Differential partitioning of thiols and glucosinolates between shoot and root in Chinese cabbage upon excess zinc exposure

Zinc (Zn) is one of the important elements of plant growth, however, at elevated level it is toxic. Exposure of Chinese cabbage to elevated Zn2+ concentrations (5 and 10 μM ZnCl2) resulted in enhancement of total sulfur and organic sulfur concentration. Transcript level of APS reductase (APR) as a key enzyme in biosynthesis of primary sulfur compounds (cysteine and thiols), was up-regulated in both shoot and root upon exposure to elevated Zn2+, which was accompanied by an increase in the concentration of cysteine in both tissues. In contrast, the concentration of thiols increased only in the root by 5.5 and 15-fold at 5 and 10 μM Zn2+, respectively, which was in accompanied by an upregulation of ATP sulfurylase, an enzyme responsible for activation of sulfate. An elevated content of glucosinolates, mostly indolic glucosinolates, only in the shoot of plants exposed to excess level of Zn2+ coincided with an increase in gene expression of key biosynthetic enzymes and regulators (CYP79B3, CYP83B1, MYB34). Thus distinct acuumulation patterns of sulfur containing compounds in root and shoot of Chinese cabbage may be a strategy for Chinese cabbage to combat with exposure to excess Zn

Sulfur metabolism in <i>Allium cepa</i> is hardly affected by chloride and sulfate salinity

Salinity as a major agricultural problem can affect crop growth and quality. Onion (Allium cepa L.) plant contains a wide variety of sulfur-containing compounds which may be involved in plant protection against salt stress. In the current study, a similar reduction in growth caused by chloride and sulfate salts was observed when onion was exposed to equimolar concentrations of Na+. Also, no difference was observed for shoot/root ratio and dry matter content of roots and shoots. Plants accumulated Na+ and the respective anions (chloride and sulfate) which in turn caused changes in the content of other nutrients. The content of potassium and calcium was decreased more than the other elements by both sodium salts. Sulfate salinity resulted in substantial increase in total sulfur and sulfate content but chloride salinity affected neither the total sulfur nor sulfate content of the roots and shoots, only in onion exposed to 200 mM chloride salt, those of roots and shoots were reduced. Furthermore, the water-soluble non-protein thiol content as well as the content of alliin remained rather unaffected. In conclusion, either salts affected the uptake and distribution of sulfate in onion, but had no or only a minor effect on the plant sulfur metabolism

Chloride and sulfate salinity differently affect biomass, mineral nutrient composition and expression of sulfate transport and assimilation genes in Brassica rapa

Background and aimsIt remains uncertain whether a higher toxicity of either NaCl or Na2SO4 in plants is due to an altered toxicity of sodium or a different toxicity of the anions. The aim of this study was to determine the contributions of sodium and the two anions to the different toxicities of chloride and sulfate salinity. The effects of the different salts on physiological parameters, mineral nutrient composition and expression of genes of sulfate transport and assimilation were studied. Methods Seedlings of Brassica rapa L. have been exposed to NaCl, Na2SO4, KCl and K2SO4 to assess the potential synergistic effect of the anions with the toxic cation sodium, as well as their separate toxicities if accompanied by the non-toxic cation potassium. Biomass production, stomatal resistance and Fv/fm were measured to determine differences in ionic and osmotic stress caused by the salts. Anion content (HPLC), mineral nutrient composition (ICP-AES) and gene expression of sulfate transporters and sulfur assimilatory enzymes (real-time qPCR) were analyzed. ResultsNa2SO4 impeded growth to a higher extent than NaCl and was the only salt to decrease Fv/fm. K2SO4 reduced plant growth more than NaCl. Analysis of mineral nutrient contents of plant tissue revealed that differences in sodium accumulation could not explain the increased toxicity of sulfate over chloride salts. Shoot contents of calcium, manganese and phosphorus were decreased more strongly by exposure to Na2SO4 than by NaCl. The expression levels of genes encoding proteins for sulfate transport and assimilation were differently affected by the different salts. While gene expression of primary sulfate uptake at roots was down-regulated upon exposure to sulfate salts, presumably to prevent an excessive uptake, genes encoding for the vacuolar sulfate transporter Sultr4;1 were upregulated. Gene expression of ATP sulfurylase was hardly affected by salinity in shoot and roots, the transcript level of 5′-adenylylsulfate reductase (APR) was decreased upon exposure to sulfate salts in roots. Sulfite reductase was decreased in the shoot by all salts similarly and remained unaffected in roots. Conclusions The higher toxicity of Na2SO4 over NaCl in B. rapa seemed to be due to an increased toxicity of sulfate over chloride, as indicated by the higher toxicity of K2SO4 over KCl. Thus, toxicity of sodium was not promoted by sulfate. The observed stronger negative effect on the tissue contents of calcium, manganese and phosphorus could contribute to the increased toxicity of sulfate over chloride. The upregulation of Sultr4;1 and 4;2 under sulfate salinity might lead to a detrimental efflux of stored sulfate from the vacuole into the cytosol and the chloroplasts. It remains unclear why expression of Sultr4;1 and 4;2 was upregulated. A possible explanation is a control of the gene expression of these transporters by the sulfate gradient across the tonoplast

Copper toxicity affects indolic glucosinolates and gene expression of key enzymes for their biosynthesis in Chinese cabbage

Excessive levels of Cu2+ are phytotoxic and exposure of Chinese cabbage to elevated Cu2+ concentrations led to reduction of the plant biomass. To get more insight into the role of glucosinolates upon copper stress, the impact of elevated Cu2+ levels on glucosinolates biosynthesis were studied in Chinese cabbage. The content of total glucosinolates was only elevated in the roots, mostly due to indolic and aromatic glucosinolates. The results showed a higher contribution of indolic glucosinolates, notably glucobrassicin, a 2- and 4-fold increase in Chinese cabbage exposed to 5 and 10 µM Cu2+, respectively. Furthermore, the increase in the indolic glucosinolates was accompanied by enhanced transcript levels of CYP79B2 and CYP83B1, two genes involved in biosynthesis of indolic glucosinolates, and that of the MYB51, a transcription factor involved in regulation of indolic glucosinolate biosynthesis pathway, at elevated Cu2+ concentrations. In addition, total sulfur and nitrogen remained unaffected in the root, but total glucosinolate was significantly enhanced upon exposure to elevated Cu2+. This result may show that relatively more sulfur and nitrogen was channeled into glucosinolates in the root. In conclusion, accumulation of indolic glucosinolates in the root can be considered as a strategy for Chinese cabbage to combat elevated Cu2+ concentrations

La regulación positiva de la expresión del gen Arl4a por acción del extracto acuoso de brócoli se asocia con una mejor espermatogénesis en los testículos de ratón

Introduction: Broccoli (Brassica oleracea) is well recognized due to its properties as an anti-cancer, antioxidant and scavenging free radicals. However, its benefit in enhancing spermatogenesis is not well understood. Objectives: To investigate the effect of broccoli aqueous extract on sperm factors and also expression of the involving genes (Catsper1, Catsper2, Arl4a, Sox5 and Sox9) in sperm factors in mice. Material and methods: Male mice were divided randomly into six groups: (1) Control, (2) Cadmium (3 mg/kg mouse body weight), (3) Orally treated with 200 broccoli aqueous extract (1 g ml-1), (4) Orally treated with 400 µl of broccoli aqueous extract, (5) Orally treated with 200 broccoli aqueous extract plus cadmium, and (6) Orally treated with 400 µl of broccoli aqueous extract plus cadmium. Sperms factors and also gene expression in Catsper1, Catsper2, Arl4a, Sox5 and Sox9 genes were studied. Results: An obvious improvement in sperm number and slight enhancement in sperm motility was observed in mice treated with broccoli extract with and without cadmium. While sperm viability was reduced by broccoli extract, except for 200 µl of broccoli extract with cadmium that was significantly increased. Interestingly, Arl4a gene expression showed an increase in 400 µl broccoli-treated group. Likewise, the Arl4a mRNA level in mice treated with cadmium along with 200 µl broccoli extract was higher than in cadmium-treated mice. Furthermore, broccoli extract enhanced the mRNA level of Catsper2 and Sox5 genes in mice treated with both 200 and 400 µl broccoli extract along with cadmium than the only cadmium-treated group. Conclusion: Generally, improvement in sperm count in broccoli-treated mice provides insight into the pharmaceutical industry to make new products available to infertile men

Atmospheric H2S and SO2 as sulfur source for Brassica juncea and Brassica rapa: impact on the glucosinolate composition

The impact of sulfate deprivation and atmospheric H2S and SO2 nutrition on the content and composition of glucosinolates was studied in Brassica juncea and B. rapa. Both species contained a number of aliphatic, aromatic and indolic glucosinolates. The total glucosinolate content was more than 5.5-fold higher in B. juncea than in B. rape, which could solely be attributed to the presence of high levels of sinigrin, which was absent in the latter species. Sulfate deprivation resulted in a strong decrease in the content and an altered composition of the glucosinolates of both species. Despite the differences in patterns in foliarly uptake and metabolism, their exposure hardly affected the glucosinolate composition of the shoot, both at sulfate-sufficient and sulfate deprived conditions. This indicated that the glucosinolate composition in the shoot was hardly affected by differences in sulfur source (viz., sulfate, sulfite and sulfide). Upon sulfate deprivation, where foliarly absorbed H2S and SO2 were the sole sulfur source for growth, the glucosinolate composition of roots differed from sulfate-sufficient B. juncea and a rapa, notably the fraction of the indolic glucosinolates was lower than that observed in sulfur-sufficient roots

Necrotrophic fungal infection affects indolic glucosinolate metabolism in <i>Brassica rapa</i>

Brassica species contains sulfur-containing secondary compounds including glucosinolates which might protect plants from pathogens. In the present investigation, the first leaves of Brassica rapa were grown in different situations such as sulfate-sufficient and deprived conditions, and infected with two types of fungi namely, Alternaria brassicicola and Botrytis cinerea as the specialist Brassica pathogen and generalist pathogen, respectively. The glucosinolates level was locally increased mainly due to indolic glucosinolates when the plant was infected with both fungi. This increase was in line with the increase in the expression of the genes including CYP79B2, CYP79B3, and CYP83B1 which are responsible for the biosynthesis of indolic glucosinolates and their regulation (MYB34 and MYB51). However, the locally induced indolic glucosinolates in plants infected with A. brassicicola were substantially higher than those of the plants infected with B. cinerea. The expression of the genes responsible for the biosynthesis of indolic glucosinolates was increased by infection of plant with A. brassicicola. The increase in the content of indolic glucosinolate occurred in the second leaf and roots, demonstrating a systemic response to fungal infection. Upon infection of plants with fungi, the content of both glucosinolates was reduced, while the expression of the most genes responsible for the biosynthesis of indolic glucosinolates was enhanced in plants infected with A. brassicicola. This may indicate that indolic glucosinolates are important in response to necrotrophic fungi in Brassica.</p