Inheritance of 10 morphological and quantitative traits related to plant and fruit development and resistance to the pathogen Phytophthora capsici was studied in an intraspecific cross between a non-pungent, susceptible Capsicum annuum parent (cv. Americano) and a wild, pungent and resistant line (Serrano Criollo de Morelos-334). Data were obtained from the segregation of 166 F₂ plants and 50 F₃ plants in four years. Three of the traits analyzed (necrosis length, leaf width and leaf length) exhibited a transgressive segregation. A multiple linear regression analysis was applied in order to establish a relationship between necrosis length and some of the morphological traits measured such as length and width of leaf, length, diameter and mass of fruit, capsaicin content in fruits, and presence of hair on leaves and stems. The results identified a linear dependence between necrosis length (as an inverse measurement of resistance) and leaf width, fruit diameter and hair presence in the stem. Pungency was not related with resistance.

Embryo-rescue was used to facilitate interspecific hybridization of Cucumis anguria L. and C. zeyheri Sond. Embryos were excised from developing fruits at one week intervals for six weeks after hand pollination. Medium containing coconut water was the most suitable for initial germination, and a medium with ascorbic acid was the best for embryo development and plant recovery. Viable plants were obtained from embryos and these plants showed morphological characteristics different from both parents. The analysis of the leucine aminopeptidase (LAP) locus revealed three hybrid types, H1.1, H1.2 and H2.

The present investigation has been performed to evaluate nitrate reductase (NR) and nitrogenase activities as well as growth and mineral nutrition of wheat plants grown under drought stress and inoculated with different Azospirillum strains (NR^- and NR⁺). Fresh, dry mass and water content decreased with decreasing soil moisture content, which was accompanied with low soluble sugars and soluble protein content and increase in the total amino acids content. Azospirillum inoculation with either bacterial strain (NR^- and NR⁺) significantly increased the above characteristics even at 40 % moisture content. NR activity decreased in both the shoots and roots by decreasing soil moisture content. NR⁺ strain exhibited increased root NR activity compared with uninoculated plants or inoculated with NR^- strain. However, plants inoculated with NR^-strain increased NR activity in the shoot more than in the root of the same plant and in the shoot of control plants. Inoculation with either NR^- and NR⁺ Azospirillum strains gave higher nitrogenase activity than uninoculated control plants. The low N supply (0.5 mM) did not affect nitrogenase activity. NR^-strain was less effective than NR⁺strain in promoting total N-yield, spike numbers and their mass per pot. Azospirillum inoculation exhibited no significant changes in wheat Mg²⁺ content. However, K⁺ and Ca²⁺ have shown significantly increased values. Azospirillum beneficial effect on plant N balance and growth are most probably composed of multiple mechanisms and beneficial NR is one of them. The importance of Azospirillum NR⁺strains for increasing wheat resistance to water stress is also supported by the obtained data.

The present paper reports a protocol for minimum growth conservation of Drosophyllum lusitanicum (L.) Link. in vitro. Double-node cuttings were maintained for 4, 8 and 12 months at 5 or 25 °C in the dark. The effects of sucrose either alone at 5, 20, 30, 40 and 60 g dm^-3 or at 20, 40 and 60 g dm^-3 in combination with 20 g dm^-3 mannitol, on survival and post-storage shoot multiplication efficiency were investigated. The cultures could effectively be conserved under minimum growth at 5 °C for 8 months on Murashige and Skoog's medium supplemented with 60 g dm^-3 sucrose, 20 g dm^-3 mannitol and 0.91 µM zeatin. Following extended conservation, the cultures could be successfully regenerated into new shoots, and they were morphologically similar to those of non-stored controls.

The accumulation of steviol glycosides (SGs) in cells of Stevia rebaudiana Bertoni both in vivo and in vitro was related to the extent of the development of the membrane system of chloroplasts and the content of photosynthetic pigments. Chloroplasts of the in vitro plants, unlike those of the intact plants, had poorly developed membrane system. The callus cells grown in the light contained proplastids of almost round shape and their thylakoid system was represented by short thylakoids sometimes forming a little number of grana consisting of 2-3 thylakoids. In cells of the etiolated in vitro regenerants and the callus culture grown in the dark, only proplastids practically lacking the membrane system were observed. All the chloroplasts having developed thylakoids and forming at least a little number of grana were equipped with photochemically active reaction centers of photosystems 1 and 2. Leaves of in vivo plants accumulated greater amount of the pigments than leaves of the in vitro plants. In both the callus culture grown in the light and the etiolated in vitro regenerants, the content of the pigments was one order of magnitude lower than that in leaves of the intact plants. The callus tissue grown in the dark contained merely trace amounts of the pigments. Leaves of the intact and the in vitro plants did not exhibit any significant differences in photosynthetic O₂ evolution rate. However, photosynthetic O₂ evolution rate in the callus cells was much lower than that in the differentiated plant cells. The in vitro cell cultures containing merely proplastids did not practically produce SGs. However, after transferring these cultures in the light, both the formation of chloroplasts and the production of SGs in them were detected.

The water-water cycle which may be helpful for dissipating the excitation pressure over electron transport chain and minimizing the risk of photoinhibition and photodamage was investigated in rice after 10-d P-deficient treatment. Net photosynthetic rate decreased under P-deficiency, thus the absorption of photon energy exceeded the energy required for CO₂ assimilation. A more sensitive response of effective quantum yield of photosystem 2 (Φ_PS2) to O₂ concentration was observed in plants that suffered P starvation, indicating that more electrons were transported to O₂ in the P-deficient leaves. The electron transport rate through photosystem 2 (PS 2) (J_f) was stable, and the fraction of electron transport rate required to sustain CO₂ assimilation and photorespiration (J_g/J_f) was significantly decreased accompanied by an increase in the alternative electron transport (J_a/J_f), indicating that a considerable electron amount had been transported to O₂ during the water-water cycle in the P-deficient leaves. However, the fraction of electron transport to photorespiration (J_o/J_f) was also increased in the P-deficient leaves and it was less sensitive than that of water-water cycle. Therefore, water-water cycle could serve as an efficient electron sink. The higher non-photochemical fluorescence quenching (q_N) in the P-deficient leaves depended on O₂ concentration, suggesting that the water-water cycle might also contribute to non-radiative energy dissipation. Hence, the enhanced activity of the water-water cycle is important for protecting photosynthetic apparatus under P-deficiency in rice.

A highly reproducible system for efficient plant regeneration from protoplast via somatic embryogenesis was developed in cotton (Gossypium hirsutum L.) cultivar ZDM-3. Embryogenic callus, somatic embryos and suspension culture cells were used as explants. Callus-forming frequency (82.86 %) was obtained in protoplast cultures from suspension culture cells in KM₈P medium with 0.45 µM 2,4-dichlorophenoxyacetic acid (2,4-D), 0.93 µM kinetin (KIN), 1.5 % glucose and 1.5 % maltose. Protocolonies formed in two months with plating efficiency of 14 %. However, the callus-forming efficiencies from other two explants were low. The calli from protoplast culture were transferred to somatic embryo induction medium and 12.7 % of normal plantlets were obtained on medium contained 3 % maltose or 1 % of each sucrose + maltose + glucose, 2.46 µM indole-3-butyric acid (IBA) and 0.93 µM KIN. Over 100 plantlets were obtained from protoplasts derived from three explants. The regenerated plants were transferred to the soil and the highest survival rate (95 %) was observed in transplanting via a new method.

Radicle growth of germinated seed of the root parasite O. ramosa is shown to be rapidly accompanied by secretion of proteins including pectinolytic enzymes, polygalacturonase and rhamnogalacturonase. These secretions peaked between 4 to 8 d after induction of germination and remained constant for some further days in the case of polygalacturonases. After 6 d, germinated seeds secreted proteins which exhibit peroxidase activity. The latter may be correlated with expression of OrPOX1, a putative gene encoding for secreted peroxidase. The involvement of these enzymes in host root attack and haustorium formation by the parasite is discussed.

In higher plants, fatty acid hydroperoxides are intermediates in the synthesis of a diverse group of bioactive compounds. We used the reverse-transcriptase polymerase chain reaction to isolate a gene responsible for the oxidization of fatty acids from Petunia hybrida. A P450 cDNA that has not previously been isolated (CYP76A3) contained an open reading frame predicted to encode a polypeptide consisting of 507 amino acid residues. The cyp76A3 cDNA was expressed in Saccharomyces cerevisiae AH22 cells under the control of an alcohol dehydrogenase promoter and terminator. The recombinant yeast microsome containing the CYP76A3 hemoprotein was found to specifically catalyze ω-hydroxylation of myristic acid. A high level of the transcripts of the cyp76A3 gene was found in the leaves and roots of P. hybrida, but not in the stems and flowers.

The possibility to improve the recovery of sugar beet plants after water stress by application of synthetic cytokinins N⁶-benzyladenine (BA) or N⁶-(m-hydroxybenzyl)adenosine (HBA) was tested. Relative water content (RWC), net photosynthetic rate (P_N), transpiration rate (E), stomatal conductance (g_s), chlorophyll (Chl) a and Chl b contents, and photosystem 2 efficiency characterized by variable to maximal fluorescence ratio (F_v/F_m) were measured in control plants, in water-stressed plants, and after rehydration (4, 8, 24, and 48 h). Water stress markedly decreased parameters of gas exchange, but they started to recover soon after irrigation. Application of BA or HBA to the substrate or sprayed on leaves only slightly stimulated recovery of P_N, E, and g_s in rehydrated plants, especially during the first phases of recovery. Chl contents decreased only under severe water stress and F_v/F_m ratio was not significantly affected by water stress applied. Positive effects of BA or HBA application on Chl content and F_v/F_m ratio were mostly not observed.

A greenhouse experiment was conducted to investigate the effects of silicon application on Phaseolus vulgaris L. under two levels of salt stress (30 and 60 mM NaCl in the irrigation water). Salinity significantly reduced growth, stomatal conductance and net photosynthetic rate, and increased Na⁺ and Cl^- content mainly in roots. Silicon application enhanced growth of salt stressed plants, significantly reduced Na⁺ content especially in leaves and counterbalanced the effects of NaCl on gas exchange; the effect was more evident at 30 mM NaCl. Cl^- content in shoots and roots was not significantly modified by silicon application; the drop in K⁺ content caused by salinity was partially counterbalanced by silicon, especially in roots.

This study was conducted to determine the reciprocal effects for anther culture response in wheat (Triticum aestivum L.) using a set of 4 × 4 full diallel crosses. Both reciprocal and nuclear genetic effects were highly significant for anther culture response and useful for selection and breeding purposes. General combining ability (GCA) effects were predominant for all investigated anther culture traits. Also, significant differences for specific combining ability (SCA) effects were detected between reciprocal crosses. Although significant reciprocal differences for responding anther, callus number and green plant regeneration were recorded in some reciprocal crosses, there were no significant reciprocal differences for albino plant regeneration. The use of one parent as male or female could lead to change at the production of green plants from the F₁ hybrids and screening of inbred lines for response to anther culture, without reciprocal effects, could decrease the utilization of breeding material.

Studies on stem (and leaf) structure and histology of a semi-natural grassland community, permanently growing in mini-FACE rings under elevated concentrations of atmospheric CO₂ (560 μmol mol^-1) are presented. Histochemical analysis of stem sections from legume plants grown under high CO₂ concentration revealed both a reduction of lignin deposition in spring vascular bundles of Trifolium repens L., and a decrease in size of the xylem vessels in Vicia hybrida L. and Vicia sativa L. Thus, the effects of elevated CO₂ on the stem histology of the species investigated are rather species-specific and/or organ-specific, and of major account especially in the early phases of vegetative growth, in particular as regards lignin deposition mechanisms. In leaves, neither differences as to lignification nor any other anatomical structure modification were found under CO₂ enrichment.

An in vitro propagation system was developed for castor-bean (Ricinus communis L. cv. TMV 6) through cotyledon derived callus cultures. The impact of different concentrations of auxins, cytokinins, additives, amino acids and sugars were evaluated for callus induction and shoot proliferation. Green compact nodular organogenic callus was obtained on the medium fortified with Murashige and Skoog (MS) salts, B5 vitamins, 2.0 mg dm^-3 6-benzyladenine and 0.8 mg dm^-3 α-naphthalene acetic acid (NAA). Multiple shoot proliferation from the callus cultures was achieved on the medium with MS salts, B5 vitamins, 2.5 mg dm^-3 thidiazuron (TDZ), 0.4 mg dm^-3 NAA and 15 mg dm^-3 glutamine. During multiple shoot induction the phenolic secretion was controlled by the addition of 15 mg dm^-3 polyvinylpyrolidone. The proliferated shoots were elongated on the medium comprising MS salts, B5 vitamins, 1.5 mg dm^-3 TDZ and 0.3 mg dm^-3 gibberellic acid. The elongated shoots were rooted on the medium containing MS salts, B5 vitamins, 0.3 mg dm^-3 indole-3-butyric acid and 0.6 mg dm^-3 silver nitrate. After root induction, the plants were hardened in earthen pots containing sand, soil and vermiculite.

Inflorescence explants of two winter wheat cultivars, Triticum durum cv. Kiziltan-91 and T. aestivum cv. Bezostaja-01, were used to evaluate the effects of vernalization period of donor plants, callus age and medium composition on regeneration capacity. Donor plants were grown for 7 d and they were exposed to 4 °C for 1, 2, 3, 4, and 5 weeks. The maximum inflorescence formation was observed as 79 % at 4 weeks and 73 % at 5 weeks of vernalization period for Kiziltan-91 and Bezostaja-01, respectively. Among 6 different callus induction and regeneration mediums, I₁-R₁ and I₃-R₃ have to be the best responding mediums for Kiziltan-91 and Bezostaja-01, respectively. In Kiziltan-91, calli induced from donor plants, vernalized for 3 weeks, showed a significantly lower regeneration capacity than counterparts vernalized for 4 and 5 weeks. The highest regeneration capacity of 69 % was obtained from 6-week-old calli produced from 4 weeks vernalized Kiziltan-91 donor plants. In contrast to Kiziltan-91 cultures, the effects of vernalization period and callus age on regeneration capacity were not significant in Bezostaja-01 cultures. The maximum numbers of tillers were obtained from 6-and 15-week-old calli for Bezostaja-01 and Kiziltan-91, respectively. In contrast to vernalization period of donor plants, callus age had no effect on seed number.

CONSTANS (CO) has a central role in the photoperiodic regulation of flowering in Arabidopsis thaliana. We show here that potato (Solanum tuberosum ssp. andigena) plants constitutively expressing Arabidopsis CO (pACo plants) flower late under all photoperiodic conditions tested. Exogenous application of gibberellic acid to pACo plants corrected their short stem phenotype but not their late flowering. To further understand the effect of CO in potato, we used three photoperiodic conditions: short days (SD), which strongly induce tuberisation of wild type plants, SD supplemented with a night break (SD+NB), which are moderately inductive, and tuberisation-inhibiting long days. Tuberisation of pACo plants was delayed under SD and very strongly delayed or completely inhibited under SD+NB, suggesting that CO affects an autonomous pathway controlling potato tuberisation. In addition, tuber yield, a trait of high agronomic relevance, was significantly increased in pACo plants expressing moderate CO levels. Our results indicate that CO affects flowering and stem elongation through distinct mechanisms and suggest that its effects on flowering and tuberisation in potato are photoperiod-independent.

In this study, bulked segregant analysis (BSA) was used on Larix leptolepis × Larix olgensis hybrids to identify a random amplified polymorphic DNA (RAPD) marker associated with high rooting ability in larch. Two DNA bulks: H (high rooting ability) bulk and L (low rooting ability) bulk were constructed according to the rooting percentages of the stock plants. Among the 328 primers, only S356 could amplify a specific band, named S356₄₄₅, which only existed in the H bulk and was further confirmed following selective genotyping of individual hybrids. Grounded on the border sequences, S356₄₄₅ was converted to a sequence characterized amplified region (SCAR) marker, HRL445, which can be useful in marker-assisted selection (MAS) to screen for larch with high rooting ability. All the results strongly indicated that S356₄₄₅ and HRL445 were closely associated with high rooting ability in larch.

The effects of Al, Cd and pH on growth, photosynthesis, malondialdehyde (MDA) content, and some antioxidant enzyme activities of the two soybean cultivars with different Al tolerance were determined using a hydroponic culture. There were six treatments as follows: pH 6.5; pH 4.0; pH 6.5 + 1.0 µM Cd; pH 4.0 + 1.0 µM Cd; pH 4.0 + 150 µM Al; pH 4.0 + 1.0 µM Cd + 150 µM Al. The results showed that the low pH (4.0) and Al treatments caused marked reduction in the growth (root and shoot length and dry mass), chlorophyll content (SPAD value) and net photosynthetic rate. Higher malondialdehyde content, superoxide dismutase (SOD) and peroxidase (POD) activities were detected in the plants exposed to both Al and Cd than in those exposed to Al treatment alone. An expressive enhancement of SOD and POD was observed in the plants exposed to 150 µM Al in the comparison with the control plants, especially in Al-sensitive cv. Zhechun 2 which had also significantly higher Al and Cd content than Al tolerant cv. Liao-1. Cd addition increased Al content in the plants exposed to Al + Cd stress, and cv. Zhechun 2 had relatively lower Al content. The present research indicated that Al and Cd are synergistic in their effects on plant growth and some physiological traits.

Callus cultures initiated from shoot base explants of Curcuma aromatica Salisb. were maintained on Murashige and Skoog (MS) media supplemented with 2 mg dm^-3 2,4-dichlorophenoxyacetic acid alone or with 0.5 mg dm^-3 kinetin. Plantlets were regenerated from 60 and 180-d-old callus on MS media supplemented with 3 mg dm^-3 benzyladenine and 0.5 mg dm^-3 α-naphthalene acetic acid. Approximately 8-10 plantlets were produced after 30-40 d of culture per 50 mg of callus inoculated. Out of 113 regenerants analyzed 85 plants were exclusively diploid and 28 were predominantly diploid revealing presence of polyploid nuclei. Frequency of polyploid cells were more in regenerants obtained from 180-d-old callus then from 6-d-old callus which might be attributed to the ageing of callus.

Maltose was four times more effective than sucrose for androgenesis in anther cultures of an indica rice cultivar IR 43. Partial substitution of maltose by mannitol considerably enhanced the regeneration of green plants.

Cowpea (Vigna sinensis L.) plants were inoculated with arbuscular mycorrhizal fungus (Acaulospora laevis) to investigate the effects of different concentrations of di-n-butyl phthalate (DBP; 0, 10, and 100 mg kg^-1) added to soil on their growth. Mycorrhizal plants were less affected by high concentration of DBP (100 mg kg^-1) than non-mycorrhizal ones. Also the uptake and transformation of DBP by mycorrhizal plants differed from that of non-mycorrhizal plants.

Immunoblot analysis was used to assess the effects of light and redox-modifying chemicals on the 52 kDa protein disulfide isomerase (PDI) from chloroplasts of Arabidopsis thaliana. A monoclonal antiserum was used that preferentially cross-reacts with the 52 kDa relative to the 65 kDa isoform of PDI. The PDI-52 was most abundant in leaves, flowers, stems and seeds, but was undetected in roots. PDI-52 formed a ∼220 kDa protein complex on blue native gels, indicating that it associates with either itself or other proteins in chloroplasts. Light decreased the levels of PDI-52 by 80 %, relative to the control protein (the CF1 subunit of chloroplast ATP synthase). Treatment with dithiothreitol decreased the content of the 52 kDa protein by half. In contrast, when the reduction of plastoquinone is blocked by DCMU, or when the plants are treated with phosphate, PDI-52 contents increased by 1.5 to 2-fold relative to CF1. The effect of the chemical treatments coincided with the effect of the light/dark cycle and implied that light decreased PDI-52 protein content by way of the cellular redox environment.

A 51-kDa soluble protein was over-expressed in wheat (Triticum aestivum) seedlings by the treatment of seeds before germination with 50 µM CdCl₂ for 48 h and subsequently washed off Cd²⁺. This protein designated as Cd stress associated protein (CSAP), was purified. Polyclonal antibody was raised against CSAP for localizing the protein in root tissue of treated and control seedlings. It was observed that CSAP was located below the plasma membrane and outer periphery of the tonoplast. This unique type of organized localization of CSAP is suggestive of defensive role against metal phytotoxicity. N-terminal analysis of CSAP and expressed sequence tags (EST) database search of wheat sequences suggests that this protein has not been reported earlier in higher plants.

In the present study, a polymerase chain reaction (PCR)-based method namely inter simple sequence repeat (ISSR) was employed to assess genetic stability in tissue culture-derived Dictyospermum ovalifolium plantlets. To study genomic stability of micropropagated plants, 14 individuals were randomly tagged among a population of 2500 regenerants and were compared with single donor mother plant. A total of 51 clear and reproducible bands ranging from 200 bp to 2.1 kb were scored corresponding to an average of 3.64 bands per primer. Two of the 51 bands were polymorphic (3.92 %) among 14 individuals, thus indicating the occurrence of low level genomic variation in the micropropagated plants. Cluster analysis indicates that genetic similarity values were 0.978 which allows classification of the plants to distinct groups. Further an attempt was made to reintroduce the micropropagated plants into their natural habitat. Over one thousand six hundred fifty plants were successfully established.

Non-transformed and transformed embryogenic cultures of alfalfa (Medicago sativa L. cv. Zaječarska 83), long-term maintained on growth regulator-free medium, were histologically analyzed. In all examined cultures, somatic embryos at various stages of development were observed and secondary embryos were formed in the cotyledonary, hypocotylary and radicular region of the primary embryos. Detailed histological analysis of the torpedo shape somatic embryo revealed that secondary somatic embryos arose directly from single epidermal cells of hypocotylary axis after an unequal periclinal division. Bipolar proembryos were composed of one smaller cytoplasm rich cell and one larger more vacuolated cell. Further cell division pattern was similar for both non-transformed and transformed embryos. However, multicellular origin of secondary embryos in a direct process and even from callus can not be excluded.

A quantitative trait loci (QTL) approach was applied to dissect the genetic control of the common wheat seedling response to osmotic stress. A set of 114 recombinant inbred lines was subjected to osmotic stress from the onset of germination to the 8^th day of seedling development, induced by the presence of 12 % polyethylene glycol. Root, coleoptile and shoot length, and root/shoot length ratio were compared under stress and control conditions. In all, 35 QTL mapping to ten chromosomes, were identified. Sixteen QTL were detected in controls, 17 under stressed conditions, and two tolerance index QTL were determined. The majority of the QTL were not stress-specific. In regions on five chromosome arms (1AS, 1BL, 2DS, 5BL and 6BL) the QTL identified under stress co-mapped with QTL affecting the same trait in controls, and these were classified as seedling vigour QTL, in addition to those expressed in controls. Tolerance-related QTL were detected on four chromosome arms. A broad region on chromosome 1AL, including five QTL, with a major impact of the gene Glu-A1 (LOD 3.93) and marker locus Xksuh9d (LOD 2.91), positively affected root length under stress and tolerance index for root length, respectively. A major QTL (LOD 3.60), associated with marker locus Xcdo456a (distal part of chromosome arm 2BS) determined a tolerance index for shoot length. Three minor QTL (LOD < 3.0) for root length and root/shoot length ratio under osmotic stress were identified in the distal parts of chromosome arms 6DL (marker locus Xksud27a) and 7DL (marker locus Xksue3b). Selecting for the favourable alleles at marker loci associated with the detected QTL for growth traits may represent an efficient approach to enhance the plants' ability to maintain the growth of roots, coleoptile and shoots in drought-prone soils at the critical early developmental stages.

Hairy roots of Plumbago indica were established at high frequency (90 %) by infecting leaf explants with Agrobacterium rhizogenes strain ATCC 15834. The axenic root cultures were established under darkness in hormone-free liquid Murashige and Skoog medium containing 3 % sucrose. The highest plumbagin content was found to accumulate in roots at their exponential phase of growth. A low pH (4.6) and a low concentration of sucrose (1 %) were beneficial for root growth in darkness, while pH 5.6 and 3 % sucrose under continuous irradiance enhanced plumbagin accumulation in roots up to 7.8 mg g^-1(d.m.). Direct shoot regeneration from hairy root culture was also achieved under continuous irradiance, thus indicated an easy way of obtaining transformed P. indica plants.

Seed germination and micropropagation protocols of the medicinal species Maytenus canariensis (Loes.) G. Kunkel & Sunding were optimized. In vitro seed germination occurred (86 to 94.7 %) only after treatment of the seeds with H₂SO₄, followed by surface sterilization and culture on solid nutrient medium without any growth regulators. Micropropagation failed when explants were taken from mature trees, and browning of the nutrient medium frequently occurred despite testing many growth media. Nonetheless, adventitious shoot regeneration was achieved employing axillary or apical buds taken from 2-2.5 months old plantlets obtained after in vitro germination of seeds, following culture on nutrient media supplemented with benzylaminopurine, kinetin and naphthalenacetic acid (NAA), attaining up to 3.9 shoots per explant, after 4-6 months. Root induction was best on a medium containing 4.0 mg dm^-3 NAA, achieving a 100 % induction. After hardening of rooted plants, survival after transfer to soil was 71.43 %.

A near isogenic line (NIL) of Brassica oleracea var. botrytis with resistant and susceptible lines C712 and C731, was used in this study. More than 100 differentially expressed cDNA fragments were obtained from black rot resistant cauliflower plants obtained using cDNA-amplified fragment length polymorphism (AFLP) after infection with the pathogen. Thirteen of these fragments were cloned and subjected to reverse Northern blot analysis using both infected and control cDNA pools. Two positive clones, M2 and M6, were isolated. Northern dot blot and Northern blot analyses showed that M2 was constitutively expressed, whereas M6 contained a gene that was differentially expressed during pathogen infection. Moreover, M6 cDNA fragment was also highly expressed 16-24 h after H₂O₂ treatment. Southern blots showed that M6 is a single copy gene in the cauliflower genome, and encodes a protein with 84 % homology to gene on Arabidopsis chromosome 1. The deduced M6 protein has 91 % positive homology with the Arabidopsis 2A6 protein, which regulates ethylene synthesis; 76 % homology with a 1-aminocyclopropane-1-carboxylate oxidase (ACO), the last enzyme in ethylene synthesis; and 70 % homology with an ethylene induced DNA binding factor. These results suggest that M6 gene fragment is a new H₂O₂ downstream defense related gene fragment and can be induced by Xanthomonas campestris pv. campestris and H₂O₂.

Effects of exogenous salicylic acid (SA) on plant growth, contents of Na, K, Ca and Mg, activities of superoxide dismutase (SOD), guaiacol peroxidase (GPX), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), glutathione reductase (GR) and catalase (CAT), and contents of ascorbate and glutathione were investigated in tomato (Lycopersicon esculentum L.) plants treated with 100 mM NaCl. NaCl treatment significantly increased H₂O₂ content and lipid peroxidation indicated by accumulation of thiobarbituric acid reactive substances (TBARS). A foliar spray of 1 mM SA significantly decreased lipid peroxidation caused by NaCl and improved the plant growth. This alleviation of NaCl toxicity by SA was related to decreases in Na contents, increases in K and Mg contents in shoots and roots, and increases in the activities of SOD, CAT, GPX and DHAR and the contents of ascorbate and glutathione.