Application Of Brassinolide Research Articles

Effects of brassinolide application on cultured tobacco BY-2 amyloplast inducing system

Effects of brassinolide application on cultured tobacco BY-2 amyloplast inducing system

Performance of summer maize (Zea mays) under varying irrigation levels and agro-chemicals in sub-humid southern plains of Rajasthan

A field experiment was conducted during summer season of 2010 and 2011 at Rajasthan college of Agricul- ture, Udaipur, to evaluate the impact of irrigation levels and agro-chemicals on yield and water-use efficiency (WUE) of maize (Zea mays L.). The application of 8 irrigations significantly improved crop-growth rate (CGR) at 2550 days after sowing (DAS) and 5075 DAS, relative water and chlorophyll contents. The maximum grain weight/cob (63.6 g), cob length (15.9 cm), 1000-seed weight (176.9 g) and shelling% (76.7) were recorded with 8 irrigations. Similarly, application of 8 irrigations also resulted in significantly higher grain and stover yields, and the highest consumptive use (279.1 ha-mm) and water-use efficiency (9.52 kg/ha-mm). Among the agro-chemicals, application of brassinolide resulted in the maximum CGR at 2550 (7.06 g/m/day) and 5075 (19.5 g/m/day) DAS, respectively. Likewise, brassinolide also superior most with respect to all the yield attributes, yields and shelling % as compared to the other chemicals. Brassinolide application also resulted in the highest consumptive use (244.7 ha-mm) and water-use efficiency (9.35 kg/ha-mm) among all the agrochemicals.

Brassinosteroid-induced exaggerated growth in hydroponically grown Arabidopsis plants.

The effects of root application of brassinolide (BL) on the growth and development of Arabidopsis plants (Arabidopsis thaliana ecotype Columbia [L.] Heynh) were evaluated. Initially, all leaves were evaluated on plants 18, 22, 26 and 29 days old. The younger leaves were found to exhibit maximal petiole elongation and upward leaf bending in response to BL treatment. Therefore, based on these results leaves 6, 7 and 8 on 22-24-day-old plants were selected for all subsequent studies. Elongation along the length of the petiole in response to BL treatment was uniform with the exception of an approximately 4 mm region next to the leaf where upward curvature was observed. Both BL and 24-epibrassinolide (24-epiBL) were evaluated, with BL being more effective at lower concentrations than 24-epiBL. The exaggerated growth induced by 0.1 µM BL was not observed in plants treated with 1 000-fold higher concentrations of GA3, IAA, NAA or 2,4-D (100 µM). In addition, no exaggerated growth effects were observed when plants were treated with 200 ppm ethylene or 1 mM ACC. All treatments with BL, NAA, 2,4-D, IAA or ACC promoted ethylene and ACC production in wild type Arabidopsis plants, but only BL triggered exaggerated plant growth. BL also promoted exaggerated growth and elevated levels of ACC and ethylene in the ethylene insensitive mutant etr1-3, showing that the effect of BR on growth is independent of ethylene. This work provides evidence that BR-induced exaggerated growth of Arabidopsis plants is independent of gibberellins, auxins and ethylene.

A putative role for the tomato genes DUMPY and CURL-3 in brassinosteroid biosynthesis and response.

The dumpy (dpy) mutant of tomato (Lycopersicon esculentum Mill.) exhibits short stature, reduced axillary branching, and altered leaf morphology. Application of brassinolide and castasterone rescued the dpy phenotype, as did C-23-hydroxylated, 6-deoxo intermediates of brassinolide biosynthesis. The brassinolide precursors campesterol, campestanol, and 6-deoxocathasterone failed to rescue, suggesting that dpy may be affected in the conversion of 6-deoxocathasterone to 6-deoxoteasterone, similar to the Arabidopsis constitutive photomorphogenesis and dwarfism (cpd) mutant. Measurements of endogenous brassinosteroid levels by gas chromatography-mass spectrometry were consistent with this hypothesis. To examine brassinosteroid-regulated gene expression in dpy, we performed cDNA subtractive hybridization and isolated a novel xyloglucan endotransglycosylase that is regulated by brassinosteroid treatment. The curl-3 (cu-3) mutant (Lycopersicon pimpinellifolium ¿Jusl. Mill.) shows extreme dwarfism, altered leaf morphology, de-etiolation, and reduced fertility, all strikingly similar to the Arabidopsis mutant brassinosteroid insensitive 1 (bri1). Primary root elongation of wild-type L. pimpinellifolium seedlings was strongly inhibited by brassinosteroid application, while cu-3 mutant roots were able to elongate at the same brassinosteroid concentration. Moreover, cu-3 mutants retained sensitivity to indole-3-acetic acid, cytokinins, gibberellin, and abscisic acid while showing hypersensitivity to 2, 4-dichlorophenoxyacetic acid in the root elongation assay. The cu-3 root response to hormones, coupled with its bri1-like phenotype, suggests that cu-3 may also be brassinosteroid insensitive.

Application of brassinosteroid to Tabebuia alba (Bignoniaceae) plants

The objective of this study was to observe the effects of brassinosteroid, gibberelin, and auxin application on the development and foliar anatomy of Tabebuia alba (Cham.) Sandw. seedlings. T. alba seedlings were grown in plastic bags with fertilized soil and treated with the following: 1- water (control); 2- brassinolide (BR1) 0.104 mM; 3- BR1 0.208 mM; 4- 3-indoleacetic acid (IAA) 0.2854 mM; 5- IAA 0.5708 mM; 6- GA3 (gibberellin A3) 0.1443 mM; 7- GA3 0.2887 mM; 8- GA3 0.072 mM + IAA 0.1427 mM; 9- GA3 0.1443 mM + IAA 0.2854 mM; 10- GA3 0.072 mM + BR1 0.052 mM; and 11- GA3 0.1443 mM + BR1 0.104 mM. Plant height and petiole length were measured before the treatments and 21 days after application of the growth regulators. These data allowed the calculation of stem and petiole growth rates. The results showed that GA3 + brassinolide produced the highest stem and petiole growth rates and brassinolide application stimulated petiole growth but not stem growth. The anatomical study of leaves showed alterations in blade and petiole thickness, palisade and spongy parenchyma height, and epidermis cells.

Brassinosteroid/Sterol synthesis and plant growth as affected by lka and lkb mutations of Pea

The dwarf pea (Pisum sativum) mutants lka and lkb are brassinosteroid (BR) insensitive and deficient, respectively. The dwarf phenotype of the lkb mutant was rescued to wild type by exogenous application of brassinolide and its biosynthetic precursors. Gas chromatography-mass spectrometry analysis of the endogenous sterols in this mutant revealed that it accumulates 24-methylenecholesterol and isofucosterol but is deficient in their hydrogenated products, campesterol and sitosterol. Feeding experiments using 2H-labeled 24-methylenecholesterol indicated that the lkb mutant is unable to isomerize and/or reduce the Delta24(28) double bond. Dwarfism of the lkb mutant is, therefore, due to BR deficiency caused by blocked synthesis of campesterol from 24-methylenecholesterol. The lkb mutation also disrupted sterol composition of the membranes, which, in contrast to those of the wild type, contained isofucosterol as the major sterol and lacked stigmasterol. The lka mutant was not BR deficient, because it accumulated castasterone. Like some gibberellin-insensitive dwarf mutants, overproduction of castasterone in the lka mutant may be ascribed to the lack of a feedback control mechanism due to impaired perception/signal transduction of BRs. The possibility that castasterone is a biologically active BR is discussed.

The DWF4 gene of Arabidopsis encodes a cytochrome P450 that mediates multiple 22alpha-hydroxylation steps in brassinosteroid biosynthesis.

dwarf4 (dwf4) mutants of Arabidopsis display a dwarfed phenotype due to a lack of cell elongation. Dwarfism could be rescued by the application of brassinolide, suggesting that DWF4 plays a role in brassinosteroid (BR) biosynthesis. The DWF4 locus is defined by four mutant alleles. One of these is the result of a T-DNA insertion. Plant DNA flanking the insertion site was cloned and used as a probe to isolate the entire DWF4 gene. Sequence analysis revealed that DWF4 encodes a cytochrome P450 monooxygenase with 43% identity to the putative Arabidopsis steroid hydroxylating enzyme CONSTITUTIVE PHOTOMORPHOGENESIS AND DWARFISM. Sequence analysis of two other mutant alleles revealed deletions or a premature stop codon, confirming that DWF4 had been cloned. This sequence similarity suggests that DWF4 functions in specific hydroxylation steps during BR biosynthesis. In fact, feeding studies utilizing BR intermediates showed that only 22alpha-hydroxylated BRs rescued the dwf4 phenotype, confirming that DWF4 acts as a 22alpha-hydroxylase.

The Arabidopsis deetiolated2 mutant is blocked early in brassinosteroid biosynthesis.

The Arabidopsis DEETIOLATED2 (DET2) gene has been cloned and shown to encode a protein that shares significant sequence identity with mammalian steroid 5 alpha-reductases. Loss of DET2 function causes many defects in Arabidopsis development that can be rescued by the application of brassinolide; therefore, we propose that DET2 encodes a reductase that acts at the first step of the proposed biosynthetic pathway--in the conversion of campesterol to campestanol. Here, we used biochemical measurements and biological assays to determine the precise biochemical defect in det2 mutants. We show that DET2 actually acts at the second step in brassinolide biosynthesis in the 5 alpha-reduction of (24R)-24-methylcholest-4-en-3-one, which is further modified to form campestanol. In feeding experiments using 2H6-labeled campesterol, no significant level of 2H6-labeled campestanol was detected in det2, whereas the wild type accumulated substantial levels. Using gas chromatography-selected ion monitoring analysis, we show that several presumed null alleles of det2 accumulated only 8 to 15% of the wild-type levels of campestanol. Moreover, in det2 mutants, the endogenous levels of (24R)-24-methylcholest-4-en-3-one increased by threefold, whereas the levels of all other measured brassinosteroids accumulated to < 10% of wild-type levels. Exogenously applied biosynthetic intermediates of brassinolide were found to rescue both the dark- and light-grown defects of det2 mutants. Together, these results refine the original proposed pathway for brassinolide and indicate that mutations in DET2 block the second step in brassinosteroid biosynthesis. These results reinforce the utility of combining genetic and biochemical analyses to studies of biosynthetic pathways and strengthen the argument that brassinosteroids play an essential role in Arabidopsis development.

Characteristics of mulberry callus proliferated by the application of brassinolide and coumarin

Characteristics of mulberry callus proliferated by the application of brassinolide and coumarin

Brassinolide application to Lepidium sativum seeds and the effects on seedling growth

Brassinosteroids have been reported to accelerate plant growth when applied to seeds. We examined the effects of seed treatment with brassinolide on early growth of Lepidium sativum (cress). Submicromolar and micromolar concentrations of brassinolide inhibited root growth within 48 h after seed treatment. Germination of cress was not affected by brassinolide. The inhibition of cress root growth by brassinolide was time specific in terms of eliciting the response. Untreated germinated seeds transferred to filter paper moistened with brassinolide solution did not exhibit the same level of root inhibition as treated seeds. Brassinolide (2 μm) had no effect on ethylene levels, suggesting that at this concentration brassinolide is acting independently of ethylene to inhibit cress root elongation. Also, brassinolide had no effect on DNA synthesis within 24 h after seed treatment, but synthesis was reduced after 48 h. The results of this study illustrate a significant specific effect on very early cress root growth by seed treatment with brassinolide.