Apple (Malus × domestica Borkh.) is a perennial woody plant that undergoes a period of dormancy (in cv. Jonathan between late September and mid-December) to survive freezing temperatures of winter. DORMANCY-ASSOCIATED MADS-BOX (DAM) genes play important roles in the regulation of growth cessation and terminal bud formation in peach. To understand the role of DAM orthologs in apple, we isolated and characterized four DAM-like genes (designated as MdDAMa, MdDAMb, MdDAMc, and MdDAMd) and monitored their expression in apical buds throughout the season by real-time quantitative polymerase chain reaction analyses. The transcription of MdDAMa peaked in October and that of MdDAMc was elevated from August to October, whereas MdDAMb and MdDAMd were practically undetectable. The tandemly arranged genes MdDAMa/MdDAMb and MdDAMc/MdDAMd were localized to chromosomes 16 and 8, respectively. Based on these observations, we infer that MdDAMa and MdDAMc acted in a dominant fashion on each locus and were correlated with the period of endodormancy.

The effects of acclimation to cold (4 °C) and heat (36/38/40 °C) on corresponding freezing and heat tolerances of one-year-old Trigonobalanus doichangensis seedlings were studied. In addition, the effects of abscisic acid (ABA) and salicylic acid (SA) pretreatments on the tolerance of this species to temperature extremes were tested. The results show that the content of soluble sugars increased with the duration of acclimation to cold (4 °C), and the relative electrical conductivity and malondialdehyde content increased significantly after 7 d; however, the content of proline did not vary significantly. After acclimation to cold for 3 and 7 d, the semilethal low temperature (LLT₅₀) was 0.8 and 1.1 °C lower, respectively, compared with that of the control. The maximum quantum yield of photosystem II (measured as variable to maximum fluorescence ratio, F_v/F_m) decreased significantly after freezing treatments (-4 to -8 °C), however, less when the plants were pretreated with 1-100 mg dm^-3 ABA. Acclimation to heat did not increase the semilethal high temperature (LHT₅₀). A low concentration (1 mg dm^-3) of SA increased LHT₅₀, but medium and high concentrations (10 and 100 mg dm^-3) decreased it. F_v/F_m decreased significantly after a heat shock (45-54 °C). The pretreatment with 1-50 mg dm^-3 SA ameliorated a subsequent heat (48 °C) stress.

Pepper (Capsicum annum L.) fruit colours vary from green, ivory, or yellow at the juvenile stage to red, orange, and yellow at the mature stage. Carotenoid accumulation causes fruit colour formation in ripe Capsicum fruits, and capsanthin is a main carotenoid in ripe red pepper fruits. In this study, pepper cultivars with red, yellow, and orange fruits were employed and four key genes named phytoene synthase (Psy), lycopene-β-cyclase (Lcyb), β-carotene hydroxylase (Crtz), and capsanthin/capsorubin synthase (Ccs) in the capsanthin biosynthetic pathway were analyzed. Results show that a clear expression of the Ccs gene in cv. CK7 (yellow) was detected, but the expressions of the Psy and Lcyb genes were low comparing with the other tested cultivars. In addition, the expression of the Ccs gene was not observed in cv. R37-1 (orange). Furthermore, though the four key genes (Psy, Lcyb, Crtz, and Ccs) were detected in red cultivar R15, the expressions of them were low. Sequence analysis further indicated that the Ccs genes in cv. CK7 and cv. R37-1 had a high sequence identity (97.36 %). Interestingly, amino acid sequences coded by the Ccs genes from cv. CK7, cv. R37-1, and cv. R15 were the same. The above results suggest that the genes Psy, Lcyb, Crtz, and Ccs were required for capsanthin synthesis in pepper, and their varied expression patterns resulted in the variety of pepper fruit colours.

The JNK motif is repeated 4 000 times in an additional heterochromatin band. Flanking sequences of a JNK region, which form extra heterochromatin in 2R rye (Secale vavilovii Grossh.) chromosomes, were studied using a genome walking technique. The results clearly indicate that there were blocks of JNK sequences adjacent to the R173 family of repeated sequences. Moreover, it appears that the R173 are sequences flanking in both directions, i.e., upstream and downstream. Downstream, the R173 is adjacent to the JNKs in an anti-parallel orientation, whereas upstream it is adjacent in a parallel orientation. In order to confirm the presence of the R173 sequence, fluorescence in situ hybridization was carried out. Using both JNK and R173 molecular probes, overlapping hybridization signals in the 2RL pair of chromosomes were observed, indicating an identical location of the two sequence elements.

Jatropha curcas L. is a perennial, drought-resistant, and non-food oilseed crop. The fatty acid composition of seed oil, especially the ratio of 16- to 18-carbon fatty acids, has a direct impact on the biodiesel quality. In plants, fatty acid chain lengths are mainly determined by the plastidial fatty acid synthase complex which includes three β-ketoacyl-acyl carrier protein synthases (KASs), KASI, KASII, and KASIII. The KASIII is thought to play a rate-limiting role in fatty acid synthesis. Here, we report the functional characterization of a putative JcKASIII gene from Jatropha curcas using Arabidopsis thaliana L. as model system. The transcripts of JcKASIII were detected in all tissues examined and increased in seeds. Overexpression of JcKASIII in Arabidopsis led to an increased content of palmitic acid and a higher ratio of 16- to 18-carbon fatty acids. Moreover, functional analysis of JcAKSIII in kasI or kasII knock down Arabidopsis mutants revealed that the composition of seed oil changed. Taken together, these results suggest that heterologous JcKASIII could function as one of the major regulators of fatty acid composition.

In plant cells, anion channels and transporters are essential for key functions. Members of the chloride channel (CLC) family located in intracellular organelles are required for anion accumulation, pH adjustment, and salt tolerance. Here, we cloned a maize (Zea mays L.) CLC gene, named ZmCLC-d, and found that its transcription was up-regulated under cold, drought, salt, and heat stresses, and after hydrogen peroxide (H₂O₂) and abscisic acid (ABA) treatments. The overexpression of ZmCLC-d in Arabidopsis conferred tolerance to cold, drought, and salt stresses; this tolerance was primarily displayed by an increased germination rate, root length, plant survival rate, antioxidant enzyme (catalase, peroxidase, and superoxide dismutase) activities, and a reduced accumulation of Cl^- in transgenic plants as compared with wild type (WT) plants. The accumulation of H₂O₂ and superoxide anion in leaves of the ZmCLC-d-overexpressing plants is much less than that of the WT plants. The expressions of some stress related genes, such as CBF1, CBF2, CBF3, DREB2A, and RCI2A, increased to a greater extent in the ZmCLC-d-overexpressing plants than in the WT. Our results strongly suggest that ZmCLC-d played an important role in stress tolerance.

We compared photosynthetic performance between cucumber (Cucumis sativus L.) leaves acclimated to saturating irradiances with high red: far red (R:FR = 10) and normal R:FR (= 1.4) ratios. The net photosynthetic rate (P_N) and stomatal conductance (g_s) of the leaves acclimated to high R:FR were greater than those of the leaves acclimated to normal R:FR; the greater g_s partly explains the greater P_N. The greater g_s of the high-R:FR-leaves probably resulted from a higher stomatal density and/or a greater size. P_N of the high R:FR leaves was still greater than that of the normal R:FR leaves at the same intercellular CO₂ concentration (c_i). This indicates that non-stomatal factors also increased the photosynthetic capacity of the high R:FR leaves. The maximum Rubisco carboxylase activity estimated from a P_N-c_i curve analysis was also greater in the high R:FR leaves, however, the intrinsic water-use efficiency (WUE_i = P_N/g_s) of the high R:FR leaves was lower than that of the normal R:FR leaves.

Roles of an altered porphyrin biosynthesis and antioxidants in protection against chilling and heat stresses were evaluated in rice (Oryza sativa L.). When exposed to the same exposure time (6 or 30 h), heat-stressed (45 °C) plants exhibited a less oxidative stress as indicated by a lower dehydration, ion leakage, and H₂O₂ production compared to chilling-stressed (4 °C) plants. Malondialdehyde production also increased after a mild chilling stress, whereas it increased only after a long-term heat stress. The content of protoporphyrin IX, Mg-protoporphyrin IX and its methyl ester, and protochlorophyllide drastically declined under both the stresses, particularly under the long-term heat stress. Greater increases in catalase and peroxidase activities in heat-stressed plants indicate more cofactors supplied for hemoproteins compared to those of chilling-stressed and untreated control plants. Intermediates of carotenoid biosynthesis, zeaxanthin and antheraxanthin, also increased under the chilling and heat stresses. In comparison to chilling-stressed plants, heat-stressed plants were more efficient in porphyrin scavenging and antioxidant enzyme responses, which may play crucial roles in plant protection under temperature stress, thereby suffering less from oxidative stress.

The secretory (Sec) pathway is one of the most important systems for transporting proteins across the thylakoid membrane into the lumen. Two Arabidopsis genes encoding SecY translocon proteins, designated SCY1 and SCY2, were characterized in this study. Semi-quantitative RT-PCR and histochemical staining β-glucuronidase (GUS) activity reveal that both SCY1 and SCY2 promoters were active in germinating seeds, etiolated cotyledons, and flowers, but not in roots. In particular, the expression of GUS gene driven by the SCY1 promoter was almost undetectable in green leaves, whereas GUS staining controlled by the SCY2 promoter was clearly detected. Moreover, homozygous scy1-1 plants could grow heterotrophically but appeared sensitive to radiation. Further studies show that chloroplasts of scy1-1 were arrested in early developmental stages with fewer thylakoid membranes. Real-time quantitative RT-PCR reveals that a number of nuclear-encoded genes involved in chlorophyll biosynthesis and photosynthesis were substantially down-regulated in the scy1-1 mutant. All these results indicate that the SCY1/2 genes were regulated developmentally and spatially, and a loss-of-function mutation in SCY1 triggered chloroplast-to-nucleus retrograde signaling in Arabidopsis thaliana.

The aim of this study was to investigate the effects of salinity on germination, seedling growth, free polyamines (putrescine, spermidine, and spermine), and ethylene metabolism of two species (Atriplex prostrata Bouchér and Plantago coronopus L.) with different salt sensitivities. Seeds collected from Barranco Hondo (salt marshes, Jaén, southern Spain) were germinated at 0, 50, 100, and 200 mM NaCl in a growth chamber. The germination of P. coronopus seeds decreased considerably with an increasing NaCl concentration, however, seeds of A. prostrata showed high germination percentages (84, 87, and 80 %) at 0 (control), 50, and 100 mM NaCl, respectively, and only at 200 mM NaCl, the germination was reduced to 25 %. In the early phase of vegetative growth (8-d-old seedlings), the fresh mass increased in A. prostrata at 50 and 100 mM NaCl but the fresh mass of P. coronopus showed no significant differences. With respect to polyamines, there was a decrease of the putrescine and spermidine content at all the NaCl treatments, however, the spermine content increased and was much higher in P. coronopus than in A. prostrata. The ethylene, 1-aminocyclopropane-1-carboxylic acid content, and the 1-amino-cyclopropane-1-carboxylic acid synthase activity increased with the increasing NaCl concentration in A. prostrata, and only the ethylene content in P. coronopus. These results indicate that P. coronopus increased the free spermine content, whereas A. prostrata increased the ethylene biosynthetic pathway in order to survive in the saline conditions.

The role of chilling in bud dormancy release and biochemical changes in different organs were evaluated in stem cuttings of pear (Pyrus pyrifolia) cv. Cuiguan selected at the leaf fall. The cuttings were exposed to 5 °C for 0, 100, 200, 300, 400, 500, 600, and 700 chilling hours (named positive chill units; PCU). A 50 % bud break was observed in floral and vegetative bud cuttings at 300 and 600 PCU, respectively. A mean time to bud break was inversely proportional to the chilling treatment. The low-temperature stimulated starch hydrolysis accompanied with sucrose accumulation in all organs. Sucrose and sorbitol content increased substantially peaking at 100, 400, and 100 PCU in floral buds, vegetative buds, and bark, respectively, thereafter decreased when buds approached chilling satisfaction (300 and 600 PCU for the floral and vegetative buds, respectively), and then increased again up to 700 PCU. Hexoses (glucose and fructose) accumulated constantly in the buds from 0 to 700 PCU. In bark, glucose and fructose content increased up to 400 PCU, and then gradually decreased. Total amylolytic and α-amylase activities increased in all organs, especially in the floral and vegetative buds up to 100 PCU and then decreased in the floral and vegetative buds before increasing again after endo-dormancy release. Invertase activity remained high in the buds during chilling satisfaction possibly because of translocation of sucrose to the buds which functioned as a strong sink. The results suggest that a low availability of hexoses may be the cause of limited bud breaks due to lack of chilling. Chilling satisfaction of the buds may increase the content of soluble sugars and acid invertase activity, and decrease the starch content, which may correlate with improved bud breaks.

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.

Maize (Zea mays L.) seedlings were pretreated with 0.001 g dm^-3 S-methylmethionine (SMM) in the nutrient solution for 24 h and then subjected to chilling (6 °C for 2, 4, 6, 10, and 24 h). Cold stress significantly decreased the maximum quantum yield of photosystem II (variable to maximum chlorophyll fluorescence ratio, F_v/F_m) during the whole experiment but SMM pretreatment significantly reduced this decline. Content of phenolics and anthocyanins increased in response to low temperature, and SMM pretreatment further intensified the synthesis of these protective agents. These findings were supported by increased expression of genes coding enzymes of the phenylpropanoid pathway leading to synthesis of cinnamate-4-hydroxylase (C4H) and chalcone-synthase (CHS). Our results indicate that SMM pretreatment alleviates the low temperature stress by reducing the damage of the photosynthetic apparatus and stimulating the phenylpropanoid pathway.

Trehalose was supplied to wheat (Triticum aestivum L.) seedlings just before a high temperature (40 °C) treatment and some physiological parameters were measured during the heat stress and recovery. The application of trehalose decreased the net photosynthetic rate (P_N) of wheat seedlings under the heat stress, but to a small extent increased the dry mass (DM) and leaf water content (LWC) after recovery from the heat stress. The trehalose-induced decrease in PN under the heat stress was not associated with a stomatal response. The heat stress slightly decreased the maximal efficiency of photosystem II (PS II) photochemistry (the variable to maximum chlorophyll a fluorescence ratio, F_v/F_m) similarly in the trehalose treated or non-treated plants. Under the heat stress, the actual efficiency of PS II photochemistry (Φ_PSII) and the efficiency of excitation energy capture by open reaction centers (F_v'/F_m') were lower in the trehalose-pretreated seedlings, whereas they were higher after the recovery. The patterns of changes in nonphotochemical quenching (NPQ) were contrary to those of ϕ_{PS II} and F_v'/F_m'. The chlorophyll content was lower, whereas the β-carotene content and the degree of de-epoxidation (DEPS) of xanthophyll cycle pigments were higher in the trehalose-pretreated wheat seedlings under the heat stress. These results suggest that exogenous trehalose partially promotes recovery of wheat by the increase of NPQ, β-carotene content, and DEPS.

Heavy metal toxicity in soils has been considered as major constraints for oilseed rape (Brassica napus L.) production. In the present study, toxic effects of chromium (Cr) were studied in 6-d-old seedlings of four different cultivars of B. napus (ZS 758, Zheda 619, ZY 50, and Zheda 622). The elevated content of Cr inhibited seedling growth, decreased the content of photosynthetic pigments, and activities of antioxidant enzymes, as well as increased the content of malondialdehyde and reactive oxygen species in all the cultivars. The Cr content in different parts of plants was higher in Zheda 622 than in other cultivars. The electron microscopic study showed changes in ultrastructure of leaf mesophyll and root tip cells at 400 μmol Cr, and these changes were more prominent in Zheda 622. An increased size and number of starch grains and number of plastoglobuli, damaged thylakoid membranes, and immature nucleoli and mitochondria were observed in leaves. In roots, enlarged vacuoles, disrupted cell walls and cell membranes, an increased number of mitochondria and a size of nucleolus, as well as plasmolysis (in Zheda 622) were observed. On the basis of these findings, it can be concluded that cv. Zheda 622 was more sensitive to Cr as compared to other three cultivars.

Durum wheat (Triticum turgidum L. var. durum) is mainly produced under rainfed but often sub-optimal moisture conditions in the Mediterranean basin. A set of 114 durum wheat recombinant inbred lines (RILs) developed from the cross of cultivars Omrabi5 × Belikh2 were tested for the ability to tolerate moisture deficiency at the germination and early seedling growth stage. The stress was imposed by exposing the germinating grain to 12 % polyethylene glycol. It induced a measurable reduction in root length, shoot length, and the percentage of normal seedlings. The germination and seedling growth of Belikh2 were more strongly inhibited than those of Omrabi5, and both parents were outperformed by > 50 % of the RILs. A quantitative trait locus (QTL) analysis was carried out by first assembling a linkage map from 265 informative microsatellites. Composite interval mapping revealed nine QTL spread over seven chromosomes. Five of these were associated with coleoptile length, and one of the five explained nearly 29 % of the relevant phenotypic variance. The coleoptile length was significantly correlated with the seedling growth, plant height, and thousand kernel mass derived from field-grown plants of the same RIL population.

Leaf hydraulic conductance (K_leaf) plays a significant part in plant-water regulation. In walnut leaves, K_leaf is stimulated by irradiance and closely relates to the accumulation of JrPIP2s aquaporin transcripts, but it is independent of stomatal aperture. To provide an insight into the early molecular events occurred during light-induced K_leaf, a large-scale transcriptomic analysis consisting of the cDNA-amplified fragment length polymorphism (AFLP) was carried out on walnut leaves maintained under irradiance or in darkness. Of the total 12 000 transcript-derived fragments (TDFs) obtained using cDNA-AFLP with 128 primer pairs, 187 TDFs were selected after sequencing, and only 93 (49 %) that had been ascribed known functions through BLAST searching of the GenBank databases. Most of these TDFs correspond to genes whose protein products are involved in cellular regulation (57.9 %) and global metabolism (39.8 %). To validate cDNA-AFLP expression patterns, 30 TDFs were further analyzed using real-time quantitative polymerase chain reaction. Moreover, exposure of leaves to irradiance was accompanied by the modification of the Ca²⁺-signaling pathway, ubiquitin-proteasome pathway, vesicle trafficking process and expression of multiple transcription factors.

The current work compared the physiological characteristics of plantain (Musa AAB) plantlets micropropagated in temporary immersion bioreactors (TIB) and on a gelled medium (GM). The plantlets were evaluated during in vitro growth (in the shoot elongation phase) and at the end of ex vitro acclimatization. TIB improved rooting and gave rise to longer shoots and higher dry mass. Respiration rate was the highest at the beginning of shoot elongation in both the TIB and GM plantlets. Photosynthetic rate in TIB was significantly higher than in GM from the midpoint of acclimatization, whereas a pyruvate kinase (PK) activity was lower. Starch accumulation was ca. two fold higher in corms than in leaves and always higher in the TIB than GM plantlets. The higher expression of genes coding for carbon metabolism enzymes PK and phosphoenolpyruvate carboxylase (PEPC) in TIB than in PM indicates a more important role of an autotrophic metabolism in the TIB plantlets when compared to the GM ones. The accumulated reserves were used during the first days of acclimatization leading to the higher survival rates and to the better plant quality of the TIB plantlets.

In vitro induction of haustoria from Castilleja tenuiflora Benth. was achieved by applying 25 μM catechin, 25 μM vanillin, or 25 μM H₂O₂. Of the treatments tested, 25 μM vanillin was the strongest inducer of haustoria in C. tenuiflora roots in vitro (up to 3 haustoria per root). Haustorium development occurred laterally and was observable 14 d after inducer application. It was characterized by elongation of the epidermal cells and division of the inner cortical cells which also possessed abundant nuclei. Histochemical analysis using 3,3-diaminobenzidine (DAB) and diphenylboric acid 2-aminoethyl ester (DBPA) indicated that the formation of haustoria was associated with the accumulation of H₂O₂ and flavonoids.

Tomato (Solanum lycopersicum Mill.) is sensitive to chilling stress during all stages of plant development. Genetic variation for chilling tolerance exists between cultivated tomato and its related wild species, but intra-specific variation has not been thoroughly investigated so far. Seedlings of 63 tomato accessions were evaluated under low temperature and two contrasting cultivars were identified for the trait: Albenga and San Marzano, the former being more chillingtolerant. To clarify the molecular mechanisms of chilling tolerance in tomato, changes in candidate gene expressions in the two tomato genotypes were analysed, using quantitative RT-PCR. Candidate genes were chosen among those known to be induced by chilling and/or with putative roles in CBF/DREB and ROS-mediated pathways. Results show that besides a CBF regulon, whose function is conserved, ROS and C2H2-type zinc finger protein-mediated cold signalling pathways were also involved in chilling tolerance. Under the chilling stress, the up-regulation of respective transcripts was consistently higher in the chilling-tolerant genotype than in the chilling-sensitive ones.

Transcription factors play vital roles in stress signal transduction and gene expression modulation. The sequence analysis shows that MdCBF1 from Malus domestica Borkh. cv. Fuji contained an AP2 core domain of 56 amino acids. By comparison of deduced amino acid sequences of CBF related proteins, we deduced that MdCBF1 is a CBF transcription factor gene which belongs to AP2/EREBP family, DREB-A1 subfamily. Further, we reported that transgenic Arabidopsis thaliana plants expressing the MdCBF1 gene exhibited stronger growth than wild type plants under freezing stress. The analysis of RT-PCR for stress-responsive genes implied that MdCBF1 over-expressing plants had a higher expression of COR15a, RD29A, and RD29B genes than wild type plants. Collectively, our results indicate that MdCBF1 might play an important role in the response of transgenic Arabidopsis plants to freezing stress.

The present study reports a natural variation in microRNA172 (MIR172) family members isolated from six species of genus Brassica. The analysis of nucleotide polymorphism across 44 Brassica MIR172 homologs revealed a higher conservation in the predicted precursors relative to flanking regions. Single nucleotide polymorphisms (SNPs) were detected in miRNA and miRNA*. The 21-nt miRNA sequence was conserved in all MIR172 members except MIR172a. However, the miRNA* sequence was conserved only in MIR172a compared to A. thaliana. Non-canonical Brassica variants of precursor miR172a were detected wherein SNP at 5' terminal in mature miR172a resulted in a sequence identical to mature miR172e. SNPs and indels in precursors resulted in varied stem-loop structures of differing stabilities (ΔG) implying a differential efficiency of miRNA biogenesis. A sequence based phylogram revealed ortholog specific groupings of MIR172 irrespective of genetic background. A Northern analysis in Brassica juncea displayed the cumulative expression of miR172 isoforms in all tissues representing different developmental stages with levels gradually increasing from vegetative to reproductive stages. Detection of high content of miR172 in roots indicates the possibility of additional roles of Brassica miR172 in root development.

The aim of this work was to assess the effect of different Cd2+concentrations on some antioxidant enzymes in Festuca arundinacea. Increased activities of ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, glutathione S-transferase, and glutathione reductase were ascertained in response to low Cd²⁺ concentrations (0-20 μM), whereas the enzyme activities were less increased or decreased at a higher Cd²⁺ dosage (50 μM) and a longer exposure. The content of reduced glutathione (GSH) decreased significantly with increasing Cd²⁺ concentrations, whereas the content of oxidized glutathione (GSSG) increased proportionally to the amount of Cd²⁺ applied. Further experiments, performed by incubating the enzyme extracts with oxidized glutathione, evidenced that the addition of GSSG to the incubation mixtures caused significant decreases of some enzymatic activities. Finally, the effect of glutathione S-transferase, FaGST I, extracted from fescue seedlings and purified till homogeneity, on these enzyme activities was investigated. It was found that FaGST I enhanced the decreased enzymatic activities caused by GSSG.

Innate immune system is employed by plants to defend against phytopathogenic microbes through specific perception of non-self molecules and subsequent initiation of resistance responses. Current researches elucidate that plants mostly rely on cell surface-located pattern recognition receptors (PRRs) and intracellular nucleotide-binding leucine-rich repeat proteins (NB-LRRs) to recognize pathogen-associated molecular patterns (PAMPs) and effector proteins from microbial pathogens, initiating PAMP- and effector-triggered immunity (PTI and ETI), respectively. Some pathogenic bacterial effector proteins are usually secreted into plant cells and play a virulence function by suppressing plant PTI, implying an evolutionary process of plant immunity from PTI to ETI. In the past several years, a great progress has been achieved to reveal fascinating molecular mechanisms underlying the pathogenic recognition, resistance signaling transduction, and plant immunity evolution. Here, we summarized the latest breakthroughs about these topics, and offered an integral understanding of plant molecular immunity.

In order to produce human lactoferrin (Lf) in alfalfa (Medicago sativa L.), a construct containing human Lf cDNA under the control of cauliflower mosaic virus 35S promoter was engineered. As selectable marker bar gene, whose expression in plant cells confers tolerance to L-phosphinothricin (ppt) was used. Plants from a highly embryogenic alfalfa clone from the Bulgarian cultivar Obnova 10 were transformed using Agrobacterium tumefaciens mediated leaf disc method. Transgenic alfalfa plants were established from ppt-resistant calli via indirect somatic embryogenesis. The presence of human Lf cDNA in the genome of the selected regenerants was confirmed by polymerase chain reaction (PCR). Reverse transcriptase (RT)-PCR and Western blot showed expression of human Lf in leaf tissue. Studies on antibacterial effect of the recombinant glycoprotein were conducted and resistance of the transgenic alfalfa plants to two phytopathogens, Pseudomonas syringae pv. syringae and Clavibacter michiganensis, was demonstrated. The obtained results suggest that the expression of human Lf in alfalfa could be beneficial not only for producing recombinant protein for clinical application but also for crop quality improvement.

The effects of cadmium on physiological and ultrastructural characteristics were evaluated in 6-d-old seedlings of two Brassica napus L. cultivars Zheda 619 and ZS 758. Results show that Cd at lower concentration (100 μM) stimulated the seedling growth but at higher concentration (500 μM) inhibited the growth of both cultivars, decreased content of photosynthetic pigments, activities of antioxidant enzymes, and increased the content of malondialdehyde and reactive oxygen species. Cd content in different parts of seedlings was higher in ZS 758 than in Zheda 619. Electron micrographs illustrated that 500 μM Cd severely damaged the leaf and root tip cells of both cultivars. Under Cd stress, the size and number of starch grains, plastoglobuli, and lipid bodies in the chloroplasts increased. In the root tip cells, enlarged vacuoles, diffused cell walls, and undeveloped mitochondria were detected.

Rice chromosome single segment substitution line (SSSL) W23-19-06-06-11 with the genotype Rf3Rf3/Rf4Rf4, a strong restorer line for wild-abortive (WA) cytoplasmic male sterility (CMS), was recently identified from the SSSL library. To investigate the genetic mode of Rf genes and the genetic relationship among WA, yegong (Y), and dwarf-wildabortive (DA) CMS systems, the plants derived from three BC3F2 populations involving W23-19-06-06-11 and the three CMS lines, that carried the Rf3Rf3/Rf4Rf4, Rf3Rf3/rf4rf4, and rf3rf3/Rf4Rf4 genotypes and WA-, Y-, and DA-CMS cytoplasm, were selected and their pollen and spikelet fertility were evaluated. The results show that the genetic effect displayed a trend of Y-CMS > WA-CMS > DA-CMS in the genetic background of W23-19-06-06-11, the effect of Rf4 appeared to be slightly larger than that of Rf3, and their effects were additive for the three CMS systems. Two pairs of dominant genes governed the fertility restoration in pollen and spikelet in the W23-19-06-06-11 which indicates that the genetic mode of the Rf genes was a qualitative character for the three CMS systems.

Nitric oxide (NO), gibberellic acid (GA), and phosphorus (P) have been reported to regulate primary root (PR) growth, but interactions between them in the growth of Arabidopsis PR remain unknown. This work confirmed that low P availability significantly inhibited PR growth and that NO arrested PR growth in either high P or low P conditions. Moreover, NO counteracted the stimulatory effects of GA on PR growth under low P conditions. Finally, the dependence of low P and NO inhibition of PR growth on the DELLA-SLY pathway revealed that NO stabilized a major DELLA protein. We therefore conclude that antagonistic interactions between NO and GA regulate PR growth under both the high and low P conditions, and a DELLA-SLY module is the node where NO, GA, and P pathways converge and interact.

Globe artichoke (Cynara cardunculus L. var. scolymus) is rich in flavonoids which contribute to its health-promoting properties. With the aim of understanding the genetic control of flavonoid accumulation in artichoke, we isolated an artichoke full-length cDNA sequence encoding flavonoid 3'-hydroxylase (F3'H), a major enzyme of the flavonoid hydroxylation pattern. In silico studies confirmed that the deduced amino acid sequence of CcF3'H is highly similar to F3'Hs isolated from other Asteraceae. The Northern blot analysis demonstrated that CcF3'H was highly expressed in leaves and in specific parts of the heads. Its expression differed slightly among artichoke cultivars. The overexpression of CcF3'H in tobacco plants led to the accumulation of flavonoids and to an increase of flower colour intensity, thus identifying CcF3'H as promising candidate for genetic engineering. CcF3'H represents the first structural gene of the flavonoid biosynthesis isolated from C. cardunculus, and its characterization sheds light on the accumulation of flavonoids.

We have earlier reported that the endophyte infection can enhance photosynthetic capacity and antioxidant enzyme activities in rice exposed to salinity stress. Now, the changes in primary photochemistry of photosystem (PS) II induced by Na₂CO₃ stress in endophyte-infected (E+) and endophyte-uninfected (E-) rice seedlings were studied using chlorophyll a fluorescence (OJIP-test). Performance indices (PI_ABS and PI_Total) of E- and E+ rice seedlings revealed the inhibitory effects of Na₂CO₃ on PS II connectivity (occurrence of an L-band), oxygen evolving complex (occurrence of a K-band), and on the J step of the induction curves, associated with an inhibition of electron transport from plastoquinone A (Q_A) to plastoquinone B (Q_B). In E+ seedlings, Na₂CO₃ effects on L and K bands were much smaller, or even negligible, and also there was no pronounced effect on the J step. Furthermore, the OJIP parameters indicated that 20 mM Na₂CO₃ had a greater influence on the photosystem (PS) II electron transport chain than did the 10 mM Na₂CO₃, and that changes were greater in E- than in E+. Endophyte infection was therefore deemed to enhance the photosynthetic mechanism of Oryza sativa exposed to salinity stress.