An efficient regeneration protocol via somatic embryogenesis was optimized for mung bean [Vigna radiata (L.) Wilczek; cv. Vamban 1]. Primary leaf explants were used for embryogenic callus induction in MMS medium (Murashige and Skoog salts with B5 vitamins) containing 2.0 mg dm^-3 2,4-dichlorophenoxyacetic acid (2,4-D), 150 mg dm^-3 glutamine and 3 % sucrose. Fast growing, highly embryogenic cell suspensions were established from 21-d-old calli in MMS medium supplemented with 0.5 mg dm^-3 2,4-D and 50 mg dm^-3 proline (Pro), and maximum recovery of globular (39.0 %), heart-shaped (26.3 %) and torpedo-stage (21.0 %) somatic embryos were observed in this medium. Mature cotyledonary-stage somatic embryos were cultured for 5 d in half strength B5 liquid medium containing 0.05 mg dm^-3 2,4-D, 20 mg dm^-3 Pro, 5 μM abscisic acid, 1000 mg dm^-3 KNO₃, 50 mg dm^-3 polyethylene glycol (PEG 6000) and 30 g dm^-3 D-mannitol. Mature somatic embryos were germinated after dessication for 3 d and complete development of plantlets accomplished in MMS medium containing 30 g dm^-3 maltose, 0.5 mg dm^-3 benzyladenine and 500 mg dm^-3 KNO₃. Profuse lateral roots, and regeneration frequency (up to 60 %) were observed in half-strength MMS medium containing 0.5 mg dm^-3 indolebutyric acid (IBA). The regenerated plants were grown to fruiting and were morphologically normal and fertile.

The impacts of solar UV (280-400 nm) radiation on photosynthetic activities and polypeptide composition of thylakoids of cluster bean (Cyamopsis tetragonoloba L, UV-B sensitive) and black gram (Vigna mungo L., UV-B resistant) plants were compared. The activity of photosystem 1 and especially photosystem 2 increased in cluster bean while decreased in black gram, when either UV-B or UV-B + UV-A radiation was removed as compared to control plants. Exclusion of UV-B radiation caused changes in the protein composition of the thylakoids particularly in the 33, 23 and 17 kDa proteins of photosystem 2.

The structural features of flavonoids which are involved in the modulation of auxin distribution in Arabidopsis thaliana were evaluated. An auxin-inducible promoter IAA2 fused to a reporter gene (GUS) was used to monitor the tissue responsiveness to auxins. The following aspects were investigated: 1) the influence of flavonoids (quercetin, naringenin, kaempferol, myricetin and isorhamnetin) on the distribution of indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) in roots and leaves, 2) differences in flavonoid uptake into roots and shoots depending on flavonoid concentration in the medium, and 3) influence of structurally different flavonoids on the gravitropic response and growth of roots. The same flavonoids differently affected IAA and IBA distribution in leaves and roots. There were several structural requirements for the flavonoids which resulted in the changes of auxin response/distribution. Great differences between the ability of shoots and roots to take up quercetin were showed. Also, flavonoids influenced gravitropism and root growth of Arabidopsis seedlings in a structure-dependent manner.

This communication presents a simple method for isolation of oxygen evolving photosystem 2 (PS 2) core complex by solubilisation of PS 2 membranes with the nonionic detergent octyl-β-D-thioglucopyranoside (OTG). This complex was free of cytochrome (Cyt) f contamination and also lacked the 22 and 10 kDa proteins that may not be directly required for primary photochemistry of the PS 2 complex and water oxidation. OTG could also remove the Cyt f contamination from the PS 2-core complex isolated using octyl-β-D-glucopyranoside (OGP). The Cyt f contamination in the PS 2 complexes could potentially interfere with spectrophotometric determinations of redox states of Cyt _b559 and its stoichiometry in the PS 2 complex.

The purpose of this work was to evaluate the effect of 2,4-dichlorophenol (2,4-DCP) and pentachlorophenol (PCP) on the activity of antioxidative system and lipid peroxidation in the leaves of reed canary grass (Phalaris arudinacea). The activity of catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), glutathione reductase (GR) and glutathione S-transferase (GST) as well as the content of glutathione, ascorbate and phenolic compounds were determined. An induced-increase in the APX, CAT, GPX and GR activities was stronger for PCP, while a significant increase in the GST activity was noted only for 2,4-DCP. Both compounds increased the content of phenolic compounds, oxidized and reduced glutathione as well as the content of ascorbic acid. PCP induced stronger increase in lipid peroxidation than 2,4-DCP. The observed changes revealed that chlorophenols induce oxidative stress and oxidative damage in the leaves of reed canary grass.

Leucoanthocyanidin reductase (LAR) converts leucoanthocyanidin to (+)-catechin, a precursor of proanthocyanidins abundant in Japanese persimmon (Diospyros kaki Thunb.) fruits. A putative LAR gene (DkLAR) was isolated by rapid amplification of cDNA ends from young fruits. The full-length cDNA of DkLAR gene was 1 356 bp long and encoded an open reading frame of 349 residues. The deduced DkLAR protein was closely related to the homolog in other plant species. The expression of the DkLAR gene in Chinese pollination-constant non-astringent (PCNA) genotype was coincident with the tannin cell development, but was not in Japanese PCNA and Chinese pollination-variant astringent (PCA) genotypes.

The role of acetylsalicylic acid (0, 1 and 10 μM) pre-treatment in amelioration of salt and osmotic stress in a wild species of potato (Solanum stoloniferum) was investigated. We compared the effects of iso-osmotic concentrations of polyethylene glycol 6000 (15 %) and NaCl (80 mM) on the physiological responses of this species in explants grown in the liquid Murashige and Skoog medium. Both salt and drought reduced shoot growth parameters, photosynthetic pigment contents and increased lipid peroxidation, electrolyte leakage, H₂O₂ content and lipoxygenase activity. The effect of NaCl was more severe than that of polyethylene glycol. Salinity also increased Na⁺ content and decreased K⁺ content and K⁺/Na⁺ ratio. Under both stresses, the activities of superoxide dismutase, guaiacol peroxidase, ascorbate peroxidase, catalase and glutathione reductase enzymes were increased. Acetylsalicylic acid pre-treatment alleviated the adverse effects of both stresses on all parameters measured.

Three highly identical cDNA clones of APETALA3 (AP3) gene, BnAP3-2, BnAP3-3 and BnAP3-4 were isolated from Brassica napus L. by RT-PCR. The sequence analysis showed that all the three AP3 cDNAs contained a complete open reading frame. Their nucleotide sequences had 91-97 % similarity and their predicted amino acid sequences shared 93-98 % identity. Real-time quantitative RT-PCR result showed that all the three BnAP3 genes were expressed at the transcriptional level in petals as well as stamens. Among the three BnAP3 genes, BnAP3-3 was expressed at the highest level and BnAP3-2 was expressed at the lowest level in petals. The transcription level of BnAP3-3 was 1.59 times than that of BnAP3-2. The transcription levels of BnAP3-2, BnAP3-3 and BnAP3-4 in stamen were 7.75, 5.11 and 3.88 times than those in petal, respectively. The yeast two-hybrid assays results showed that all the three BnAP3 proteins could form strong heterodimers with BnPI, and obviously different dimerization affinities among the three proteins to BnPI were observed. The ratio of the affinity of BnAP3-2, BnAP3-3 and BnAP3-4 to BnPI-1 was 1.27:1:1.62. Although the three BnAP3 genes were highly identical, the differences of their expression and affinity of protein interaction might reflect some functional divergence.

A protocol for in vitro multiplication of Capparis decidua (Forsk.) Edgew. has been developed from cultured leaves procured from multiplying axillary shoots on the cultured nodal explants. The highest efficiency of shoot formation was observed on Murashige and Skoog (MS) medium containing 2 mg dm^-3 benzyladenine (BA) and 0.5 mg dm^-3 1-naphthaleneacetic acid. The regenerated shoots were transferred to MS medium containing 3 mg dm^-3 BA for growth and proliferation. Shoots above 2 cm in length were transferred to MS medium supplemented with 1 mg dm-3 indole-3-butyric acid plus 0.5 mg dm^-3 indole-3-acetic acid for root induction. No variation was detected among the micropropagated plants by randomly amplified polymorphic DNA (RAPD) markers.

The DNA of fifteen Italian cultivars of durum wheat (Triticum turgidum L. ssp. durum) were analyzed by in fluorescence amplified fragment length polymorphism (fAFLP) in order to obtain the characteristic fingerprintings of genotypes and assess their genetic relatedness. Among 64 combinations of fluorescence labelled primers, three different combinations were chosen as producing a total of 6630 AFLP fragments, 2277 (34.3 %) of them being polymorphic. By using this fAFLP methodology a DNA fingerprinting of each durum wheat cultivar was generated for genotype identification. Analysis of the genetic relationships show the low variability among durum wheat cultivars.

Cadmium (100, 400 and 1000 μM CdCl₂) treatments resulted in the inhibition of root dry biomass, root elongation and increased Cd accumulation in wheat (Triticum aestivum L.) roots. Further, these treatments decreased relative water content, chlorophyll content, ¹⁴CO₂-fixation, activities of phosphoenolpyruvate carboxylase and ribulose-1,5-bisphosphate carboxylase and abscisic acid content while increased malondialdehyde, hydrogen peroxide and free proline contents. Chloroplast and root ultrastructure was also changed. Pretreatment of seeds with SA (500 μM) for 20 h resulted in amelioration of these effects.

Proline (Pro) accumulation under water stress was measured in safflower (Carthamus tinctorius L.) drought tolerant cv. A1 and sensitive cv. Nira. Activities of pyrroline-5-carboxylate reductase (P5C reductase) and pyrroline-5-carboxylate synthetase (P5C synthetase), two enzymes involved in the Pro biosynthetic pathway were also estimated. Water stress resulted in a reduction in the leaf dry mass and chlorophyll content along with a gradual accumulation of Pro. RT-PCR results show higher expression of Δ¹-pyrroline-5-carboxylate synthetase (p5cs) gene in correlation with up-regulated Pro accumulation in cv. A1. P5C reductase was found to be the Pro synthesis rate limiting whereas P5C synthetase did not show any specific response to the drought stress in both cultivars.

The mean effective water self-diffusion coefficient in maize root segments under the effect of aquaporin blocker (mercuric chloride, 0.1 mM) was measured using the spin-echo NMR method with pulsed magnetic field gradient within the temperature range from 10 to 35 °C. HgCl₂ caused the reduction in water diffusion by 30 % as compared to the control samples. Temperature dependences of water self-diffusion coefficients showed two linear regions with different values of Q₁₀ and activation energy, E_a. As the temperature reduced from 20 to 10 °C, E_a values calculated from the Arrhenius plots were close to those of bulk water (20 ± 3 kJ mol^-1) and slightly changed for the sample pretreated HgCl₂. Within the temperature range from 25 to 35 °C the slope of temperature dependences became steeper and E_a values were 31 ± 3 kJ mol^-1 for the control and 40 ± 4 kJ mol^-1 for the treated sample. In the vicinity of 20 °C, the temperature dependence of water diffusion via the mercury-sensitive water channels showed extreme value. In the region, the specific area of the mercury-sensitive aquaporins was 0.004 % of the total cell surface area. The data indicate that water transfer via aquaporins is sensitive to temperature, and the contributions of the transmembrane pathways (aquaporins, lipid bilayer) differ in different temperature ranges.

TaCer6 was firstly cloned by rapid amplification of cDNA ends (RACE) and identified as a tissue-specific gene in wheat. To determine if environmental factors such as drought and low temperature induce TaCer6 transcription, we examined the effects of these factors on TaCer6 in two wheat cultivars. Our results demonstrated that light was essential for TaCer6 transcription, salt stress inhibited TaCer6 expression and application of salicylic acid enhanced TaCer6 transcripts accumulation. In addition, polyethylene glycol (PEG 6000) and abscisic acid increased the expression of TaCer6 more in the drought- and cold-tolerant cultivar Jinmai47 than in non-tolerant cultivar Shi4185. Low temperature increased TaCer6 transcription in Jinmai47 while decreased it in Shi4185.

The changes in the fresh biomass accumulation, photosynthetic and anthocyanin pigments, photosystem 2 (PS 2) activity, ultrastructure of chloroplast, total lipids and fatty acid composition of thylakoid membrane were followed in the aquatic fern Azolla caroliniana grown on medium either deficient or supplied with various phosphorus concentrations. The content of photosynthetic pigments and the anthocyanin/chlorophyll ratio increased significantly with increasing PO₄ ^3- concentration. Phosphate deficiency inhibited growth and PS 2 activity and decreased content of total lipids and phospholipids in isolated thylakoids. This was accompanied with a significant increase in the percentage of galalactolipids.

Leaf gas exchange, chlorophyll fluorescence and activities of antioxidant enzymes were studied in two pepper (Capsicum annuum L.) cultivars grown under drought (D) and heat (H), as well as under drought and heat in combination (HD). The drought-tolerant cv. Zhengjiao 13 exhibited greater net photosynthetic rate (P_N) and cytochrome respiratory pathway activity (R_SHAM), and lower contents of superoxide radical and hydrogen peroxide, as compared to the drought-sensitive cv. Longkouzaojiao. The P_N and R_SHAM decreased and ROS production increased under D and HD in both cultivars. As compared to the Longkouzaojiao, Zhengjiao 13 retained higher non-photochemical quenching (NPQ), photorespiration rate (R_L), and alternative respiratory pathways (R_KCN) under D and HD. Drought increased the superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities in the cytosol, chloroplasts and mitochondria in the two cultivars. Although SOD and APX activities decreased in Longkouzaojiao under HD, SOD activity increased in Zhengjiao 13. There was no H-induced reactive oxygen species production due to increase of R_L, NPQ, R_SHAM, R_KCN and activities of SOD and APX. However, H slightly decreased the P_N. The results indicated that HD was more detrimental than either stress alone.

The effect of various hormonal combinations on callus formation and regeneration of shoot and root from leaf derived callus of Acanthophyllum sordidum Bunge ex Boiss. has been studied. Proteins and activity of antioxidant enzymes were also evaluated during shoot and root organogenesis from callus. Calli were induced from leaf explants excised from 30-d-old seedlings grown on Murashige and Skoog medium containing 4.52 µM 2,4-dichlorophenoxyacetic acid + 4.65 µM kinetin. Maximum growth of calli and the most efficient regeneration of shoots and roots occurred with 2.69 µM 1-naphthalene acetic acid (NAA), 2.69 µM NAA + 4.54 µM thidiazuron and 2.46 µM indole-3-butyric acid. Protein content decreased in calli and increased significantly during regeneration of shoots from callus. Superoxide dismutase activity decreased in calli comparing to that of seedlings, then increased in regenerated shoots and roots. High catalase activity was detected in seedlings and regenerated shoots, whereas high peroxidase activity was observed in calli and regenerated roots.

In pot experiments performed on maize seedlings chilled at 5 °C, leaf injury was diminished by the application of elevated temperature (1 or 5 h at 15 or 20°C, "warm breaks" treatment) in a dose-dependent manner. The lower the injury count, the higher the catalase (CAT) activity. In a separate experiment, the application of 100 % relative humidity also protected the plants from chilling injury and water loss, increased their gas exchange and variable to maximum chlorophyll fluorescence ratio (F_v/F_m), but did not influence CAT activity. Another protective environmental factor, elevated atmospheric CO₂ concentration [700 µmol(CO₂) mol^-1(air)] diminished CAT activity inhibition, but only in plants of chilling-resistant cultivar. The positive impact of specific environmental factors accompanying chilling is not obviously related to the suppression of the inhibition of CAT activity, although the enzyme is considered as chilling-sensitive.

A novel method of organogenesis in neem (Azadirachta indica A. Juss.) from unfertilized ovaries is described. The Murashige and Skoog's (MS) medium with 9 % sucrose, 1 µM 2,4-dichlorophenoxyacetic acid (2,4-D) and 5 µM 6-benzylaminopurine (BAP) was the best for callus induction from unfertilized ovaries. However, further proliferation of callus occurred better on MS medium supplemented with 0.5 µM 2,4-D either alone or in combination with 4.5 µM kinetin. Maximum shoot regeneration (78 %) was observed when calli, induced from ovaries of 4 mm size flower buds and proliferating on MS + 0.5 µM 2,4-D, were subcultured to MS medium containing 5 µM BAP. Histological analysis revealed that 4 mm sized flower bud corresponds to a 2-nucleate stage of embryo sac. The shoots were then multiplied by forced axillary branching on MS medium supplemented with 1.0 µM BAP and 250 mg dm^-3 casein hydrolysate. The shoots could be rooted on 1/4 strength MS medium supplemented with 0.5 µM indole-3-butyric acid (IBA) at a frequency of 79 %. Cytological analysis by root tip squash preparations revealed that all the plantlets were diploids. These plants were subsequently hardened and established in soil with transplantation rate of 81.8 %.

Expansins, found in the cell wall, have the unique ability to induce immediate cell wall extension. In this study, a β-expansin gene (TaEXPB23) isolated from wheat (Triticum aestivum L.) coleoptiles was transformed to tobacco (Nicotiana tabacum) to investigate its role in plant growth and development. TaEXPB23 was preferentially expressed in wheat coleoptile and a close correlation between TaEXPB23 expression and coleoptile growth was observed. The over-expression of TaEXPB23 in tobacco also resulted in accelerating growth of leaves and internodes at earlier developmental stages, and it was involved in regulating plant development.

Two rice (Oryza sativa L.) cultivars differing in chilling sensitivity, Changbaijiu (chilling-tolerant) and Zhongjian (chilling-sensitive) were pre-treated with 0.5, 1.0 and 2.0 mM salicylic acid (SA) for 24 h before chilling at 5°C for 1 d. Chilling induced SA accumulation, particularly conjugated SA in both leaves and roots of the two rice cultivars. After SA administration, SA accumulated in the roots of both cultivars at a concentration-dependent manner, whereas only a slight increase was observed in their leaves. Conjugated SA accounted for most of the increase. The beneficial effect of SA treatment on protecting rice seedlings from chilling injury was not observed at any concentration in either cultivar. Pre-treatment with SA even decreased their chilling tolerance confirmed by increased electrolyte leakage and lipid peroxidation. Further, most of the activities of antioxidant enzymes decreased or remained unchanged in leaves and roots of SA pre-treated seedlings after chilling. These results implied that down-regulation of antioxidant defence might be involved in the reduction of chilling tolerance in SA-pre-treated plants.

A cDNA-encoding γ-tocopherol methyltransferase (γ-TMT) from Arabidopsis thaliana was overexpressed in deoduck (Codonopsis lanceolata L.) to improve the tocopherol composition. Deoduck (T₂) containing the γ-TMT transgene was produced by Agrobacterium-mediated transformation. Transgene expression was confirmed by polymerase chain reaction and RNA gel blot analysis. The transgenic plants produced more leaves than control plants. In addition, the transgenic plants showed higher levels of the CSOD, CTRX, CAPX, CNADP ⁺-IDCH, and CSO transcripts and higher SOD-like activity compared with the control plants.

Black gram [Vigna mungo (L.) Hepper] cv. IPU 94 plants grown in sand culture with deficient zinc (0.1 µM Zn) nutrition and those deprived of normal (1 µM) Zn supply at the initiation of flowering, showed decrease in dry matter production and especially seed yield. These plants showed a decrease in the size of anthers and stigmatic heads, pollen producing capacity of the anthers and stigmatic exudations. Zn deficiency caused structural alterations in exine and retarded germination of pollen grains and tube growth. The pollen extracts and stigmatic exudates of the Zn-deficient plants showed increase in activity of acid phosphatase isoforms and inhibition of esterase isoforms. Zn deficiency led to decrease in number of pods, seeds per pod and seed mass, altered seed coat topography and reduced seeds germinability. Low seed yield under Zn deficiency is attributed to a role of Zn in pollen function, as also in pollen-pistil interaction conducive to fertilization and development of seeds.

The influence of cytokinin thidiazuron (TDZ) and auxin indole-3-acetic acid (IAA) on in vitro shoot organogenesis of fifteen Rhododendron genotypes was investigated and a protocol for high frequency adventitious shoot regeneration from leaf explants was developed. High genotypic variation was observed and regeneration frequencies ranged from 0 to 100 %. Genotype Ovation had the highest number of shoots (26.4 per explant) after 12 weeks on medium with 0.57 µM IAA and 1.20 µM TDZ, but only 65 % of explants regenerated. Catawbiense Grandiflorum had 17.7 shoots per explant and 75 % regeneration on medium with 5.70 µM IAA and 0.45 µM TDZ and Van Werden Poelman had 14.3 shoots per explant and 100 % regeneration on medium with 0 57 µM IAA and 0.45 µM TDZ.

The genetic relationship of 36 Dendrobium species in China was determined based on sequence analysis of the internal transcribed spacer (ITS) region of ribosomal DNA. Aligned sequences of the complete ITS region obtained from the 36 Dendrobium species and 2 outgroup species (Epigeneium amplum and Epigeneium nakaharaei) by using PCR amplification and direct DNA sequencing. The nrDNA ITS1 of Dendrobium was 225-234 bp and ITS2 was 239-248 bp. Phylogenetic tree was constructed, and seven main clusters were generated among the 36 Dendrobium species. From the results, D. moulmeinense was not grouped in the classification of Dendrobium and E. amplum and E. nakaharaei were shown to be divergent from Dendrobium species. The phylogenetic relationships revealed by ITS DNA analysis partially supported previously published morphological data.

The effects of NaCl stress on growth, water status, contents of protein, proline, malondialdehyde (MDA), various sugars and photosynthetic pigments were investigated in seedlings of Salicornia persica and S. europaea grown in vitro. Seeds were germinated under NaCl (0, 100, 200, 300, 400, 500 and 600 mM) on Murashige and Skoog medium for 45 d. The shoot growth of both species increased under low NaCl concentration (100 mM) and then decreased with increasing NaCl concentrations. In contrast to S. persica, root length in S. europaea reduced steadily with an increase in salinity. Proline content in S. persica was higher than in S. europaea at most NaCl concentrations. Proline, reducing saccharide, oligosaccharide and soluble saccharide contents increased under salinity in both species. In contrast, contents of proteins and polysaccharides reduced in both species under salt stress. MDA content remained close to control at moderate NaCl concentrations (100 and 200 mM) and increased at higher salinities. MDA content in S. europaea was significantly higher than S. persica at higher salinities. Salt treatments decreased K⁺ and P contents in seedlings of both species. Significant reduction in contents of chlorophylls and carotenoids due to NaCl stress was also observed in seedlings of both species. Some differences appeared between S. persica and S. europaea concerning proteins profile. On the basis of the data obtained, S. persica is more salt-tolerant than S. europaea.

This study examined the impacts of elevated CO₂ or O₃ on indole-3-acetic acid (IAA) content, activities of IAA oxidase (IAAO) and peroxidase (POD) in Ginkgo biloba leaves. Plants grown in open-top chambers were exposed to ambient atmosphere (control; C), elevated CO₂ and elevated O₃ from 1 June to 30 September. An increase in IAA content and decrease in IAAO and POD activities were observed in plants exposed to elevated CO₂ compared with C. Elevated O₃ had no significant effect on IAA content and IAAO activity, but increased POD activity during the early days. When trees pre-exposed to elevated CO₂ were transferred to elevated O₃ or C, the increase in IAAO activity resulted in the decrease in IAA content. When trees pre-exposed to elevated O₃ were transferred to elevated CO₂ or C, IAA content, IAAO and POD activities showed no significant changes. The influence of POD activity on the IAA activity was low.