A protocol for somatic embryogenesis in Azadirachta indica A Juss. has been standardized using in vivo leaflets. Experiments were carried out to examine the effect of various auxins, cytokinins, sucrose, inorganic and organic salts on subsequent somatic embryo induction and maturation. Embryogenic calli were induced on Murashige and Skoog (MS) medium supplemented with 1.5 mg dm^-3 kinetin and 1.5 mg dm^-3 indole-3-acetic acid and subsequently all the stages of somatic embryo development (globular, cordate, torpedo and cotyledonary) were observed. Maturation of these embryos was accomplished with the same growth regulators after three subcultures. The histological study of somatic embryos showed resembles to zygotic embryos. The matured somatic embryos were transferred onto half strength MS-medium devoid of growth regulators for their germination (82 %). Plantlets were acclimatized in the field with a survival rate of 80-83.5 %.

A highly efficient protocol for plant regeneration from cotyledonary node of two chickpea (Cicer arietinum L.) cultivars ICCV-10 and Annigeri used phenylacetic acid (PAA). The Murashige and Skoog (MS) medium supplemented with 2.0 mg dm^-3 6-benzylaminopurine (BAP) and 1.0 mg dm^-3 PAA was used for induction of bud formation. Buds were elongated on MS medium supplemented either with only 0.75 mg dm^-3 gibberellic acid (GA₃) or 0.2 mg dm^-3 GA₃ + 0.6 mg dm^-3 PAA. The elongated shoots were then transferred onto rooting medium containing 1 mg dm^-3 PAA. The frequency of multiple shoot induction and rooting was higher in Annigeri as compared to ICCV-10. The complete plantlets with well-developed roots were transferred to pots containing sterilized soil and sand in the ratio 3:1 where they survived (74 %) and set normal seeds.

The objective of this work was to test whether Ca²⁺, a second messenger in stress response, is involved in ABA-induced antioxidant enzyme activities in Stylosanthes guianensis. Plants were sprayed with abscisic acid (ABA), calcium channel blocker, LaCl₃, calcium chelator, ethylene glycol-bis(β-amino ethyl ether)-N,N,N', N'-tetraacetid acid (EGTA), and ABA in combination with LaCl₃ or EGTA. Their effects on superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities and chilling resistance were compared. The results showed that ABA decreased electrolyte leakage and lipid peroxidation but increased maximum photochemical efficiency measured as variable to maximum fluorescence ratio (F_v/F_m) under chilling stress. Treatment with LaCl₃ or EGTA alone and in combination with ABA increased electrolyte leakage and lipid peroxidation, decreased Fv/Fm, suggesting that the block in Ca²⁺ signalling decreased chilling resistance of S. guianensis and the ABA-enhanced chilling resistance. ABA-induced SOD and APX activities were suppressed by LaCl₃ or EGTA. The results suggested that Ca²⁺ is involved in the ABA-enhanced chilling resistance and the ABA-induced SOD and APX activities in S. guianensis.

Plant β-glucosidases catalyze the hydrolysis of glycosidic linkages and play a vital role in defense against pathogens and stress. The present work investigated the relationship between leaf development and β-glucosidase protein content in Olea europea L. (cv. Picual) leaves. The total chlorophyll content increased with leaf age in current-season leaves. Immunoblot analysis revealed that the content of 61 kD protein of β-glucosidase also increased with leaf age, and that the enzyme existed in three isoforms (pI 5.8-6.2). Statistical analysis indicated a strong correlation between chlorophyll and β-glucosidase protein contents.

Recent developments in knowledge about the interactions between lichens and heavy metals at different levels, from populations to cells and from ecology to molecular biology are reviewed. Sources of heavy metals, mechanisms of heavy metal accumulation and detoxification by lichens are discussed. Special emphasis is placed on ultrastructural changes as well as physiological parameters such as membrane integrity, pigment composition, chlorophyll a fluorescence, photosynthesis, respiration, contents of ATP, amino acids, ergosterol, ethylene, non-protein thiols, activity of antioxidant enzymes and expression of stress proteins.

Barley seedlings were pre-treated with 1 and 5 µM H₂O₂ for 2 d and then supplied with water or 150 mM NaCl for 4 and 7 d. Exogenous H₂O₂ alone had no effect on the proline, malondialdehyde (MDA) and H₂O₂ contents, decreased catalase (CAT) activity and had no effect on peroxidase (POX) activity. Three new superoxide dismutase (SOD) isoenzymes appeared in the leaves as a result of 1 µM H₂O₂ treatment. NaCl enhanced CAT and POX activity. SOD activity and isoenzyme patterns were changed due to H₂O₂ pre-treatment, NaCl stress and leaf ageing. In pre-treated seedlings the rate of ¹⁴CO₂ fixation was higher and MDA, H₂O₂ and proline contents were lower in comparison to the seedlings subjected directly to NaCl stress. Cl^- content in the leaves 4 and 7 d after NaCl supply increased considerably, but less in pre-treated plants. It was suggested that H₂O₂ metabolism is involved as a signal in the processes of barley salt tolerance.

We have investigated the effects of cadmium on the microtubular (MT) cytoskeleton in the root tip cells of Allium sativum L. using indirect immunofluorescence microscopy. Cd affected the mechanisms controlling the organization of MT cytoskeleton, as well as tubulin assembly/disassembly processes. Cd induced the formation of abnormal MT arrays, consisting of discontinuous wavy MTs or short MT fragments at the cell periphery. Cadmium caused irregular nuclear disorder in cells where the MT organization and function was disturbed. Furthermore, with increased Cd concentration and duration of treatment the MTs depolymerized more severely, the frequency of abnormal cell increased and the mitotic index decreased progressively. The above findings showed that MT cytoskeleton is one of target sites of Cd toxicity in root tip cells.

An experiment was conducted with two contrasting pigeon pea (Cajanus cajan L.) genotypes, ICPL 84023 (tolerant) and ICP 7035 (susceptible), to study the physiological and molecular basis of waterlogging tolerance in relation to oxidative stress and antioxidant enzyme activities. Waterlogging resulted in visible yellowing and premature senescence of leaves, and greater decline in relative water content, chlorophyll content, and membrane stability index in ICP 7035 than in ICPL 84023. Superoxide radical and hydrogen peroxide contents increased at day 4 and 6 of waterlogging probably due to activation of NADPH-oxidase. O₂ ^.- production was inhibited, by diphenylene iodonium chloride, a specific inhibitor of NADPH oxidase and expression of NADPH oxidase-mRNA was increased under waterlogging condition in ICPL 84023. ICP 7035 showed higher contents of ROS in control condition and after recovery, however, during waterlogging the O₂ ^.- production was higher in ICPL 84023. Activities of antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase and catalase increased under waterlogging more in ICPL 84023 than in ICP 7035. Cu/Zn-SOD and APX-mRNA expression in 24-h waterlogged plants showed enhanced expression in ICPL 84023 compared to ICP 7035. The cloning and sequencing of APX gene of tolerant and susceptible genotypes yielded cDNAs of 622 and 623 bp, having 95 % homology with each other and 92 % with the corresponding sequences of Vigna unguiculate APX-gene.

In this communication, we report the binding of abscisic acid responsive elements (ABREs) of rice Osem, namely motif A and motif B, with a cognate trans-acting factor present in the nuclear extract of tobacco leaf. The binding is specific as both the complexes were disrupted with an excess of homologous non-radioactive DNA like motif A or motif B themselves or with cis-elements of rice Rab16A, motif I (ABRE) and motif IIa (non-ACGT ABRE-like sequences). Four tandem repeats of ABRE from wheat Em (4X ABRE) or two tandem repeats of Em ABRE, plus two copies of coupling element (CE1) from barley HVA22 (2X ABRC), also showed specific complexes, that were competed out by an excess of homologous competitors like motif I, motif IIa, motif A, motif B, 4X ABRE and 2X ABRC, but not by the unrelated 4X DRE sequence. Elution of the protein from all the complexes showed a single 26 kDa polypeptide band. Introgression of two of the above synthetic promoters 4X ABRE and 2X ABRC, each fused with minimal promoter of cauliflower mosaic virus 35S (CaMV 35S), could induce the expression of the reporter gene β-glucuronidase (gus) in transgenic tobacco in response to high NaCl concentration, dehydration or abscisic acid, but not at the constitutive level, proving that they can be used as efficient stress-inducible promoters. Our work shows both in vivo and in vitro activity of the promoters from monocot genes in the model dicot plant tobacco.

Thalli of Xanthoparmelia somloensis with natural content of polyols (control) and polyol-free thalli (acetone-rinsed) were used to study ribitol effects at low temperatures. Thalli segments were cultivated in ribitol concentration of 32 or 50 mM for 168 h at temperatures +5, 0, and -5 °C. The chlorophyll fluorescence parameters (potential yield of photochemical reactions in PS 2 (variable to maximum fluorescence ratio, F_v/F_m), effective quantum yield of photochemical reactions in PS 2 (Φ_PS2), and non-photochemical quenching (NPQ) were monitored in 24-h intervals using an imaging system. The effect of 32 mM ribitol on F_v/F_m and Φ_PS2 was apparent only at -5 °C, however, the effect was seen throughout the whole exposure. Surprisingly, 50 mM ribitol concentration treatment led to a decrease in F_v/F_m and Φ_PS2 and to an increase in NPQ values at -5 °C, while no change was observed at 0 °C and +5 °C. Acetone-rinsing caused decrease of F_v/F_m, Φ_PS2 and NPQ.

To get deeper insight on the molecular mechanism underlying production of volatile compounds in apple (Malus domestica Borkh.), we performed the isolation and expression analysis of one R2R3-type MYB gene named MdMYBB. The amino acid sequence and the structural features of MdMYBB highly resembled those of PhODO1, which is a key regulator for floral scent biosynthesis in petunia. The expression of MdMYBB was repressed concomitantly with the inhibition of ethylene production, which regulates the volatile synthesis in apple. However, MdMYBB expression was not detected in the flesh from nearly ripened apple fruits, although the detection of exogenous volatiles had actually occurred in the same portion. In addition, overexpression of MdMYBB did not cause any induction of the volatile compounds in the transgenic tobacco lines. Thus, the features of MdMYBB were not in accordance with the aroma volatile emission, unlike the case of PhODO1, suggesting that MdMYBB may not be involved in the regulation of the biosynthesis for apple aroma volatiles. On the basis of the specific expression patterns, we discussed possible physiological roles of MdMYBB in apple.

Tobacco (Nicotiana tabacum L.) plants were cultured in vitro photoautotrophically at three levels of irradiance (PAR 400-700 nm): low (LI, 60 µmol m^-2 s^-1), middle (MI, 180 µmol m^-2 s^-1) and high (HI, 270 µmol m^-2 s^-1). Anatomy of the fourth leaf from bottom was followed during leaf development. In HI and MI plants, leaf area expansion started earlier as compared to LI plants, and both HI and MI plants developed some adaptations of sun species: leaves were thicker with higher proportion of palisade parenchyma to spongy parenchyma tissue. Furthermore, in HI and MI plants palisade and spongy parenchyma cells were larger and relative abundance of chloroplasts in parenchyma cells measured as chloroplasts cross-sectional area in the cell was lower than in LI plants. During leaf growth, chloroplasts crosssectional area in both palisade and spongy parenchyma cells in all treatments considerably decreased and finally it occupied only about 5 to 8 % of the cell cross-sectional area. Thus, leaf anatomy of photoautotrophically in vitro cultured plants showed a similar response to growth irradiance as in vivo grown plants, however, the formation of chloroplasts and therefore of photosynthetic apparatus was strongly impaired.

A glutathione S-transferase (GST) gene cloned from the lepidopteran spruce budworm, Choristoneura fumiferana Clem. was transformed into the model plant Arabidopsis thaliana. The CfGST-transgenic and wild-type A. thaliana were subjected to 4 and 10 °C for 48 h and their cold resistance was studied. The GST activity of the transgenic plants was 46.6 and 35.7 % higher than that of the wild-type plants after 48 h under 4 and 10 °C, respectively. Relative membrane permeability and malondialdehyde content in the transgenic plants were lower while contents of the chlorophyll and proline were higher than those in the wild-type plants under 4 and 10 °C. The survival rate of the transgenic plants was 43.7 % for 24 h under 0 °C, while survival rate of wild-type plants was 28.3 %. The results indicated that the insect GST could enhance cold resistance in the transgenic A. thaliana.

There are significant changes in the structure of the upper tobacco (Nicotiana tabacum L.) leaves systemically infected with tobacco mosaic virus (TMV) especially in the light green tissue (LGT). Dark green areas (DGI) had intermediate status between healthy tissue and LGT. DGI contained significantly less infectious TMV and viral antigen than the LGT. The DGI, LGT and healthy tissues did not differ in the permeability of cell membranes and in the set of acidic pathogenesis-related (PR) proteins but the total content of PR-proteins in the healthy plants was higher than in the infected ones with the DGI being intermediate between healthy tissue and LGT. The crude leaf extracts from DGI and LGT showed less total ribonuclease activity and ribonuclease isozymes in comparison with control.

Studies on cadmium effects in the root meristematic cells of Allium sativum L. were carried out using electron microscopy in order to explain the possible mechanisms of garlic seedlings' tolerance to Cd stress. Seedlings were treated with 0.01, 0.10 and 1.00 mM CdCl₂ solutions for 0.5, 1, 2, 4, 8, 10, 12, 24 and 48 h, respectively. The results indicated that cell walls, plasma membrane and main organelles actively participated in Cd detoxification and tolerance at low Cd concentrations. Once excessive Cd ions entered the cytosol, a defence mechanism becomes activated, protecting the cells against cadmium toxicity. However, under high Cd content in cells, the cell structure was damaged, even leading to cells death.

5-Methyltryptophan (5MT), a tryptophan analog, resistant M4 rice mutants with high free amino acid contents were obtained through in vitro mutagenesis. To evaluate the 5MT resistance mechanism, a cDNA library was constructed by using the leaves and roots of the 5MT resistant mutant plants. Expressed sequenced tags (ESTs) of 1 019 randomly selected clones were analyzed and then assembled 588 unigens. A total of 389 unigenes had significant homologies with known protein sequences at the NCBI database and the remaining 199 unigenes were designated unidentified genes. These unigens were grouped into 13 categories according to their putative functions. Of the 233 randomly selected clones, 25 were identified as differentially expressed genes between 5MT resistant and 5MT sensitive wild type plants. For further study of the differential expression of the genes, expression patterns of 12 genes related to various biological functions were evaluated in response to 5MT treatment in both the resistant plants and sensitive plants. All of the tested 12 genes exhibited higher expression levels in mutant plants than wild type plants under the 5MT inhibition. These expression patterns of the 12 genes suggested that the genes related to 5MT resistance in the rice mutants have a variety of functions, and yield remarkably diverse expression patterns upon 5MT treatment. Many genes that were identified tend to be related to defense and stress responses, suggesting "cross-talking" between biotic/abiotic stresses including the 5MT treatment. Therefore, 5MT resistant mutants might be of value for identifying genes related to plant defenses and stresses.

Endogenous contents of indolyl-3-acetic acid (IAA) and abscisic acid (ABA) were quantified in excised roots of Catasetum fimbriatum (Orchidaceae) cultured in vitro on solidified Vacin and Went medium with 1, 2, 4, 6, 8 and 10 % sucrose, as well as 2 % sucrose plus mannitol. Maximum root growth was observed in media with 4 % sucrose and 2 % sucrose plus 2.2 % mannitol, suggesting that a moderate water or osmotic stress promotes orchid root growth. Contents of both ABA and IAA increased in parallel to increasing sucrose concentration and a correlation between root elongation and the ABA/IAA ratio was observed. Incubating isolated C. fimbriatum roots with radiolabeled tryptophan, we showed an accumulation of IAA and its conjugates.

AP2 (APETALA2)/EREBPs (ethylene responsive element binding proteins) are the primary members of a family of transcription factors and OsAP211 was isolated from Oryza sativa L using the yeast one-hybrid system. It can specifically bind to the promoter containing three tandem repeats of DRE core sequence: TACCGACAT and activate the transcription of the downstream lacZ gene in the yeast one-hybrid system. OsAP211 contained a single open reading frame of 225 amino acids and encoded a protein containing a conserved AP2/EREBP domain featuring the DREB family. The semi-quantitative RT-PCR (s-Q RT-PCR) analysis indicated OsAP211 was strongly induced by low temperatures but not by NaCl and drought. It accumulates primarily in shoot tips during the tillering stage and young spikes during the booting stage. OsAP211 might function as a DRE-binding transcription factor in stress signal transduction pathways in rice.

A simple and reliable regeneration system from leaf bases of barley (Hordeum vulgare L.) has been developed. The in vitro regeneration frequencies of seven commercial barley genotypes were compared using segments from the first leaves of 5-d-old seedlings. The regeneration frequency ranged from 31.56 to 72.22 % among the barley genotypes. Murashige and Skoog medium supplemented with 6-benzyladenine (0.5 mg dm^-3) and kinetin (0.5 mg dm^-3) was optimum for the regeneration. Longitudinal cut of the segments or the removal of coleoptiles further increased plantlet regeneration frequency.

In 7-d-old seedlings of Brassica juncea chromium (VI) promoted photosystem 2 (PS 2) mediated photoreactions. The increase in PS 2 activity in the thylakoids from Cr-treated seedlings, in the presence of uncoupler (5 mM NH₄Cl), was similar to that recorded with the control thylakoids. Thus Cr enhanced PS 2 activity was not due to uncoupling of electron transport from photophosphorylation. Photon saturation kinetics revealed that the PS 2 activity of thylakoids from Cr-treated seedlings was significantly higher at almost all irradiances in comparison to that of controls. PS 2 activity of thylakoids from Cr-treated plants at 25 % of the saturating irradiance was in par with the PS 2 activity of the thylakoids from control plants at saturating irradiance. Thylakoids from both control and Cr-treated seedlings exhibited maximum PS 2 activity at pH 7.5. The PS 2 activity of thylakoids from Cr-treated plants remained high even at pH 8.0 and 8.5, demonstrating Cr enhances tolerance of PS 2 to alkaline pH.

Forty one simple sequence repeats were isolated from two microsatellite enriched libraries of date palm (Phoenix dactylifera L.). After screening, 17 selected microsatellite loci were characterized and evaluated on a set of 31 cultivars and clones from Algerian and Californian germplasm. All primer pairs produced an amplification product of the expected size and detected high polymorphism among the analysed samples. These nuclear simple sequence repeat (SSR) markers are expected to be a very effective tool for evaluating genetic diversity in date palm germplasm. Acrosstaxa amplification showed the usefulness of most SSR markers in 14 other species across the genus Phoenix.

In order to better understand the role of cold acclimation in alleviating freezing injury, two barley cultivars with different cold tolerance, i.e. a sensitive cv. Chumai 1 and a tolerant cv. Mo 103, were used. The freezing treatment increased leaf soluble protein content more in the tolerant cultivar than in the sensitive one. Cold acclimation increased H₂O₂ content of the two cultivars during freezing treatment, especially in Mo 103. Glutathione and ascorbate contents during freezing and recovery were significantly higher in cold-acclimated plants than in non-acclimated ones. Activities of peroxidase, ascorbate peroxidase and glutathione reductase were also higher in cold-acclimated plants than non-acclimated plants during freezing treatment. However, there was no significant difference between cold-acclimated plants and the control plants in catalase activity. It may be assumed that cold acclimation induced H₂O₂ production, which in turn enhanced activities of antioxidative enzymes and synthesis of antioxidants, resulting in alleviation of oxidative stress caused by freezing.

An efficient micropropagation protocol for annatto (Bixa orellana L.) was achieved using nodal shoot tip explants. Shoot buds were obtained on the Murashige and Skoog (MS) medium supplemented with various concentrations and combinations of indole-3-acetic acid (IAA), N⁶-benzyladenine (BA) and triacontanol (TRIA). Maximum of 213 shoot buds along with 18 primary shoots were produced on MS medium containing 0.05 µM IAA, 8.87 µM BA, and 11.2 µM TRIA. The primary shoots elongated best on MS medium containing 6.66 µM BA and 2.45 µM indole-3-butyric acid (IBA). The regenerated shoots rooted best on MS medium supplemented with 4.9 µM IBA. The in vitro rooted plantlets were hardened and establishment rate under field conditions was 70 to 80 %.

In order to evaluate effects of γ-rays on adventitious root formation and ginsenoside production, embryogenic calli induced from cotyledon explants of Panax ginseng C.A. Meyer were treated with γ-rays of 0, 10, 30, 50, 70, and 100 Gy. The highest frequency of adventitious root formation of 75 % occurred at γ-irradiation of 30 Gy, which is considered adequate dosage for selecting mutant cell lines. Five mutated adventitious roots (MAR)3-lines out of the propagation of 142 adventitious root lines treated with 30 Gy were selected based a 100-fold increase in proliferation rate compared to control adventitious roots (CAR) and content of the seven major ginsenosides (Rb₁, Rb₂, R_c, R_d, R_e, R_f, and Rg₁) was determined. In the CAR and four of the MAR3-lines (except for MAR3-109), the Rb/Rg ratio was greater than 1.0, thereby indicating altered ginsenoside composition in these root lines. The HPLC analysis of the MAR3-13 and MAR3-26 lines confirmed different ginsenoside profiles, including the three unidentified ginsenoside candidates, Gm₁, Gm₂, and Gm₃. The ginsenosides of the MAR3-13 and MAR3-26 lines showed high hydroxyl and superoxide radical scavenging activities.

Specific activities and isoform patterns of peroxidases, acid phosphatases, DNases and RNases were studied in relation to in vitro rooting of Petunia × hybrida microshoots in the presence of 4 µM indole-3-butyric acid (IBA). Specific activities of the above enzymes increased in the course of rooting. Rhizogenesis could be related with an increased specific activity of peroxidases during the initiation phase, in parallel with increased lignin content. Twelve peroxidases, six anionic (A1-A6) and six cationic (C1-C6), seven acid phosphatases (ACP1-ACP7), seven RNases (R1-R7) and four DNases (D1-D4) isoforms were detected following native PAGE. Variation in the number of the above isoforms and their quantity was observed during different stages of rooting. Particularly, A2, A3, C3, C4, C5, ACP2, R1, R2, R3, and D4 isoforms appeared after the induction phase and could be related to emergence of root primordia. Additionally, R3 and D4 could be associated with cell division and differentiation, since these are only expressed in rooted microshoots. Moreover, the higher number of roots in IBA-treated microshoots could be related to the higher expression of RNase and DNase isoforms during initiation and expression phases.

In order to study chloroplast biogenesis, we chose natural variegated Epipremnum aureum (golden pothos) and regenerated pale yellow, variegated and green plants from all three types of tissue explants. The percentage of three types of regenerated shoots from three different explants was very close. Regenerated plants have been maintained for a year and show no sign of a colour switch. By comparing their protein profiles, two major differences between pale yellow and green plants were observed at the 15 and 40 to 50 kDa proteins. Moreover, pale yellow plants had unexpected high molecular mass proteins (greater than 60 kDa). Both variegated and green plants had more chlorophyll (Chl) a than Chl b, the ratios were about 1.46 and 1.93, respectively. In contrast, the pale yellow plants not only had less total Chl, but also the reduction of Chl a was much greater than Chl b, resulting in a higher content of Chl b than Chl a. Microscopic analysis revealed that pale yellow plants contained predominantly undeveloped chloroplasts with low Chl contents, even though their mesophyll cells were similar to green and variegated plants. PCR amplification of chloroplast DNA with 14 universal chloroplast primers did not reveal any difference among these regenerated plants.

Twenty accessions of the sparsely cultivated diploid Musa cultivars Matti (AA) and Rasakadali (AB) were subjected to random amplified polymorphic DNA (RAPD) assay. A total of 14 random primers were used for the estimation of interand intracultivar variations. Out of 86 bands generated, 64 were polymorphic (74.4 % polymorphism). The cluster analysis grouped the cultivars into two major clusters: cluster I with 10 accessions of Matti and 2 of Rasakadali and cluster II comprising the remaining 8 accessions of Rasakadali. The coefficient of genetic similarity (GS) was from 0.73 to 0.99, suggesting low level of intercultivar variation. The accessions of Rasakadali with mean GS of 0.89 were genetically more diverse than those of Matti (GS = 0.93).

The possible involvement of nitric oxide in response of Solanum nigrum seedlings to Fe deficiency was investigated. Iron deficiency resulted in decreased shoot height and chlorophyll content and increased proliferation of root hairs and H₂O₂, K⁺ and Ca²⁺ content. NO donor S-nitrosoglutathione (GSNO) was effective in preventing Fe deficiency-induced increase in content of H₂O₂ and the ion uptake. The protective effects of GSNO were reversed by cPTIO, an NO scavenger, and tungstate, a nitrate reductase (NR) inhibitor.

β-1,3-Glucanase activity was detected in extracts of different tissues of healthy mature petunia flowers except the filament. The stigma was studied further as it had the highest enzyme activity and there is a paucity of information on the occurrence of this enzyme in this tissue. Specific activity of the enzyme was found to increase within the stigmatic tissue from early development until just before anthesis. Following non-denaturing polyacrylamide gel electrophoresis at pH 8.8, extracts of dehiscent stigma seem to contain three acidic isoforms of β-1,3-glucanase. Crude extracts of stigma was passed through a pachyman affinity column. A fraction of affinity-purified active β-1,3-glucanase enzyme was found to have no antifungal activity against Trichoderma viride, Phloma clematidina and Cladosporium fulvum.