Expression Of PAL Research Articles

Inductive effect of titanium dioxide nanoparticles on the anticancer compounds production and expression of rosmarinic acid biosynthesis genes in Dracocephalum kotschyi transformed roots

Methoxylated flavonoids, mainly xanthomicrol and cirsimaritin that can be extracted from Dracocephalum kotschyi Boiss, have anticancer, antispasmodic and antiplatelet effects. The production of these valuable pharmaceutical compounds is one of the major goals of biotechnology studies. In this work, induced transformed roots were influenced by various concentrations of titanium dioxide nanoparticles (TiO2 NPs) at 24 or 48 h exposure time. The effects of TiO2 NPs were assessed on growth rate, activity of antioxidant enzymes, total phenol and flavonoid content (TPC and TFC) and rosmarinic acid (RA) and some flavonoids accumulation. The gene expression level of phenylalanine ammonia-lyase (pal) and rosmarinic acid synthase (ras) genes were assessed by real time PCR analysis. The transformed roots biomass was substantially increased in elicited roots in comparison with the control. The TPC, TFC and antioxidant enzymes activitywere affected by TiO2 NPs concentration and exposure time. Valuable flavonoids with anticancer characteristics along with xanthomicrol, cirsimaritin and isokaempferide exhibited an increase (70, 34.28 and 7.81-fold, respectively) versus the control. The maximum content of RA (530.5 μg g−1 FW), which was 4.30 times as great as that of control was detected in samples treated with TiO2 NPs (50 mg L−1) 24 h after elicitation. Real-time PCR analysis revealed a considerable increase in pal and ras expression rate engaged by TiO2 NPs levels and exposure time. Overall D. kotschyi transformed roots elicitation by TiO2 NPs led to a massive increment in the production of valuable anticancer flavonoids such as xanthomicrol, cirsimaritin and RA as polyphenol.

Prohydrojasmon Promotes the Accumulation of Phenolic Compounds in Red Leaf Lettuce.

Prohydrojasmon (PDJ) is a synthetic jasmonate derivative that is primarily used as a growth regulator, but its mechanism of action is unclear. In this study, we elucidated the effects of PDJ on phytochemical production in red leaf lettuce. The PDJ treatments promoted the accumulation of phenolic compounds in aerial plant parts. An LC-MS analysis revealed that these accumulated compounds were identified as cyanidin-3-O-glucoside, cyanidin-3-O-(6″-O-malonyl)-glucoside and cyanidin-3-O-(6″-O-malonyl)-glucoside methyl ester. The abundance of these compounds in lettuce extracts increased significantly in response to the PDJ treatment. Additionally, the LC-MS analysis also identified the accumulated phenolic compounds in the extracts of PDJ-treated lettuce, including caffeoyltartaric acid, chlorogenic acid, caffeoylmalic acid, chicoric acid, and dicaffeoylquinic acid. Gene expression analyses indicated the PDJ treatments upregulated the expression of PAL, F3H, and ANS genes in lettuce. These results suggest that PDJ treatments enhance the expression of genes involved in the synthesis of anthocyanins and phenolic compounds, resulting in an increase in the quantities of these compounds, which reportedly have various functions affecting human physiology.

Effects of water regulation on biosynthesis of calycosin-7-O-β-D-glucoside in Astragalus membranaceus var. mongholicus

The effects of water regulation on the biosynthesis of calycosin-7-O-β-D-glucoside in 2-year-old Astragalus membranaceus var. mongholicus were studied,and the mechanism was explained from the aspects of key enzyme gene expression and antioxidant enzyme system. The content of calycosin-7-O-β-D-glucoside was determined by HPLC,and the expression levels of six key enzyme genes( PAL,4 CL,CHS,CHI,IFS,13'H) in the synthesis pathway were analyzed by q RT-PCR. The activities of protective enzymes and contents of osmoregulation substances and malondialdehyde were also determined. In the water deficit group,the maximum concentration of calycosin-7-O-β-D-glucoside was 0. 49 mg·g-1 on the 24 th day of treatment. In the whole water regulation,the water deficit group outweighed the water adequate group in osmoregulation substance and MDA contents. The activities of A. membranaceus var.mongholicus antioxidant enzymes SOD,POD,and CAT increased during the initial period of water regulation,but decreased with time.The expression of PAL,CHS,and 13'H in the water deficit group was at a low level,and the 4 CL had active expression,slightly lower than that in the water adequate group. The expression of CHI and IFS elevated rapidly when water deficit occurred. Correlation analysis showed that the content of calycosin-7-O-β-D-glucoside was positively correlated with CHI expression( P<0. 01) and IFS expression( P<0. 05). Therefore,water regulation can change the accumulation pattern of calycosin-7-O-β-D-glucoside,and water deficit may be an effective way to increase its content. CHI and IFS are the key genes in response to water deficit.

Validation of Reference Genes for Studying Different Abiotic Stresses in Oat (Avena sativa L.) by RT-qPCR

Oat (Avena sativa L.) is a widely cultivated cereal with high nutritional value and it is grown mainly in temperate regions. The number of studies dealing with gene expression changes in oat continues to increase, and to obtain reliable RT-qPCR results it is essential to establish and use reference genes with the least possible influence caused by experimental conditions. However, no detailed study has been conducted on reference genes in different tissues of oat under diverse abiotic stress conditions. In our work, nine candidate reference genes (ACT, TUB, CYP, GAPD, UBC, EF1, TBP, ADPR, PGD) were chosen and analysed by four statistical methods (GeNorm, Normfinder, BestKeeper, RefFinder). Samples were taken from two tissues (leaves and roots) of 13-day-old oat plants exposed to five abiotic stresses (drought, salt, heavy metal, low and high temperatures). ADPR was the top-rated reference gene for all samples, while different genes proved to be the most stable depending on tissue type and treatment combinations. TUB and EF1 were most affected by the treatments in general. Validation of reference genes was carried out by PAL expression analysis, which further confirmed their reliability. These results can contribute to reliable gene expression studies for future research in cultivated oat.

Root Endophytism by Pochonia chlamydosporia Affects Defense-Gene Expression in Leaves of Monocot and Dicot Hosts under Multiple Biotic Interactions.

A study was carried out on the effect of the root endophytic fungus Pochonia chlamydosporia on plant systemic signal of defense related genes during fungal or nematode parasitism. Different biotic stress factors were examined, inoculating roots of dicot and monocot hosts with the endophyte, and measuring the expression of defense genes in leaves. A first greenhouse assay was carried out on expression of PAL, PIN II, PR1 and LOX D in leaves of tomato cv Tondino inoculated with Phytophthora infestans (CBS 120920), inoculating or not the roots of infected plants with P. chlamydosporia DSM 26985. In a second assay, plants of banana (Musa acuminata cv Grand Naine) were artificially infected with Fusarium oxysporum f. sp. cubense Tropical race 4 (TR4) and inoculated or not with DSM 26985. In a further experiment, banana plants were inoculated or not with P. chlamydosporia plus juveniles of the root knot nematode (RKN) Meloidogyne incognita. A similar assay was also carried out in vitro with adults and juveniles of the lesion nematode Pratylenchus goodeyi. Differential expression of the defense genes examined was observed for all plant-stress associations, indicative of early, upward systemic signals induced by the endophyte. Changes in expression profiles included a 5-fold down-regulation of PIN II at 2 dai in leaves of tomato plants treated with P. infestans and/or P. chlamydosporia, and the up-regulation of PAL by the endophyte alone, at 2 and 7 dai. In the TR4 assay, PR1 was significantly up-regulated at 7 dai in banana leaves, but only in the P. chlamydosporia treated plants. At 10 dai, PIN II expression was significantly higher in leaves of plants inoculated only with TR4. The banana-RKN assay showed a PR1 expression significantly higher than controls at 4 and 7 dai in plants inoculated with P. chlamydosporia alone, and a down-regulation at 4 dai in leaves of plants also inoculated with RKN, with a PR1 differential up-regulation at 10 dai. Pratylenchus goodeyi down-regulated PIN at 21 dai, with or without the endophyte, as well as PAL but only in presence of P. chlamydosporia. When inoculated alone, the endophyte up-regulated PR1 and LOX. The gene expression patterns observed in leaves suggest specific and time-dependent relationships linking host plants and P. chlamydosporia in presence of biotic stress factors, functional to a systemic, although complex, activation of defense genes.

Nanosilicon enhances maize resistance against oriental armyworm (Mythimna separata) by activating the biosynthesis of chemical defenses.

Silicon, in its nanoscale form, has shown plant-promoting and insecticidal properties. To date, however, we lack mechanistic evidence for how nanoscale silicon influences the regulation of plant chemical defenses against herbivore attacks. To address this gap, we compared the effect of Si nanodots (NDs) and sodium silicate, a conventional silicate fertilizer, on maize (Zea mays L.) chemical defenses against the oriental armyworm (Mythimna separata, Walker) caterpillars. We found that Si NDs and sodium silicate additions, at the dose of 50mg/L, significantly inhibited the growth of caterpillars by 53.5% and 34.2%, respectively. This increased plant resistance was associated with a 44.2% increase in the production of chlorogenic acid, as well as the expression of PAL, C4H, 4CL, C3H and HCT, core genes involved in the biosynthesis of chlorogenic acid, by 1.7, 2.4, 1.9, 1.8 and 4.5 folds, respectively. Particularly, in the presence of M. separata, physiological changes in maize plants treated with 50mg/L Si NDs, including changes in shoot biomass, leaf nutrients (e.g., K, P, Si), and chemical defense compounds (e.g., chlorogenic acid, total phenolics), were higher than those of plants added with equivalent concentrations of conventional silicate fertilizer. Taken together, our findings indicate that Si, in nanoscale form, could replace synthetic pesticides, and be implemented for a more effective and ecologically-sound management of insect pests in maize crop farming.

Expression patterns of ASR1, PIN2, and PAL genes in tomato and eggplant after treatment with different inducers

Salicylic acid (SA) and β-aminobutyric acid (BABA) are signaling compounds that regulate a large number of defense responses in plants after exposure to the biotic and abiotic stresses. The antagonistic fungus Trichoderma harzianum is well-known as a potential biocontrol agent that also induces defensive responses. In the present study, we tested the up- and down-regulation of defense responses of eggplant and tomato mediated by root application of SA and BABA as well as T. harzianum. Especially, we analyzed and compared the expression of ASR1, PIN2, and PAL in 4, 10, and 14 d post treatment. In all time courses, the root Trichoderma application + root β-aminobutyric acid application (RT + RBABA)- and root Trichoderma application + root salicylic acid application (RT + RSA)-treated plants had a much higher expression of genes than those on RT-treated plants and controls. Also, control and treated plants had significantly higher expression of ASR1 and PIN2 on the 4th day compared to other time courses. The PAL gene expression reached the maximum level at 10 days after treatment and it increased to about twofold level than 4 days after treatment. Information on expression profiles of the genes in different plants and under various inducers helps to identify candidates to the increase of resistance to environmental stress conditions.

Identification of candidate genes influencing anthocyanin biosynthesis during the development and ripening of red and white strawberry fruits via comparative transcriptome analysis.

Strawberries are one of the most economically important berry fruits worldwide and exhibit colours ranging from white to dark red, providing a rich genetic resource for strawberry quality improvement. In the present study, we conducted transcriptome analyses of three strawberry cultivars, namely, ‘Benihoppe’, ‘Xiaobai’, and ‘Snow White’, and compared their gene expression profiles. Among the high-quality sequences, 5,049 and 53,200 differentially expressed genes (DEGs) were obtained when comparing the diploid and octoploid strawberry genomes and analysed to identify anthocyanin-related candidate genes. Sixty-five DEGs in the diploid genome (transcriptome data compared to the diploid strawberry genome) and 317 DEGs in the octoploid genome (transcriptome data compared to the octoploid strawberry genome) were identified among the three cultivars. Among these DEGs, 19 and 70 anthocyanin pathway genes, six and 42 sugar pathway genes, 23 and 101 hormone pathway genes, and 17 and 104 transcription factors in the diploid and octoploid genomes, respectively, correlated positively or negatively with the anthocyanin accumulation observed among the three cultivars. Real-time qPCR analysis of nine candidate genes showed a good correlation with the transcriptome data. For example, the expression of PAL was higher in ‘Benihoppe’ and ‘Xiaobai’ than in ‘Snow White’, consistent with the RNA-seq data. Thus, the RNA-seq data and candidate DEGs identified in the present study provide a sound basis for further studies of strawberry fruit colour formation.

Exogenous phytosulfokine α application delays senescence and promotes antioxidant nutrient accumulation in strawberry fruit during cold storage by triggering endogenous phytosulfokine α signaling

In this study, the mechanism by which the exogenous application of 150 nM signaling bioactive peptide phytosulfokine α (PSKα) delays senescence and improves antioxidant nutrient accumulation in strawberry fruit during storage at 4 °C for 18 d was investigated. Results showed that the higher endogenous accumulation of PSKα in strawberry fruit treated with 150 nM PSKα may result from the higher expression of PSK3 and PSK6 genes. Besides, the higher endogenous accumulation of Ca2+ in strawberry fruit treated with 150 nM PSKα may be ascribed to the higher cytosolic accumulation of cGMP, resulting from the triggering of endogenous PSKα signaling pathway, represented by higher expression of PSKR1 gene. Besides, the higher endogenous melatonin accumulation resulting from higher expression of TDC, T5H, SNAT, and ASMT genes in strawberry fruit treated with 150 nM PSKα may be ascribed to the higher endogenous accumulation of Ca2+. Moreover, the higher ABTS and DPPH scavenging capacity in strawberry fruit treated with 150 nM PSKα may be ascribed to the higher accumulation of phenols, flavonoids, and anthocyanins, resulting from higher gene expression and activities of PAL and CHS. Based on our findings, the exogenous application of PSKα could be employed as a beneficial procedure for delaying senescence and improving antioxidant nutrient accumulation in strawberry fruit during cold storage, by triggering endogenous PSKα signaling, promoting endogenous melatonin accumulation, and activating the phenylpropanoid pathway.

Pseudomonas putida P3-57 induces cucumber (Cucumis sativus L.) defense responses and improves fruit quality characteristics under commercial greenhouse conditions

The possibility of chemical fertilizer residues in cucumber has raised concerns about the consumption of this beneficial fruit. Although very good studies have been reported on the effect of growth-promoting bacteria on increasing the health of cucumber plants, their performance in commercial greenhouse conditions has been less studied. A two-year study was conducted to evaluate the effect of P. putida strain P3-57 with 100 % or 70 % of the recommended amount of NPK fertilizers on cucumber fruit yield and quality compared to Barvar NPK® commercial biofertilizer under commercial greenhouse conditions. The 30 % reduction in chemical fertilizers reduced yield and overall fruit acceptance score in the sensory evaluation test. Plant treatment with P3-57 or Barvar had no significant effect on yield but when 70 % of chemical fertilizers were used, they increased the quality of cucumber due to the increase in the score of some sensory traits. P3-57-100% had the highest overall acceptance score, which was associated with increased aroma, flavor and fruit juice, and the lowest levels of nitrate, Zn, Mg, Mo, Sr, Ba and Li. Also, the concentration of protein and CAT activity of fruits was higher compared to control-100 % and Barvar-100 %. Evaluation of CAT, APX and POX activity and expression of PR1-1a, GLU, APX, CHIT, LOX and PAL showed that P3-57-100 % and Barvar-100 % stimulate plant immune system through ISR/SAR and SAR pathways respectively. Based on the results of this study, strain P3-57, as a bio-stimulator that increases cucumber quality, has great potential to enter the market.

Nutrition and antioxidant profiling in the unpolished and polished grains of eleven indigenous aromatic rice cultivars.

The present study emphasized on the yet-unexplored exhaustive analyses of nutritional and antioxidant parameters in the unpolished and polished grains of eleven indigenous aromatic rice varieties. Tulaipanji appeared to be a highly demanding variety by virtue of having sufficient levels of micronutrients like Fe, Zn and Cu (linked with higher expression of fer2, ZIP and NAS3), inorganic phosphorus, hexose sugars, total amino acids and lysine (correlated with higher expression of glutelin and RLRH1), tocopherol (due to higher HGGT expression), total phenolic content, flavonoids, anthocyanins (concomitant with higher expression of PPO, PAL and ANS), LOX activity and LOX1 gene expression, and overall higher total antioxidant capacity, particularly in the polished grains. The importance of IET-21261, with regard to higher content of phytic acid and total phosphorus (with high IPK1 expression), β-carotene (with high PSY expression) and tocopherol (with high HGGT expression), and of Kalonunia, with respect to cysteine and γ-oryzanol in the polished grains, was also significant. Lower α-amylase enzyme activity and α-amylase expression led to considerable starch accumulation, with lower sucrose content, in the unpolished grains of Radhunipagal and polished grains of Pusa Basmati-1. Paramanya registered the highest content of thiamine and TH1 expression, together with minimum methylglyoxal level (low TPI expression). Paramanya and Radhunipagal maintained a higher pool of majority of the nutritional and antioxidant components in their unpolished grains. The polished grains of all the genotypes showed strikingly lower nutritional constituents, as compared to unpolished grains. The knowledge gained from this study will largely provide a road map to the farmers and rice consumers for making proper choice of the aromatic genotypes for large-scale cultivation and dietary consumption to derive maximum nutritional benefits.

Antagonistic Potential of Novel Endophytic Bacillus Strains and Mediation of Plant Defense against Verticillium Wilt in Upland Cotton.

Verticillium wilt caused by Verticillium dahliae is a threatening disease of cotton, causing economic loss worldwide. In this study, nine endophytic Bacillus strains isolated from cotton roots exhibited inhibitory activity against V. dahliae strain VD-080 in a dual culture assay. B. altitudinis HNH7 and B. velezensis HNH9 were chosen for further experiments based on their high antagonistic activity. The secondary metabolites of HNH7 and HNH9 also inhibited the growth of VD-080. Genetic marker-assisted detection revealed the presence of bacillibactin, surfactin, bacillomycin and fengycin encoding genes in the genome of HNH7 and HNH9 and their corresponding gene products were validated through LC-MS. Scanning electron microscopy revealed mycelial disintegration, curling and shrinkage of VD-080 hyphae after treatment with methanolic extracts of the isolated endophytes. Furthermore, a significant reduction in verticillium wilt severity was noticed in cotton plants treated with HNH7 and HNH9 as compared to control treatments. Moreover, the expression of defense-linked genes, viz., MPK3, GST, SOD, PAL, PPO and HMGR, was considerably higher in plants treated with endophytic Bacillus strains and inoculated with VD-080 as compared to control.

THE EFFECT OF CHITOSAN ON GENE EXPRESSION, SOME MORPHOLOGICAL AND PHYSIOLOGICAL TRAITS OF SWEET BASIL (Ocimum basilicum L.) UNDER SALINITY STRESS

Sweet basil is an important medicinal plant belonging to Lamiaceae family. In this plant, Phenylpropanoid pathway possesses some enzymes involving in generating suitable essential oil constituents. The main purpose of conducting this study was to investigate the effects of chitosan on sweet basil’s growth and physiological parameters as well as gene expression subjected to salinity stress. After employing a foliar-spray of chitosan at 0 (as control) and 0.2 gl–1, the plants were subjected to salinity treatments at 0, 25, 50, 100, and 150 mM NaCl. The results of this research revealed that chitosan, compared to the controls, improved growth parameters under stressed or non-stressed conditions. In this regard, chitosan increased protein and chlorophyll contents as well as the expression of PAL and COVMT genes leading to an increase in phenolic compounds. To sum up, chitosan improved sweet basil tolerance to salinity through influencing the genes involved in the pathway of phenylpropanoid so as to produce secondary metabolites.

COMPARATIVE GROWTH PERFORMANCE AND ACTIVITY OF DEFENSE RELATED ENZYMES AND GENE EXPRESSION IN RUBBER CLONES AGAINST RIGIDOPORUS MICROPORUS INFECTION

Rigidoporus microporus is the causal agent of rubber white root disease (WRD). Control of this is commonly carried out by chemical treatment. The use of tolerant rootstocks may present an effective method to lessen its impact. The screening of rubber rootstocks for tolerance of WRD was investigated by both defense-related enzymes and gene expression, and assessment of disease symptoms.Two recommended clones in Thailand (RRIT251 and RRIT408) and RRIM623 (Malaysian clone) were screened and compared with susceptible clones (RRIM600 and BPM24) and tolerant clone (PB5/51) by inoculating young rubber seedling with R. microporus. The expression of PRs and PAL were analyzed at 0, 1, 3, 5, and 7 days post inoculation (dpi) along with the defense-related enzyme activities. Based on observed transcriptional level of PRs and PAL genes, CHI, PAL, and POD enzyme activities, and also evidence from WRD symptom assessment in the field, we concluded that PB 5/51 had the best tolerance with the lowest disease incidence, high PAL and POD enzyme activities, with the next best being RRIM 623 and RRIT 251, respectively. Meanwhile, BPM 24, RRIM 600, and RRIT 408 clones are moderately susceptible to WRD. The study introduces new possibilities for the control of WRD using alternative rubber rootstock clones.

Enhanced stress tolerance in transformed Ajuga bracteosa Wall. ex Benth. regenerants by upregulated gene expression of metabolic pathways

The rol oncogenes of Agrobacterium rhizogenes enhance the production of medicinally important compounds in plants and provide a first barrier against the overproduction of reactive oxygen species during biotic and abiotic stress. 'this study was designed to evaluate the expression of genes involved in biosynthetic pathways and their impact on metabolic contents and environmental stress tolerance in regenerated Ajuga bracteosa Wall. ex Benth. After successful transformation, real-time quantitative PCR confirmed the increased expression (1.94-6.59-fold) of HMGR, HDS, FDS, PAL, and TTG1 genes in transgenic lines. Furthermore, GC-MS coupled with principal component analysis revealed diverse concentrations of 97 metabolites in A. bracteosa. Transgenic lines showed greater survival under multiple stresses. This was revealed by significant chlorophyll content (8.13-21 mu moles/m(2)), higher quantum efficiency of PSII (F-v/F-m), and the performance index (PIabs) value. Similarly, catalase and peroxidase enzyme activities were enhanced during extreme drought (300-400 mM mannitol) and salinity (150-200 mM NaCl) conditions, compared to untransformed control. Wild type control plant leaves were completely necrotized by Aspergillus fumigatus (FCBP 66) and Fusarium solani (FCBP 0291), whereas transformed leaves had improved antifungal resistance. In conclusion, our data suggest that rolABC genes have a significant impact on the synthesis of metabolites involved in enhancing multistress tolerance in A. bracteosa.

АНАЛИЗ ЭКСПРЕССИИ ГЕНОВ СТРЕССОУСТОЙЧИВОСТИ В УСЛОВИЯХ ВОЗДЕЙСТВИЯ ЗАСУХИ НА РАСТЕНИЯ БЕРЕЗЫ В ЦЕНТРАЛЬНО-ЧЕРНОЗЕМНОМ РЕГИОНЕ

Birch is one of the main deciduous forest-forming species in the European part of Russia, but the impact of stress (in particular, drought) greatly limits its distribution. In this regard, it seems relevant to identify resistance mechanisms in order to select promising genotypes for their further reproduction. The aim of this work is to identify drought-tolerant genotypes of European birch (B. pendula Roth.), pubescent birch (B. pubescens Ehrh.) аnd their hybrids. For the study, we have taken samples of birch at the age of 26 years, which remained viable after the droughts of 2010 and 2013. Birch leaves have been selected in the third decade of June 2019 to analyze drought resistance. Leaves of birch, selected during the period with optimal conditions of air temperature and precipitation, have been used as control ones. A modified CTAB method has been proposed for RNA isolation. We studied the expression of genes encoding proteins involved in the activation of cell defense pathways under the influence of abiotic stress (pal, PR-1, PR-10, lea8, DREB2) during the drought period (June 2019). A study of the expression of genes encoding proteins of metabolic pathways that are activated in response to abiotic stress (phenylpropanoid pathway) associated with the pathogenesis of proteins (PR1 and PR10), transcription factors (DREB2), and late embryogenesis proteins (LEA) has been made. As a result of the effects of drought, a significant increase in the expression of pal, PR-1, PR-10 and DREB2 genes has been detected in the analyzed samples. At the same time, changes in lea8 gene expression were detected for two out of ten genotypes. The largest increase in expression for all five genes is shown for birch samples 29-58 and 233. It indicates the development of adaptive mechanisms in these genotypes and can characterize them as the most stable. The studied genes can be recommended as markers for the analysis of stress resistance in various species of woody plants

Physiological and Molecular Effects of Silver Nanoparticles Exposure on Purslane (Portulaca oleracea L.)

Due to the antifungal and antibacterial properties, silver nanoparticles (AgNPs) are now widely used in consumer products. In this research, the effects of various concentrations of AgNPs (0, 2.5, 5, 10, 20, 40 and 80 ppm) on growth, contents of micro- and macroelements, physiological traits and expression of PAL and GSH genes of purslane (Portulaca oleracea L.) plants were investigated. The results showed that application of AgNPs resulted in a dose-dependent enhancement in accumulation of silver (Ag) in both root and leaf tissues, however, the Ag accumulated at the root more than the leaf at all levels of the AgNPs treatment. AgNPs treatment over 20 ppm reduced the growth, biomass production and accumulation of macroelements (Ca and Mg) and microelements (Zn, Cu, Mn and B) and increased contents of H2O2, MDA and DPPH scavenging activity. Application of AgNPs also increased the activity of antioxidant enzymes such as SOD, CAT and POD enzymes compared to control treatments. The activity and expression of PAL and CHS enzymes significantly increased under treatment of AgNPs. Our results indicate that increasing the activity of antioxidant enzymes and regulating the expression and activity of PAL and CHS enzymes are mechanisms to counteract the oxidative stress induced by AgNPs in the purslane plants.

Expression of PAL and PR2 pathogenesis related genes in barley plants challenged with closely related Pyrenophora species

Net blotch and leaf stripe caused by Pyrenophora teres and Pyrenophora graminea, respectively, are economical diseases of barley worldwide. Relatively little is known about the defense responses of barley challenged with these two closely related species. In the current work, expression of two well known defense-related genes PAL and PR2 were monitored in resistant and susceptible barley cultivars at early points of infection using quantitative real-time PCR (qPCR). Data showed significant variance in the expression patterns of the both genes between barley P. teres or P. graminea interactions as compared to the non-inoculated controls. It is also noteworthy that PAL and PR2 genes have a higher constitutive expression and faster induction in the resistant cultivar as compared with the susceptible one after infection with each pathogen. However, PCR (qPCR) analysis revealed higher gene expression in resistant barley plants inoculated with P. graminea as compared with P. teres, with a maximum expression for PR2 (13.8 and 6.41-fold) and PAL (14.8 and 7.89-fold) respectively, at 6 days post inoculation. The obtained results suggest that PAL and PR2 genes, positively regulate P. teres and P. graminea—resistance in barley plants during disease progress, which can provide testable hypotheses that will need direct future tests to determine how these changes may be specified in the genome of these closely related Pyrenophora species.

Effect of natural light on the phenolic compounds contents and coloration in the peel of ‘Xiyanghong’ (Pyrus bretschneideri×Pyrus communis)

Pear (Pyrus) is one of the most important fruit trees in the world. As an important pear cultivar, ‘Xiyanghong’ (P. bretschneideri × P. communis) is widely cultivated. However, its red skin is commonly occurred in the light exposed part, which restrictes its commercial value. Here, to investigate the effect of natural light on coloration and the phenolic compounds of the ‘Xiyanghong’ peel, the bag surface of bagged pears was cut to expose the peel to natural light, and exposed peel versus bagged peel were compared. The results showed that the exposed peel started to be colored in red at 57 days after full bloom (DAFB) and kept in red until the final stage, while the bagged peel was not colored among all stages. Anthocyanin content of exposed skin was significantly higher than that of bagged skin at the 57 DAFB and the following two stages. This similar higher level in exposed skin was also observed in the contents of other five phenolic compounds, including syringic acid, gallic acid, procyanidin B2, quercetin-3-galactoside, and quercetin-3-rutinoside. In addition, the expression of pathway genes, PAL, CHS, CHI, F3H, DFR, ANS, and UFGT, correlated highly with anthocyanin accumulation. And the expression of regulative genes MYB10, bHLH3, and light response gene HY5 were also with a consistent trend at 57 DAFB. These results will contribute to an improved understanding of the mechanism of red pears response for light, and will aid development of new cultivation techniques to improve coloration and quality of pear.

Transcriptional analysis of wheat seedlings inoculated with Fusarium culmorum under continual exposure to disease defence inductors.

A facultative parasite of cereals, Fusarium culmorum is a soil-, air- and seed-borne fungus causing foot and root rot, fusarium seedling blight, and especially Fusarium head blight, a spike disease leading to decreased yield and mycotoxin contamination of grain. In the present study, we tested changes in expression of wheat genes (B2H2, ICS, PAL, and PR2) involved in defence against diseases. We first compared expression of the analysed genes in seedlings of non-inoculated and artificially inoculated wheat (variety Bohemia). The second part of the experiment compared expression of these genes in seedlings grown under various treatment conditions. These treatments were chosen to determine the effects of prochloraz, sodium bicarbonate, ergosterol, aescin and potassium iodide on expression of the analysed defence genes. In addition to the inoculated and non-inoculated cultivar Bohemia, we additionally examined two other varieties of wheat with contrasting resistance to Fusarium sp. infection. These were the blue aleurone layer variety Scorpion that is susceptible to Fusarium sp. infection and variety V2-49-17 with yellow endosperm and partial resistance to Fusarium sp. infection. In this manner, we were able to compare potential effects of inductors upon defence gene expression among three varieties with different susceptibility to infection but also between inoculated and non-inoculated seedlings of a single variety. The lowest infection levels were detected in the sodium bicarbonate treatment. Sodium bicarbonate had not only negative influence on Fusarium growth but also positively affected expression of plant defence genes. Expression of the four marker genes shown to be important in plant defence was significantly affected by the treatments. The greatest upregulation in comparison to the water control was identified under all treatments for the B2H2 gene. Only expression of PAL under the ergosterol and prochloraz treatments were not statistically significant.