Effects of nanocarbon solution treatment on the nutrients and glucosinolate metabolism in broccoli

Abstract

The effects of a nanocarbon solution on the nutrients, glucosinolate metabolism and glucoraphanin pathway in broccoli were investigated. Significant positive linear relationships were observed between the nanocarbon solution and total protein yield, although effects on the soluble sugars, vitamin C and dry matter production were not observed. All nanocarbon solutions significantly increased the glucoraphanin content (p < 0.05), and the 18.75 L·ha^-1 nanocarbon solution maximally increased the glucoraphanin content by 22.9 %. However, these treatments also significantly reduced the contents of glucobrassicin, 4-methoxyglucobrassicin, 4-hydroxyglucobrassicin and neoglucobrassicin. Further research demonstrated that the 18.75 L·ha^-1 nanocarbon solution significantly upregulated the MAM1, IPMI2, CYP79F1, FMOgs-ox2, AOP2, and TGG1 expression levels, which directly resulted in the accumulation of glucoraphanin and glucoerucin. This study provides insights into the prospective nanotechnological approaches for developing efficient and environmentally friendly nanocarbon solution for use on crops.

Keywords: Broccoli; Glucoraphanin; Glucosinolate; HPLC; Nanocarbon solution; Nutrient.

Fig. 1

Design of the nanocarbon solution effect on nutrients, glucosinolate metabolism and glucoraphanin pathway in broccoli.

Fig. 2

Statistical analysis of the nanocarbon solution and nutrients in broccoli. The letters in the colored bars show significant differences in the nanocarbon solution that affected the contents of soluble sugars, total protein, vitamin C and dry matter based on one-way ANOVA at p < 0.05 (two-tailed) (a). The linear regression between the nanocarbon solution and nutrients (soluble sugars, total protein, vitamin C and dry matter) is shown in (b) at p < 0.05, and SS is short for the sum of squares.

Fig. 3

Profile of the glucosinolate contents (a) and chromatogram (b) detected in broccoli florets by HPLC. (a) Effects of 3.75 L·ha⁻¹ (T1), 11.25 L·ha⁻¹ (T2), 18.75 L·ha⁻¹ (T3) nanocarbon solutions on glucosinolate content compared with the control (T0). Data are the mean ± standard error from three biological replicate assays (n = 3). Different letters show significant differences (p < 0.05) for each sampling date among treatments. GSL(s): glucosinolate(s); GIB: glucoiberin (3-methylsulfinylpropyl); PRO: progoitrin (2-R-hydroxy-3-butenyl); SIN: sinigrin (2-propenyl); GRA: glucoraphanin (4-methylsulfinylbutyl); GAL: glucoalyssin (5-methylsulfinyl); GNA: gluconapin (3-butenyl); 4HGBS: 4-hydroxyglucobrassicin (4-hydroxy-3-indolylmethyl); GER: glucoerucin (4-methylthiobutyl); GBS: glucobrassicin (3-indolylmethyl); 4MGBS: 4-methoxyglucobrassicin (4-methoxy-3-indolylmethyl); NGBS: neoglucobrassicin (1-methoxy-3-indolylmethyl).

Fig. 4

Metabolic profile of the biosynthesis pathways for 3C, 4C and 5C aliphatic glucosinolates and indolic glucosinolates in Brassica plants. Black and blue arrows indicate the pathways for aliphatic and indolic glucosinolate biosynthesis, respectively. Glucosinolates in orange frames were detected in this study (broccoli florets). The rectangles in red, green, and blue represent the three steps of glucosinolate biosynthesis: chain elongation, core structure formation and side chain modification, respectively. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 5

Expression profile of the glucosinolate genes in broccoli florets. Significant differences were observed in the relative glucosinolate gene expression (MAM1, IPMI2, CYP79F1, FMOgs-ox2, AOP2, and TGG1) in florets treated with 0.00 (T0), 3.75 L·ha⁻¹ (T1), 11.25 L·ha⁻¹ (T2), 18.75 L·ha⁻¹ (T3) nanocarbon solution at p < 0.05 (*) and p < 0.01 (**) (a). (b) Linear regression analysis of the nanocarbon solution and glucosinolate gene expression levels in broccoli florets.