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

Lemarié 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.


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Clubroot symptoms and accumulation of DNA from Plasmodiophora brassicae in infected roots of the HIFs 499 and 508. 499-Bur and 499-Col harbor the Bur and Col alleles, respectively, at the QTL PbAt5.2. 508-Bur and 508-Col harbor the Bur and Col alleles, respectively, at the QTL PbAt1. (A,B) Clubroot symptoms evaluated using the GA/LA disease index from image analysis as described in the Materials and Methods Section. Error bars represent standard error (Four independent biological replicates, 18 plants per biological replicate). (C,D) Pathogen DNA quantification (Pb) by qPCR after normalization with the Fbox gene from Arabidopsis, at 10, 14, and 17 dpi (Three independent replicates, 12–54 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 7: Clubroot symptoms and accumulation of DNA from Plasmodiophora brassicae in infected roots of the HIFs 499 and 508. 499-Bur and 499-Col harbor the Bur and Col alleles, respectively, at the QTL PbAt5.2. 508-Bur and 508-Col harbor the Bur and Col alleles, respectively, at the QTL PbAt1. (A,B) Clubroot symptoms evaluated using the GA/LA disease index from image analysis as described in the Materials and Methods Section. Error bars represent standard error (Four independent biological replicates, 18 plants per biological replicate). (C,D) Pathogen DNA quantification (Pb) by qPCR after normalization with the Fbox gene from Arabidopsis, at 10, 14, and 17 dpi (Three independent replicates, 12–54 plants per biological replicate). Asterisks indicate statistically significant differences according to the Wald tests applied on a linear mixed model (P < 0.05).

Mentions: We first validated the effect of QTL PbAt5.2 and PbAt1 on clubroot and pathogen development at 17 and 21 dpi in these two HIF lines (Figure 7). In the HIF lines 499, the Col-to-Bur allelic substitution (in the genomic regions of PbAt5.2) significantly reduced the severity of gall symptoms (Figure 7A) and conferred a one third reduction of pathogen growth at 17 dpi (Figure 7C). In contrast, the allelic substitution at PbAt1, between 508 HIF lines, significantly reduced clubroot symptoms (Figure 7B) but did not have an impact on pathogen growth (Figure 7D), suggesting that different genetic factors may control gall development and pathogen growth.


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

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

Clubroot symptoms and accumulation of DNA from Plasmodiophora brassicae in infected roots of the HIFs 499 and 508. 499-Bur and 499-Col harbor the Bur and Col alleles, respectively, at the QTL PbAt5.2. 508-Bur and 508-Col harbor the Bur and Col alleles, respectively, at the QTL PbAt1. (A,B) Clubroot symptoms evaluated using the GA/LA disease index from image analysis as described in the Materials and Methods Section. Error bars represent standard error (Four independent biological replicates, 18 plants per biological replicate). (C,D) Pathogen DNA quantification (Pb) by qPCR after normalization with the Fbox gene from Arabidopsis, at 10, 14, and 17 dpi (Three independent replicates, 12–54 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 7: Clubroot symptoms and accumulation of DNA from Plasmodiophora brassicae in infected roots of the HIFs 499 and 508. 499-Bur and 499-Col harbor the Bur and Col alleles, respectively, at the QTL PbAt5.2. 508-Bur and 508-Col harbor the Bur and Col alleles, respectively, at the QTL PbAt1. (A,B) Clubroot symptoms evaluated using the GA/LA disease index from image analysis as described in the Materials and Methods Section. Error bars represent standard error (Four independent biological replicates, 18 plants per biological replicate). (C,D) Pathogen DNA quantification (Pb) by qPCR after normalization with the Fbox gene from Arabidopsis, at 10, 14, and 17 dpi (Three independent replicates, 12–54 plants per biological replicate). Asterisks indicate statistically significant differences according to the Wald tests applied on a linear mixed model (P < 0.05).
Mentions: We first validated the effect of QTL PbAt5.2 and PbAt1 on clubroot and pathogen development at 17 and 21 dpi in these two HIF lines (Figure 7). In the HIF lines 499, the Col-to-Bur allelic substitution (in the genomic regions of PbAt5.2) significantly reduced the severity of gall symptoms (Figure 7A) and conferred a one third reduction of pathogen growth at 17 dpi (Figure 7C). In contrast, the allelic substitution at PbAt1, between 508 HIF lines, significantly reduced clubroot symptoms (Figure 7B) but did not have an impact on pathogen growth (Figure 7D), suggesting that different genetic factors may control gall development and pathogen growth.

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