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Camalexin contributes to the partial resistance of Arabidopsis thaliana to the biotrophic soilborne protist Plasmodiophora brassicae.

LemariƩ S, Robert-Seilaniantz A, Lariagon C, Lemoine J, Marnet N, Levrel A, Jubault M, Manzanares-Dauleux MJ, Gravot A - Front Plant Sci (2015)

Bottom Line: This induction correlated with slower P. brassicae growth in Bur-0 compared to Col-0, thus suggesting a relationship between the levels of camalexin biosynthesis and the different levels of resistance.The Bur/Col allelic substitution in the region of the previously identified clubroot resistance QTL PbAt5.2 (Chromosome 5) was associated with both the enhanced clubroot-triggered induction of camalexin biosynthesis and the reduced P. brassicae development.Altogether, our results suggest that high levels of clubroot-triggered camalexin biosynthesis play a role in the quantitative control of partial resistance of Arabidopsis to clubroot.

View Article: PubMed Central - PubMed

Affiliation: UMR1349 IGEPP, INRA Le Rheu, France.

ABSTRACT
Camalexin has been reported to play defensive functions against several pathogens in Arabidopsis. In this study, we investigated the possible role of camalexin accumulation in two Arabidopsis genotypes with different levels of basal resistance to the compatible eH strain of the clubroot agent Plasmodiophora brassicae. Camalexin biosynthesis was induced in infected roots of both Col-0 (susceptible) and Bur-0 (partially resistant) accessions during the secondary phase of infection. However, the level of accumulation was four-to-seven times higher in Bur-0 than Col-0. This was associated with the enhanced transcription of a set of camalexin biosynthetic P450 genes in Bur-0: CYP71A13, CYP71A12, and CYP79B2. This induction correlated with slower P. brassicae growth in Bur-0 compared to Col-0, thus suggesting a relationship between the levels of camalexin biosynthesis and the different levels of resistance. Clubroot-triggered biosynthesis of camalexin may also participate in basal defense in Col-0, as gall symptoms and pathogen development were enhanced in the pad3 mutant (Col-0 genetic background), which is defective in camalexin biosynthesis. Clubroot and camalexin responses were then studied in Heterogeneous Inbred Families (HIF) lines derived from a cross between Bur-0 and Col-0. The Bur/Col allelic substitution in the region of the previously identified clubroot resistance QTL PbAt5.2 (Chromosome 5) was associated with both the enhanced clubroot-triggered induction of camalexin biosynthesis and the reduced P. brassicae development. Altogether, our results suggest that high levels of clubroot-triggered camalexin biosynthesis play a role in the quantitative control of partial resistance of Arabidopsis to clubroot.

No MeSH data available.


Related in: MedlinePlus

(A) Clubroot symptoms and (B) quantification of Plasmodiophora brassicae DNA in infected roots of the clubroot susceptible WT Col-0 and pad3. (A) Clubroot symptoms were evaluated using the GA/LA disease index calculated by image analysis at 21 dpi. GA/LA is the ratio between gall area (GA in cm2) and an estimation of the rosette extent (LA in cm2). Error bars represent standard error (Four biological replicates, six plants per biological replicate). (B) Pathogen DNA quantification (Pb) by qPCR, expressed as a ratio relative to the expression level of the plant Fbox gene, at 21 dpi (Four biological replicates, six plants per biological replicate). Asterisks indicate statistically significant differences according to the Wald tests applied on a linear mixed model (P < 0.05).
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Figure 4: (A) Clubroot symptoms and (B) quantification of Plasmodiophora brassicae DNA in infected roots of the clubroot susceptible WT Col-0 and pad3. (A) Clubroot symptoms were evaluated using the GA/LA disease index calculated by image analysis at 21 dpi. GA/LA is the ratio between gall area (GA in cm2) and an estimation of the rosette extent (LA in cm2). Error bars represent standard error (Four biological replicates, six plants per biological replicate). (B) Pathogen DNA quantification (Pb) by qPCR, expressed as a ratio relative to the expression level of the plant Fbox gene, at 21 dpi (Four biological replicates, six plants per biological replicate). Asterisks indicate statistically significant differences according to the Wald tests applied on a linear mixed model (P < 0.05).

Mentions: Although it accumulated at lower levels than in Bur-0, as described above, there was significant clubroot-triggered biosynthesis of camalexin in Col-0 at 17 dpi. Thus, we evaluated whether, under our experimental conditions, this camalexin accumulation is involved in the control of post-invasive basal resistance to the eH isolate. To test this hypothesis, clubroot symptoms and root pathogen content were evaluated in the pad3 mutant (Col-0 background). The results are shown in Figure 4 and clearly indicated that, at 21 dpi, both symptom severity and pathogen content in infected roots were enhanced in pad3 compared to the wild type Col-0. This suggests that the camalexin response does contribute to a late and weak basal control of clubroot symptoms and pathogen development in Col-0.


Camalexin contributes to the partial resistance of Arabidopsis thaliana to the biotrophic soilborne protist Plasmodiophora brassicae.

LemariƩ S, Robert-Seilaniantz A, Lariagon C, Lemoine J, Marnet N, Levrel A, Jubault M, Manzanares-Dauleux MJ, Gravot A - Front Plant Sci (2015)

(A) Clubroot symptoms and (B) quantification of Plasmodiophora brassicae DNA in infected roots of the clubroot susceptible WT Col-0 and pad3. (A) Clubroot symptoms were evaluated using the GA/LA disease index calculated by image analysis at 21 dpi. GA/LA is the ratio between gall area (GA in cm2) and an estimation of the rosette extent (LA in cm2). Error bars represent standard error (Four biological replicates, six plants per biological replicate). (B) Pathogen DNA quantification (Pb) by qPCR, expressed as a ratio relative to the expression level of the plant Fbox gene, at 21 dpi (Four biological replicates, six plants per biological replicate). Asterisks indicate statistically significant differences according to the Wald tests applied on a linear mixed model (P < 0.05).
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Figure 4: (A) Clubroot symptoms and (B) quantification of Plasmodiophora brassicae DNA in infected roots of the clubroot susceptible WT Col-0 and pad3. (A) Clubroot symptoms were evaluated using the GA/LA disease index calculated by image analysis at 21 dpi. GA/LA is the ratio between gall area (GA in cm2) and an estimation of the rosette extent (LA in cm2). Error bars represent standard error (Four biological replicates, six plants per biological replicate). (B) Pathogen DNA quantification (Pb) by qPCR, expressed as a ratio relative to the expression level of the plant Fbox gene, at 21 dpi (Four biological replicates, six plants per biological replicate). Asterisks indicate statistically significant differences according to the Wald tests applied on a linear mixed model (P < 0.05).
Mentions: Although it accumulated at lower levels than in Bur-0, as described above, there was significant clubroot-triggered biosynthesis of camalexin in Col-0 at 17 dpi. Thus, we evaluated whether, under our experimental conditions, this camalexin accumulation is involved in the control of post-invasive basal resistance to the eH isolate. To test this hypothesis, clubroot symptoms and root pathogen content were evaluated in the pad3 mutant (Col-0 background). The results are shown in Figure 4 and clearly indicated that, at 21 dpi, both symptom severity and pathogen content in infected roots were enhanced in pad3 compared to the wild type Col-0. This suggests that the camalexin response does contribute to a late and weak basal control of clubroot symptoms and pathogen development in Col-0.

Bottom Line: This induction correlated with slower P. brassicae growth in Bur-0 compared to Col-0, thus suggesting a relationship between the levels of camalexin biosynthesis and the different levels of resistance.The Bur/Col allelic substitution in the region of the previously identified clubroot resistance QTL PbAt5.2 (Chromosome 5) was associated with both the enhanced clubroot-triggered induction of camalexin biosynthesis and the reduced P. brassicae development.Altogether, our results suggest that high levels of clubroot-triggered camalexin biosynthesis play a role in the quantitative control of partial resistance of Arabidopsis to clubroot.

View Article: PubMed Central - PubMed

Affiliation: UMR1349 IGEPP, INRA Le Rheu, France.

ABSTRACT
Camalexin has been reported to play defensive functions against several pathogens in Arabidopsis. In this study, we investigated the possible role of camalexin accumulation in two Arabidopsis genotypes with different levels of basal resistance to the compatible eH strain of the clubroot agent Plasmodiophora brassicae. Camalexin biosynthesis was induced in infected roots of both Col-0 (susceptible) and Bur-0 (partially resistant) accessions during the secondary phase of infection. However, the level of accumulation was four-to-seven times higher in Bur-0 than Col-0. This was associated with the enhanced transcription of a set of camalexin biosynthetic P450 genes in Bur-0: CYP71A13, CYP71A12, and CYP79B2. This induction correlated with slower P. brassicae growth in Bur-0 compared to Col-0, thus suggesting a relationship between the levels of camalexin biosynthesis and the different levels of resistance. Clubroot-triggered biosynthesis of camalexin may also participate in basal defense in Col-0, as gall symptoms and pathogen development were enhanced in the pad3 mutant (Col-0 genetic background), which is defective in camalexin biosynthesis. Clubroot and camalexin responses were then studied in Heterogeneous Inbred Families (HIF) lines derived from a cross between Bur-0 and Col-0. The Bur/Col allelic substitution in the region of the previously identified clubroot resistance QTL PbAt5.2 (Chromosome 5) was associated with both the enhanced clubroot-triggered induction of camalexin biosynthesis and the reduced P. brassicae development. Altogether, our results suggest that high levels of clubroot-triggered camalexin biosynthesis play a role in the quantitative control of partial resistance of Arabidopsis to clubroot.

No MeSH data available.


Related in: MedlinePlus