Phenylalanine ammonia-lyase2.1 contributes to the soybean response towards Phytophthora sojae infection (original) (raw)
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Frontiers in plant science, 2015
Isoflavone reductase (IFR) is an enzyme involved in the biosynthetic pathway of isoflavonoid phytoalexin in plants. IFRs are unique to the plant kingdom and are considered to have crucial roles in plant response to various biotic and abiotic environmental stresses. Here, we report the characterization of a novel member of the soybean isoflavone reductase gene family GmIFR. Overexpression of GmIFR transgenic soybean exhibited enhanced resistance to Phytophthora sojae. Following stress treatments, GmIFR was significantly induced by P. sojae, ethephon (ET), abscisic acid (placeCityABA), salicylic acid (SA). It is located in the cytoplasm when transiently expressed in soybean protoplasts. The daidzein levels reduced greatly for the seeds of transgenic plants, while the relative content of glyceollins in transgenic plants was significantly higher than that of non-transgenic plants. Furthermore, we found that the relative expression levels of reactive oxygen species (ROS) of transgenic so...
Journal of Fungi
Phytophthora sojae, the agent responsible for stem and root rot, is one of the most damaging plant pathogens of soybean. To establish a compatible-interaction, P. sojae secretes a wide array of effector proteins into the host cell. These effectors have been shown to act either in the apoplastic area or the cytoplasm of the cell to manipulate the host cellular processes in favor of the development of the pathogen. Deciphering effector-plant interactions is important for understanding the role of P. sojae effectors in disease progression and developing approaches to prevent infection. Here, we review the subcellular localization, the host proteins, and the processes associated with P. sojae effectors. We also discuss the emerging topic of effectors in the context of effector-resistance genes interaction, as well as model systems and recent developments in resources and techniques that may provide a better understanding of the soybean-P. sojae interaction.
Canadian Journal of Botany, 1988
Phenylalanine ammonia-lyase activity increased rapidly beginning 2 h after inoculation with Phytophthora megasperma (Drechs.) f.sp. glycinea (Hildeb.) Kuan & Erwin race 1 in unwounded hypocotyls of soybean cv. Harosoy 63 (resistant) but did not change significantly in cv. Harosoy (susceptible). Small increases in phenylalanine ammonia-lyase activity also were caused by wounding. Activity increased more slowly in hypocotyls (cv. Harosoy 63) wounded just before inoculation than in intact inoculated hypocotyls, but most activity developed in hypocotyls wounded 12 h before inoculation. There were comparable effects of wounding on symptom development. Trifoliolate leaves of 14-day-old cv. Harosoy 63 plants are resistant, but trifoliolate leaves of 12-day-old cv. Harosoy 63 plants and of 14-day-old cv. Harosoy plants are susceptible to race 1. Increases in phenylalanine ammonia-lyase activity following inoculation were demonstrated only in 14-day-old Harosoy 63 plants but not until 24–36 ...
New Phytologist, 2016
Salicylic acid (SA), an essential regulator of plant defense, is derived from chorismate via either the phenylalanine ammonia lyase (PAL) or the isochorismate synthase (ICS) catalyzed steps. The ICS pathway is thought to be the primary contributor of defense-related SA, at least in Arabidopsis. We investigated the relative contributions of PAL and ICS to defenserelated SA accumulation in soybean (Glycine max). Soybean plants silenced for five PAL isoforms or two ICS isoforms were analyzed for SA concentrations and SA-derived defense responses to the hemibiotrophic pathogens Pseudomonas syringae and Phytophthora sojae. We show that, unlike in Arabidopsis, PAL and ICS pathways are equally important for pathogen-induced SA biosynthesis in soybean. Knock-down of either pathway shuts down SA biosynthesis and abrogates pathogen resistance. Moreover, unlike in Arabidopsis, pathogen infection is associated with the suppression of ICS gene expression. Pathogeninduced biosynthesis of SA via the PAL pathway correlates inversely with phenylalanine concentrations. Although infections with either virulent or avirulent strains of the pathogens increase SA concentrations, resistance protein-mediated response to avirulent P. sojae strains may function in an SA-independent manner. These results show that PAL-and ICS-catalyzed reactions function cooperatively in soybean defense and highlight the importance of PAL in pathogen-induced SA biosynthesis.
A B S T R A C T Asian soybean rust (ASR), caused by the obligate biotrophic fungus Phakopsora pachyrhizi, is responsible for severe yield losses of up to 90% in all soybean producing countries. Till today, eight resistance to Phakopsora pachyrhizi (Rpp) loci have been mapped in soybean. Their resistance mechanism is race specific but largely unknown. The transcriptomes of susceptible BRS184 and Rpp3 with ASR isolates T1-2 at 24 h after inoculation (hai) and without ASR inoculation (mock) were annotated by similarity searching with different databases. A total of 4518 differentially expressed genes were identified. We found 70.89%, 56.61%, 32.13%, and 56.04% genes in the protein family databases (PFAM), Gene Ontology (GO), Eukaryotic clusters of Orthologous Groups (KOG), and Kyoto Encyclopedia of Genes and Genomes Pathway (KEGG), respectively. KEGG disclosed that 52% of the phenylpropanoid pathway related genes were up-regulated. The relative gene expression study for selected genes of that pathway was conducted by RT-qPCR using Rpp1-Rpp4 carrying lines with T1-2 infection. The RT-qPCR results revealed that the Rpp lines utilized these genes in a rate limiting manner as a defence response. With the exception of glycinol 4-dimethylallyltransferase (G4DT) and chalcone reductase (CHR), all the genes showed the greatest expression at 12 hai, but the gene expressions which occur between 24 and 96 hai make these Rpp lines unique to their respective ASR isolates. Moreover, functional coordination of arogenate dehy-dratase 6 (ADT6) and 4-hydroxy-3-methylbut-2-enyl diphosphate synthase (ispG), chalcone synthase (CHS) and CHR, and G4DT and phytyltransferase 3 (PT3) may have a great impact on soybean resistance against ASR.
Phytopathology, 2013
The response of soybean transgenic plants, with suppressed synthesis of isoflavones, and nontransgenic plants to two common soybean pathogens, Macrophomina phaseolina and Phytophthora sojae, was studied. Transgenic soybean plants of one line used in this study were previously generated via bombardment of embryogenic cultures with the phenylalanine ammonia lyase, chalcone synthase, and isoflavone synthase (IFS2) genes in sense orientation driven by the cotyledon-preferable lectin promoter (to turn genes on in cotyledons), while plants of another line were newly produced using the IFS2 gene in sense orientation driven by the Cassava vein mosaic virus constitutive promoter (to turn genes on in all plant parts). Nearly complete inhibition of isoflavone synthesis was found in the cotyledons of young seedlings of transgenic plants transformed with the IFS2 transgene driven by the cotyledon-preferable lectin promoter compared with the untransformed control during the 10-day observation per...
Experientia, 2003
The phytotoxic protein PcF (Phytophthora cactorum-Fragaria) is a 5.6-kDa cysteine-rich, hydroxyproline- containing protein that is secreted in limited amounts by P. cactorum, an oomycete pathogen of tomato, strawberry and other relevant crop plants. Although we have shown that pure PcF triggers plant reactivity, its mechanism of action is not yet understood. Here we show that PcF, like other known fungal protein elicitors involved in pathogen-plant interaction, stimulates the activity of the defense enzyme phenylalanine ammonia a key step in understanding the mechanism of action of PcF at a molecular level is knowledge of its three-dimensional structure, we overexpressed this protein extracellularly in Pichia pastoris. The preliminary structural and functional characterization of a recombinant PcF homologue, N4-rPcF, is reported. Interestingly, although N4-rPcF is devoid of proline hydroxylation and has four additional amino acid residues attached to its N terminus, its secondary structure and biological activity are indistinguishable from wild-type PcF.
Tomato Phenylalanine Ammonia-Lyase Gene Family, Highly Redundant but Strongly Underutilized
Journal of Biological Chemistry, 2008
Phenylalanine ammonia-lyase (PAL) is an important enzyme in both plant development and pathogen defense. In all plants it is encoded by a multi-gene family, ranging in copy number from four in Arabidopsis to a dozen or more copies in some higher plants. Many studies indicate that alternate genes are differentially regulated in response to environmental stimuli. In this study, Southern blot and dot blot analyses in tomato indicate a surprisingly large family of related sequences with ϳ26 copies in the diploid genome, some easily distinguished by restriction enzyme digestion. Analyses of a BAC genome library suggest that the genes are generally not clustered. A more detailed comparison of the gene sequences using PCR to isolate the individual copies and reverse transcription-PCR to study the transcripts that they encode indicates a significant diversity in the gene sequences themselves, but surprisingly only one mRNA transcript can be detected even when additional expression is induced by pathogen growth or wounding. Consistent with previous reports in other plants, a parallel study with a closely related plant, the potato, indicates a much broader utilization of the PAL genes, highlighting the unusual nature of this family in tomato and of the mechanism(s) that silences so many members. Plant transformation analyses further demonstrate the presence of very active silencing, suggesting aggressive competition between PAL gene duplication and copy inactivation during PAL gene evolution.