To investigate whether exogenous sucrose can protect cucumber from water stress, cucumber (Cucumis sativus L.) seedlings were pretreated with 90 mM sucrose or 90 mM mannitol for 1 d and then were dehydrated with 10 % (m/v) polyethylene glycol (PEG) 6000 for further 1 d. Dehydration inhibited plant growth and decreased osmotic potential and relative water content (RWC) in leaves. The pretreatment with 90 mM sucrose further reduced the osmotic potential but increased the RWC and alleviated the growth inhibition. Compared with the PEG treatment alone, the combination of sucrose + PEG increased the activities of superoxide dismutase, guaiacol peroxidase, glutathione reductase, dehydroascorbate reductase, monodehydroascorbate reductase, ascorbate peroxidase, and glutathione peroxidase, and elevated the content of endogenous sucrose, glucose, and fructose together with the activities of soluble acid invertase and neutral invertase. This was in accordance with the enhanced transcription of genes encoding copper/zinc superoxide dismutase, guaiacol peroxidase, and glutathione reductase. Furthermore, the sucrose pretreatment decreased the content of malondialdehyde and hydrogen peroxide and increased the content of ascorbate, reduced glutathione, and proline under the dehydration. Taken together, the pretreatment with 90 mM sucrose, but much less with mannitol, induced antioxidants, proline, and soluble sugars and thus reduced dehydration-caused damage to the cucumber seedlings.

Barley (Hordeum vulgare L.), an important food and fodder crop, is potentially tolerant to salinity. To identify quantitative trait loci (QTLs) controlling salt tolerance, the population of 162 recombinant inbred lines (RILs) derived from F8 generation of Arigashar (an extremely salt tolerant Iranian six-rowed barley landrace) crossed with Igri (a salt semi-sensitive two-rowed cultivar) were evaluated. The growth of shoots, roots, and coleoptiles, and root numbers are four important growth characteristics severely affected by salt stress at seedling growth stages. A linkage map was constructed using 106 AFLP and SSR markers spanning six barley chromosomes including 2(2H), 3(3H), 4(4H), 7(5H), 6(6H), and 1(7H). Out of totally 26 detected QTLs, 17 QTLs were found effective for salt tolerance at 250 and 350 mM NaCl which localized on chromosomes 2H, 3H, 4H, 6H, 7H, and linkage group L1, whereas considering equivalent overlapped QTLs with a pleiotropic effect led to detection of totally 9 distinctive QTLs (QClgH2.1b, QSdgH2.1b, QSlgH2.1c, QNrgH2.1b, QTwgH2.2c, QSdg3Hb, QSlg4Hb1, QClg4Hb, and QSlg6Hc2) effective for salinity tolerance. 2(2H), 4(4H), and 6(6H) were major chromosomes harboring QTLs which effectively controlled salt tolerance in the Igri×Arigashar population. An interesting QTL, QTwg4Hc, was localized on chromosome 4H in the XE41-M61 marker distance that controls several traits including shoot and coleoptile lengths and shoot fresh mass under salt stress. A dense marker cluster around a resistance gene could offer a starting point for positional cloning.

Protein synthesis is a ubiquitous and essential process in all organisms, including plants. It is primarily regulated at translation initiation stage which is mediated through a number of translation initiation factors (eIFs). It is now becoming more apparent that in addition to synthesis of proteins, eIFs also regulate various aspects of plant development and their interaction with environment. Translation initiation factors, such as eIF3, eIF4A, eIF4E, eIF4G, and eIF5A affect different processes during vegetative and reproductive growth like embryogenesis, xylogenesis, flowering, sporogenesis, pollen germination, etc. On the contrary, eIF1A, eIF2, eIF4, and eIF5A are associated with interaction of plants with different abiotic stresses, such as high temperature, salinity, oxidative stress, etc. Similarly, eIF4E and eIF4G have roles in interaction with many viruses. Therefore, the translation initiation factors are important candidates for improving plant performance and adaptation. A large number of genes encoding eIFs can functionally be validated and utilized through genetic engineering approaches for better adaptability and performance of plants by inhibiting/minimizing or increasing expression of desired eIF(s).

The effects of a short (30 min) heat shock (HS) on plants subsequently grown under a salinity stress (SS, 200 mM NaCl) for 10 d were investigated in barley (Hordeum vulgare L.) cv. Tokak 157/37. The maximum temperature for HS allowing plant survival was 45 °C. The root length was significantly decreased by SS, whereas HS alone did not affect root growth. Interestingly, HS stimulated root elongation under SS. An osmotic adjustment was promoted in leaves by SS. On the contrary, HS increased the osmotic potential in leaves in the absence of SS, and partly counteracted the effect of SS in the HS+SS treatment. Cu/Zn-SOD, HvAPX, HvCAT2, HSP17, HSP18, and HSP90 were transcribed in leaves of HS-treated plants, but not in control plants. The HSP70 was constitutively transcribed in both the SS and control plants, but after HS, a shorter amplicon was also observed. The genes coding antioxidants, Cu/Zn-SOD, HvCAT2 and HvAPX, were differentially influenced by SS or HS+SS in the roots and leaves. In the roots, the mRNA content of BAS1, HvDRF1, HvMT2, and HvNHX1 increased after the HS treatment. In a recovery experiment in which plants were grown to maturity after HS and HS+SS stress exposure, the plant height increased and the time to maturity was reduced in comparison with SS. Our results show that HS could stimulate plant growth and reduce some of the negative effects of SS, and that it affected the transcription of several stress-related genes.

Cytosine methylation (C meth) is a ubiquitous regulator of gene transcription. The maize gene ZmGRP3 is a notable marker for root initiation, but how its root-specific transcription is regulated is not understood. Here, bisulfite sequencing and a C meth sensitive Southern blot assay were used to show that the transcription of ZmGRP3 was promoted by a reduction in the extent of C meth both in its promoter and in the vicinity of its translation start site. The result was validated by revealing the effect of 5-aza-2-deoxycytidine on the C meth status in various seedling organs. An analysis of methylation patterns indicates that the C meth of cytosine-guanine dinucleotides was the most important determinant of transcription, however, the C meth of CHG or CHH trinucleotides had little influence.

Two barley (Hordeum vulgare L.) cultivars, Czech spring cv. Amulet and Syrian landrace Tadmor, were subject to different salinity treatments: 1) the NaCl concentration was gradually increased from 0 (the control) to either 100 (a moderate salt stress) or 300 mM NaCl (a high salt stress), 2) the NaCl concentration was increased directly either from 0 to 300 mM NaCl or from 100 to 300 mM NaCl, and 3) a recovery when all variants were transferred back to control conditions and cultivated for seven additional days before sampling. The following parameters were determined: water saturation deficit (WSD), osmotic potential (ψ_s), leaf proline content, maximum quantum yield of photosystem (PS) II photochemistry (measured as variable to maximum chlorophyll a fluorescence ratio, F_v/F_m), and relative accumulation of dehydrins (DHN). Both quantitative and qualitative differences in dehydrins were found between NaCl-treated Amulet and Tadmor. A principal component analysis (PCA) of all experiment data revealed a differential ability of Amulet and Tadmor to recover after the 300 mM NaCl treatments indicating better salt tolerance in Tadmor. Correlation analyses have shown statistically significant correlations between WSD, ψ_s, proline, and DHN.

Lipase class 3 is part of the triacylglycerol lipase family involved in lipid degradation, esterification, and transesterification processes in plants. In this study, a lipase class 3 gene and promoter from oil palm (Elaeis guineensis Jacq.) were isolated and characterized by Northern blot, Southern blot, oil palm genome sequence, and transient expression GUS assay. The full-length lipase class 3 (FLL1) deduced polypeptide encoded 483 amino acids and was identical to that deduced from lipase (EgLip1) cDNA (GI: 409994625). It contained the lipase consensus sequence, GxSxG motif, and a putative catalytic triad and had a 3-dimensional protein model similar to that of a lipase from Giberella zeae with a 50 % identity. The Northern blot and reverse transcription polymerase chain reaction (RT-PCR) show that FLL1 was predominantly expressed in the mesocarp and the expression increased as fruits reached maturity. A lower expression was detected in germinated seedlings and especially in roots. The expression of FLL1 was also enhanced in the mesocarp of cold treated fruits. A high oil accumulation in the mesocarp during fruit development makes this tissue a suitable target for a genetic modification, hence the isolation of the FLL1 promoter. The transient expression of the β-glucuronidase (GUS) gene driven by the FLL1 promoter detected the GUS expression in mesocarp slices, especially in vascular bundles. This suggests the potential role of using the promoter as tool to direct the expression of a transgene to the mesocarp of transgenic oil palm.

The growth of the Cd-hyperaccumulator Solanum nigrum L. and its physiological responses to a short-term (7 d) Cd stress and to exogenous methyl jasmonate (MeJA) were investigated. Compared with the leaves of S. nigrum, the roots were more liable to Cd and showed a significantly decreased dry mass and increased malondialdehyde content. Cd accumulation in the shoots and roots of S. nigrum were proportional to the Cd concentration in the hydroponic solution. The application of a low concentration of MeJA (0.01 μM) significantly reduced the translocation/accumulation of Cd in both the shoots and roots compared with a 40 mg dm^-3 Cd treatment only. Moreover, 40 mg dm^-3 Cd significantly decreased the activity of leaf superoxide dismutase, but 0.01 μM MeJA restored it. MeJA also enhanced the activity of catalase in the leaves but showed no significant effect on peroxidase activity. The content of both endogenous jasmonic acid (JA) and MeJA in the leaves of S. nigrum increased with the increase of exogenous MeJA concentration.

The GhMYB9 encodes a R2R3 MYB transcription factor in the upland cotton (Gossypium hirsutum L.) genome. Our studies show that GhMYB9 predominantly expressed in flowers and fibers. To gain a better understanding of its regulatory mechanism, we isolated the 5'-flanking region of GhMYB9 which was 1 487 bp in length. The cis-acting element prediction shows that this region contained the basic structure of the core promoter elements (TATA-box, CAAT-box) and the transcription start site (TSS). Other motifs, such as defense and stress responsiveness (TC-rich repeats), anaerobic induction (ARE), and MYB binding sites involved in drought-inducibility (MBS), were also found. Histochemical assay shows that the GhMYB9 promoter governed β-glucuronidase (GUS) expression mainly in seeds, fibers, and flowers of transgenic cotton. Also, the activity of the promoter was induced by auxin in fibers of transgenic cotton. This is consistent with its transcript abundance in different tissues. A further deletion analysis confirms that a promoter region from -1 231 to -860 was required for auxin response. Our findings provide a useful reference for the understanding of the transcriptional regulation mechanism of the GhMYB9 gene.

Actinidia kolomikta (Rupr. & Maxim.) Maxim. leaves showed dramatic colour changes during plant growth phases, and we studied structure and optical properties of variegated leaves. Leaf surface cells were smooth, and there were no surface appendages (wax or trichomes) observed in variegated leaves. Palisade tissue cells in white and pink leaves were looser and contained relatively fewer chloroplasts. White leaves contained many intercellular spaces between the epidermal and mesophyll cells or within the palisade cell layer. Variegated leaves had three distinct radiation reflection patterns: a bright white area, a spotted pattern, and a polygonal pattern. Reflectance at 450-1100 nm from the adaxial surface of white leaves was greater than that of green leaves, but anthocyanin accumulation in pink leaves decreased the reflectance at 500-600 nm. When variegated leaves turned green, the reflectance at 500-600 nm increased. On abaxial surfaces, the reflectance of variegated leaves was similar to green leaves at 450-700 nm. In conclusion, reflection patterns and the formation of variegated leaves of A. kolomikta were significantly correlated with the leaf anatomy. The white and pink colours of leaves were a result of an internal reflection between air spaces and cells in the leaves, chlorophyll deficiency in palisade tissue, and anthocyanin accumulation. Variegated leaves turned green when the chlorophyll content in palisade tissue increased.

In order to identify target region amplification polymorphism (TRAP) markers linked to three physiological traits in wheat (Triticum aestivum L.), the segregating F₄ population from the cross between drought-sensitive (Yecora Rojo) and drought-tolerant (Pavon 76) genotypes was made. The parents and 150 F₄ families were evaluated phenotypically for drought tolerance using two irrigation treatments [2.5 and 7.5 m³(H₂O) m^-2(soil)]. Using 40 different TRAP primer combinations tested for polymorphism in parental and F4 family genotypes, the results revealed that quantitative trait locus (QTL) for chlorophyll content was associated with TRAP 5, TRAP 14, and TRAP 20 and explained 18, 16, and 23 % phenotypic variation, respectively. The genetic distance between chlorophyll content QTL and TRAP 5, TRAP 14, and TRAP 20 were 12.3, 19.8, and 13.6 cM, respectively. QTL for flag leaf senescence was associated with TRAP 2, TRAP 3, TRAP 15, and TRAP 16 and explained 33, 27, 28, and 23 % phenotypic variations, respectively. The genetic distance between flag leaf senescence QTL and TRAP 2, TRAP 3, TRAP 15, and TRAP 16 were 9.4, 14.7, 18.1, and 17.3 cM, respectively. QTL for cell membrane stability was associated with TRAP 8, TRAP 9, and TRAP 37 and explained 27, 30, and 24 % phenotypic variation, respectively. The markers TRAP 8, TRAP 9, and TRAP 37 had genetic distances of 17.0, 10.0, and 9.0 cM, respectively. Therefore, these TRAP markers can be used in breeding for drought tolerance in wheat.

This study was carried out to understand the mechanism of protection of plants under cold stress by exogenous 24-epibrassinolide (EBR). The eggplant (Solanum melongena L.) seedlings were pretreated with five concentrations of EBR (0, 0.05, 0.1, 0.2 and 0.4 °M) and then exposed to day/night temperatures of 10/5 °C for 8 d. The results show that EBR, especially 0.1 °M EBR, dramatically alleviated growth suppression and a decrease in chlorophyll content and photosynthetic rate caused by the cold stress. In addition, EBR also decreased malondialdehyde content and O₂ ^.- production rate induced by the cold stress, and increased the activities of superoxide dismutase, guaiacol peroxidase, catalase, and ascorbate peroxidase, and proline content. The results of the present study suggest that exogenous EBR could improve cold tolerance of eggplant by regulating photosynthesis and antioxidative systems.

The effect of UV-B irradiation at temperatures of 22 and 4 °C on flash induced oxygen yields, photochemical activity, and energy transfer in pea thylakoid membranes in the absence and presence of scavengers of reactive oxygen species (ROS) was studied. Three different scavengers were used: dimethyl sulfoxide (DMSO), histidine (His), and n-propyl gallate (nPG). As result of the UV-B treatment of isolated membranes, the flash oxygen yields were considerably affected - the amplitudes decreased and the oscillation pattern was lost. The analysis of the flash oxygen yields and initial oxygen burst showed alterations of a number of oxygen evolving centers in the S0 state as well as changes of decay kinetics of the oxygen burst under continuous irradiation. ROS scavengers exhibited more or less expressed protective effects, nPG being the most effective against UV-B induced damages of the flash oxygen yields. At both the temperatures, photosystem II (PS II) mediated electron transport was more sensitive to the UV-B treatment in comparison with photosystem I (PS I). The analysis of 77 K fluorescence spectra showed that the fluorescence ratio F735/F685 increased by the UV-B treatment probably due to a redistribution of excitation energy between both photosystems most likely caused by partial unstacking and due to a decrease of PS II fluorescence resulting from reaction center-type quenching. The nPG was the most powerful scavenger which protected the oxygen evolution capacity of PS II in the absence and presence of an exogenous electron acceptor to the highest extent.

BABY BOOM (BBM), initially identified in Brassica napus, can enhance the shoot regeneration capacity in tissue culture and is involved in the conversion from the vegetative to embryogenic state. This study aimed to isolate BBM orthologue genes from Rosa canina and analyse their functions. Two full-length cDNAs, designated RcBBM1 and RcBBM2, were isolated from R. canina by the rapid amplification of cDNA ends (RACE). The predicted amino acid sequences of the two RcBBMs contained the bbm-1 motif and the motifs typically conserved in the eudicotANT (euANT) lineage. Phylogenetic tree analysis showed that the RcBBMs were most closely related to the BBM orthologue genes identified in Glycine max and Medicago truncatula. The transcripts of the RcBBMs were detected in young roots, calluses, and protocorm-like bodies (PLBs), whereas they were undetectable in stems, leaves, and flowers. RcBBM1-GFP and RcBBM2-GFP fusion proteins were both localized in the nucleus. 35S::RcBBM1 and 35S::RcBBM2 transgenic Arabidopsis thaliana lines exhibited enhanced shoot regeneration capacity in tissue culture, but did not undergo spontaneous somatic embryogenesis. The results suggest that RcBBMs may be candidate genes for improving the shoot regeneration efficiency of R. canina.

Two types of hairpin RNA (hpRNA) constructions were designed using a chimeric gene formed from two genes, the coat protein (CP) gene or the silencing suppressor gene, from the Cucumber mosaic virus (CMV) and the Potato virus Y (PVY_N), respectively; one type generated a single hairpin structure, whereas the other formed a two-hairpin structure. Four constructs, pDCPSH (double CP gene fragments, single hairpin), pDCPDH (double CP gene fragments, double hairpins), pHC2bSH (two silencing suppressor gene fragments, single hairpin), and pHC2bDH (two silencing suppressor gene fragments, double hairpins), were individually introduced into tobacco plants. A transcript analysis demonstrates that the small interference RNA (siRNA) processing efficiency was greater with the double-hairpin construct than with the single-hairpin construct, although the expression of their target genes were similar. A viral resistance assay shows that the transgenic tobacco plants effectively resisted a mixed infection of CMV and Potato virus Y (PVY^N) and that pDCPDH exhibited the highest silencing efficiency. The accumulation of siRNA in the inoculated transgenic plants expressing different hairpin structures was similar. A genetic analysis reveals that viral resistance in the transgenic plants was stably inherited from the T₀ to T₁ generation. A transcript analysis and a viral resistance assay indicate that the double-hairpin structure of the same target sequences tended to produce more siRNA before the virus inoculation and thus strengthened RNA-mediated viral resistance.

Interaction between aluminum (Al) and boron (B) in Al accumulator species has not been characterized so far. In this work, tea [Camellia sinensis (L.) O. Kuntze] plants were cultivated hydroponically and treated with adequate (control) or low B supply (-B) without or with 300 μM Al (-B+Al) for 14 weeks. Growth of B-deficient plants was completely resumed by Al supplementation or even surpassed control plants regarding shoot biomass. Net photosynthetic rate was negatively influenced by the low B supply, and the Al treatment increased it up to the level of the control plants that was reflected in the higher content of saccharides. The activity of ascorbate peroxidase (APX) in the younger leaves decreased at the low B supply accompanied with an increased H₂O₂ content. The Al treatment increased the APX activity up to the level of the control plants simultaneously with the reduction of H₂O₂. Activities of superoxide dismutase (SOD) and peroxidase (POD) increased in the low B plants and the Al treatment augmented this effect. The content of malondialdehyde (MDA) in the leaves increased by low B but declined upon the Al treatment. In the Al-treated plants, the activity of nitrate reductase (NR) and the content of free α-amino acids exceeded those of the control plants, and nitrite concentration diminished. The shoot and root B content of the B-deficient plants supplemented with Al was similar with the B-sufficient ones. The results demonstrate that the up-regulation of C and N metabolism, the activation of antioxidative defense, and the enhancement of B uptake and transport were mechanisms for growth amelioration of the B-deficient plants by Al supplementation in tea.

Two of the abundant transcripts encoding type 2 metallothionein (MT) proteins designated as MET2a and MET2b were selected in our previous study due to their high abundance (16.05 %) in the suppression subtractive hybridization library and their involvement in fruit development and maturation. The present study involves the isolation of the full-length cDNA encoding MET2a and MET2b from the ripening oil palm fruit mesocarp, examining their expression pattern compared to the other two previously reported type-3 MT members (MT3-A and MT3-B) in various oil palm organs including different vegetative and reproductive tissues. The full-length cDNA sequences of MET2a and MET2b were 571 and 553 bp and they were designated as EgMT2a and EgMT2b, respectively. The sequences of the EgMT2a and EgMT2b were then compared for sequence similarities in the database using both BLASTN and BLASTX programs. Their sequences were homologous (67-77 %) with several type-2 MTs in plants. All four MT encoding genes were differentially expressed in the ripening oil palm mesocarp tissues, but undetectable in the vegetative tissues examined. All MT genes examined were significantly up-regulated in the mature developmental stages of oil palm fruit mesocarp, except for EgMT2b which was expressed only at 17 weeks after anthesis. The type 2 MT proteins are related to a greater degree to the late fruit-ripening stage than the type 3 MT proteins consistent with their reported functions in homeostasis or detoxification. The findings in the present study contribute to better understanding the molecular mechanisms involved in fruit ripening in oil palm.

Needles of Larix gmelinii seedlings grown under different irradiances (100, 52, and 26 % of natural sunlight) were collected from June to August 2009. The content of phenolic compounds and condensed tannins in needles were strongly affected by different irradiances. The highest content of phenolic acids occurred under the lowest irradiance. Chlorogenic acid and syringic acid were detected only under the shade. In contrast, the needles under full irradiance showed the highest content of condensed tannins.

Water transport across the cell membranes is regulated largely by a family of proteins known as aquaporins (AQPs). Plasma membrane intrinsic protein (PIP) is an important subfamily of plant AQPs localized on the plasma membrane. To investigate the molecular mechanism of water regulation in seed germination, seven genes encoding PIP were initially cloned and sequenced from the germinating seed cDNA pool of Brassica napus. They belong to the PIP1 and PIP2 subfamilies. The transcription of the seven cloned genes plus three previously identified AQP genes from B. napus were analyzed in different organs and different stages of seed germination by quantitative real-time PCR (qRT-PCR). The results show that the expressions of the ten AQP genes were lower or scarcely detected in dry seeds, but were up-regulated during germination as well as in young seedlings. In addition, the expression of these ten AQP genes in response to an abiotic stress during seed germination was investigated and the results also show differential responses to abiotic stress treatments. Our findings suggest that these ten genes play different roles during plant development and response to abiotic stresses in B. napus.

The effects of salt stress on dry mass, lipid peroxidation, polyphenol and hydrogen peroxide content and activities of antioxidative enzymes were investigated in seedlings of Salicornia persica and S. europaea grown in vitro. Seeds were germinated under a broad range of NaCl concentrations (0, 100, 200, and 300 mM) on Murashige and Skoog medium for 45 d. Dry mass of both species increased at low (100 mM) salinity but decreased at higher NaCl concentrations. Malondialdehyde (MDA) content decreased at low salinity, whereas increased at 200 and 300 mM NaCl. H₂O₂ content in S. europaea was considerably enhanced by salinity, but it was not significantly affected in S. persica. The salt stress progressively enhanced the polyphenol content in S. persica, whereas in S. europaea, it increased with respect to the control only at higher salinities. In both species, the salinity progressively enhanced the superoxide dismutase (SOD) and peroxidase (POD) activities, whereas the CAT activity was only registered at the low salinity and the APX activity decreaseed in both species. The results indicate that S. persica exhibited a better protection mechanism against oxidative damage and it is more salt-tolerant than S. europaea.

Plant vacuoles play several roles in controlling development, pathogen defence, and stress response. γVPE is a vacuolarlocalised cysteine protease with a caspase-1 like activity involved in the activation and maturation of downstream vacuolar hydrolytic enzymes that trigger hypersensitive cell death and tissue senescence. This work provides evidence that γVPE is strongly expressed in Arabidopsis guard cells and is involved in water stress response. The γvpe knock-out mutants showed reduced stomatal opening and an increased resistance to desiccation suggesting a new role of γVPE in control of stomatal movements.

Sulfur dioxide (SO₂) is a well-known and widespread air pollutant but it also acts as signaling molecule in various processes in animals. However, there is limited information on the role of SO₂ in plants except of its toxicity. Here we studied the role of SO₂ on stomatal movements in sweet potato (Ipomoea batatas) leaves. SO₂, generated by Na₂SO₃/NaHSO₃ solutions, was applied on epidermal strips. We found that the SO₂ donor induced stomatal closure in a dose-dependent manner. Rapid increases in endogenous hydrogen sulfide and nitric oxide content levels were observed in leaves after the treatment with the SO₂ donor. The SO₂-induced stomatal closure was reversed by the H₂S scavenger hypotaurine and the NO-specific scavenger cPTIO. Our results indicate that the SO₂-induced stomatal closure was likely mediated by the H₂S and NO signaling pathways.

The present research is aimed towards molecular marker assisted pyramiding Tomato leaf curl virus (ToLCV) disease resistance genes into two ToLCV susceptible tomato (Solanum lycopersicum L.) cvs. Pbc and H-86 (resistance genes recipient parents). Resistance gene donors were EC-538408 (Solanum chilense) and EC-520061 (S. peruvianum) in the case of cv. Pbc, and EC-520061 (S. peruvianum) and H-24 (S. lycopersicum) in the case of cv. H-86. A ToLCV resistance gene associated co-dominant simple sequence repeat (SSR) marker SSR-218 was used to discriminate between homozygotes and heterozygotes at the seedling stage prior to pollination, which enabled the rejection of nontarget back crosses and pyramiding progenies of the crosses PbcxEC-520061 and H-86xEC-520061, whereas SSR-306 was used for the cross PbcxEC-538408. Ty-2 gene cleaved amplified polymorphic sequences (CAPS) marker was used for the cross H-86xH-24. Out of 279 pyramiding progenies of the cross PbcxEC-538408/PbcxEC-520061, total 91 plants showed the presence of both resistance allele 1 and 2 along with both susceptibility alleles, and in 243 pyramiding progenies of the cross H-86xEC-520061/H-86xH-24, total 82 plants showed the presence of both resistance allele 1 and Ty-2 along with both susceptible alleles. The pyramiding lines that carried both pyramided resistance genes were resistant to tomato leaf curl disease throughout its life cycle.

LeAN2 encoding an anthocyanin-associated R2R3-MYB transcription factor was isolated from tomato. The expression of LeAN2 in tomato was induced by low temperature and oxidative stress. Green fluorescent protein was fused to LeAN2 and the complex was expressed transiently in onion epidermal cells. Green fluorescence was observed only in the nucleus. Overexpression of LeAN2 under the control of the CaMV35S promoter in tobacco induced expression of several anthocyanin biosynthetic genes and the content of anthocyanin was markedly higher in transgenic tobacco compared with wild type plants. Transgenic tobaccos conferred tolerance to chilling stress by maintaining a higher chlorophyll content, net photosynthetic rate, and maximal photochemical efficiency of PS II compared to the wild type plants. Furthermore, the transgenic plants showed lower ion leakage, a lower content of reactive oxygen species, and a higher content of non-enzymatic antioxidans under the chilling stress. They also showed an enhanced resistance to the oxidative stress induced by methyl viologen based on a decreased chlorophyll content loss, lower ion leakage, and an enhanced maximal photochemical efficiency of PS II. These results indicate that overexpression of LeAN2 resulted in an increased anthocyanin accumulation and enhanced resistance to the chilling and oxidative stresses in transgenic tobacco.

ATP binding cassette (ABC) proteins constitute one of the largest families of transporters. In Arabidopsis thaliana, over 100 genes encoding ABC transporters have been identified. Here, we described the expression pattern of AtABCC13/MRP11, a member of the multidrug resistance associated protein MRP/ABCC subfamily, previously uncharacterized. The histochemical analysis of transgenic Arabidopsis harboring AtABCC13 promoter-β-glucuronidase gene fusion shows that the AtABCC13 expression was specifically associated with vascular bundles. Moreover, AtABCC13 displayed a complex hormonal regulation. β-glucuronidase (GUS) fluorimetric assays revealed that the gene expression was induced by gibberellic acid and downregulated by naphthalene acetic acid, abscisic acid, and zeatin. Because AtABCC13 is also expressed during seed development and during germination, its expression was assessed upon exposure to various nutrients: nitrate, phosphate, and sucrose stimulated the AtABCC13 expression in seedlings, whereas their lack strongly reduced it.

Interactions between three genotypes of a silver fir (Abies alba Mill.) embryogenic callus and Heterobasidion abietinum, H. parviporum, and H. annosum were examined in dual cultures. The aim of this study was to determine whether dual cultures can be used to evaluate the degree of fungal virulence at an embryogenic level, and whether different genotypes of a callus show different susceptibility. The dual cultures were performed on Schenk and Hildebrandt medium. Mycelial growth of H. parviporum and H. annosum was significantly stimulated in the presence of the callus but was not directional in nature. The embryogenic callus died between six and nine days after being colonized by H. parviporum suggesting that this was the most virulent species. By contrast, the callus remained healthy for up to 50 d after colonization with H. abietinum suggesting that this was the least virulent species. The callus of the A. alba genotype which originated in the mountain region of Poland remained healthy and alive for a significantly longer period than the other two genotypes in the dual cultures with all three Heterobasidion species even though overgrown by mycelium suggesting that the mountain genotype had the strongest defence response to Heterobasidion infection.

To gain a deep understanding of the regulatory mechanism of Cu-responsive microRNAs (miRNAs) in non-heading Chinese cabbage (Brassica campestris ssp. chinensis Makino), the transcription of 10 annotated stress-inducible miRNAs and their target genes were investigated in two cultivars Suzhouqing and Wutacai exposed to excess of copper. Results show that these miRNAs were negatively correlated with their target genes under the Cu stress and showed different transcriptions in different tissues and cultivars. The transcriptions of bra-miR1530a and bra-miR1533v were highest in petioles and lowest in roots. Bra-miR1533ah, bra-miR1533m, bra-miR1533t, bra-miR414a, and bra-miR398b had the highest and lowest transcriptions in leaves and roots, respectively. In contrast, the transcription of bra-miR172f was highest in roots and lowest in leaves. Bra-miR1533aj and bra-miR1533d had similar transcriptions in petioles and leaves. The promoter analysis further revealed that seven miRNAs contained the Cu-response element (CuRE). In addition, miRNAs with more CuREs in the 5'-flanking sequences showed a lower expression following the Cu treatment. It imply that CuREs likely played a role in increasing the response to Cu in non-heading Chinese cabbage.

Anthocyanins from mulberry fruits are used in medicine. However, little anthocyanin can be detected in other tissues and sometimes also mulberry fruits are colorless. The aim of this study was to investigate which gene or genes have the strongest correlation with the anthocyanin biosynthesis. The expression of several anthocyanin synthesis genes were determined in different tissues of two white and two purple fruit cultivars. Genes encoding dihydroflavonol reductase (MaDFR) and anthocyanidin synthase (MaANS) showed a high expression only in fruit tissue of purple-fruit cultivars. During the development of mulberry fruits, the anthocyanin content was well correlated with the transcripts abundance of MaDFR, MaANS, and MaCHS (encoding chalcone synthase). The skin of female mulberry flowers turns red under irradiance because of up-regulated expressions of MaCHS, MaDFR, and MaANS. These three genes may control the anthocyanin biosynthesis in mulberry and up-regulation of them may greatly increase the anthocyanin content.

Aluminum stress usually reduces plant root growth due to the accumulation of Al in specific zones of the root apex. The objectives of this study were to determine the localization of Al in the root apex of Sorghum bicolor (L.) Moech. and its effects on membrane integrity, callose accumulation, and root growth in selected cultivars. Seedlings were grown in a nutrient solution containing 0, 27, or 39 μM Al³⁺ for 24, 48, and 120 h. The Al stress significantly reduced root growth, especially after 48 and 120 h of exposure. A higher Al accumulation, determined by fluorescence microscopy after staining with a Morin dye, occurred in the root extension zone of the sensitive cultivar than in the tolerant cultivar. The membrane damage and callose accumulation were also higher in the sensitive than resistant cultivar. It was concluded that the Al stress significantly reduced root growth through the accumulation of Al in the root extension zone, callose accumulation, and impairment of plasma membrane integrity.

Oxidative stress plays an important role in plant ageing and in response to different stresses. Oxidative DNA damage, unless repaired, may have detrimental consequences and increase genetic instability. Therefore, we determined the role of heat-shock induced oxidative stress on induction and repair of DNA damage in relation to oxidative stress tolerance in senescent tobacco plants. One-month-old (young) and three-month-old (senescent) plants were exposed to 42 °C for 2 and 4 h and left to recover at 26 °C for 24 and 72 h. The progression of senescence was characterized by the lower soluble protein and malondialdehyde content compared to young plants. Immediately after the heat shock, an increase in lipid peroxidation and guaiacol peroxidase activity, as well as DNA damage measured by the Comet assay were induced to higher extent in the young plants than in the senescent ones compared to their respective controls. Moreover, after 24-h recovery, the DNA damage further increased in the young plants whereas tendency of DNA repair was observed in the senescent plants. Upon 72-h recovery, no significant differences were noticed in all parameters studied (regardless of plant age) compared to the controls. The random amplified polymorphic DNA (RAPD) analysis confirmed genetic stability of the tobacco plants during the heat-shock exposures as well as the subsequent recovery periods.