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): Changes in phenylalanine ammonia lyase, tyrosine ammonia lyase and lipoxygenase activities in the leaves of Brassica juncea L. infected with Albugo candida . Physiol. Mol. Biol. Plants. 8, 261–266. Chawla

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, W. W. and Sederoff , R. R. ( 1992 ): Phenylalanine ammonia lyase from loblolly pine: purification of the enzyme and isolation of complementary DNA clones . Plant Physiol. 98 , 380 – 386 . Saravanakumar , D. , Harish , S. , Loganathan

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40 853 858 Dickerson, D. P., Pascholati, S. F., Hagerman, A. E., Butler, L. G., Nicholson, R. L. (1984) Phenylalanine ammonia-lyase and hydroxyl

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Acta Alimentaria
Authors: M.Y. Jiang, Z.R. Wang, K.W. Chen, J.Q. Kan, K.T. Wang, Zs. Zalán, F. Hegyi, K. Takács, and M.Y. Du

After suffering from mechanical injury and fungal infection, grapes are perishable. Botrytis cinerea, the causal agent of gray mould, is a critical pathogen for grapes. In this study, the inhibitory effect of Pseudomonas fluorescens on the formation of gray mould on grapes during the postharvest storage was investigated on “Kyoho” grape. The results suggest that a living cell suspension of P. fluorescens significantly inhibited spore germination of B. cinerea, and significantly reduced the incidence of grape gray mould. Moreover, compared with the control, the fruit inoculated with P. fluorescens had elevated activities of polyphenol oxidase (PPO), peroxidase (POD), catalase (CAT), phenylalanine ammonia-lyase (PAL), chitinase (CHI), and β-1,3-glucanase (GLU). Increase in enzyme activity correlated with enhanced host resistance. In addition, there was little difference in storage quality between the treated group and control group, indicating no adverse effects of the induced defence response on fruit quality.

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The phenolic profile and specific activity of oxidative enzymes in sorghum leaves and stem resistant and susceptible to Chilo partellus (Swinhoe) were analyzed at 45 and 60 days after germination. Resistant varieties had higher content of total phenols, o-dihydric phenols, flavanols and tannins than the susceptible varieties at both the stages of plant growth and the concentration of these biomolecules increased after infestation as well as with plant age in both sets of varieties. Moreover, resistant varieties exhibited higher specific activity of polyphenol oxidase, peroxidase, phenylalanine ammonia-lyase and tyrosine ammonia-lyase in their leaves and stem in comparison to the corresponding activities in susceptible ones. Peroxidase activity was several folds than the polyphenol oxidase. Healthy leaves of susceptible varieties showed higher catalase activity in comparison with resistant ones at day 45 and this trend was reversed at day 60. Role of phenolic compounds and oxidative enzymes particularly the peroxidase in determining resistance against stem borer has been high lighted.

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Crown rot caused by Fusarium pathogens is one of the most economically destructive diseases of wheat. The objective of this study was to investigate defense-related enzyme responses in wheat seedlings infected with Fusarium graminearum. Three wheat varieties were employed to the experiment. Physiological analysis of varieties indicated that defensive-related enzymes were induced by F. graminearum infection. The superoxide dismutase and peroxidase activities increased dramatically and the phenylalanine ammonia-lyase activity was stimulated to a higher level in resistant variety Hongyouzi than in susceptible variety Wo0102. However, the chitinase activity was higher in susceptible variety Wo0102 than in Hongyouzi after infection. These results suggest that the defense enzymes could be stimulated in wheat seedlings by Fusarium infection.

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Cereal Research Communications
Authors: Barbara Steiner, Katharina Schieszl, Ewelina Litwicka, Harald Kurz, Marc Lemmens, Haiyan Jia, Gary Muehlbauer, and Hermann Buerstmayr

Molecular mapping led to the identification of two major Fusarium head blight (FHB) resistance QTL, Fhb1 and Qfhs.ifa-5A . The actual function of the resistance genes is still unknown. The resistant line CM82036, the susceptible line Remus and six closely related lines were analyzed for differential gene expression after Fusarium attack. The related lines show contrasting levels of FHB resistance due to the possession of Fhb1 and Qfhs.ifa-5A . At anthesis plants were challenged by Fusarium graminearum or water and at six time points after inoculation gene expression of specific wheat floral tissue was analyzed by cDNA-AFLPs and the Affymetrix Wheat GeneChip.0.44% of the analyzed gene tags by cDNA-AFLPs displayed differential expressions after Fusarium attack depending on the genotype. Five of the gene tags were associated with the FHB resistance level of the genotypes and the possession of resistance alleles at Fhb1 and Qfhs.ifa-5A . These gene tags show homologies to a UDP-glucosyltransferase, wheat phenylalanine ammonia-lyase, DnaJ-like protein, pathogenesis-related family protein and a rice cDNA clone with unknown function. A thorough comparative analysis with the data gained by the Wheat GeneChip experiments is in progress.

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Cereal Research Communications
Authors: P. Motallebi, S. Tonti, V. Niknam, H. Ebrahimzadeh, A. Pisi, P. Nipoti, M. Hashemi, and A. Prodi

Fusarium culmorum is a soilborne fungal pathogen, agent of crown and root rot disease (FCRR), responsible of major economic losses in wheat plants. This host—pathogen interaction, following methyl jasmonate (MeJA) application at the beginning of the necrotrophic stage of infection, has not been previously studied at molecular level. In this study, using real-time quantitative PCR, the emerging role of MeJA in the basal resistance of two bread wheat cultivars against F. culmorum has been investigated. MeJA treatment was dispensed 6 hours after pathogen inoculation (6 hai) to detect the defense response at the beginning of the necrotrophic stage. The expression of phenylalanine ammonia-lyase (PAL), lipoxygenase (LOX), cytochrome P450 (CYP709C1) genes and of some pathogenesis related (PR) genes, including PR3, PR4 and PR9, was examined in both root and crown tissues of the susceptible wheat cultivar Falat and the tolerant cultivar Sumai3. The pathogen responsive defense genes were induced in both cultivars, with a higher level of induction in Sumai3 than in Falat. MeJA treatment reduced the symptoms in cv Falat, whereas no significant effects have been detected in cv Sumai3. In fact, MeJA treatment caused a striking difference in defense gene induction. The genetic change was present in root and crown tissues of both wheat cultivars, demonstrating a systemic signaling pathway. The chemically induced protection correlated with induction of the F. culmorum-responsive genes supports a possible role of jasmonate signaling in regulating basal resistance in wheat–F. culmorum interaction.

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Dickerson, D. P., Pascholati, S. F., Hagerman, A. E., Butler, L. G. and Nicholson R. L. (1984): Phenylalanine ammonia-lyase and hydroxy cinnamate: CoA ligase in maize mesocotyls inoculated with Helminthosporium maydis or Helminthosporium carbonum

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. & Dixon, R.A. (2004): Colocalization of L-phenylalanine ammonia-lyase and cinnamate 4-hydroxylase for metabolic channeling in phenylpropanoid biosynthesis. Pl. Cell , 16 , 3098–3109. Dixon R

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