Effect of maleic hydrazide on peroxidase isoenzymes in relation to rooting hypocotyl cuttings ofPhaseolus mungo

A time course study of changes in the pattern of peroxidase isoenzymes shows that two new isoenzymesa andb appeared in hypocotyl cuttings cultured either in indolyl-3 acetic acid (IAA) + sucrose or in water but not in maleic hydrazide (MH). Roots were also initiated in the former two cases but not in the last case. That these isoenzymes may be associated with root initiation is also evident from the fact that these appeared when hypocotyl cuttings were transferred from MH to IAA + sucrose. The time of appearance of these isoenzymes in different cultures also synchronized with the time of microscopic root initiation. While the isoenzymea disappeared,b persisted in cuttings transferred from IAA + sucrose to MH. The number of roots produced on cuttings transferred to MH was very low, though their development was normal. It is suggested that isoenzymesa andb may be associated with root initiation andc andd with root development.     

DIFFERENTIAL RESPONSES OF PLANT FOLIAGE TO SIMULATED ACID RAIN

Experiments were performed to show the responses of foliage of several clones of Tradescantia sp., Pteridium aquilinum, Quercus palustris, and Glycine max to simulated acid rain. These experiments were performed to (a) predict the relative sensitivities of foliage of these plants to acid rain, and (b) identify leaf surface and anatomical alterations to simulated acid rain that may be used to diagnose acid rain injury. Plants were exposed to simulated rain at pH levels of 5.7, 3.4, 3.1, 2.9, 2.7, 2.5, and 2.3. Sporophyte leaves of bracken fern {P. aquilinum) were most sensitive to simulated acid rain among the species tested. About 10% of the surface area of older leaves of P. aquilinum was injured after exposure to 10 rainfalls at pH 2.5 (a single 20-min rainfall daily). Foliage of pin oak (Q. palustris) exhibited less than one-percent leaf area injury after exposure to simulated rain at pH 2.5 after 10 rainfalls (one 20-min rainfall daily). The responses of soybeans (G. max) and spiderwort (Tradescantia sp.) were intermediate between these two extremes. Histological observations show that lesion development results in collapsed leaf tissue in all four species. Gall formation that resulted from both cell hypertrophy and hyperplasia occurred in lesions of Tradescantia, and Q. palustris. Limited hyperplastic and hypertrophic reactions occurred in G. max foliage after exposure to simulated acid rain but no leaf galls resulted. Sporophyte foliage of P. aquilinum exhibited a “granular” type abnormality in the cytoplasm prior to the collapse of some epidermal cells injured by simulated rain. Injury occurred most frequently near vascular tissues and trichomes in all four species. In general, plant species that show cell hyperplasia and hypertrophy of leaf tissues after exposure to simulated acid rain are injured less than species that do not show these responses.     

Invasion by a Perennial Herb Increases Decomposition Rate and Alters Nutrient Availability in Warm Temperate Lowland Forest Remnants

We determined the impact of the invasive herb, Tradescantia fluminensis Vell., on litter decomposition and nutrient availability in a remnant of New Zealand lowland podocarp–broadleaf forest. Using litter bags, we found that litter beneath mats of Tradescantia decomposed at almost twice the rate of litter placed outside the mat. Values of k (decomposition quotient) were 9.44±0.42 yrs for litter placed beneath Tradescantia and 5.42±0.42 yrs for litter placed in native, non-Tradescantia plots. The impact of Tradescantia on decomposition was evident through the smaller forest floor mass in Tradescantia plots (2.65±1.05 t ha⁻¹) compared with non-Tradescantia plots (5.05±1.05 t ha⁻¹), despite similar quantities of annual leaf litterfall into Tradescantia plots (6.85±0.85 t ha⁻¹ yr⁻¹) and non-Tradescantia plots (7.45±1.05 t ha⁻¹ yr⁻¹). Moreover, there was increased plant nitrate available, as captured on resin bags, in Tradescantia plots (25.77 ± 8.32 cmol(−)/kg resin) compared with non-Tradescantia plots (9.55±3.72 cmol(−)/kg resin). Finally, the annual nutrient uptake by Tradescantia represented a large proportion of nutrients in litterfall (41% N, 61% P, 23% Ca, 46% Mg and 83% K), exceeded the nutrient content of the forest floor (except Ca), but was a small proportion of the topsoil nutrient pools. Taken together, our results show that Tradescantia increases litter decomposition and alters nutrient availability, effects that could influence the long-term viability of the majority of podocarp–broadleaf forest remnants affected with Tradescantia in New Zealand. These impacts are likely mostly due to Tradescantia's vegetation structure (i.e., tall, dense mats) and associated microclimate, compared with native ground covers. This revised version was published online in July 2006 with corrections to the Cover Date.     

Isolation of 24-epibrassinolide from leaves of <Emphasis Type="Italic">Aegle marmelos</Emphasis> and evaluation of its antigenotoxicity employing <Emphasis Type="Italic">Allium cepa</Emphasis> chromosomal aberration assay

Brassinosteroids are of universal occurrence in plants. They have been reported to affect plant growth and development through a spectrum of physiological responses. Recently they are reported to confer resistance in plants against a number of biotic and abiotic stresses. In the present study, a brassinosteroid was isolated from Aegle marmelos Correa. (Rutaceae) which was characterized to be 24-epibrassinolide (EBL) using various spectroscopic techniques (TLC and ESI-MS analysis). It was evaluated for the antigenotoxicity against maleic hydrazide (MH) induced genotoxicity in Allium cepa chromosomal aberration assay. It was shown that the percentage of chromosomal aberrations induced by maleic hydrazide (0.01%) declined significantly with 24-epibrassinolide treatment. EBL (10⁻⁷ M) proved to be the most effective concentration with 91.8% inhibition. This is the first report on the isolation of 24-epibrassinolide from Aegle marmelos and its antigenotoxic effects against MH employing Allium cepa chromosomal aberration assay.     

Uptake of maleic hydrazide and related compounds into willow. A comparison between molecular structure and biological activity

Summary A study has been made of a range of maleic hydrazide (MH) derivatives to compare their molecular structures with what has already been found concerning MH behaviour in willow (Salix viminalis L.). Use was made of two properties of MH, one of which was the ability to become concentrated into root apices of young willow roots (Coupland and Peel, 1971); the other was the ability of MH to inhibit the uptake of uracil into the sieve elements in bark strip material (Coupland and Peel, 1972). As a result of the present investigations it appears that an unsaturated heterocyclic ring system, including the grouping-CH=CH–CO–NH- is essential to retain the characteristics of the MH molecule.     

Estimation of mutagenicity and metabolic activation after recurrent exposures ofnicotiana tabacum L. var.xanthi to 14 pesticides

Recurrent application (17 administrations in 38 days) of 14 pesticides (Karathane FN 57, Fundazol 50 WP, Dithane M 45, Topsin M 70 WP, Perozin 75 B, Fademorf EK 20, Novozir MN 80, Metation E 50, Pirimor DP, Decemtion EK 20, Zeazin 50 DP, Fatex EK 80, maleic hydrazide and Ethrel) did not increase (with the exception of maleic hydrazide) the frequency of somatic mutations in a heterozygous chlorophyll mutant ofNicotiana tabacumL. var.xanthi n. c. None of the four tested pesticides (Fademorf EK 20, Decemtion EK 20, maleic hydrazide and Ethrel) were transformed in tobacco plants to a stable mutagenic or promutagenic product active in theSalmonella (Ames) mutagenicity assay.     

Tradescantia‐based models: a powerful looking glass for investigation of photoacclimation and photoadaptation in plants

Here, we summarize diverse evidence from species that belong to the genus Tradescantia, which we propose as handy and versatile models for studies of the ecology of photosynthesis and the mechanisms of photoacclimation in higher plants. A valuable feature of this genus is the amazingly broad range of ecological niches occupied by its species: from shady understory of tropical rainforest to deserts and semideserts. The former habitats demand shade tolerance (e.g. that featured by Tradescantia fluminensis), whereas the latter requires succulence and/or high light stress tolerance (evident in e.g. Tradescantia navicularis). At the same time, the acclimative traits of Tradescantia species seem quite moderate at first glance. Certainly, their basic principles of acclimation seem to differ in some aspects from the ones typical for most of other higher plants. This review presents a systematic analysis of irradiance responses of Tradescantia species studied on different timescales. The specifics of Tradescantia responses to irradiance make the plants of this genus a ‘multitool’ for studies in this field. Similarity of irradiance acclimation patterns is a characteristic feature in the ecologically contrasting Tradescantia species, which may inspire further insights into physiology and evolution of plants.     

Effects of ethidium bromide and nalidixic acid pretreatment on the induction of chromatid aberrations by TEM and maleic hydrazide in Vicia faba main root meristems

Pretreatment of Vicia faba main root meristems with ethidium bromide (EB) or nalidixic acid (NA) significantly reduced the yield of metaphases with chromatid aberrations induced by maleic hydrazide (MH), i.e., triggered clastogenic adaptation to MH. No such protection occurred when the alkylating agent triethylenemelamine (TEM) was used for challenge treatment. The differential response of pretreated cells to MH on the one hand (protection) and to TEM (no protection) on the other supports the conclusion that clastogenic adaptation is due to different inducible (repair?) functions, which eventually exert protection against clastogenic impacts.     

Genotoxic effects in <Emphasis Type="Italic">Tradescantia</Emphasis> plant (clone 2) induced by benzo(a)pyrene

This work surveys the genetic toxicity of benzo(a)pyrene added to soil for Tradescantia plants (clone 02). Different adaptation levels of Tradescantia (clone 02) to soil pollution with benzo(a)pyrene have been estimated. Plant adaptation was not observed at the morphological level, but found for the physiological and genetic (with every adaptation stage) levels. The products of benzo(a)pyrene metabolism act as auxin on plants influencing the growth of root biomass and the cell size.     

Studies on the Enzymatic Production of l-Aspartic Acid from Maleic Acid

The enzymatic production of l-aspartic acid from maleic acid with cell suspensions of Alcaligenes faecalis 5-24, isolated from solid by the authors, was investigated.

The optimum conditions of this reaction and some cultural conditions which influenced on the ability of the cells to catalyze the above reaction were mainly studied.

The cells grown on maleic acid as a sole source of carbon showed exclusively the strong ability. The cells grown on a carbon source other than maleic acid showed no activity of this reaction.

It was concluded that an inducibles enzyme whose formation was stimulated by the presence of maleic acid might be involved in the reaction for the production of l-aspartic acid from maleic acid.

It was found that malonic acid was replaceable for maleic acid which played an inductive role for the formation of the enzyme system concerned with the reaction of l-aspartic acid production from maleic acid.

The cells grown in the medium containing malonic acid showed a stronger activity of the above reaction than the cells grown on maleic acid. The induction effect of malonic acid was remarkable when the organism was cultured in an acid medium. Whereas, consumption of C¹⁴-malonic acid in the medium by the organism was not observed at all in any pH milieu even where the formation of the enzyme system essential for the reaction was fully conducted. It indicated that malonic acid penetrated preferentially in acid milieu into the cells was a non-metabolic inducer like thiomethyl-β-d-galactoside in β-galactosidase system and that permeability barrier might exist in the organism.

The formation of cis-trans isomerase which catalyzed the conversion of maleic acid to fumaric acid was much stimulated by the addition of either malonic acid or maleic acid. From these results, it was concluded that l-aspartic acid was produced from maleic acid and ammonium ion by both actions of the inducible cis-trans isomerase and the constitutive aspartase.     

Fruit-set of unpollinated ovaries of Pisum sativum L.

The influence of removing the apical shoot and different leaves above and below the flower on the fruit-set of unpollinated pea ovaries (Pisum sativum L. cv. Alaska) has been studied. Unpollinated ovaries were induced to set and develop either by topping or by removing certain developing leaves of the shoot. Topping had a maximum effect when carried out before or on the day of anthesis, and up to four consecutive ovaries were induced to set in the same plant. The inhibition of fruit-set was due to the developing leaves and not to the apex. The third leaf above the first flower, which had a simultaneous development to the ovary, had the stronger inhibitory effect on parthenocarpic fruit-set. The application of different plant-growth regulators (indoleacetic acid, naphthylacetic acid, 2,4-dichlorophenoxyacetic acid, gibberellic acid, benzyladenine and abscisic acid) did not mimic the negative effect of the shoot.Abbreviations CCC (2-chloroethyl)trimethylammonium chloride - MH maleic hydrazide - IAA indole-3-acetic acid - NAA 1-naphthaleneacetic acid - 2,4-D 2,4-dichlorophenoxyacetic acid - GA₃ gibberellic acid - 6-BAP benzyladenine - ABA abscisic acid     

Response of Tradescantia albiflora to growth irradiance: Change versus changeability

Most chloroplasts undergo changes in composition, function and structure in response to growth irradiance. However, Tradescantia albiflora, a facultative shade plant, is unable to modulate its light-harvesting components and has the same Chl a/Chl b ratios and number of functional PS II and PS I reaction centres on a Chl basis at all growth irradiances. With increasing growth irradiance, Tradescantia leaves have the same relative amount of chlorophyll—proteins of PS II and PS I, but increased xanthophyll cycle components and more zeaxanthin formation under high light. Despite high-light leaves having enhanced xanthophyll cycle content, all Tradescantia leaves acclimated to varying growth irradiances have similar non-photochemical quenching. These data strongly suggest that not all of the zeaxanthin formed under high light is necessarily non-covalently bound to major and minor light-harvesting proteins of both photosystems, but free zeaxanthin may be associated with LHC II and LHC I or located in the lipid bilayer. Under the unusual circumstances in light-acclimated Tradescantia where the numbers of functional PS II and PS I reaction centres and their antenna size are unaltered during growth under different irradiances, the extents of PS II photoinactivation by high irradiances are comparable. This is due to the extent of PS II photoinactivation being a light dosage effect that depends on the input (photon exposure, antenna size) and output (photosynthetic capacity, non-radiative dissipation) parameters, which in Tradescantia are not greatly varied by changes in growth irradiance.This revised version was published online in October 2005 with corrections to the Cover Date.     

Chromosomal damage induced by maleic hydrazide in mammalian cells in vitro and in vivo

The induction of sister-chromatid exchanges (SCE) and chromosomal aberrations (Ch.Ab.) by the herbicide maleic hydrazide (MH) has been investigated in Chinese hamster ovary (CHO) cells grown in vitro and in bone marrow cells of mice treated in vivo. MH induces SCE and Ch.Ab. in CHO cells without metabolic activation; however, no induction of SCE was found in the in vivo experiments.     

Similar degree of methyl methanesulphonate-induced DNA damage in two clones ofTradescantia differing in mutagenic sensitivity to alkylating agents

In two clones ofTradescantia (4430 and 02) differing in the sensitivity to the mutagenic action of alkylating agents, equimolar doses of [¹⁴C] methyl methanesulphonate (MMS) elicited a similar degree of protein, RNA and DNA alkylation and a similar amount of DNA-7-methylguanine and DNA-3-methyladenine in cells of inflorescence. Moreover, in the same clones and tissues the same doses of nonlabelled MMS produced a similar amount of DNA single strand breaks and/or alkali labile sites as measured in alkaline sucrose gradients. None of the DNA lesions followed is therefore decisive for explanation of the different mutagenic sensitivity ofTradescantia clones.     

o-Phenylenediamine-induced DNA damage and mutagenicity in tobacco seedlings is light-dependent.

Of the three isomers of the aromatic amine phenylenediamine (PDA), only o-PDA, but not m- and p-PDA, induced DNA damage (as measured by the Comet assay), and somatic mutations in the leaves of the chlorophyll-deficient tester strain Nicotiana tabacum var. xanthi. With increasing light intensity (0, 30, 80 or 140 micromol m(-2)s(-1) photosynthetic photon fluence rate) during a 72h mutagenic treatment of tobacco seedlings, o-PDA-induced DNA damage and the yield of somatic mutations were significantly increased. The peroxidase inhibitor diethyldithiocarbamate (DEDTC) repressed o-PDA-induced DNA damage. The effect of light is caused by the light-dependent increase of peroxidase activity and the accumulation of hydrogen peroxide, which participate in the metabolic activation of the promutagen o-PDA to mutagenic product(s). In contrast, DNA damage induced by the direct-acting alkylating mutagen ethyl methanesulphonate was the same whether treatment was in the light or in the dark, and was not repressed by the peroxidase inhibitor DEDTC.     

Promoting branching of a potential biofuel crop <Emphasis Type="Italic">Jatropha curcas</Emphasis> L. by foliar application of plant growth regulators

Jatropha curcas L. (Euphorbiaceae) has the potential to become a key biofuel crop. Manual pruning (MP) is one of the major management practices in commercial plantations of this crop, resulting in production of more branches and thus increased potential for more inflorescences leading to a higher seed yield. However, this method is time-consuming, labour-intensive and expensive. This study was conducted to determine the potential of different plant growth regulators (PGRs) to increase the number of lateral branches of J. curcas. A single foliar application of N ⁶-benzyladenine (BA) at 12 mM significantly increased branches in both the pot (4.0) and field (13.2) trials compared to MP (1.8 and 5.7, respectively) and control (no new branches) plants. In the field, a single foliar application of 1.0 mM 2,3,5-triiodobenzoic acid (TIBA) resulted in a significant increment in the number of branches (15.9) after 7 months. Of all the PGRs examined, 2,3:4,6-di-O-isopropylidene-2-keto-l-gluconic acid (dikegulac; DK) at 2.0 mM produced the maximum number of branches (18.0) in the field 7 months after application. Concentrations of 2.0 and 3.0 mM of 1,2-dihydro-3,6-pyridazinedione (maleic hydrazide; MH) significantly increased the number of branches, 4 and 7 months after spraying in both the pot trial in the shade house and field, respectively. Under field conditions, J. curcas plants responded better to all the PGRs (DK < TIBA < BA < MH) when treated once, with insignificant variations in other growth parameters. This study indicates that a single foliar application of PGRs under field conditions can be an alternative method to MP for increasing the number of lateral branches of J. curcas.     

Tradescantia management in a New Zealand National Park

The invasive plant species, Tradescantia fluminensis, first appeared in the Whakapohai Reserve in South Westland, New Zealand, during the 1960s, and by 2002, it had spread throughout the 43‐ha riparian reserve. It was presumed at high risk of spreading to neighbouring National Parks because of its ability to spread by floodwaters. A restoration project with the aim of eradicating Tradescantia in the reserve began in May 2002, at which time eight transects were established. The cover of Tradescantia was measured before control, and after on six subsequent occasions. The initial cover of Tradescantia was estimated to be about 17% of the entire reserve in 2002 and declined with annual control to <0.1% in 2011. The effects of this management regime on the forest community are described along with documentation of the costs and time put into achieving these outcomes.     

Tobacco-smoke exposure indicators and urinary mutagenicity

In this study, the correlation of indicators of external (i.e. mean daily intake of condensate, nicotine, tobacco and tobacco proteins, and daily number of cigarettes smoked) and of internal tobacco-smoke exposure (i.e. urinary 1-pyrenol, nicotine and its metabolites and trans,trans-muconic acid) with urinary mutagenicity, detected on YG1024 Salmonella typhimurium strain with S9, were examined in 118 smokers.An increase in urinary mutagenicity was clearly significantly correlated with each external and internal indicators of exposure to tobacco smoke (correlation coefficient (r) ranging between 0.22 and 0.54, P<0.01), with a greater extent in the case of indicators of internal dose. In multiple regression analysis, among the indicators of external exposure, daily tobacco intake was the only variable significantly associated with urinary mutagenicity (t=2.47, P=0.015, with partial contribution to r²=5.15%). Instead, when all indicators of exposure (external and internal) were considered in the analysis, the influence of urinary 1-pyrenol on urinary mutagenicity was predominant, followed by those of urinary trans,trans-muconic acid and nicotine plus metabolites (t=4.63, 2.73 and 2.08, P<0.001, P=0.002 and 0.04, with partial contribution to r²=17.0, 6.66 and 3.96%, respectively), with no influence at all of external tobacco-smoke exposure indicators.In conclusion, our results show that indicators of internal dose are better correlated with formation of mutagens in urine of smokers. Among these, the best indicator was urinary 1-pyrenol and this result designates the combustion processes of tobacco as the determining step for the formation of urinary mutagens. However, as these biomarkers cannot be analysed the amount of daily tobacco intake represent the best valuable index of external (presumptive) exposure to tobacco-smoke genotoxins.     

Maleic Acid Utilization by Mixed Cultures of Microorganisms

In a mixed batch culture, Alcaligenes xylosoxidans subsp. xylosoxidans 260 transformed maleic acid into malic acid. Bacillus subtilis 271 used malic acid as a substrate, thus stimulating further transformation of maleic acid. Both bacterial cultures dissociated with the formation of R, S, and M forms. At a concentration of 5.0 g/l, maleic acid was utilized maximally by RS and SS forms of the association A. xylosoxidans and B. subtilis. At concentrations 15.0 and 25.0 g/l, maleic acid was utilized maximally by SS and MS forms of the mixed culture, respectively. Association of bacteria A. xylosoxidans and B. subtilis was not stable under flow conditions of water.     

The effect of maleic hydrazide and exogenous DNA on chromosomes ofVicia faba

The mitotic activity of merstematic cells ofVicia faba, the frequency of chromosomal abnormalities and their interchromosomal distribution are evaluated in dependence on the concentration of maleic hydrazide (MH) and on the recovery period. The influence of exogenous DNA of different genetic origin on the course of repair of primary root cells damaged by MH was also studied. Isologous DNA which exhibited a strong repair effect in authors' previous experiments was quite ineffective in the case of maleic hydrazide. Heterologous DNA, on the other hand, had to some extent a parallel effect with MH in breaking down the structural integrity of chromosomes and increased the frequency of aberrations induced by maleic hydrazide in meristematic cells ofVicia faba.