Reactions of chitosan: 5. The reaction of chitosan with 2,4-dinitrofluorobenzene and determination of the extent of the reaction

The reaction between chitosan and 2,4-dinitrofluorobenzene has been studied and suitable conditions established for hydrolysis of the product prior to determination of the extent of reaction by u.v./visible spectroscopy. The chromophore system in $\text{N-(2,4-}\text{dinitrophenyl}\text{)-2-}\text{amino}\text{-2-}\text{deoxy-}\text{d}\text{-glucose}$, the final product from the acid hydrolysis of N-(2,4-dinitrophenyl)chitosan, is unstable to heating in solution in either water or aqueous acid. The temperature of hydrolysis should therefore not exceed 50°C and at this temperature the u.v./visible absorption spectrum of $\text{N-(2,4-}\text{dinitrophenyl}\text{)-2-}\text{amino}\text{-2-}\text{deoxy-}\text{d}\text{-glucose}$ is constant for up to 50 h. Complete reaction of the amine groups is not achieved under heterogeneous or homogeneous conditions, only approximately 50% of the available amine groups undergoing reaction under homogeneous conditions. This restricted reactivity results from the bulky N-(2,4-dinitrophenyl) residues shielding adjacent unreacted amine groups on the same chain, thereby preventing their reaction with 2,4-dinitrofluorobenzene. Such intramolecular steric hindrance would be expected to increase with increase in the free amine group content of the sample, due to the increase in the fraction of amine groups occurring in sequence length of two or more, and an inverse relationship between the total initial free amine group content and the percentage of these that react with 2,4-dinitrofluorobenzene has been found     

Color reaction of cholesterol with trichloracetic acid and antimony trichloride. On the reaction mechanism

The color reaction of cholesterol with trichloracetic acid and antimony trichloride was examined to elucidate its reaction mechanism. 3,5-Cholestadiene, 3,3'bis(3,5-cholestadiene), 3,3'bis(2,4-cholestadiene), and cholesteryl trichloroacetate were isolated as the reaction products from the colored reaction mixture of cholesterol, and the first three compounds were found to be responsible for the coloration. It was assumed that cholesterol was dehydrated to 3,5-cholestadiene and 2,4-cholestadiene, which were dimerized to 3,3'-bis(3,5-cholestadiene) and 3,3'-bis(2,4-cholestadiene), respectively, and 3,3'-bis(2,4-cholestadiene) was in part converted to 3,3'-bis(3,5-cholestadiene) in trichloroacetic acid and antimony trichloride. The free radicals were detected in the colored solutions of choelsterol, 3,5-cholestadiene, 3,3'-bis(3,5-cholestadiene), and 3,3'-bis(2,4-cholestadiene), and inferred to be the radical cations of the steroids. The radical cation was postulated to be responsible with respect to the mechanism of the coloration. The relationship between the color reagent and the formation of dimeric steroids was described.     

Somatic embryogenesis and subsequent plant regeneration from inflorescence callus of Bambusa beecheyana Munro var. beecheyana

Somatic embryos of bamboo, Bambusa beecheyana Munro var. beecheyana were developed in callus derived from young florets and adventive roots obtained from floret callus. The medium was a modified Murashige and Skoog medium (1962) supplemented with 3 mg/l 2,4-dichlorophenoxyacetic acid, 2 mg/l kinetin, a high content of sucrose (6%) and 0.7% agar. The embryoids germinated spontaneously to yield whole plantlets on this medium with or without the hormonal adjuvants.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - IBA indole-3-butyric acid - NAA naphthaleneacetic acid - MS Murashige and Skoog's (1962) medium     

Aminations of guanosine and deoxyguanosine with hydroxylamine-O-sulfonic acid and 2,4-dinitrophenoxyamine. Dependence on the reaction medium

Amination of guanosine (Guo) with 2,4-dinitrophenoxyamine in aqueous DMF gave 7-amino-Guo, which was readily converted to 8,5'-O-cyclo-Guo, and 8-hydroxy-Guo. Deoxyguanosine (dG) gave only deglycosylated 7-amino-G under the same reaction condition. Aminations of Guo and dG with hydroxylamine-O-sulfonic acid above pH 9 gave the corresponding 1-amino derivatives, whereas those in acidic media at pH 2-4 gave 8-amino-Guo and 7-amino-G as the main products, respectively. Amination of Guo in neutral media gave 1-amino-Guo and decomposed products of 7-amino-Guo. The mechanisms of these amination reactions are described.     

On the mutagenic and recombinogenic activity of certain herbicides in Salmonella typhimurium and in Aspergillus nidulans

The plant growth-regulating hormones indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA), both strong recombinogens in Aspergillus nidulans, were tested in Salmonella typhimurium strains for his revertants at a range of concentrations from 1 to 2000 micrograms/plate with and without metabolic activation and were found negative. Also 3 herbicides of the chlorophenoxy group, 2,4-(dichlorophenoxy)acetic acid (2,4-D), 2,4-(dichlorophenoxy)butyric acid (2,4-DB) and 4-chloro-2-methylphenoxyacetic acid (MCPA), which show a plant growth hormone-like activity, and 2 of the triazine group, 2-ethylamino-4-chloro-6-isopropylamino-1,3,5-triazine (atrazine) and 2,4-bis(isopropylamino)6-chloro-1,3,5-triazine (propazine) were tested in S. typhimurium for point mutations and in A. nidulans for mitotic recombination. 2,4-D and MCPA were found to be weakly mutagenic at concentrations between 250 and 750 micrograms/plate in strain TA97a and only after metabolic activation and were recombinogens by inducing mainly mitotic crossing-over in A. nidulans at concentrations of 4-48 microM and 1500-3000 microM, respectively. 2,4-DB, atrazine and propazine were negative in both the Ames and the Aspergillus tests.     

Synthesis of 7-(2,4-dichlorophenyl)-D-erythro-3-hydroxy-5-heptanolide, 6-(2,4-dichlorophenyl)-D-erythro-2,4-dihydroxyhexane-1-sulfonic acid, and 6-(2,4-dichlorophenyl)-D-erythro-2,4-dihydroxyhexylphosphonic acid.

6-(2,4-Dichlorophenyl)-D-erythro-1,2,4-hexanetriol, synthesised from D-glucose, was partially silylated, then reacted with 2-methoxypropene to afford 1-O-tert-butyldimethylsilyl-6-(2,4- dichlorophenyl)-2,4-O-isopropylidene-D-erythro-1,2,4-hexanetriol (17). Desilylation of 17 gave 6-(2,4-dichlorophenyl)-2,4-O-isopropylidene-D- erythro-1,2,4-hexanetriol, which was converted into the 1-tosylate 18 and the 1-bromo derivative 19. Reaction of 18 with potassium thiolbenzoate gave, after debenzoylation, oxidation, and deprotection, 6-(2,4-dichlorophenyl)-D-erythro-2,4-dihydroxyhexane-1-sulfonic acid (4). Reaction of 18 or 19 with triethyl phosphite gave, after deprotection, 6-(2,4-dichlorophenyl)-D-erythro-2,4-dihydroxyhexyl-phosphonic acid (5), and reaction of 19 with potassium cyanide gave, after subsequent hydrolysis and deprotection, 7-(2,4-dichlorophenyl)-D-erythro-3-hydroxy-5-heptanolide (3).     

Characterization of (R/S)-mecoprop [2-(2-methyl-4-chlorophenoxy) propionic acid]-degrading Alcaligenes sp.CS1 and Ralstonia sp. CS2 isolated from agricultural soils

The herbicide mecoprop [2-(2-methyl-4-chlorophenoxy) propionic acid] is widely applied to corn fields in order to control broad-leaved weeds. However, it is often detected in groundwater where it can be a persistent contaminant. Two mecoprop-degrading bacterial strains were isolated from agricultural soils through their capability to degrade ( R/S )-mecoprop rapidly. 16S rDNA sequencing of the isolates demonstrated that one was closely related to the genera Alcaligenes sp. (designated CS1) and the other to Ralstonia sp. (designated CS2). Additionally, these isolates demonstrated ability to grow on other related herbicides, including 2,4- D (2,4-dichlorophenoxyacetic acid), MCPA [4-chloro-2-methyl phenoxy acetic acid] and ( R/S )-2,4-DP [2-(2,4-dichlorophenoxy)propionic acid] as sole carbon sources. tfdABC gene-specific probes derived from the 2,4- D -degrading Variovorax paradoxus TV1 were used in hybridization analyses to establish whether tfd -like genes are present in mecoprop-degrading bacteria. Hybridization analysis demonstrated that both Alcaligenes sp. CS1 and Ralstonia sp. CS2 harboured tfdA , tfdB and tfdC genes on plasmids that have approximately > 60% sequence similarity to the tfdA , tfdB and tfdC genes of V. paradoxus . It is therefore likely that tfd -like genes may be involved in the degradation of mecoprop, and we are currently investigating this further.     

Plantlets from somatic callus tissue of the woody legume Sesbania bispinosa (Jacq.) W. F. Wight

In vitro regeneration of plantlets and multiplication of Sesbania bispinosa (Jacq.) W.F. Wight plants from cultured callus tissue were demonstrated. Callus was established from both cotyledons and mature leaflets on Murashige and Skoog (MS) basal medium supplemented with BAP (0.5 mg/l) and 2,4-D (2 mg/l). Callus mediated shoot bud differentiation was studied under defined nutritional, hormonal and cultural conditions. Various concentrations of BAP or kinetin (Kn) with coconut milk (CM) in MS media induced different levels of shoot bud differentiation as well as multiplication. Multiple shoot bud differentiation occurred in most of the primary calli. The best medium for shoot bud differentiation from cotyledon derived callus, contained BAP (2 mg/l) and 15% CM (V/V). More efficient shoot bud organogenesis was recorded with BAP than Kn. Supplementation with CM in MS media accelerated shoot bud organogenesis in differentiating callus tissue. Rooting of differentiated shoots was achieved by a three step culture procedure involving (a) MS solid medium containing IBA (2 mg/l), (b) growth regulator free half strength MS medium with 1% charcoal, and (c) half strength MS liquid medium free of vitamins, growth regulators and charcoal.Abbreviations IAA indoleacetic acid - IBA indole-3-butyric acid - NAA naphthaleneacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - BAP 6-benzylaminopurine - Kn kinetin - CM coconut milk - MS Murashige and Skoog's medium - SBI shoot bud inducing medium     

Pyruvylated glycolipids from Mycobacterium smegmatis. Nature and location of the lipid components

The dipyruvylated glycolipid from Mycobacterium smegmatis (Saadat, S., and Ballou, C.E. (1983) J. Biol. Chem. 258, 1813-1818) has been shown to have the following structure in which FA1 is tetra- or hexadecanoic acid and FA2 is 2,4-dimethyl-2-eicosenoic acid. (formula; see text) The fast atom bombardment mass spectrum showed two major ions [M - H]- at m/z 1511 and 1539 (Mr 1512 and 1540) in a ratio of 1.4:1, suggesting that the glycolipid was a mixture of homologs that differed in fatty acid composition by 2 methylene groups. Analysis revealed C14, C16, and C22 fatty acids in ratios of 0.6:0.4:1.0, indicating that 60% of the molecules contained a C14 and C22 fatty acid whereas 40% contained a C16 and C22 fatty acid. The fragmentation pattern showed that a single glucose unit along with the smaller fatty acid could be lost to yield a tetrasaccharide with attached C22 fatty acid, and a second fragmentation yielded a trisaccharide containing 2 pyruvic acids but without attached fatty acid. The C14 and C16 fatty acids were identified as myristic and palmitic acid, whereas the C22 fatty acid was 2,4-dimethyl-2-eicosenoic acid. Precise localization of the fatty acids came from periodate oxidation and methylation analysis.     

Studies on plant growth-regulating substances XXVII. The growth-regulating activity and metabolism of 2,4-dichlorophenoxyethylamine and related compounds in higher plants

2-(2,4-Dichlorophenoxy)ethylamine (2,4-D ethylamine) was converted to 2,4-dichlorophenoxyacetaldehyde (2,4-D acetaldehyde) by extracts of pea cotyledons. The 2,4-D acetaldehyde was further converted to 2,4-dichloro-phenol and 2,4-dichlorophenoxyacetic acid (2,4-D). Under the same conditions, 2-(2,6-dichlorophenoxy)ethylamine was converted to 2,6-dichloro-phenoxyacetaldehyde and 2,6-dichlorophenol, although at a relatively slow rate. In pea stem segments and wheat coleoptiles the main products of 2,4-D ethylamine metabolism were 2,4-dichlorophenol, 2,4-D acetaldehyde and 2,4-D. In comparison with the wheat coleoptiles, larger amounts of these products were found in the pea stem segments. Metabolism of 2,4-D acetaldehyde gave 2-(2,4-dichlorophenoxy)ethanol (2,4-D ethanol) and 2,4-D in both pea and wheat tissues. Pretreatment with the amine oxidase inhibitor, 2-hydroxyethylhydrazine (HEH) completely prevented the extension of pea stem segments and substantially prevented the extension of wheat coleoptiles on subsequent treatment with 2,4-D ethylamine. No such protection was found against 2,4-D acetaldehyde or 2,4-D after pretreating the tissues with HEH. In pea, radish, and tomato plants, epinasty resulted from treatment with 2,4-D ethylamine, 2,4-D acetaldehyde and 2,4-D. Prior treatment with HEH prevented the epinasty due to the 2,4-D ethylamine, but no protection was given by HEH against 2,4-D acetaldehyde or 2,4-D.     

Inhibitory Effects of Turf Pesticides on Bacillus popilliae and the Prevalence of Milky Disease

Fourteen pesticides (fungicides, herbicides, and insecticides) were tested to determine whether they had deleterious effects on the bioinsecticide Bacillus popilliae, the causal agent of milky disease. All of these pesticides reduced levels of spore viability, spore germination, and/or vegetative cell growth when they were tested over a range of concentrations from 0 to 1,000 ppm of active ingredient, and the fungicides had the greatest detrimental effects. As determined by tests in water, the level of spore viability was significantly reduced by chlorothalonil, iprodione, (2,4-dichlorophenoxy)acetic acid plus 2-(2,4-dichlorophenoxy)propionic acid, and 2-[(4-chloro-o-tolyl)oxy]propionic acid plus (2,4-dichlorophenoxy)acetic acid. In tests performed with iprodione, loss of viability was evident at concentrations less than the concentration calculated to result from recommended use. Tests performed in soil demonstrated that triadimefon, chlorothalonil, (2,4-dichlorophenoxy)acetic acid plus 2-(2,4-dichlorophenoxy)propionic acid, and pendimethalin at concentrations resulting from recommended rates of application reduced spore titers. Spore germination did not occur in the continued presence of 2-[(4-chloro-otolyl)oxy]propionic acid plus (2,4-dichlorophenoxy)acetic acid, isofenphos, and chlordane, whereas exposure of spores to triadimefon or pendimethalin for 2 days stimulated germination. The tests to determine effects on spore germination were inconclusive for all other pesticides. Triadimefon, chlorothalonil, iprodione, pendimethalin, and chlorpyrifos at concentrations less than the concentrations recommended for use inhibited vegetative cell growth of B. popilliae, and chlordane at a concentration that was twice the concentration expected to result from the recommended rate of application repressed cell growth. My data support the hypothesis that use of synthetic pesticides can contribute to a low incidence of milky disease in white grubs.     

3-(2-hydroxyphenyl)catechol as substrate for proximal meta ring cleavage in dibenzofuran degradation by Brevibacterium sp. strain DPO 1361.

Brevibacterium sp. strain DPO 1361 oxygenates dibenzofuran in the unusual angular position. The 3-(2-hydroxyphenyl)catechol thus generated is subject to meta ring cleavage in the proximal position, yielding 2-hydroxy-6-(2-hydroxyphenyl)-6-oxo-2,4-hexadienoic acid, which is hydrolyzed to 2-oxo-4-pentenoate and salicylate by 2-hydroxy-6-oxo-6-phenyl-2,4-hexadienoic acid hydrolase. The proximal mode of ring cleavage is definitely established by isolation and unequivocal structural characterization of a cyclization product of 2-hydroxy-6-(2-hydroxyphenyl)-6-oxo-2,4-hexadienoic acid, i.e., 3-(chroman-4-on-2-yl)pyruvate.     

Induction of somatic embryos in cotyledonary tissue of soybean,Glycine max L. Merr

A method for the induction of somatic embryos in soybean tissue cultures is described. Cotyledons from immature embryos were utilized as explant source. Supplementing the culture medium with auxins (2,4-D, MCPA, 2,4,5-T, NAA, IAA, IBA) caused formation of meristematic tissue on cotyledon explants. The extent of meristematic tissue formed depended on the kind and concentration of auxin in the culture medium. With 2,4-D and MCPA, embryoids originated from meristematic tissue. Embryoid formation rates were influenced by the developmental stage of the embryos serving as explant source and auxin concentration. Addition of cytokinins to the medium containing 2,4-D or supplementing it with high sugar concentrations inhibited the formation of meristematic tissue and of embryoids on cotyledon explants.Abbreviations BA 6-benzyladenin - 2,4-D 2,4-dichlorphenoxyacetic acid - IAA indoleacetic acid - IBA indolebutyric acid - MCPA 2-methyl-4-chlorophenoxyacetic acid - NAA -naphthaleneacetic acid - 2,4,5-T 2,4,5-trichlorophenoxyacetic acid - L2 Phillips and Collins (1979) medium Present and correspondence address: Akademie der Landwirtschaftswissenschaften der DDR, Institut für Pflanzenernährung, DDR-6909, Jena     

Introduction of antigenic determining 2,4-dinitrophenyl residues into 4-thiouridine, N3-(3-L-amino-3-carboxypropyl) uridine and tRNA-Phe from E. coli.

The introduction of antigenic determining 2,4-dinitrophenyl residues into the rare ribonucleosides 4-thiouridine (1a), and N3-(3-L-amino-3-carboxypropyl) uridine (2) as well as into tRNA-Phe from E. coli has been investigated. Alkylation of 1a with omega-bromo-2,4-dinitroacetophenone (3b) gives S-(2,4-dinitrophenacyl)-4-thiouridine (5A). Applying the reaction to the 5'-monophosphate of 1a, 5b is formed, but this product decomposes at pH 7. However, acylation of 2 with 2,4-dinitrobenzoic acid N-hydroxysuccinimide ester (4b) leads to N3-[3-carboxy-3-L-(2,4-dinitrobenzamido)propyl]uridine (6) which is stable in aqueous solution. The latter reaction was used for the introduction of an antigenic determining 2,4-dinitrophenyl residue into tRNA-Phe from E. coli. The modified tRNA-Phe was isolated and by degradation of the molecule with RNase T2 and alkaline phosphatase the nucleoside derivative 6 was obtained and found to be identical with the synthetic product.     

Comamonas acidovorans strain MC1: a new isolate capable of degrading the chiral herbicides dichlorprop and mecoprop and the herbicides 2,4-D and MCPA

A gram-negative prototrophic bacterial species, strain MC1, was isolated from the vicinity of herbicide-contaminated building rubble and identified by 16S rDNA sequence analysis, its physiological properties, GC content, and fatty acid composition as Comamonas acidovorans. This strain displays activity for the productive degradation of the two enantiomers of dichlorprop [(RS)-2-(2,4-dichlorophenoxy-)propionate; (RS)-2,4-DP] and mecoprop [(RS)-2-(4-chloro-2-methyl-) phenoxypropionate; (RS)-MCPP] in addition phenoxyacetate herbicides, i.e. 2,4-dichlorophenoxyacetate (2,4-D) and 4-chloro-2-methylphenoxyacetate (MCPA), and various chlorophenols were utilized. Rates amounted to 1.2 mmoles/h g dry mass (2,4-D) and 2.7 mmoles/h g dry mass [(RS)-2,4-DP]. Degradation of (RS)-2,4-DP was not inhibited up to concentrations of 500 mg/l, nor of 2,4-D up to 200 mg/l. The optimum pH value of (RS)-2,4-DP degradation was around 8. The application of respective primers for PCR amplification revealed the presence of tfdB and tfdC genes.     

Plant regeneration from protoplasts of long-term callus cultures of Actinidia deliciosa var. deliciosa cv. Hayword (Kiwifruit)

Plant regeneration of Actinidia deliciosa var. deliciosa cv. Hayword was obtained from protoplasts isolated from petiole derived long-term callus cultures. Protoplasts were cultured in liquid medium over agarose gelled medium. Regenerated green callus, plated on solid medium, could develop shoots that rooted spontaneously in hormone-less medium. The plants obtained are growing fast in soil and present a normal phenotype.Abbreviations BAP benzylaminopurine - 2,4-D 2,4-dichlorophenoxyacetic acid - DTT dithiotreitol - IAA indole-3-acetic acid - IBA indole-3-butyric acid - Kin kinetin - MES 2-(N-morpholino) ethanesulphonic acid - MS Murashige and Skoog (1962) medium - NAA naphthalene-1-acetic acid - SH Schenk and Hildebrandt (1972) medium This Research was supported by JNICT and INIC     

Plant regeneration from in vitro cultures of anthers and mature seeds of rice (Oryza sativa L.) cv. Basmati-370

Pollen plants were obtained from anther-derived calli of the indica rice variety Basmati-370. Anther-response (anthers producing pollen derived calli) and plant regeneration frequency from the pollen derived calli. was very low. Donor plants which flowered at the average max/min. temperature of 34.2°/23.3°C gave a significantly higher anther-response to in vitro techniques, than did those which flowered at 29.1°/16.4°C. Somatic callus induction and subsequent plant regeneration was readily obtained from mature seed embryos. While 2,4-D or 2,4,5-T (1 or 2 mg/l) proved highly efficient for callus induction, tryptophan (50 or 100 mg/l) induced a high frequency of green plants from the calli.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - 2,4,5-T 2,4,5-trichlorophenoxyacetic acid - NAA naphthaleneacetic acid - IAA indoleacetic acid - K kinetin - BA benzyladenine - Trp tryptophan - CW coconut water     

Effect of growth regulators concentrations on morphological development of meristem-tips in Dioscorea cayenensis-D. rotundata complex and D. praehensilis

The use of the synthetic auxin 2,4-dichlorophenoxyacetic acid (2,4-d) has played an important role in the production and maintenance of totipotent cereal callus. However, 2,4-d has been implicated in the loss of totipotency from barley callus. To examine the effect of 2,4-d on barley callus, regenerability and karyotype were examined over time as influenced by cultivar differences and 2,4-d levels, during a period in which initially vigorous plant regeneration typically declines dramatically. Higher (20.4–27.1 M) versus lower (6.8–13.6 M) concentrations of 2,4-d were positively associated with the number of green plantlets recovered from calli maintained for 10 and 16 weeks before transfer to regeneration media, and with the longevity of regenerability. There was a positive relationship between 2,4-d concentration and normal karyotype. We also investigated the use of phenylacetic acid for the initiation of regenerable barley callus. Very poor callus growth and plant regeneration was supported by phenylacetic acid.Abbreviations PAA phenylacetic acid - SPDL(s) single plant-derived lines(s) - 2,4-d 2,4-dichlorophenoxyacetic acid - MS Murashige and Skoog (1962) - MSO Murashige and Skoog medium lacking growth regulators     

A reassessment of the binding of napthaleneacetic acid by membrane preparations from maize

Naphthalene-1-acetic acid (NAA) binding by membrane fractions derived from maize has been re-evaluated. Using a computer curve-fitting procedure only one major type of NAA binding, in terms of binding affinity, could be identified. Auxins, antiauxins and structurally related compounds have been tested for their competitive effect on NAA binding and the inhibitor constants for a number of these have been determined. Extracts from various plant species have been examined for their NAA binding ability, but all showed much less binding than maize leaf or coleoptile preparations. The possibility of the NAA binding by maize extracts being due to a true hormone receptor is discussed.Abbreviations BA benzoic acid - CPIB p-chlorophenoxyisobutyric acid - 2,4-D 2,4-dichlorophenoxyacetic acid - DCB 2,4-dichlorobenzoic acid - IAA indolyl-3-acetic acid - NAA napthalene-1-acetic acid - 2-NAA napthalene-2-acetic acid - NAOA napthalene-2-oxyacetic acid - PA phenylacetic acid - PU phenylurea - 2,4,5-T 2,4,5-trichlorophenoxyacetic acid - TIBA 2,3,5-triiodobenzoic acid     

Comparison of developmental stages of inflorescence for high frequency plant regeneration in Triticum aestivum L. and T. durum Desf.

Summary Whole immature inflorescences at 4 different developmental stages (0.5, 1.0, 1.5, 2.0 cm in size) of different genotypes of Triticum aestivum and T. durum were cultured to see the morphogenetic responses on Murashige and Skoog's (MS) medium supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D) (2.5 mg/l). Very young inflorescences 0.5 and 1.0cm long formed embryogenic callus from their entire surface while 1.5 and 2.0 cm long inflorescences formed embryogenic callus from the basal spikelets and rachis only. This embryogenic callus was maintained by regular subcultures on MS medium with 2,4-D (2.5 mg/l) for more than a year. Plantlets were regenerated by transferring the embryogenic callus on hormone-free MS medium. Inflorescences (0.5 and 1.0 cm long) responded best in forming callus as well as plantlets at a very high frequency. Variation in response was observed amongst the genotypes but the qualitative response of formation of embryogenic callus and later regeneration of plantlets was observed from all the genotypes. Immature young inflorescence explants could provide a suitable material for particle gun mediated genetic transformation in wheat.Abbreviations BAP 6-benzylaminopurine - 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indole-3-acetic acid - MS Murashige and Skoog (1962)