UV-B irradiation changes specifically the secondary metabolite profile in broccoli sprouts: induced signaling overlaps with defense response to biotic stressors.
ABSTRACT: Only a few environmental factors have such a pronounced effect on plant growth and development as ultraviolet light (UV). Concerns have arisen due to increased UV-B radiation reaching the Earth's surface as a result of stratospheric ozone depletion. Ecologically relevant low to moderate UV-B doses (0.3-1 kJ m(-2) d(-1)) were applied to sprouts of the important vegetable crop Brassica oleracea var. italica (broccoli), and eco-physiological responses such as accumulation of non-volatile secondary metabolites were related to transcriptional responses with Agilent One-Color Gene Expression Microarray analysis using the 2×204 k format Brassica microarray. UV-B radiation effects have usually been linked to increases in phenolic compounds. As expected, the flavonoids kaempferol and quercetin accumulated in broccoli sprouts (the aerial part of the seedlings) 24 h after UV-B treatment. A new finding is the specific UV-B-mediated induction of glucosinolates (GS), especially of 4-methylsulfinylbutyl GS and 4-methoxy-indol-3-ylmethyl GS, while carotenoids and Chl levels remained unaffected. Accumulation of defensive GS metabolites was accompanied by increased expression of genes associated with salicylate and jasmonic acid signaling defense pathways and up-regulation of genes responsive to fungal and bacterial pathogens. Concomitantly, plant pre-exposure to moderate UV-B doses had negative effects on the performance of the caterpillar Pieris brassicae (L.) and on the population growth of the aphid Myzus persicae (Sulzer). Moreover, insect-specific induction of GS in broccoli sprouts was affected by UV-B pre-treatment.
Project description:Brassica sprouts contain abundant phytochemicals, especially glucosinolates (GSs). Various methods have been used to enhance GS content in sprouts. However, the molecular basis of GS metabolism in sprouts remains an open question. Here we employed RNA-seq analysis to compare the transcriptomes of high-GS (JL-08) and low-GS (JL-09) Brassica alboglabra sprouts. Paired-end Illumina RNA-seq reads were generated and mapped to the Brassica oleracea reference genome. The differentially expressed genes were analyzed between JL-08 and JL-09. Among these, 1477 genes were up-regulated and 1239 down-regulated in JL-09 compared with JL-08. Enrichment analysis of these differentially expressed genes showed that the GS biosynthesis had the smallest enrichment factor and the highest Q-value of all metabolic pathways in Kyoto Encyclopedia of Genes and Genomes database, indicating the main metabolic difference between JL-08 and JL-09 is the GS biosynthetic pathway. Thirty-seven genes of the sequenced data were annotated as putatively involved in GS biosynthesis, degradation, and regulation, of which 11 were differentially expressed in JL-08 and JL-09. The expression level of GS degradation enzyme myrosinase in high-GS JL-08 was lower compared with low-GS JL-09. Surprisingly, in high-GS JL-08, the expression levels of GS biosynthesis genes were also lower than those in low-GS JL-09. As the GS contents in sprouts are determined by dynamic equilibrium of seed stored GS mobilization, de novo synthesis, degradation, and extra transport, the result of this study leads us to suggest that efforts to increase GS content should focus on either raising GS content in seeds or decreasing myrosinase activity, rather than improving the expression level of GS biosynthesis genes in sprouts.
Project description:Sulforaphane is a significant chemopreventive compound which is the predominant glucosinolate in broccoli sprouts. However, the existence of the epithiospecifier protein could direct the hydrolysis of glucosinolates toward sulforaphane nitrile formation instead of sulforaphane. Therefore, the study aimed on improving the yielding of sulforaphane in broccoli sprouts with a new method of the united hydrolysis of cruciferous sprouts. According to the results, the addition of radish, rocket and rape sprouts to broccoli sprouts could promote the hydrolysis of the glucoraphanin to anticancer effective sulforaphane to 2.03, 2.32 and 1.95-fold, respectively, compared to single broccoli sprouts. Meanwhile, the formation of non-bioactive sulforaphane nitrile in these three groups decreased greatly. However, the addition of mustard sprouts had no positive effect. These observations could make a contribution to the potential chemoprotective effects of broccoli sprouts.
Project description:BACKGROUND: Broccoli (Brassica oleracea var. italica), a member of Cruciferae, is an important vegetable containing high concentration of various nutritive and functional molecules especially the anticarcinogenic glucosinolates. The sprouts of broccoli contain 10-100 times higher level of glucoraphanin, the main contributor of the anticarcinogenesis, than the edible florets. Despite the broccoli sprouts' functional importance, currently available genetic and genomic tools for their studies are very limited, which greatly restricts the development of this functionally important vegetable. RESULTS: A total of ?85 million 251 bp reads were obtained. After de novo assembly and searching the assembled transcripts against the Arabidopsis thaliana and NCBI nr databases, 19,441 top-hit transcripts were clustered as unigenes with an average length of 2,133 bp. These unigenes were classified according to their putative functional categories. Cluster analysis of total unigenes with similar expression patterns and differentially expressed unigenes among different tissues, as well as transcription factor analysis were performed. We identified 25 putative glucosinolate metabolism genes sharing 62.04-89.72% nucleotide sequence identity with the Arabidopsis orthologs. This established a broccoli glucosinolate metabolic pathway with high colinearity to Arabidopsis. Many of the biosynthetic and degradation genes showed higher expression after germination than in seeds; especially the expression of the myrosinase TGG2 was 20-130 times higher. These results along with the previous reports about these genes' studies in Arabidopsis and the glucosinolate concentration in broccoli sprouts indicate the breakdown products of glucosinolates may play important roles in the stage of broccoli seed germination and sprout development. CONCLUSION: Our study provides the largest genetic resource of broccoli to date. These data will pave the way for further studies and genetic engineering of broccoli sprouts and will also provide new insight into the genomic research of this species and its relatives.
Project description:To determine the response of Chinese kale (<i>Brassica alboglabra</i>) sprouts to photoperiods under different light sources, we used four photoperiods (0-h light/24-h dark, 8-h light/16-h dark, 12-h light/12-h dark, and 16-h light/8-h dark) to investigate their sprout growth and secondary metabolite glucosinolates (GSs) accumulation under white or combined red-and-blue (RB) light sources. We found that the 16-h light condition under RB light produced plants with the greatest dry matter. Sprouts grown under 16-h RB light condition achieved greater length than those under white light. To investigate the role of RB light in plant growth and GS accumulation, we applied RB light sources with different RB ratios (0:10, 2:8, 5:5, 8:2, and 10:0) to cultivate sprouts. The results showed that significant differential accumulation of GSs existed between sprouts grown under blue (RB, 0:10) and red (RB, 10:0) light; there was greater GS content under blue light. The underlying mechanism of differential GS content in sprouts under red or blue light condition was studied using RNA sequencing technique. Interestingly, abundant GS biosynthetic gene transcripts were observed in sprouts grown under red light compared with under blue light. The expression of ?-glucosidase family homolog genes related to GS degradation differed under red and blue light conditions, among those <i>TGG4</i> homolog was detected with higher expression under red light than with blue light. Taking into consideration, the lower GS accumulation in sprouts under red rather than blue light, we conclude that the degradation of GSs may play a key role in sprouts GS homeostasis.
Project description:BACKGROUND: Broccoli is a Brassica vegetable that is believed to possess chemopreventive properties. Selenium also shows promise as an anticancer agent. Thus, selenium enrichment of broccoli has the potential to enhance the anticancer properties of broccoli sprouts. METHOD: Selenium-enriched broccoli sprouts were prepared using a sodium selenite solution. Their anticancer properties were evaluated in human prostate cancer cell lines and compared with those of a control broccoli sprout extract. RESULTS: Selenium-enriched broccoli sprouts were superior to normal broccoli sprouts in inhibiting cell proliferation, decreasing prostate-specific antigen secretion, and inducing apoptosis of prostate cancer cells. Furthermore, selenium-enriched broccoli sprouts but, not normal broccoli sprouts, induced a downregulation of the survival Akt/mTOR pathway. CONCLUSION: Our results suggest that selenium-enriched broccoli sprouts could potentially be used as an alternative selenium source for prostate cancer prevention and therapy.
Project description:The study compares lyophilized broccoli sprouts and florets in terms of their chemical composition, cytotoxic and proapoptotic potential against hepatocellular carcinoma HepG2, colorectal cancer SW480, and skin fibroblast BJ cells. Sinapic and isochlorogenic acids were predominant phenolics in the sprouts and florets, respectively. The amount of sulforaphane in the sprouts was significantly higher vs. florets. Oleic and linoleic acids dominated in the sprouts, while caproic, stearic and oleic acids in the florets. Broccoli sprouts were selectively cytotoxic on HepG2 and SW480 cells, with proapoptotic effect for the latter, while the florets were less selective, but more active, with profound proapoptotic effect for HepG2 cells (77.4%). Thus, lyophilized broccoli sprouts may be effectively used in dietary chemoprevention.
Project description:Sprouts and microgreens, the edible seedlings of vegetables and herbs, have received increasing attention in recent years and are considered as functional foods or superfoods owing to their valuable health-promoting properties. In particular, the seedlings of broccoli (Brassica oleracea L. var. Italica) have been highly prized for their substantial amount of bioactive constituents, including glucosinolates, phenolic compounds, vitamins, and essential minerals. These secondary metabolites are positively associated with potential health benefits. Numerous in vitro and in vivo studies demonstrated that broccoli seedlings possess various biological properties, including antioxidant, anticancer, anticancer, antimicrobial, anti-inflammatory, anti-obesity and antidiabetic activities. The present review summarizes the updated knowledge about bioactive compounds and bioactivities of these broccoli products and discusses the relevant mechanisms of action. This review will serve as a potential reference for food selections of consumers and applications in functional food and nutraceutical industries.
Project description:Hypertension, hyperlipidemia, and diabetes are important precursors of cardiovascular disease. Here, we evaluated the antihypertensive, antihyperlipidemic, and antidiabetic potential of five types of sprouts in fructose-loaded spontaneously hypertensive rats (SHRs). Powdered sprouts (PSs) were produced from mung bean, broccoli, radish, and buckwheat sprouts and germinated soybeans by lyophilization. The PSs were analyzed for nutritional composition and bioactive agents (?-aminobutyric acid [GABA], coenzyme Q10 [CoQ10], rutin, and myo-inositol-1,2,3,4,5,6-hexakisphosphate [IP6]) and functionally tested in SHRs given water containing 25 % fructose and diets containing 30 % PS for 46 days. All PSs were nutritionally rich in protein and dietary fiber. CoQ10, GABA/rutin, and GABA/IP6 were abundant in broccoli, buckwheat, and germinated soybean PSs, respectively. Mung bean, broccoli, and buckwheat PSs caused significant reductions in heart rates and/or serum triglycerides. Mung bean PS also significantly reduced serum total cholesterol. These data supported the antihypertensive and antihyperlipidemic potential of mung bean, broccoli, and buckwheat sprouts.
Project description:Effects of high-pressure processing (HPP, 100-600 MPa for 3 min at 30 °C) on the glucosinolate content, conversion to isothiocyanates, and color changes during storage in fresh broccoli sprouts were investigated. A mild heat treatment (60 °C) and boiling (100 °C) were used as positive and negative controls, respectively. Glucosinolates were quantified using liquid chromatography-mass spectrometry, and isothiocyanates were quantified using high-performance liquid chromatography-photodiode array detection. A formation of isothiocyanates was observed in all high-pressure-treated sprouts. The highest degree of conversion (85%) was observed after the 600 MPa treatment. Increased isothiocyanate formation at 400-600 MPa suggests an inactivation of the epithiospecifier protein. During storage, color changed from green to brownish, reflected by increasing a* values and decreasing L* values. This effect was less pronounced for sprouts treated at 100 and 600 MPa, indicating an influence on the responsible enzymes. In summary, HPP had no negative effects on the glucosinolate-myrosinase system in broccoli sprouts.