Effect of brassinosteroids on nucleic acids and protein content in cultured cells of Chlorella vulgaris (original) (raw)
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Plant Physiology and Biochemistry, 2014
Interaction between brassinosteroids (BRs) (brassinolide, BL; 28homobrassinolide, castasterone, CS; and adenine-(trans-zeatin, tZ; kinetin, Kin) as well as phenylurea-type (1,3-diphenylurea, DPU) cytokinins (CKs) in the regulation of cell number, phytohormone level and the content of chlorophyll, monosaccharide and protein in unicellular green alga Chlorella vulgaris (Trebouxiophyceae) were examined. Chlorella vulgaris exhibited sensitivity to CKs in the following order of their stimulating properties: 10 nM tZ > 100 nM Kin >1 mM DPU. Exogenously applied BRs possessed the highest biological activity in algal cells at concentration of 10 nM. Among the BRs, BL was characterized by the highest activity, while 28-homoCS -by the lowest. The considerable increase in the level of all endogenous BRs by 27e46% was observed in C. vulgaris culture treated with exogenous 10 nM tZ. It can be speculated that CKs may stimulate BR activity in C. vulgaris by inducing the accumulation of endogenous BRs. CKs interacted synergistically with BRs increasing the number of cells and endogenous accumulation of proteins, chlorophylls and monosaccharides in C. vulgaris. The highest stimulation of algal growth and the contents of analyzed biochemical parameters were observed for BL applied in combination with tZ, whereas the lowest in the culture treated with both 28-homoCS and DPU. However, regardless of the applied mixture of BRs with CKs, the considerable increase in cell number and the metabolite accumulation was found above the level obtained in cultures treated with any single phytohormone in unicellular green alga C. vulgaris.
Journal of Plant Physiology, 2009
The present study was undertaken to test the influence of exogenously applied 10 nM brassinolide (BL) on the abscisic acid (ABA) content in Chlorella vulgaris cultures subjected to short-term (3 h) heat stress (30-40 1C). We found that BL enhanced the ABA content with increase in temperature. In parallel, under these conditions treatment with BL resulted in growth levels very similar to those of control cell cultures (non-treated). BL had no significant effect on the content of chlorophyll or sugar in Chlorella vulgaris cells. Only a slight effect of BL on the protein content was observed. Under normal growth conditions (25 1C), BL showed a minor increase in the ABA content in Chlorella vulgaris cells. The present work also demonstrates that Chlorella vulgaris can synthesize ABA. This is the first evidence of ABA detection in Chlorella vulgaris cells.
Straightforward method for brassinosteroid detection in microalgae
Acta Physiologiae Plantarum/Acta physiologiae plantarum, 2024
Biostimulants, including phytohormones, are of high agricultural importance. Thus far, several methods have been developed for phytohormone detection/determination in microalgal cultures. Most of them require expensive, state-of-the-art machinery which often has limited availability in developing, agricultural countries. The main goal of our study was to develop a cheap and straightforward method for brassinosteroid determination in microalgal cultures. We used a Klebsormidium strain whose genus members have reportedly high brassinosteroid content. Using brassinolide standard, we compared the response of four different rice cultivars in a rice lamina inclination bioassay (RLIA), and from these found the variety 'Koshihikari' the most suitable one. A dynamic response over a broad concentration range from 0.001 to 0.1 mg/L brassinolide concentration was observed. Attempts with commonly used mechanical methods for disrupting Klebsormidium cells resulted in only negligible brassinolide release, while methanolic extraction liberated almost all cellular brassinosteroids. To overcome the negative effect of methanol on rice lamina inclination, solid-phase extraction was applied to get rid of methanol from the assay. The estimated brassinolide concentration in Klebsormidium culture by RLIA was validated using ultra-high performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS).
Brassinosteroids and lead as stimulators of phytochelatins synthesis in Chlorella vulgaris
Journal of Plant Physiology, 2002
The effect of brassinosteroids 10 -8 mol/L (BR) (brassinolide, BL; 24-epiBL; homoBL; castasterone, CS; 24-epiCS; homoCS) together with two levels of lead (10 -6 and 10 -4 mol/L) on the phytochelatins (PC) content of Chlorella vulgaris was studied. The BR and lead (10 -4 mol/L) showed a stronger stimulation of the synthesis of PC by the algal cell than the culture treated with lead alone. The effect of BR and lead on Chlorella vulgaris growth was very quick. The stimulatory activity of BR on PC synthesis was arranged in the following order: BL > 24-epiBL > homoBL > CS > 24-epiCS > homoCS.
Endogenous brassinosteroids in microalgae exposed to salt and low temperature stress
European Journal of Phycology, 2018
Brassinosteroids are part of the hormonal network that regulates growth processes and stress responses in plants. There is evidence for a similar hormonal network in microalgae. In the present study, six microalgae (Chlorococcum ellipsoideum, Gyoerffyana humicola, Nautococcus mamillatus, Acutodesmus acuminatus, Protococcus viridis and Chlorella vulgaris) were subjected to salt and low temperature stress with the addition of 36 g l-1 NaCl and transfer from 25°C to 15°C. There was a rapid response to salt stress with the brassinosteroid content (mainly castasterone with lower amounts of brassinolide, homocastasterone and typhasterol) increasing within 30 min of the salt treatment and remaining at these elevated levels after 7 h. The decrease in temperature had little effect on the brassinosteroid content. This was the first study to show that endogenous brassinosteroids increase in response to abiotic stress in a number of microalgae species.
Environmental and Experimental Botany, 2010
A concentration-dependent increase in activity of antioxidant enzymes (catalase, ascorbate peroxidase, glutathione reductase, ssuperoxide dismutase) and the level of total ascorbate and reduced glutathione have been observed in the green alga Chlorella vulgaris following heavy metals exposure. It was arranged in the following order: copper > lead > cadmium. It was also found that brassinolide activated enzymatic and non-enzymatic system in C. vulgaris cultures treated with heavy metals. Brassinolide plays an important role in plant responding to heavy metals' stress. It has an anti-stress effect on C. vulgaris contaminated by heavy metals.
Brassinosteroids play a significant role in the amelioration of various abiotic and biotic stresses. In order to elaborate their roles in plants subjected to heavy metals stress, Chlorella vulgaris cultures treated with 10 -8 M brassinolide (BL) were exposed to 10 -6 -10 -4 M heavy metals (cadmium, lead and copper) application. Under heavy metals stress, the growth and chemical composition (chlorophyll, monosaccharides, and protein content) have been decreased during the first 48 h of cultivation. The inhibitory effect of heavy metals on C. vulgaris cultures was arranged in the following order: copper [ lead [ cadmium. C. vulgaris cultures treated with BL in the absence or presence of heavy metals showed no differences in the endogenous level of BL. On the other hand, treatment with heavy metals results in BL level very similar to that of control cell cultures. These results suggest that the activation of brassinosteroids biosynthesis, via an increase of endogenous BL, is not essential for the growth and development of C. vulgaris cells in response to heavy metals stress. Simultaneously, BL enhanced the content of indole-3-acetic acid, zeatin, and abscisic acid in cultures treated with heavy metals. Levels per cell of chlorophylls, protein, and monosaccharides are all increased by BL treatment when compared to nontreated control cells. Application of BL to C. vulgaris cultures reduced the accumulation of heavy metals stress on growth, prevented chlorophyll, monosaccharides, and protein loss, and increased phytochelatins content. The arrested growth of C. vulgaris cells treated with heavy metals was restored by the coapplication of BL. It suggested that BL overcame the inhibitory effect of heavy metals. From these results, it can be concluded that BL plays the positive role in the alleviation of heavy metals stress.
Metabolism of Brassinolide in Suspension Cultured Cells of Phaseolus vulgaris
Brassinosteroids (BRs) are steroidal plant hormones which are involved in growth and development of plants. In many biological systems, brassinolide ) exhibits the highest biological activity among naturally-occurring BRs, 1-3 indicating that brassinolide is biologically active. Recently, two biosynthetic pathways to brassinolide, namely the early and late C-6 oxidation pathway, have been established in cultured cells of Catharanthus roseus. 4,5 These pathways seem to be ubiquitous in the plant kingdom because BRs belonging to these pathways have been observed in a variety of higher plants. Recently, various BR-deficient mutants were isolated and found to have defects in the BR or sterol biosynthesis. However, very little is known about the metabolism of brassinolide. We earlier demonstrated that brassinolide fed to mung bean explants was deactivated to its 23-O-β-glucoside. In explants and seedlings of rice, exogenously applied brassinolide was also metabolized to unknown polar metabolites that were water-soluble but non-glycosidic. Recently, it was demonstrated that 24-epimers of brassinolide and castasterone are converted to various metabolites and their conjugates in suspension cultured cells of tomato 13,14 and Ornithopus sativus. These findings prompted us to investigate the metabolism of brassinolide in cultured cells of Phaseolus vulgaris by feeding brassinolide as a substrate. The presence of brassinolide in P. vulgaris has been already demonstrated in the immature seed. The endogenous level of brassinolide in suspension cultured cells (100 g) of P. vulgaris was negligible. Thus, 95% ethanolic solution of brassinolide was supplied to the medium at 14 th day of culture. After incubation for 7 days, the cultured cells were harvested and extracted with 80% methanol. The aqueous residue obtained from the extracts was combined with the culture medium before being subjected to a column of ODS. The fractions eluted with 70, 80 and 90% methanol exhibited biological activity in the rice lamina inclination assay. These fractions were combined, and then purified by a Sephadex LH-20 column chromatography. The biologically active fractions with 0.65-0.75 of the elution volume/total volume (Ve/Vt) were combined, and purified further by reversed phase HPLC. No significant biological activity except biological activity due to unmetabolized brassinolide fractions 32-34 was detected. However, silica gel thin layer chromatography suggested that fraction 19 contained a BR because of the presence of a blue-purple fluorescent spot characteristic for BRs at R f 0.27. The compound in fraction 19 was derivatized into a bismethaneboronate (BMB) and analyzed by a capillary GC-MS.
Role of Brassinosteroids in Alleviating Various Abiotic and Biotic Stresses -A Review
Brassinosteroids (BRs) are a new class of plant hormones with significant growth-promoting influence. BRs were first isolated and characterized from the pollen of Brassica napus L. Subsequently they were reported from 44 plants (9 monocots, 28 dicots, 5 gymno-sperms, 1 pteridophyte and 1 alga) so far and are regarded probably ubiquitous in plant kingdom. BRs are considered as hormones with pleiotropic effects as they influence various developmental processes like growth, germination of seeds, rhizogenesis, flowering and senescence. BRs also confer resistance to plants against various abiotic stresses. The article reviews the work relating to their effect to alleviate various abiotic and biotic stresses.
Brassinosteroids roles and applications: an up-date
Brassinosteroids are plant steroidal compounds involved in many functions related with plant development, metabolism, signalling and defense against a wide range of biotic and abiotic stresses. Plant architecture, which has a major effect on crop yield, is strongly influenced by brassinosteroids action. Brassinosteroids are recognized as key regulators of plant growth and development involved in a broad spectrum of processes at the molecular, cellular, and physiological levels. These roles suggest that many of the constraints of present agricultural production might be alleviated by manipulation of genetic determinants dealing with brassinosteroids, as well as by its exogenous application. Brassinosteroids are natural, nontoxic, non-genotoxic, biosafe, and eco-friendly, and can therefore be used in agriculture and horticulture to improve the growth, yields, quality, and tolerance of various plants to biotic and abiotic stresses. The present paper comprehensively reviews the latest results in the field of brassinosteroids and envisages future impacts in agriculture.