium accumulation in broccoli accessions and on plant nutrient synthesis in general. The discovery of broad diversity in broccoli germplasm provides the opportunity to breed broccoli cultivars that simultaneously accumulate selenium and other health benefit compounds.

Technical Abstract: Broccoli (Brassica oleracea var. italic) fortified with selenium (Se) has been promoted as a functional food. Here we evaluated 38 broccoli accessions for their capacity to accumulate Se and for their responses to selenate treatment in terms of nutritional qualities and sulfur gene expression. We found that total Se content varied with over 2-fold difference among the leaf tissues of broccoli accessions when the plants were treated with 20 uM Na2SeO4. Approximately half of total Se accumulated in leaves was Se-methylselenocysteine and selenomethione. Transcriptional regulation of adenosine 5'-phosphosulfate sulfurylase and selenocysteine Se-methyltransferase gene expression might contribute to the different levels of Se accumulation in broccoli. Total glucosinolate contents were not affected by the concentration of selenate application for the majority of broccoli accessions. Essential micronutrients (i.e. Fe, Zn, Cu, and Mn) remained unchanged among half of the germplasm. Moreover, total antioxidant capacity was greatly stimulated by selenate in over half of the accessions. The diverse genotypic variation in Se, glucosinolate, and antioxidant contents among accessions provides the opportunity to breed broccoli cultivars that simultaneously accumulate Se and other health benefit compounds.