Broccoli, rich in a variety of nutrients, is known as a vegetable with high nutritional value. Among them, sulforaphane, which is produced by glucosinolate under the action of myrosinase, has a significant anti-cancer effect.
Selenium and sulfur are both VIA group elements, and there is competition inhibition and synergy between them. Therefore, increasing the content of nutrients and functional components in broccoli through fertilization and other technical means has become a key direction of agricultural development.
Glucosinolate was discovered in the 17th century when people studied the special pungent taste of mustard seeds, and are anionic hydrophilic secondary metabolites rich in nitrogen and sulfur in plants. Its structure is very stable, it is a water-soluble substance, and can be easily dissolved in water, ethanol, methanol and acetone.
When ingested or mechanically damaged, glucosinates are decomposed by enzymatic hydrolysis of glucosinase or by non-enzymatic degradation reactions under high temperature and high pressure conditions.
Effect of Na2SEO3 on broccoli quality: One of the key indicators of broccoli quality is vitamin C content. The results showed that with the increase of Na2SEO3 concentration, the content of vitamin C first increased and then decreased, and there were obvious differences among the treatments.
When the concentration of Na2SEO3 was 50, the vitamin C content of broccoli reached its maximum value of 9243mg 100g, which is 1008%。
However, when the Na2SEO3 concentration was 200, the vitamin C content dropped to a minimum of 7482mg 100g, 10 lower than the control group90%。
The 200 treatment had a 19 reduction in vitamin C compared to the 50 treatment05%。
The protein metabolism of broccoli in the body can be indirectly reflected by its soluble protein content. Based on Figure 3-2, we found that the broccoli treated with SE10 had the highest soluble protein content and the SE5 treatment had the lowest content.
At the same time, the differences between SE25 and SE100 and between control and SE200 were not significant, but their differences with other treatments were very significant.
In particular, the soluble protein content of broccoli treated with SE5 was reduced by 935%, compared to the highest content treatment SE10, a reduction of 1595%。
The flavor and nutritional value of broccoli can be evaluated, focusing on its soluble sugar content. Studies have shown that changes in the concentration of Na2SEO3 have an effect on its content.
Specifically, the soluble sugar content showed a trend of decreasing first, then increasing and then decreasing, with the peak at SE25 and the lowest at SE10, with obvious differences.
SE25 is 16 higher than SE1039%, and an increase of 6. compared to the control55%, but the difference was not significant with the control. In contrast, se10 was reduced by 845%, but the decline is not significant.
The soluble sugar content of SE50 was significantly higher than that of SE10.1384%。
Broccoli is rich in phytochemicals such as polyphenols and anthocyanins, which have the effect of protecting cardiovascular health and inhibiting cancer. In particular, broccoli is also rich in phenols such as total flavonoids, which give it excellent antioxidant capacity.
However, from Figures 3-4 and 3-5, we can see that with the gradual increase of Na2SEO3 concentration, the total flavonoid content in broccoli showed a trend of first decreasing and then increasing.
At SE25 and SE50, the total flavonoid content reached the minimum value, and there was no significant difference between the two. Compared with the control group, the total flavonoid content decreased by 2296% and 2467%。
It is worth noting that the total flavonoid content in the control group was the highest, which was not significantly different from SE5, but significantly higher than that of other treatments. The total flavonoid content at SE5 is 485mg 100g-1, which was 713%, an increase of 20. compared with SE25 and SE50, respectively55% and 2328%。
Fig. 3-6 showed that with the gradual increase of Na2SEO3 concentration, the MDA content in broccoli first increased, then decreased and then increased. Each treatment exceeded the control group, with the highest MDA content at SE200.
Compared to the control group, SE200 increased MDA content by 8480%；However, there was no significant difference between SE25 and SE200, and SE25 increased MDA content by 7356%。
On the other hand, as can be seen from Figures 3-7, the SOD activity reaches the minimum and maximum values at SE10 and SE200, which are 136., respectively52U G-1 and 22933U g-1, there is a significant difference between the two.
The SOD activity of SE10 is reduced by 200 compared to SE4047%, while also a decrease of 3307%。In addition, there were significant differences between se10 and control groups.
In contrast, SE200 had a 12-more SOD activity than the control group44%, but the difference between the two was not significant.
After the application of the exogenous substance Na2SEO3 to broccoli, we found a total of 9 glucosinolate components, including 5 aliphatic glucosinolates and 4 indole glucosinolates.
Among these 9 glucosinolate components, aliphatic glucosinolate accounts for 27 of the total glucosinolate content03%~33.03%, while indole glucosinates account for 66 percent of the total glucosinolate content97%~72.97%。
It is worth noting that except for SE5 and SE10, the total aliphatic glucosinolate content in the other treatment groups was higher than that of the control, and these differences were significant. Among them, the total aliphatic glucosinolate content reached the highest at SE25, which was 468 mol g-1, an increase of 120 times.
At SE5, the total aliphatic glucosinolate content was the lowest, which was reduced by 1474%, which is 25% less than SE3064%。In addition, the aliphatic glucosinolates, Pro, Sin, Raa and NAP, were the most abundant at SE25, while ERU was the most abundant at SE200.
In particular, the glucosinolate content of SE25, SE100 and SE200 treatments in PRO was higher than that of the control, while the other treatments were lower than those of the control, and there were significant differences among the treatments.
SE25 and SE100 had a significant synergistic effect on broccoli, which increased by 1429% and 136%。In contrast, SE5, SE10 and SE50 had an inhibitory effect on broccoli and decreased respectively. 41% and 1497%。
In SIN, only the se25 and se200 treatments had higher glucosinolate content than the control group, and the other treatments had less glucosinolate content than the control group, and there was a significant difference between the treatments.
SE25 and SE200 were 667% and 167%, the increase in SIN in SE25 is 4 times that of SE200.
RAA is one of the main components in broccoli glucosinolates. As can be seen from Table 3-1, high concentration of Na2SEO3 treatment significantly increased the content of Raa, while Se5 and Se10 inhibited the content of Raa, and there was a significant difference between treatments.
Compared to the control, SE5 and SE10 each decreased by 1643% and 1457%, while compared to SE25, a decrease of 32., respectively27% and 3076%。
SE25 increased by 2338% Nap glucosinolate content, twice as much as control. Under the SE5 treatment, the NAP content was the lowest, at only 0005 mol g-1, a decrease of 1667%, a decrease of 58 compared to SE2533%。
There was no significant difference between SE5 and control, but significant difference between SE25 and SE25. All treatments in ERU were larger than those in the control, and there were significant differences between treatments, indicating that Na2SEO3 concentration treatment had a significant promoting effect on ERU.
Compared with the control, the increase in se200 was the largest, which was 2687%, with the smallest increase in SE10 at 164%。The content of total indole glucosinols changed significantly under different concentrations of Na2SEO3 treatment, which was as follows: SE50> SE25> SE200> SE0>SE10>SE100> SE5.
SE50, SE25, and SE200 increased respectively compared to controls. 02% and 243%, compared to SE5, respectively, an increase. 16% and 4085%。
SE10, SE100, and SE5 were reduced compared to the control, respectively. 16% and 2727%。
Under SE50 treatment, the contents of 4OH, GBC and NEO in broccoli indole glucosinates reached the highest point, which was in complete agreement with the total glucosinolate content.
The content of 4OH was higher than that of the control under the Se25 and Se50 treatments, and lower than the control in the rest of the treatments, and reached the lowest in the Se10 treatment.
The treatments of SE25 and SE50 were increased by 117% and 235%。The SE10 treatment was 4031%, which is 50 lower than SE4168%。
GBC was one of the main anticancer glucosinates in broccoli indole, but the content of GBC was the lowest under SE5 treatment, which was lower than that of the control, and the differences between treatments were significant.
SE5 treatment was reduced by 2400%, which is 50% lower than SE3654%。The SE50 treatment was 1977%。
High levels of Na2SEO3 treatment can effectively increase the content of 4Me, but SE5 and SE10 treatments can inhibit the content of 4ME. At the highest concentration, SE200, the content of 4ME was the highest, and the lowest was at SE5.
The SE200 treatment increased by 6 compared to the control and SE5 treatments, respectively27% and 2553%, while the SE5 treatment was reduced by 1534%。
The Neo content was the highest in the SE50 treatment and the lowest in the SE5 treatment, which was similar to that of GBC, and the differences between the treatments were significant.
After the treatment of SE5, SE10 and SE100, the NEO content was reduced compared with the control. 75% and 051%。
However, the amount of SE50 increased by 2577%, and there is a significant improvement compared to SE5, an increase of 10361%。With the increase of Na2SEO3 concentration, the content of total glucosinolate showed a trend of SE50>SE25> SE200> SE0>SE100>SE10>SE5, which was also roughly consistent with the change trend of total indole glucosinolate content.
Compared to the control, the se50, se25, and se200 were increased, respectively. 78% and 562%。The SE100, SE10 and SE5 were reduced, respectively. 04% and 2353%。
In particular, the content of SE50 is 50 higher than that of SE598%。In terms of aliphatic glucosinolate content, 25 mg L-1 Na2SEO3 treatment worked best, while 50 mg L-1 Na2SEO3 treatment worked best in terms of indole and total glucosinolate content.
By detecting the serial dilutions of the standard on a high-performance liquid chromatograph, we found that when the retention time was 11At 67 minutes, the absorption peak appears. With the area of the absorption peak as the y-axis and the concentration of the standard as the x-axis, we established a regression equation: y=311173x+0.13604, the correlation coefficient is 09999, indicating a significant correlation between the concentration of the standard and the peak area.
Therefore, we can say that this chromatographic condition is credible. We determined the retention time of sulforaphane under this chromatographic condition at 1167 minutes. Then, we detected sulforaphane extract from broccoli by high performance liquid chromatography and found that,11At 67 minutes, an absorption peak was observed and the spectrum of this absorption peak was consistent with that of the standard.
Based on the regression equation, we can calculate the amount of sulforaphane in the sample.
After the gradual increase of Na2SEO3 concentration, the sulforaphane content in broccoli reached a peak in the SE50 treatment, which was increased by 4723%, an increase of 4380%。
Even under the treatment with the highest concentration of Na2SEO3 in Se200, there was no significant difference in sulforaphane content compared to Se50, and Se200 increased by 3811%, an increase of 34 compared to SE590%。
Therefore, both SE50 and SE200 treatments can significantly increase the sulforaphane content in broccoli.
The myrosinase activity in broccoli showed a decreasing trend with increasing Na2SEO3 concentrations, suggesting that excessive Na2SEO3 concentrations may lead to myrosinase inactivation.
The probable reason is that sulforaphane is related to the biosynthetic pathway of glucosinolate, because sulforaphane is a type of isothiocyanate, which is hydrolyzed by glucosinolate by myrosinase.
Sulforaphane is a common antioxidant and the most effective plant active found to be cancer-fighting to date. The control enzyme activity was the highest under different concentrations of Na2SEO3, and there were significant differences between the control and other treatments.
The control enzyme activity increased sequentially compared with the six treatments. 60% and 5334%。
Notably, the difference between high concentrations of Na2SEO3 treatments (Se25, Se50, Se100, and Se200) was not significant.
By comparing broccoli with treatment and control, we detected the synthesis and regulation of key genes in the glucosinolate synthesis pathway. The results showed that when we treated with SE25, the expression of the CYP79B2 gene increased significantly and even reached the highest value.
However, when we treated with SE5, the expression of the CYP79B2 gene, although decreased, did not reach a significant level.
The expressions of CYP83B1, CYP79F1, BCAT4, MAM1 and UGT74B1 decreased first and then increased, but the expressions of CYP83B1 and CYP79F1 decreased significantly under SE5 and SE25 treatments, showing inhibitory effect.
In contrast, although the expression levels of BCAT4, MAM1 and UGT74B1 were lower under selenium treatment, there was no significant difference in expression levels between different selenium treatments.
The expression of CYP83A1 showed a gradual downward trend and was significantly inhibited under SE5 or SE25 treatment. The expression of FMO2 was similar to that of CYP79B2, which was slightly reduced under SE5 treatment, but did not reach a significant level compared with the control, while SE25 treatment significantly up-regulated the expression of FMO2.
Through a single factor trial of 7 different selenium levels and 4 different sulfur levels, we came up with an optimal treatment for selenium and sulfur application. Flower bulbs were sprayed with selenium-containing fertilizers, bottom applied to sulfur-containing fertilizers, and samples were taken separately after broccoli flower bulbs were ripened, and various nutrients and active substances were determined, including VC, soluble protein, soluble sugars, polyphenols, total flavonoids, MDA, glucosinolates and sulforaphane content, as well as SOD and myrosinase activities.
We also tested the expression levels of key genes for glucosinolate synthesis to gain insight into the regulatory mechanism of broccoli glucosinolate synthesis after Na2SEO3 and K2SO4 treatments.
1.Broccoli treated with 10-25 mg L of Na2SEO3 could effectively improve its nutritional quality, aliphatic glucosinolate content and related gene expression.
2.The application of 150 g m2 of K2SO4 treatment not only improved the nutritional quality and antioxidant activity of broccoli, but also increased the content of glucosinolate, total glucosinolate and sulforaphane, and increased the expression of related genes.
Through the optimization of selenium-sulfur interactions, we found that the nutritional value of broccoli could be improved by using the S150 + SE25 treatment combination. The antioxidant capacity of broccoli can be enhanced by using the S150 + SE50 treatment combination; Treatment with S25 + SE50 increased the glucosinolate fraction, total glucosinolate, sulforaphane, and myrosinase activities of broccoli.