Transcriptional profiling of catalase genes in juglone-treated seeds of maize (Zea mays L.) and wheat (Triticum aestivum L.)

The major aim of the present study was to investigate the influence of juglone (JU; 5-hydroxy-1,4 naphthoquinone) treatments on the expression level of Cat1, Cat2 and Cat3 genes, encoding the respective catalase isozymes in maize (Zea mays L.) and wheat (Triticum aestivum L.) seeds. In parallel, germination efficiency, catalase (CAT) activity and hydrogen peroxide (H2O2) content in juglone-exposed cereal seeds were assessed. Juglone applications significantly stimulated abundance of three target catalase transcripts as well as induced CAT activity and generation of H2O2 in both maize and wheat kernels. Furthermore, germination process of juglone-affected maize seeds was more severe suppressed than in case of wheat kernels. The role of juglone in triggering the oxidative stress as well as antioxidative responses in seeds of the studied model cereal species are discussed

Expression Patterns of Glutathione Transferase Gene (GstI) in Maize Seedlings Under Juglone-Induced Oxidative Stress

Juglone (5-hydroxy-1,4-naphthoquinone) has been identified in organs of many plant species within Juglandaceae family. This secondary metabolite is considered as a highly bioactive substance that functions as direct oxidant stimulating the production of reactive oxygen species (ROS) in acceptor plants. Glutathione transferases (GSTs, E.C.2.5.1.18) represent an important group of cytoprotective enzymes participating in detoxification of xenobiotics and limiting oxidative damages of cellular macromolecules. The purpose of this study was to investigate the impact of tested allelochemical on growth and development of maize (Zea mays L.) seedlings. Furthermore, the effect of juglone-induced oxidative stress on glutathione transferase (GstI) gene expression patterns in maize seedlings was recorded. It was revealed that 4-day juglone treatment significantly stimulated the transcriptional activity of GstI in maize seedlings compared to control plants. By contrast, at the 6th and 8th day of experiments the expression gene responses were slightly lower as compared with non-stressed seedlings. Additionally, the specific gene expression profiles, as well as the inhibition of primary roots and coleoptile elongation were proportional to juglone concentrations. In conclusion, the results provide strong molecular evidence that allelopathic influence of juglone on growth and development of maize seedlings may be relevant with an induction of oxidative stress in acceptor plants

Expression Patterns of Genes Involved in Ascorbate-Glutathione Cycle in Aphid-Infested Maize (Zea mays L.) Seedlings

Reduced forms of ascorbate (AsA) and glutathione (GSH) are among the most important non-enzymatic foliar antioxidants in maize (Zea mays L.). The survey was aimed to evaluate impact of bird cherry-oat aphid (Rhopalosiphum padi L.) or grain aphid (Sitobion avenae F.) herbivory on expression of genes related to ascorbate-glutathione (AsA-GSH) cycle in seedlings of six maize varieties (Ambrozja, Nana, Tasty Sweet, Touran, Waza, Złota Karłowa), differing in resistance to the cereal aphids. Relative expression of sixteen maize genes encoding isoenzymes of ascorbate peroxidase (APX1, APX2, APX3, APX4, APX5, APX6, APX7), monodehydroascorbate reductase (MDHAR1, MDHAR2, MDHAR3, MDHAR4), dehydroascorbate reductase (DHAR1, DHAR2, DHAR3) and glutathione reductase (GR1, GR2) was quantified. Furthermore, effect of hemipterans’ attack on activity of APX, MDHAR, DHAR and GR enzymes, and the content of reduced and oxidized ascorbate and glutathione in maize plants were assessed. Seedling leaves of more resistant Z. mays varieties responded higher elevations in abundance of target transcripts. In addition, earlier and stronger aphid-triggered changes in activity of APX, MDHAR, DHAR and GR enzymes, and greater modulations in amount of the analyzed antioxidative metabolites were detected in foliar tissues of highly resistant Ambrozja genotype in relation to susceptible Tasty Sweet plants

Biochemiczne i anatomiczne aspekty żerowania mszycy czeremchowo-zbożowej (Rhopalosiphum padi /L./) na żywicielu pierwotnym

Wydział PrzyrodniczyStreszczenie: Rozprawa doktorska pt. „Biochemiczne i anatomiczne aspekty żerowania mszycy czeremchowo zbożowej (Rhopalosiphum padi /L./) na żywicielu pierwotnym” stanowi wielopłaszczyznowe studium interakcji zachodzących między mszycą czeremchowo zbożową a jej gospodarzem pierwotnym (czeremchą zwyczajną). W pierwszym etapie badań określano dyna-mikę liczebności i strukturę populacji R. padi na żywicielu pierwotnym w sezo-nach 2001-2003. Następnie wykonywano analizy biochemiczne, których celem było ustalenie wpływu żerowania wymienionej mszycy na: • zawartość w liściach czeremchy zwy-czajnej cukrowców rozpuszczalnych i redukujących, sacharozy, celulozy, hemiceluloz, substancji pektynowych, wolnych aminokwasów, albumin, glo-bulin, całkowitego RNA, chlorofilu a i b oraz karotenoidów, • aktywność następujących enzymów: β-fruktofuranozydazy, α- i β-glukozy-dazy, proteinaz wyodrębnianych w pH 5,0 i 7,0, leucyloaminopeptydazy, aminotransferazy asparaginianowej, rybonukleaz izolowanych w pH 4,0 i 7,6, chlorofilazy oraz dechelatazy magnezowej w liściach żywiciela pierwotnego. Zakres podjętych badań obejmował również określenie różnic w poziomie analizowanych komponentów chemicznych i aktywności wybranych enzymów w liściach czeremchy zwyczajnej podczas ich rozwoju ontogenetycznego. Ponadto doko-nano oceny zmian anatomicznych w tkankach gospodarza pierwotnego wywołanych żerowaniem R. padi.Summary: Doctoral dissertation: „Biochemical and anatomical aspects of bird cherry-oat aphid (Rhopalosiphum padi /L./) feeding on primary host” is a multi-level study of interactions occurring between the bird cherry-oat aphid and its primary host (bird cherry). During the first phase of experiments, the dynamics of abundance and the structure of R. padi population on primary host during three vegetation seasons (2001-2003) were established. Subsequently, biochemical analyses were carried out, which purpose was to determine the influence of aphid feeding on: • the content of soluble and reducing sugars, sucrose, cellulose, hemicelluloses, pectin substances, free amino acids, albumins, globulins, total RNA, chlorophyll a and b, carotenoids, • activity of the following enzymes: β-fructofuranosidase, α- and β-gluco-sidase, proteinases extracted at pH 5.0 and 7.0, leucylaminopeptidase, asparagine aminotransferase, ribonucleases isolated at pH 4.0 and 7.6, chlorophyllase and Mg-dechelatase in bird cherry leaves. The purpose of research was also to define the differences in the levels of the examined chemical compounds and in the activity of selected enzymes in the bird cherry leaves during their ontogenetical development. Furthermore, the anatomical changes in tissues of the primary host caused by R. padi feeding were analyse

Results of the factorial ANOVA of experimental factors (maize genotype, aphid species, treatment = infestation level, time post-infestation) and their interactions influencing the relative expression of <i>sod2</i> and <i>sod3.4</i> genes in maize seedlings.

<p>Df, degree of freedom; values of P ≤ 0.05 were considered statistically significant.</p

Transcription of <i>sod9</i> in aphid-colonized seedling leaves of the Tasty Sweet and Ambrozja maize varieties.

<p>(I) – infestation level (number of aphids per seedling). Values represent the average fold changes in relative gene expression (± SD) in the aphid-infested maize seedlings compared with control (non-infested) plants. For each experimental combination, three independent biological replicates were performed. Different letters indicate statistically significant differences (Tukey's test; P≤0.05).</p

Differential Expression of Superoxide Dismutase Genes in Aphid-Stressed Maize (<i>Zea mays</i> L.) Seedlings

<div><p>The aim of this study was to compare the expression patterns of superoxide dismutase genes (<i>sod2</i>, <i>sod3.4</i>, <i>sod9</i> and <i>sodB</i>) in seedling leaves of the <i>Zea mays</i> L. Tasty Sweet (susceptible) and Ambrozja (relatively resistant) cultivars infested with one of two hemipteran species, namely monophagous <i>Sitobion avenae</i> F. (grain aphid) or oligophagous <i>Rhopalosiphum padi</i> L. (bird cherry-oat aphid). Secondarily, aphid-elicited alternations in the antioxidative capacity towards DPPH (1,1-diphenyl-2-picrylhydrazyl) radical in insect-stressed plants were evaluated. Comprehensive comparison of expression profiles of the four <i>sod</i> genes showed that both insect species evoked significant upregulation of three genes <i>sod2</i>, <i>sod3.4</i> and <i>sod9</i>). However, aphid infestation affected non-significant fluctuations in expression of <i>sodB</i> gene in seedlings of both maize genotypes. The highest levels of transcript accumulation occurred at 8 h (<i>sod2</i> and <i>sod3.4</i>) or 24 h (<i>sod9</i>) post-infestation, and aphid-induced changes in the expression of <i>sod</i> genes were more dramatic in the Ambrozja cultivar than in the Tasty Sweet variety. Furthermore, bird cherry-oat aphid colonization had a more substantial impact on levels of DPPH radical scavenging activity in infested host seedlings than grain aphid colonization. Additionally, Ambrozja plants infested by either hemipteran species showed markedly lower antioxidative capacity compared with attacked Tasty Sweet plants.</p></div

Transcription of <i>sod2</i> in aphid-colonized seedlings of Tasty Sweet (susceptible) and Ambrozja (relatively resistant) maize varieties.

<p>(I) – infestation level (number of aphids per seedling). Values represent the average fold change in relative gene expression (± SD) in the aphid-infested maize seedlings compared with control (uninfested) plants. For each experimental combination, three independent biological replicates were performed. Different letters indicate statistically significant differences (Tukey's test; P≤0.05).</p