Differential accumulation of plant defense gene transcripts in a compatible and an incompatible plant-pathogen interaction

Phenylalanine ammonia-lyase and chalcone synthase catalyze the first reaction of phenylpropanoid biosynthesis and the first reaction of a branch pathway specific for flavonoid-isoflavonoid biosynthesis, respectively. These enzymes are key control elements in the synthesis of kievitone, phaseollin, and related isoflavonoid-derived phytoalexins. RNA blot hybridization with 32P-labeled cDNA sequences was used to demonstrate marked accumulation of phenylalanine ammonia-lyase and chalcone synthase mRNAs in excision-wounded hypocotyls of Phaseolus vulgaris L. (dwarf French bean) and during race-cultivar-specific interactions between hypocotyls of P. vulgaris and the partially biotrophic fungus Colletotrichum lindemuthianum, the causal agent of anthracnose. In an incompatible interaction (host resistant), early concomitant accumulation of phenylalanine ammonia-lyase and chalcone synthase mRNAs, localized mainly but not entirely in tissue adjacent to the site of infection, was observed prior to the onset of phytoalexin accumulation and expression of localized, hypersensitive resistance. In contrast, in a compatible interaction (host susceptible) there was no early accumulation of these transcripts; instead, there was a delayed widespread response associated with phytoalexin accumulation during attempted lesion limitation. Two-dimensional gel electrophoresis of [35S]methionine-labeled polypeptides synthesized in vitro by translation of isolated polysomal RNA demonstrated stimulation of the synthesis of characteristic sets of phenylalanine ammonia-lyase and chalcone synthase isopolypeptides in directly infected tissue and distant, hitherto uninfected tissue in both compatible and incompatible interactions. Our data show that specific accumulation of plant defense gene transcripts is a key early component in the sequence of events leading to expression of defense responses in wounded tissue and in infected tissue during race-cultivar-specific interactions and that an elicitation signal is transmitted intercellularly in response to infection.

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A small cysteine-rich phytotoxic protein of Phytophthora capsici functions as both plant defense elicitor and virulence factor

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-01-21-0025-r ◽

2021 ◽

Author(s):

Zi-Hui Zhang ◽

Jinghao Jin ◽

Gui-Lin Sheng ◽

Yu-Ping Xing ◽

Wang Liu ◽

...

Keyword(s):

Plant Defense ◽

Virulence Factor ◽

Phytophthora Capsici ◽

Ectopic Expression ◽

Defense Responses ◽

Phytophthora Species ◽

Plant Interactions ◽

Defense Gene Expression ◽

Callose Deposition ◽

Defense Gene

Small cysteine-rich (SCR) proteins including fungal avirulence proteins play important roles in the pathogen-plant interactions. SCR protein-encoding genes have been discovered in the genomes of Phytophthora pathogens, but their functions during the pathogenesis remain obscure. Here, we report the characterization of one Phytophthora capsici SCR protein, namely SCR82 with similarity to Phytophthora cactorum phytotoxic protein PcF. The scr82 gene has 10 allelic sequences in the P. capsici population. Homologues of SCR82 were not identified in fungi or other organisms but in Phytophthora relative species. Initially scr82 was weakly expressed during the mycelium, sporangium and zoospore stages, but quickly upregulated when the infection initiated. Both ectopic expression of SCR82 and recombinant yeast-expressed protein (rSCR82) caused cell death on tomato leaves. Upon treatment, rSCR82 induced plant defense responses including the induction of defense gene expression, reactive oxygen species burst and callose deposition. Knockout of scr82 in P. capsici by CRISPR/Cas9 severely impaired its virulence on host plants and reduced significantly its resistance againstoxidative stress. Inversely, its overexpression increased the pathogen’s virulence and tolerance to oxidative stress. Our results collectively demonstrate that SCR82 functions as both an important virulence factor and plant defense elicitor, which is conserved across Phytophthora species.

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Induction of chalcone synthase and phenylalanine ammonia-lyase by salicylic acid and Colletotrichum lindemuthianum in common bean

Brazilian Journal of Plant Physiology ◽

10.1590/s1677-04202003000300001 ◽

2003 ◽

Vol 15 (3) ◽

pp. 129-134 ◽

Cited By ~ 33

Author(s):

Ângela Diniz Campos ◽

Alfredo Gui Ferreira ◽

Magdolna Maria Vozári Hampe ◽

Irajá Ferreira Antunes ◽

Nely Brancão ◽

...

Keyword(s):

Enzyme Activity ◽

Salicylic Acid ◽

Common Bean ◽

Phenylalanine Ammonia Lyase ◽

Chalcone Synthase ◽

Colletotrichum Lindemuthianum ◽

Water Control ◽

Leaf Extracts ◽

The Common ◽

Two Stages

The activities of the enzymes chalcone synthase (CHS) and phenylalanine ammonia-lyase (PAL) were measured in leaf extracts obtained from four cultivars of the common bean (AB 136, Rio Tibagi, Carioca and Macanudo). Two stages of plant development were examined: plantlets (V2) and the onset of blooming (R6). Initially, the plants were either treated with salicylic acid or inoculated with the delta race of Colletotrichum lindemuthianum (inductive fungus) and after three days they were evaluated for enzyme activity. Afterwards, all plants were inoculated (challenged) with the virulent pathotype 33/95 of C. lindemuthianum except for the water control. Five days later, the activities of PAL and CHS were evaluated. There were significant changes in the activities of both enzymes three days after treatment with salicylic acid or inductive fungus when compared to the control. Five days after inoculation with with the virulent pathotype 33/95 of C. lindemuthianum CHS activity in the Macanudo was similar to control plants that were not treated with salicylic acid or the inductive fungus but inoculated with 33/95 C. lindemuthianum. The increase in enzyme activity after challenge with 33/95 C. lindemuthianum was greatest for the salicylic acid treatment in the cultivar AB 136, followed by Rio Tibagi and Carioca.

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Real-Time Quantitative RT-PCR of Defense-Associated Gene Transcripts of Rhizoctonia solani-Infected Bean Seedlings in Response to Inoculation with a Nonpathogenic Binucleate Rhizoctonia Isolate

Phytopathology ◽

10.1094/phyto-95-0345 ◽

2005 ◽

Vol 95 (4) ◽

pp. 345-353 ◽

Cited By ~ 30

Author(s):

Kui Wen ◽

Philippe Seguin ◽

Marc St.-Arnaud ◽

Suha Jabaji-Hare

Keyword(s):

Real Time ◽

Phenylalanine Ammonia Lyase ◽

Gene Activation ◽

Disease Suppression ◽

Rt Pcr ◽

Disease Symptoms ◽

Defense Gene ◽

Binucleate Rhizoctonia ◽

Gene Transcripts ◽

Polymerase Chain

Certain isolates of nonpathogenic binucleate Rhizoctonia spp. (np-BNR) are effective biocontrol agents against seedling root rot and damping-off. Inoculation of bean seed with np-BNR strain 232-CG at sowing reduced disease symptoms in bean (Phaseolus vulgaris) seedlings caused by R. solani. Molecular analyses of the spatial expression of three defense-associated genes were carried out using real-time quantitative reverse transcription-polymerase chain reaction (QRT-PCR) assays. This method allowed accurate quantitative evaluation of transcript levels of pG101 encoding for 1,3-β-D-glucanase, gPAL1 encoding for phenylalanine ammonia lyase, and CHS17 encoding for chalcone synthase in 1- and 2-week-old bean seedlings that were inoculated simultaneously with np-BNR and infected with R. solani, and in seedlings that were singly inoculated with either fungi or not inoculated. In the seedlings that were infected with R. solani only, results revealed that, following infection, activation of all defense-associated gene transcripts was achieved with significant increases ranging from 7- to 40-fold greater than the control, depending on the defense gene and tissue analyzed. Seedlings that were treated with np-BNR and infected with R. solani had expression similar to those that were treated with np-BNR only, but the levels were significantly down-regulated compared with those that were infected with R. solani only. These findings indicate that disease suppression by np-BNR isolate is not correlated to pG101, gPAL1, and CHS17 gene activation.

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Functional Analysis of Plant Defense Suppression and Activation by the Xanthomonas Core Type III Effector XopX

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-09-14-0263-r ◽

2015 ◽

Vol 28 (2) ◽

pp. 180-194 ◽

Cited By ~ 23

Author(s):

William Stork ◽

Jung-Gun Kim ◽

Mary Beth Mudgett

Keyword(s):

Plant Defense ◽

Defense Responses ◽

Effector Proteins ◽

Immune Signaling ◽

Type Iii ◽

Effector Triggered Immunity ◽

Gene Transcripts ◽

Type Iii Secretion Effector ◽

Susceptible Tomato

Many phytopathogenic type III secretion effector proteins (T3Es) have been shown to target and suppress plant immune signaling but perturbation of the plant immune system by T3Es can also elicit a plant response. XopX is a “core” Xanthomonas T3E that contributes to growth and symptom development during Xanthomonas euvesicatoria infection of tomato but its functional role is undefined. We tested the effect of XopX on several aspects of plant immune signaling. XopX promoted ethylene production and plant cell death (PCD) during X. euvesicatoria infection of susceptible tomato and in transient expression assays in Nicotiana benthamiana, which is consistent with its requirement for the development of X. euvesicatoria-induced disease symptoms. Additionally, although XopX suppressed flagellin-induced reactive oxygen species, it promoted the accumulation of pattern-triggered immunity (PTI) gene transcripts. Surprisingly, XopX coexpression with other PCD elicitors resulted in delayed PCD, suggesting antagonism between XopX-dependent PCD and other PCD pathways. However, we found no evidence that XopX contributed to the suppression of effector-triggered immunity during X. euvesicatoria–tomato interactions, suggesting that XopX's primary virulence role is to modulate PTI. These results highlight the dual role of a core Xanthomonas T3E in simultaneously suppressing and activating plant defense responses.

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Induction of Chalcone Synthase Expression by Rhizobia and Nod factors in Root Hairs and Roots

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.1997.10.3.388 ◽

1997 ◽

Vol 10 (3) ◽

pp. 388-393 ◽

Cited By ~ 11

Author(s):

Andrea Krause ◽

Vo T. T. Lan ◽

William J. Broughton

Keyword(s):

Chalcone Synthase ◽

Root Hairs ◽

Signal Transduction Pathway ◽

Defense Responses ◽

Nod Factors ◽

Nod Factor ◽

Transcript Levels ◽

Gene Transcripts ◽

Infection Pathway ◽

Rhizobium Sp

Chalcone synthase (CHS) of Vigna unguiculata is encoded by a gene family that is abundantly transcribed in leaves and nodules. Inoculation with Rhizobium sp. NGR234, which nodulates V. unguiculata, or with NGRΔnodABC, a mutant deficient in Nod factor production, induced rapid accumulation of CHS mRNAs in roots and root hairs. As both Nod+ and Nod- bacteria provoke responses, induction of CHS gene expression may involve symbiotic or defense responses. Four days after inoculation with the wild-type Rhizobium sp., the transcript levels increased in roots but decreased in root hairs. Use of a region unique to the 5′ end of a specific CHS gene (VuCHS1) showed that increases of transcript levels in root hairs 24 h after inoculation with both rhizobia were specific to this gene. Transcripts of this gene in roots were only detectable 4 days after treatment with NGR234. It is possible therefore that accumulation of VuCHS1 follows the infection pathway of rhizobia entering legume roots. Purified Nod factors induced accumulation of transcripts, showing that they might be part of the signal transduction pathway leading to CHS expression.

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Transcriptional activation of plant defense genes by fungal elicitor, wounding, and infection.

Molecular and Cellular Biology ◽

10.1128/mcb.7.1.335 ◽

1987 ◽

Vol 7 (1) ◽

pp. 335-341 ◽

Cited By ~ 242

Author(s):

M A Lawton ◽

C J Lamb

Keyword(s):

Plant Defense ◽

Transcriptional Activation ◽

Gene Activation ◽

Defense Responses ◽

Colletotrichum Lindemuthianum ◽

Defense Genes ◽

Plant Defense Genes ◽

Elicitor Treatment ◽

Stimulation Of

Activation of plant defense genes was investigated by analysis of transcripts completed in vitro by isolated nuclei. Elicitor treatment of suspension-cultured bean (Phaseolus vulgaris L.) cells caused marked transient stimulation of transcription of genes encoding apoproteins of cell wall hydroxyproline-rich glycoproteins (HRGP) and the phenylpropanoid biosynthetic enzymes phenylalanine ammonia-lyase (PAL) and chalcone synthase (CHS), concomitant with the onset of rapid accumulation of the respective mRNAs and hence expression of the phytoalexin (PAL, CHS), lignin (PAL), and HRGP defense responses. While there was a lag of 2 h prior to stimulation of HRGP gene transcription, induction of the transcription of PAL and CHS genes occurred within 5 min of elicitor treatment. Induction of transcription of PAL, CHS, and HRGP genes was also observed in wounded hypocotyls and in infected hypocotyls during race-cultivar-specific interactions with the fungus Colletotrichum lindemuthianum, the causal agent of anthracnose. Transcriptional activation occurred not only in directly infected tissue but also in distant, hitherto uninfected tissue, indicating intercellular transmission of an endogenous signal for defense gene activation. It is concluded that transcriptional activation of defense genes characteristically underlies induction of the corresponding defense responses and expression of disease resistance.

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Rapid changes in gene expression in response to microbial elicitation

Philosophical Transactions of the Royal Society of London Series B Biological Sciences ◽

10.1098/rstb.1986.0062 ◽

1986 ◽

Vol 314 (1166) ◽

pp. 411-426 ◽

Cited By ~ 20

Keyword(s):

Phenylalanine Ammonia Lyase ◽

Chalcone Synthase ◽

Blot Hybridization ◽

Enzyme Synthesis ◽

Chalcone Isomerase ◽

Colletotrichum Lindemuthianum ◽

Specific Gene ◽

Gene Products

Treatment of cell suspension cultures of French bean ( Phaseolus vulgaris ) with polysaccharide elicitor molecules from cell walls of the anthracnose fungus, Colletotrichum lindemuthianum , results in the rapid accumulation of isoflavonoid phytoalexins, deposition of wall-bound phenolic compounds and synthesis of hydroxyproline-rich glycoproteins. These changes are dependent upon a highly selective induction of gene products, including the enzymes L-phenylalanine ammonia-lyase, cytochrome P450-dependent cinnamic acid 4-hydroxylase, chalcone synthase, chalcone isomerase, prolyl hydroxylase and protein: arabinosyl transferase. Use of in vivo labelling, in vitro translation and RNA blot hybridization techniques has shown that these elicitormediated changes arise from rapid but transient induction of enzyme synthesis, resulting from the accumulation of specific mRNAs. Similar phenomena are observed in bean hypocotyls at the onset of phytoalexin synthesis in response to infection by incompatible and compatible races of C. lindemuthianum . In bean, both L-phenylalanine ammonia-lyase and chalcone synthase are encoded by multigene families and, at the protein level, both exhibit subunit and intact enzyme polymorphism. A number of less than full-length phenylalanine ammonialyase copy DNAs containing identical open reading frames have been produced from mRNA from elicitor-induced bean cells. Analysis of phenylalanine ammonia-lyase genomic clones predicts the presence of enzyme forms of differing amino acid sequence. In cultured bean cells, elicitor differentially induces the two apparent phenylalanine ammonia-lyase iso-forms with the lowest K m values. In addition to transcriptional control of the appearance of specific gene products, post-translational processes may result in increased subunit polymorphism for phenylalanine ammonia-lyase, and in the activation of chalcone isomerase. Changes in endogenous phenylpropanoid intermediate pools may signal the rapid removal of phenylalanine ammonia-lyase activity, in addition to exerting less specific inhibitory effects on the formation and/or activity of the mRNAs encoding phenylalanine ammonia-lyase and other phytoalexin biosynthetic enzymes.

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Transcriptional activation of plant defense genes by fungal elicitor, wounding, and infection

Molecular and Cellular Biology ◽

10.1128/mcb.7.1.335-341.1987 ◽

1987 ◽

Vol 7 (1) ◽

pp. 335-341

Author(s):

M A Lawton ◽

C J Lamb

Keyword(s):

Plant Defense ◽

Transcriptional Activation ◽

Gene Activation ◽

Defense Responses ◽

Colletotrichum Lindemuthianum ◽

Defense Genes ◽

Plant Defense Genes ◽

Elicitor Treatment ◽

Stimulation Of

Activation of plant defense genes was investigated by analysis of transcripts completed in vitro by isolated nuclei. Elicitor treatment of suspension-cultured bean (Phaseolus vulgaris L.) cells caused marked transient stimulation of transcription of genes encoding apoproteins of cell wall hydroxyproline-rich glycoproteins (HRGP) and the phenylpropanoid biosynthetic enzymes phenylalanine ammonia-lyase (PAL) and chalcone synthase (CHS), concomitant with the onset of rapid accumulation of the respective mRNAs and hence expression of the phytoalexin (PAL, CHS), lignin (PAL), and HRGP defense responses. While there was a lag of 2 h prior to stimulation of HRGP gene transcription, induction of the transcription of PAL and CHS genes occurred within 5 min of elicitor treatment. Induction of transcription of PAL, CHS, and HRGP genes was also observed in wounded hypocotyls and in infected hypocotyls during race-cultivar-specific interactions with the fungus Colletotrichum lindemuthianum, the causal agent of anthracnose. Transcriptional activation occurred not only in directly infected tissue but also in distant, hitherto uninfected tissue, indicating intercellular transmission of an endogenous signal for defense gene activation. It is concluded that transcriptional activation of defense genes characteristically underlies induction of the corresponding defense responses and expression of disease resistance.

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