Immobilization of Low-Cost Alternative Vegetable Peroxidase (Raphanus sativus L. peroxidase): Choice of Support/Technique and Characterization.

In the present work the radish (Raphanus sativus L.) was used as the low-cost alternative source of peroxidase. The enzyme was immobilized in different supports: coconut fiber (CF), calcium alginate microspheres (CAMs) and silica SBA-15/albumin hybrid (HB). Physical adsorption (PA) and covalent binding (CB) as immobilization techniques were evaluated. Immobilized biocatalysts (IBs) obtained were physicochemical and morphologically characterized by SEM, FTIR and TGA. Also, optimum pH/temperature and operational stability were determined. For all supports, the immobilization by covalent binding provided the higher immobilization efficiencies-immobilization yield (IY%) of 89.99 ± 0.38% and 77.74 ± 0.42% for HB and CF, respectively. For CAMs the activity recovery (AR) was of 11.83 ± 0.68%. All IBs showed optimum pH at 6.0. Regarding optimum temperature of the biocatalysts, HB-CB and CAM-CB maintained the original optimum temperature of the free enzyme (40 °C). HB-CB showed higher operational stability, maintaining around 65% of the initial activity after four consecutive cycles. SEM, FTIR and TGA results suggest the enzyme presence on the IBs. Radish peroxidase immobilized on HB support by covalent binding is promising in future biotechnological applications.

Effects of selenium on antioxidant enzyme activity and bioaccessibility of arsenic in arsenic-stressed radish.

Consuming arsenic (As)-contaminated vegetables is the main route of As exposure in humans. The present study focused on the alterations in antioxidant enzymatic activities and As bioaccessibility in As-contaminated radish subjected to Se. Compared to the CK group, the total As content in raw radish was reduced by 27.5 ± 1.3%, and the bioaccessibility of As was reduced by 21.9 ± 2.3% in the 6 mg Se kg-1 treatment group. The total As content in the treatment groups decreased first but then increased with increasing Se application in raw radish, gastric (G) fraction and gastrointestinal (GI) fraction, while the antioxidant activity exhibited the opposite trend. The results revealed that a low amount of Se effectively blocks the accumulation of As in radish, improves the antioxidant activity in radish and reduces the bioaccessibility of As. These findings provide new ideas for effectively alleviating the spread of As to the human body through the food chain.

Identification and characterization of the glutathione S-Transferase (GST) family in radish reveals a likely role in anthocyanin biosynthesis and heavy metal stress tolerance.

Glutathione S-transferases (GSTs) are a large complex family of enzymes (EC 2.5.1.18) that play vital roles in flavonoid metabolism and plant growth and development and are responsive to heavy metal stress. However, knowledge about GST genes in radish (a vegetable crop with an extraordinary capacity to adapt to heavy metal stresses) is limited. Therefore, it is critical to identify putative candidate GST genes responsible for heavy metal stress tolerance and anthocyanin biosynthesis. In this study, we first identified 82 R. sativus GST (RsGST) genes using various bioinformatic approaches, and their expression profiles were characterized from RNAseq data. These RsGST genes could be grouped into 7 major subclasses: tau (43 members), phi (21 members), tetrachlorohydroquinone dehalogenase (7 members), dehydroascorbat reductase (5 members), zeta (3 members), lambda (2 members) and theta (1 member). In addition, most of the RsGST genes showed organ-specific expression in our study. Moreover, the transcripts of RsGSTF12-1 and RsGSTF12-2, belonging to the phi class, might be candidates encoding anthocyanin transporters in carmine radish, whereas the tau class, consisting of RsGSTU13-1, RsGSTU19, RsGSTU24-1, and RsGSTU3, and theta class, consisting of RsGSTT1-1, might be defend radish against adverse heavy metal stresses. These results will aid in understanding the functions of the GST family related to heavy metal stress and anthocyanin biosynthesis, thereby potentially improving radish breeding programs for high-pigment-content material as well as HM-tolerant material.

Bioinformatics Analysis of the Lipoxygenase Gene Family in Radish (Raphanus sativus) and Functional Characterization in Response to Abiotic and Biotic Stresses.

Lipoxygenases (LOXs) are non-heme iron-containing dioxygenases involved in many developmental and stress-responsive processes in plants. However, little is known about the radish LOX gene family members and their functions in response to biotic and abiotic stresses. In this study, we completed a genome-wide analysis and expression profiling of RsLOX genes under abiotic and biotic stress conditions. We identified 11 RsLOX genes, which encoded conserved domains, and classified them in 9-LOX and 13-LOX categories according to their phylogenetic relationships. The characteristic structural features of 9-LOX and 13-LOX genes and the encoded protein domains as well as their evolution are presented herein. A qRT-PCR analysis of RsLOX expression levels in the roots under simulated drought, salinity, heat, and cold stresses, as well as in response to a Plasmodiophora brassicae infection, revealed three tandem-clustered RsLOX genes that are involved in responses to various environmental stresses via the jasmonic acid pathway. Our findings provide insights into the evolution and potential biological roles of RsLOXs related to the adaptation of radish to stress conditions.

Purification of peroxidase enzyme from radish species in fast and high yield with affinity chromatography technique.

In this study, an effective single step affinity method is presented for purifying plant peroxidase (POD) enzymes from radish species. This method make possible to purify the enzymes in high yield and purity. Briefly, 10 different 4-amino benzohydrazide derivatives were synthesized and identified as new competitive POD inhibitors. Then, these derivatives were coupled to Sepharose 4B-L-Tyrosine support matrix by diazotization to form the affinity gels. Purification factors were recorded as 54.8% yield - 665-fold, 33.8% yield - 613-fold, 22.7% yield - 595-fold, 34.4% yield - 781-fold, 40.9% yield - 282-fold for turnip (T-POD), black radish (BR-POD), daikon (D-POD), sweet radish (SR-POD) and kohlrabi radish, (KR-POD), respectively. It has also been shown that the affinity gels, which prepared using the 4-amino 3-bromo benzohydrazide and 4-amino 2-nitro benzohydrazide molecules, capable to purify all radish species POD enzymes in high purity and yield.

Horseradish and radish peroxidases eaten with fish could help explain observed associations between fish consumption and protection from age-related dementia.

A juxtaposition of regional cuisines and recent prospective studies of fish consumption in China and Japan points to fresh horseradish and/or radish (HRR) as possible contributors to delaying age-related dementia. The hypothesis is that the inverse association found sometimes between fish intake and cognitive decline is partially due to exposure of the oral cavity to active peroxidases from HRR served in conjunction with fish. This hypothesis can be tested by specifically looking at whether HRR is consumed with fish and whether such HRR is prepared in a way that preserves activity of HRR peroxidases. It is possible that by putting active HRR peroxidases in their mouths, elderly people supplement their age-diminished salivary antioxidant capacity and break down additional hydrogen peroxide (H2O2) in the oral cavity before it can migrate into the brain, thus decreasing the incidence of brain cell death induction by chronically-elevated H2O2. Intentional exposure of the oral cavity to active HRR peroxidases could be a prophylactic for delaying dementia. Because vegetable peroxidases are inactivated by gastric juices, it will be difficult to obtain benefit from HRR peroxidases' antioxidant effect via ingestion in encapsulated dietary supplements.

Detection of Guaiacol Peroxidase on Electrophoretic Gels.

It is possible to analyze peroxidase (POD) from different vegetable sources by electrophoresis. Zymography, i.e., a SDS-PAGE method to detect enzyme activity, is used to specifically detect POD activity and to visualize the total protein profile. For this purpose, we describe how a radish homogenate is prepared and submitted first to electrophoresis, and then, the POD activity present in the gel is reactivated and selectively stained using guaiacol as substrate. After scanning the gel, the same gel is further stained with Coomassie blue to determine the whole protein profile of the sample.

A hierarchical assembly of flower-like hybrid Turkish black radish peroxidase-Cu2+ nanobiocatalyst and its effective use in dye decolorization.

Effective dye decolorization in wastewater still shows a big challenge. Although the biological methods, especially using enzymes, offer alternative and effective process for dye degradation and overcome the limitations of chemical and physical methods such as the instability, lack of reusability and high cost of free enzymes strictly, which limit their use in many scientific and technical applications. Enzymes rapidly lose their activities in aqueous solutions and against environmental changes due to their very susceptibility and unfavorable conformations. Herein, we report preparation of the enzyme-inorganic hybrid nanostructures with flower-like shape consisting of Turkish black radish peroxidase and Cu2+ metal ions using an encouraging enzyme immobilization approach. The peroxidase-Cu2+ hybrid nanoflowers (NFs) exhibited enhanced stability and activity towards various pH values and provided excellent dye decolorization efficiency for Victoria blue (VB) dye with more than 90% within 1 h. The NFs were also repeatedly used in efficient and caused 77% VB decolorization efficiency even at tenth cycles. However, to the best of our knowledge, for the first time, we prepared peroxidase enzyme isolated from Turkish black radish incorporated NFs and used them for dye decolorization. We believe that the NFs can be promising materials for dye decolorization in real wastewater treatment.

Growth inhibition and efficiency of the antioxidant system in spring barley and common radish grown on soil polluted ionic liquids with iodide anions.

Ionic liquids (ILs) constitute a huge group of substances that are increasingly common in the commercial use. This situation may lead to the contamination of the soil environment which being the basic of plants vegetation. This paper presents the effect of four ILs with I- anion on the growth and development of spring barley (Hordeum vulgare) and common radish (Raphanus sativus L. subvar. radicula Pers) and changes in metabolism of the plants. Seedlings of spring barley and common radish cultivated on soil with increasing ILs concentration exhibited typical phytotoxicity symptoms. A considerable reduction of shoot and root lengths, decrease of fresh weight (FW) and increase of dry weight (DW) occurred in both test plants. Ionic liquids concentration increase in soil was correlated with the decrease of concentrations of all photosynthetic pigments in the plants. The observed increase of malondialdehyde (MDA) concentration and changes in the H2O2 level indicated presence of oxidative stress in spring barley and common radish, which usually led to the increase of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) activity. The most reliable biomarker of oxidative stress was chlorophyll level and changes in POD activity.

A 2-Oxoglutarate-Dependent Dioxygenase Mediates the Biosynthesis of Glucoraphasatin in Radish.

Glucosinolates (GSLs) are secondary metabolites whose degradation products confer intrinsic flavors and aromas to Brassicaceae vegetables. Several structures of GSLs are known in the Brassicaceae, and the biosynthetic pathway and regulatory networks have been elucidated in Arabidopsis (Arabidopsis thaliana). GSLs are precursors of chemical defense substances against herbivorous pests. Specific GSLs can act as feeding blockers or stimulants, depending on the pest species. Natural selection has led to diversity in the GSL composition even within individual species. However, in radish (Raphanus sativus), glucoraphasatin (4-methylthio-3-butenyl glucosinolate) accounts for more than 90% of the total GSLs, and little compositional variation is observed. Because glucoraphasatin is not contained in other members of the Brassicaceae, like Arabidopsis and cabbage (Brassica oleracea), the biosynthetic pathways for glucoraphasatin remain unclear. In this report, we identified and characterized a gene encoding GLUCORAPHASATIN SYNTHASE 1 (GRS1) by genetic mapping using a mutant that genetically lacks glucoraphasatin. Transgenic Arabidopsis, which overexpressed GRS1 cDNA, accumulated glucoraphasatin in the leaves. GRS1 encodes a 2-oxoglutarate-dependent dioxygenase, and it is abundantly expressed in the leaf. To further investigate the biosynthesis and transportation of GSLs in radish, we grafted a grs1 plant onto a wild-type plant. The grafting experiment revealed a leaf-to-root long-distance glucoraphasatin transport system in radish and showed that the composition of GSLs differed among the organs. Based on these observations, we propose a characteristic biosynthesis pathway for glucoraphasatin in radish. Our results should be useful in metabolite engineering for breeding of high-value vegetables.

The Effects of Cadmium Exposure on Cadmium Fractionation and Enzyme Activities in the Rhizosphere of Two Radish Cultivars (Raphanus sativus L.).

The effects of increasing Cd additions on plant growth and Cd fractionation and enzyme activities in rhizosphere soil of two radish cultivars were investigated. The results showed that Cd concentrations in shoot and root of cultivar 4 were both higher than for cultivar 19 under different Cd levels. Compared with cultivar 19, the total, shoot and root biomasses of cultivar 4 were significantly reduced with increasing Cd levels. A decrease in soil pH was observed for cultivar 4. The exchangeable Cd concentration of soil from cultivar 4 was significantly higher than for soil from cultivar 19, while the carbonate-bound Cd concentration of soil from cultivar 4 was significantly lower than for cultivar 19. Enzyme activities, especially acid phosphatase activity, were more susceptible to Cd in soil from cultivar 4. These results indicated that cultivar 19 exhibits a stronger ability to adapt to Cd stress than cultivar 4.

Myrosinase Compatible Simultaneous Determination of Glucosinolates and Allyl Isothiocyanate by Capillary Electrophoresis Micellar Electrokinetic Chromatography (CE-MEKC).

INTRODUCTION: The functional food Cruciferous vegetables contain glucosinolates which are decomposed by the myrosinase enzyme upon tissue damage. The isothiocyanates are the most frequent decomposition products. Because of their various bioactivities, these compounds and the myrosinase is of high interest to many scientific fields. OBJECTIVE: Development of a capillary electrophoresis method capable of myrosinase-compatible, simultaneous quantification of glucosinolates and isothiocyanates. METHODS: Capillary electrochromatography parameters were optimised, followed by optimisation of a myrosinase-compatible derivatisation procedure for isothiocyanates. Vegetable extracts (Brussels sprouts, horseradish, radish and watercress) were tested for myrosinase activity, glucosinolate content and isothiocyanate conversion rate. Allyl isothiocyanate was quantified in some food products. RESULTS: The method allows quantification of sinigrin, gluonasturtiin and allyl isothiocyanate after myrosinase compatible derivatisation in-vial by mercaptoacetic acid. The chromatograhpic separation takes 2.5 min (short-end injection) or 15 min (long-end injection). For the tested vegetables, measured myrosinase activity was between 0.960-27.694 and 0.461-26.322 µmol/min/mg protein, glucosinolate content was between 0-2291.8 and 0-248.5 µg/g fresh weight for sinigrin and gluconastrutiin, respectively. The possible specificity of plants to different glucosinolates was also shown. Allyl isothiocyanate release rate was different in different vegetables (73.13 - 102.13%). The method could also be used for quantification of allyl isothiocyanate from food products. CONCLUSIONS: The presented capillary electrophoresis method requires a minimal amount of sample and contains only a few sample preparation steps, and can be used in several applications (glucosinolate determination, myrosinase activity measurement, isothiocyanate release estimation). Copyright © 2016 John Wiley & Sons, Ltd.

Oxidative stress in spring barley and common radish exposed to quaternary ammonium salts with hexafluorophosphate anion.

Quaternary ammonium salts (QAS), including ionic liquids (ILs), constitute a huge group of substances, which due to their desirable physical and chemical properties still attracts great interest in many industrial sectors. An increased concentration of this compound in the environment may lead to the contamination of the natural environment and may pose a potential threat to all organisms, including terrestrial higher plants. The present study demonstrates the interaction of three QAS with PF6(-) anions - tetramethylammonium [TMA][PF6], tetrabutylammonium [TBA][PF6], and tetrahexylammonium [THA][PF6] hexafluorophosphates - and its impact on the physiological and biochemical changes in spring barley seedlings and common radish plants. A similar study was also carried out by introducing the inorganic salt - ammonium hexafluorophosphate [A][PF6] to the soil; the results showed the soil became highly toxic to both plants. All the salts used led to significant changes in the metabolism of both spring barley and common radish which can be evidenced, for example, by a decrease in the content of chlorophyll a (Chla), chlorophyll b (Chlb), and total chlorophyll (Chla + b), as well as carotenoids (Car). The decrease in assimilation pigments was linearly correlated with an increasing concentration of QAS in the soil. QAS and [A][PF6] led to the formation of oxidative stress in both experimental plants, as evidenced by an increase in malondialdehyde (MDA) content in their cells and the changes in H2O2 level. In response to stress, the plants synthesized enzymatic free radicals (ROS) scavengers that lead to changes in the activity of superoxide dismutase (SOD) and catalase (CAT), as well as significantly increased peroxidase (POD) activity. A decrease in the content of assimilation pigments and an increased POD activity are the most reliable indices of oxidative stress, and concurrently the signs of premature plants aging. Common radish proved to be more resistant to the presence of QAS in the soil compared to spring barley.

Investigation of photo-assisted and crude peroxidase mediated transformations of chlorinated phenols (CPs) from spiked and industrial wastewaters: identification of reaction products.

This work focused on photo-assisted crude peroxidase mediated transformations of chlorinated phenols (CPs) from spiked and industrial wastewaters and the identification of reaction products formed. Garden radish Raphanus sativus was the source of crude peroxidase. No chlorine bearing compounds were detected by gas chromatography-high resolution mass spectrometry analysis. Under identical test conditions, the concentrations of 4-chlorophenol and 2,4-dichlorophenol were demoted to zero from 514 mg/L, 652 mg/L and that of 2,4,6-trichlorophenol and pentachlorophenol were reduced to 18 mg/L and 37 mg/L from 790 mg/L and 1066 mg/L, respectively (high-pressure liquid chromatography analysis). Chloride ion release profiles also showed a progressively increasing trend. A neat chemical oxygen demand removal to the extent of 63-79% was achieved in the case of spiked wastewater sample and to the extent of 77% for industrial wastewaters. A hypothesis reaction scheme was also suggested to comprehend the mechanism of degradation reactions.

Purification of active myrosinase from plants by aqueous two-phase counter-current chromatography.

INTRODUCTION: Myrosinase (thioglucoside glucohydrolase; E.C. 3.2.1.147), is a plant enzyme of increasing interest and importance to the biomedical community. Myrosinase catalyses the formation of isothiocyanates such as sulforaphane (from broccoli) and 4-(α-l-rhamnopyranosyloxy)benzyl isothiocyanate (from moringa), which are potent inducers of the cytoprotective phase-2 response in humans, by hydrolysis of their abundant glucosinolate (ß-thioglucoside N-hydroxysulphate) precursors. OBJECTIVE: To develop an aqueous two-phase counter-current chromatography (CCC) system for the rapid, three-step purification of catalytically active myrosinase. METHODS: A high-concentration potassium phosphate and polyethylene glycol biphasic aqueous two-phase system (ATPS) is used with a newly developed CCC configuration that utilises spiral-wound, flat-twisted tubing (with an ovoid cross-section). RESULTS: Making the initial crude plant extract directly in the ATPS and injecting only the lower phase permitted highly selective partitioning of the myrosinase complex before a short chromatography on a spiral disk CCC. Optimum phase retention and separation of myrosinase from other plant proteins afforded a 60-fold purification. CONCLUSION: Catalytically active myrosinase is purified from 3-day broccoli sprouts, 7-day daikon sprouts, mustard seeds and the leaves of field-grown moringa trees, in a CCC system that is predictably scalable.

Effect of detergents, trypsin, and bivalent metal ions on interfacial activation and functioning of phospholipase D.

The effects of detergents, trypsin, and bivalent metal ions on production of phosphatidic and lysophosphatidic acids by the action of phospholipase D (PLD) on lecithin and lysolecithin were studied. It was found that these reaction products and dodecyl sulfate ions activate PLD, whereas other anionic detergents are less effective. A protective effect of the functioning enzyme against its hydrolytic inactivation by trypsin was found. Bivalent metal ions can be arranged in the following sequence by their ability to activate PLD in the hydrolysis of lecithin and lysolecithin: Ca2+>Sr2+>Ba2+>Mg2+. These results are considered in relation to a proposed mechanism of activation and functioning of PLD with the participation of clusters of phosphatidates and lysophosphatidates. Such Me2+-induced formation of rafts or microdomains from the products of hydrolysis of phospholipids can rationalize not only PLD activation and self-regulation, but also the action of this mechanism on other components and properties of biomembranes. PLD and other lipolytic enzymes can be classified as lateral vector enzymes.

Single-step purification of peroxidase by 4-aminobenzohydrazide from Turkish blackradish and Turnip roots.

Peroxidases (PODs) were purified from the Turkish blackradish (Raphanus sativus L.) (TBR) and Turnip (Brassica rapa L.) using a simple and effective single-step method. An affinity resin was synthesised by coupling the 4-aminobenzohydrazide ligand and the l-tyrosine spacer-arm to CNBr-activated-Sepharose-4B. The purification factors for the TBR-POD and the Turnip-POD were 40.3-fold (with a yield of 10.6%) and 269.3-fold (with a yield of 9%), respectively. The molecular masses of the TBR-POD and Turnip-POD were approximately 67.3 and 65.8kDa, respectively. For guaiacol, the Km and Vmax values were calculated as 24.88mM and 3.23EU/mL, respectively for TBR-POD and as 4.09mM and 0.797EU/mL for the Turnip-POD. For H2O2, the Km and Vmax values were calculated as 3.247mM and 0.799EU/mL, respectively for TBR-POD, and as 12.49mM and 4.055EU/mL, respectively for the Turnip-POD. Furthermore, 4-aminobenzohydrazide was determined to be a non-competitive inhibitor of TBR-POD and Turnip-POD.

A vacuolar processing enzyme RsVPE1 gene of radish is involved in floral bud abortion under heat stress.

Radish floral bud abortion (FBA) is an adverse biological phenomenon that occurs during reproduction. Although FBA is a frequent occurrence, its molecular mechanism remains unknown. A transcript-derived fragment (TDF72), which was obtained by cDNA amplified fragment length polymorphism (cDNA-AFLP), was up-regulated in the aborted buds and exhibited 89% sequence homology with the AtγVPE gene. In this study, TDF72 was used to clarify the role of VPE in FBA by isolation of the VPE gene RsVPE1 from radish flower buds. The full-length genomic DNA was 2346 bp including nine exons and eight introns. The full-length cDNA was 1825 bp, containing a complete open reading frame (ORF) of 1470 bp, which encoded a predicted protein containing 489 amino acid residues, with a calculated molecular mass of 53.735 kDa. Expression analysis demonstrated that RsVPE1 was expressed in all tested organs of radish at different levels. Highest expression was detected in aborted flower buds, suggesting that RsVPE1 has a role in FBA. In order to analyze the role of RsVPE1 in FBA, RsVPE1 was overexpressed in transgenic Arabidopsis thaliana plants. Aborted flower buds appeared in transgenic plants subjected to heat stress. In addition, RsVPE1 expression in the transgenic plants reached a maximum when subjected to heat stress for 24 h and increased by 2.1-fold to 2.8-fold in three homozygous transgenic lines. These results indicated that RsVPE1 led to FBA when its expression levels exceeded a particular threshold, and provided evidence for the involvement of RsVPE1 in promoting FBA under heat stress.

Expression profiling of genes involved in ascorbate biosynthesis and recycling during fleshy root development in radish.

Ascorbate is a primary antioxidant and an essential enzyme cofactor in plants, which has an important effect on the development of plant root system. To investigate the molecular mechanisms of ascorbate accumulation during root development and reveal the key genes of the ascorbate biosynthesis and recycling pathways, the expression of 16 related genes together with ascorbate abundance were analyzed in the flesh and skin of radish (Raphanus sativus L.) fleshy root. The content of ascorbate decreased with root growth in both the flesh and skin. Expression of GDP-d-mannose pyrophosphorylase, GDP-d-mannose-3',5'-epimerase and d-galacturonate reductase were also decreased and correlated with ascorbate levels in the flesh. In the skin, the expression of GDP-d-mannose pyrophosphorylase and l-galactose dehydrogenase was correlated with ascorbate levels. These results suggested that ascorbate accumulation is affected mainly by biosynthesis rather than recycling in radish root, and the l-galactose pathway may be the major biosynthetic route of ascorbate, and moreover, the salvage pathway may also contribute to ascorbate accumulation. The data suggested that GDP-d-mannose pyrophosphorylase could play an important role in the regulation of ascorbate accumulation during radish fleshy taproot development.

ALS herbicide resistance mutations in Raphanus raphanistrum: evaluation of pleiotropic effects on vegetative growth and ALS activity.

BACKGROUND: Gene mutations that endow herbicide resistance may cause pleiotropic effects on plant ecology and physiology. This paper reports on the effect of a number of known and novel target-site resistance mutations of the ALS gene (Ala-122-Tyr, Pro-197-Ser, Asp-376-Glu or Trp-574-Leu) on vegetative growth traits of the weed Raphanus raphanistrum. RESULTS: The results from a series of experiments have indicated that none of these ALS resistance mutations imposes negative pleiotropic effects on relative growth rate (RGR), photosynthesis and resource-competitive ability in R. raphanistrum plants. The absence of pleiotropic effects on plant growth occurs in spite of increased (Ala-122-Tyr, Pro-197-Ser, Asp-376-Glu) and decreased (Trp-574-Leu) extractable ALS activity. CONCLUSION: The absence of detrimental pleiotropic effects on plant growth associated with the ALS target-site resistance mutations reported here is a contributing factor in resistance alleles being at relatively high frequencies in ALS-herbicide-unselected R. raphanistrum populations.